Queue and execute work from scheduler threads on other threads to prevent schedulers from sleeping.

c_src/async_nif.h

@@ -0,0 +1,282 @@
+/*
+ *
+ * async_nif: An async thread-pool layer for Erlang's NIF API
+ *
+ * Copyright (c) 2012 Basho Technologies, Inc. All Rights Reserved.
+ * Author: Gregory Burd <greg@basho.com> <greg@burd.me>
+ *
+ * This file is provided to you under the Apache License,
+ * Version 2.0 (the "License"); you may not use this file
+ * except in compliance with the License.  You may obtain
+ * a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *
+ */
+
+#ifndef __ASYNC_NIF_H__
+#define __ASYNC_NIF_H__
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+/* Redefine this in your NIF implementation before including this file to
+   change the thread pool size.  The maximum number of threads might be
+   bounded on your OS.  For instance, to allow 1,000,000 threads on a Linux
+   system you must do the following before launching the process.
+     echo 1000000 > /proc/sys/kernel/threads-max
+   and for all UNIX systems there will be ulimit maximums. */
+#ifndef ASYNC_NIF_MAX_WORKERS
+#define ASYNC_NIF_MAX_WORKERS 16
+#endif
+
+#include "queue.h"
+
+struct async_nif_req_entry {
+  ERL_NIF_TERM ref, *argv;
+  ErlNifEnv *env;
+  ErlNifPid pid;
+  void *args;
+  void *priv_data;
+  void (*fn_work)(ErlNifEnv*, ERL_NIF_TERM, void *, ErlNifPid*, void *);
+  void (*fn_post)(void *);
+  STAILQ_ENTRY(async_nif_req_entry) entries;
+};
+STAILQ_HEAD(reqs, async_nif_req_entry) async_nif_reqs = STAILQ_HEAD_INITIALIZER(async_nif_reqs);
+
+struct async_nif_worker_entry {
+  ErlNifTid tid;
+  LIST_ENTRY(async_nif_worker_entry) entries;
+};
+LIST_HEAD(idle_workers, async_nif_worker_entry) async_nif_idle_workers = LIST_HEAD_INITIALIZER(async_nif_worker);
+
+static volatile unsigned int async_nif_req_count = 0;
+static volatile unsigned int async_nif_shutdown = 0;
+static ErlNifMutex *async_nif_req_mutex = NULL;
+static ErlNifMutex *async_nif_worker_mutex = NULL;
+static ErlNifCond *async_nif_cnd = NULL;
+static struct async_nif_worker_entry async_nif_worker_entries[ASYNC_NIF_MAX_WORKERS];
+
+
+#define ASYNC_NIF_DECL(decl, frame, pre_block, work_block, post_block)  \
+  struct decl ## _args frame;                                           \
+  static void fn_work_ ## decl (ErlNifEnv *env, ERL_NIF_TERM ref, void *priv_data, ErlNifPid *pid, struct decl ## _args *args) work_block \
+  static void fn_post_ ## decl (struct decl ## _args *args) {           \
+    do post_block while(0);                                             \
+  }                                                                     \
+  static ERL_NIF_TERM decl(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv_in[]) { \
+    struct decl ## _args on_stack_args;                                 \
+    struct decl ## _args *args = &on_stack_args;                        \
+    struct decl ## _args *copy_of_args;                                 \
+    struct async_nif_req_entry *req = NULL;                             \
+    ErlNifEnv *new_env = NULL;                                          \
+    /* argv[0] is a ref used for selective recv */                      \
+    const ERL_NIF_TERM *argv = argv_in + 1;                             \
+    argc--;                                                             \
+    if (async_nif_shutdown)                                             \
+      return enif_make_tuple2(env, enif_make_atom(env, "error"),        \
+                              enif_make_atom(env, "shutdown"));         \
+    if (!(new_env = enif_alloc_env())) {                                \
+      return enif_make_tuple2(env, enif_make_atom(env, "error"),        \
+                              enif_make_atom(env, "enomem"));           \
+    }                                                                   \
+    do pre_block while(0);                                              \
+    req = (struct async_nif_req_entry*)enif_alloc(sizeof(struct async_nif_req_entry)); \
+    if (!req) {                                                         \
+      fn_post_ ## decl (args);                                          \
+      enif_free_env(new_env);                                           \
+      return enif_make_tuple2(env, enif_make_atom(env, "error"),        \
+                              enif_make_atom(env, "enomem"));           \
+    }                                                                   \
+    copy_of_args = (struct decl ## _args *)enif_alloc(sizeof(struct decl ## _args)); \
+    if (!copy_of_args) {                                                \
+      fn_post_ ## decl (args);                                          \
+      enif_free_env(new_env);                                           \
+      return enif_make_tuple2(env, enif_make_atom(env, "error"),        \
+                              enif_make_atom(env, "enomem"));           \
+    }                                                                   \
+    memcpy(copy_of_args, args, sizeof(struct decl ## _args));           \
+    req->env = new_env;                                                 \
+    req->ref = enif_make_copy(new_env, argv_in[0]);                     \
+    enif_self(env, &req->pid);                                          \
+    req->args = (void*)copy_of_args;                                    \
+    req->priv_data = enif_priv_data(env);                               \
+    req->fn_work = (void (*)(ErlNifEnv *, ERL_NIF_TERM, void*, ErlNifPid*, void *))fn_work_ ## decl ; \
+    req->fn_post = (void (*)(void *))fn_post_ ## decl;                  \
+    async_nif_enqueue_req(req);                                         \
+    return enif_make_tuple2(env, enif_make_atom(env, "ok"),             \
+                            enif_make_tuple2(env, enif_make_atom(env, "enqueued"), \
+                                             enif_make_int(env, async_nif_req_count))); \
+  }
+
+#define ASYNC_NIF_LOAD() if (async_nif_init() != 0) return -1;
+#define ASYNC_NIF_UNLOAD() async_nif_unload();
+#define ASYNC_NIF_UPGRADE() async_nif_unload();
+
+#define ASYNC_NIF_RETURN_BADARG() return enif_make_badarg(env);
+#define ASYNC_NIF_WORK_ENV new_env
+
+#ifndef PULSE_FORCE_USING_PULSE_SEND_HERE
+#define ASYNC_NIF_REPLY(msg) enif_send(NULL, pid, env, enif_make_tuple2(env, ref, msg))
+#else
+#define ASYNC_NIF_REPLY(msg) PULSE_SEND(NULL, pid, env, enif_make_tuple2(env, ref, msg))
+#endif
+
+static void async_nif_enqueue_req(struct async_nif_req_entry *r)
+{
+  /* Add the request to the work queue. */
+  enif_mutex_lock(async_nif_req_mutex);
+  STAILQ_INSERT_TAIL(&async_nif_reqs, r, entries);
+  async_nif_req_count++;
+  enif_mutex_unlock(async_nif_req_mutex);
+  enif_cond_broadcast(async_nif_cnd);
+}
+
+static void *async_nif_worker_fn(void *arg)
+{
+  struct async_nif_worker_entry *worker = (struct async_nif_worker_entry *)arg;
+  struct async_nif_req_entry *req = NULL;
+
+  /*
+   * Workers are active while there is work on the queue to do and
+   * only in the idle list when they are waiting on new work.
+   */
+  for(;;) {
+    /* Examine the request queue, are there things to be done? */
+    enif_mutex_lock(async_nif_req_mutex);
+    enif_mutex_lock(async_nif_worker_mutex);
+    LIST_INSERT_HEAD(&async_nif_idle_workers, worker, entries);
+    enif_mutex_unlock(async_nif_worker_mutex);
+    check_again_for_work:
+    if (async_nif_shutdown) { enif_mutex_unlock(async_nif_req_mutex); break; }
+    if ((req = STAILQ_FIRST(&async_nif_reqs)) == NULL) {
+      /* Queue is empty, join the list of idle workers and wait for work */
+      enif_cond_wait(async_nif_cnd, async_nif_req_mutex);
+      goto check_again_for_work;
+    } else {
+      /* `req` is our work request and we hold the lock. */
+      enif_cond_broadcast(async_nif_cnd);
+
+      /* Take the request off the queue. */
+      STAILQ_REMOVE(&async_nif_reqs, req, async_nif_req_entry, entries); async_nif_req_count--;
+
+      /* Now we need to remove this thread from the list of idle threads. */
+      enif_mutex_lock(async_nif_worker_mutex);
+      LIST_REMOVE(worker, entries);
+
+      /* Release the locks in reverse order that we acquired them,
+         so as not to self-deadlock. */
+      enif_mutex_unlock(async_nif_worker_mutex);
+      enif_mutex_unlock(async_nif_req_mutex);
+
+      /* Finally, let's do the work! :) */
+      req->fn_work(req->env, req->ref, req->priv_data, &req->pid, req->args);
+      req->fn_post(req->args);
+      enif_free(req->args);
+      enif_free_env(req->env);
+      enif_free(req);
+    }
+  }
+  enif_thread_exit(0);
+  return 0;
+}
+
+static void async_nif_unload(void)
+{
+  unsigned int i;
+
+  /* Signal the worker threads, stop what you're doing and exit. */
+  enif_mutex_lock(async_nif_req_mutex);
+  async_nif_shutdown = 1;
+  enif_cond_broadcast(async_nif_cnd);
+  enif_mutex_unlock(async_nif_req_mutex);
+
+  /* Join for the now exiting worker threads. */
+  for (i = 0; i < ASYNC_NIF_MAX_WORKERS; ++i) {
+    void *exit_value = 0; /* Ignore this. */
+    enif_thread_join(async_nif_worker_entries[i].tid, &exit_value);
+  }
+
+  /* We won't get here until all threads have exited.
+     Patch things up, and carry on. */
+  enif_mutex_lock(async_nif_req_mutex);
+
+  /* Worker threads are stopped, now toss anything left in the queue. */
+  struct async_nif_req_entry *req = NULL;
+  STAILQ_FOREACH(req, &async_nif_reqs, entries) {
+    STAILQ_REMOVE(&async_nif_reqs, STAILQ_LAST(&async_nif_reqs, async_nif_req_entry, entries),
+                  async_nif_req_entry, entries);
+#ifdef PULSE
+    PULSE_SEND(NULL, &req->pid, req->env,
+              enif_make_tuple2(req->env, enif_make_atom(req->env, "error"),
+                               enif_make_atom(req->env, "shutdown")));
+#else
+    enif_send(NULL, &req->pid, req->env,
+              enif_make_tuple2(req->env, enif_make_atom(req->env, "error"),
+                               enif_make_atom(req->env, "shutdown")));
+#endif
+    req->fn_post(req->args);
+    enif_free(req->args);
+    enif_free(req);
+    async_nif_req_count--;
+  }
+  enif_mutex_unlock(async_nif_req_mutex);
+
+  memset(async_nif_worker_entries, sizeof(struct async_nif_worker_entry) * ASYNC_NIF_MAX_WORKERS, 0);
+  enif_cond_destroy(async_nif_cnd); async_nif_cnd = NULL;
+  enif_mutex_destroy(async_nif_req_mutex); async_nif_req_mutex = NULL;
+  enif_mutex_destroy(async_nif_worker_mutex); async_nif_worker_mutex = NULL;
+}
+
+static int async_nif_init(void)
+{
+  int i;
+
+  /* Don't init more than once. */
+  if (async_nif_req_mutex) return 0;
+
+  async_nif_req_mutex = enif_mutex_create(NULL);
+  async_nif_worker_mutex = enif_mutex_create(NULL);
+  async_nif_cnd = enif_cond_create(NULL);
+
+  /* Setup the requests management. */
+  async_nif_req_count = 0;
+
+  /* Setup the thread pool management. */
+  enif_mutex_lock(async_nif_worker_mutex);
+  memset(async_nif_worker_entries, sizeof(struct async_nif_worker_entry) * ASYNC_NIF_MAX_WORKERS, 0);
+
+  for (i = 0; i < ASYNC_NIF_MAX_WORKERS; i++) {
+    if (enif_thread_create(NULL, &async_nif_worker_entries[i].tid,
+                            &async_nif_worker_fn, (void*)&async_nif_worker_entries[i], NULL) != 0) {
+      async_nif_shutdown = 1;
+      enif_cond_broadcast(async_nif_cnd);
+      enif_mutex_unlock(async_nif_worker_mutex);
+      while(i-- > 0) {
+        void *exit_value = 0; /* Ignore this. */
+        enif_thread_join(async_nif_worker_entries[i].tid, &exit_value);
+      }
+      memset(async_nif_worker_entries, sizeof(struct async_nif_worker_entry) * ASYNC_NIF_MAX_WORKERS, 0);
+      enif_cond_destroy(async_nif_cnd); async_nif_cnd = NULL;
+      enif_mutex_destroy(async_nif_req_mutex); async_nif_req_mutex = NULL;
+      enif_mutex_destroy(async_nif_worker_mutex); async_nif_worker_mutex = NULL;
+      return -1;
+    }
+  }
+  enif_mutex_unlock(async_nif_worker_mutex);
+  return 0;
+}
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif // __ASYNC_NIF_H__

c_src/queue.h

@@ -0,0 +1,648 @@
+/*-
+ * Copyright (c) 1991, 1993
+ *      The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *      @(#)queue.h     8.5 (Berkeley) 8/20/94
+ * $FreeBSD: src/sys/sys/queue.h,v 1.75.2.3 2012/11/17 11:37:26 svnexp Exp $
+ */
+
+#ifndef _SYS_QUEUE_H_
+#define _SYS_QUEUE_H_
+
+#ifndef __offsetof
+#define __offsetof(st, m) \
+          ((size_t) ( (char *)&((st *)0)->m - (char *)0 ))
+#endif
+
+#ifndef __containerof
+#define __containerof(ptr, type, member) ({ \
+          const typeof( ((type *)0)->member ) *__mptr = (ptr);              \
+                (type *)( (char *)__mptr - __offsetof(type,member) );})
+#endif
+
+/*
+ * This file defines four types of data structures: singly-linked lists,
+ * singly-linked tail queues, lists and tail queues.
+ *
+ * A singly-linked list is headed by a single forward pointer. The elements
+ * are singly linked for minimum space and pointer manipulation overhead at
+ * the expense of O(n) removal for arbitrary elements. New elements can be
+ * added to the list after an existing element or at the head of the list.
+ * Elements being removed from the head of the list should use the explicit
+ * macro for this purpose for optimum efficiency. A singly-linked list may
+ * only be traversed in the forward direction.  Singly-linked lists are ideal
+ * for applications with large datasets and few or no removals or for
+ * implementing a LIFO queue.
+ *
+ * A singly-linked tail queue is headed by a pair of pointers, one to the
+ * head of the list and the other to the tail of the list. The elements are
+ * singly linked for minimum space and pointer manipulation overhead at the
+ * expense of O(n) removal for arbitrary elements. New elements can be added
+ * to the list after an existing element, at the head of the list, or at the
+ * end of the list. Elements being removed from the head of the tail queue
+ * should use the explicit macro for this purpose for optimum efficiency.
+ * A singly-linked tail queue may only be traversed in the forward direction.
+ * Singly-linked tail queues are ideal for applications with large datasets
+ * and few or no removals or for implementing a FIFO queue.
+ *
+ * A list is headed by a single forward pointer (or an array of forward
+ * pointers for a hash table header). The elements are doubly linked
+ * so that an arbitrary element can be removed without a need to
+ * traverse the list. New elements can be added to the list before
+ * or after an existing element or at the head of the list. A list
+ * may be traversed in either direction.
+ *
+ * A tail queue is headed by a pair of pointers, one to the head of the
+ * list and the other to the tail of the list. The elements are doubly
+ * linked so that an arbitrary element can be removed without a need to
+ * traverse the list. New elements can be added to the list before or
+ * after an existing element, at the head of the list, or at the end of
+ * the list. A tail queue may be traversed in either direction.
+ *
+ * For details on the use of these macros, see the queue(3) manual page.
+ *
+ *
+ *                              SLIST   LIST    STAILQ  TAILQ
+ * _HEAD                        +       +       +       +
+ * _HEAD_INITIALIZER            +       +       +       +
+ * _ENTRY                       +       +       +       +
+ * _INIT                        +       +       +       +
+ * _EMPTY                       +       +       +       +
+ * _FIRST                       +       +       +       +
+ * _NEXT                        +       +       +       +
+ * _PREV                        -       +       -       +
+ * _LAST                        -       -       +       +
+ * _FOREACH                     +       +       +       +
+ * _FOREACH_SAFE                +       +       +       +
+ * _FOREACH_REVERSE             -       -       -       +
+ * _FOREACH_REVERSE_SAFE        -       -       -       +
+ * _INSERT_HEAD                 +       +       +       +
+ * _INSERT_BEFORE               -       +       -       +
+ * _INSERT_AFTER                +       +       +       +
+ * _INSERT_TAIL                 -       -       +       +
+ * _CONCAT                      -       -       +       +
+ * _REMOVE_AFTER                +       -       +       -
+ * _REMOVE_HEAD                 +       -       +       -
+ * _REMOVE                      +       +       +       +
+ * _SWAP                        +       +       +       +
+ *
+ */
+#ifdef QUEUE_MACRO_DEBUG
+/* Store the last 2 places the queue element or head was altered */
+struct qm_trace {
+        char * lastfile;
+        int lastline;
+        char * prevfile;
+        int prevline;
+};
+
+#define TRACEBUF        struct qm_trace trace;
+#define TRASHIT(x)      do {(x) = (void *)-1;} while (0)
+#define QMD_SAVELINK(name, link)        void **name = (void *)&(link)
+
+#define QMD_TRACE_HEAD(head) do {                                       \
+        (head)->trace.prevline = (head)->trace.lastline;                \
+        (head)->trace.prevfile = (head)->trace.lastfile;                \
+        (head)->trace.lastline = __LINE__;                              \
+        (head)->trace.lastfile = __FILE__;                              \
+} while (0)
+
+#define QMD_TRACE_ELEM(elem) do {                                       \
+        (elem)->trace.prevline = (elem)->trace.lastline;                \
+        (elem)->trace.prevfile = (elem)->trace.lastfile;                \
+        (elem)->trace.lastline = __LINE__;                              \
+        (elem)->trace.lastfile = __FILE__;                              \
+} while (0)
+
+#else
+#define QMD_TRACE_ELEM(elem)
+#define QMD_TRACE_HEAD(head)
+#define QMD_SAVELINK(name, link)
+#define TRACEBUF
+#define TRASHIT(x)
+#endif  /* QUEUE_MACRO_DEBUG */
+
+/*
+ * Singly-linked List declarations.
+ */
+#define SLIST_HEAD(name, type)                                          \
+struct name {                                                           \
+        struct type *slh_first; /* first element */                     \
+}
+
+#define SLIST_HEAD_INITIALIZER(head)                                    \
+        { NULL }
+
+#define SLIST_ENTRY(type)                                               \
+struct {                                                                \
+        struct type *sle_next;  /* next element */                      \
+}
+
+/*
+ * Singly-linked List functions.
+ */
+#define SLIST_EMPTY(head)       ((head)->slh_first == NULL)
+
+#define SLIST_FIRST(head)       ((head)->slh_first)
+
+#define SLIST_FOREACH(var, head, field)                                 \
+        for ((var) = SLIST_FIRST((head));                               \
+            (var);                                                      \
+            (var) = SLIST_NEXT((var), field))
+
+#define SLIST_FOREACH_SAFE(var, head, field, tvar)                      \
+        for ((var) = SLIST_FIRST((head));                               \
+            (var) && ((tvar) = SLIST_NEXT((var), field), 1);            \
+            (var) = (tvar))
+
+#define SLIST_FOREACH_PREVPTR(var, varp, head, field)                   \
+        for ((varp) = &SLIST_FIRST((head));                             \
+            ((var) = *(varp)) != NULL;                                  \
+            (varp) = &SLIST_NEXT((var), field))
+
+#define SLIST_INIT(head) do {                                           \
+        SLIST_FIRST((head)) = NULL;                                     \
+} while (0)
+
+#define SLIST_INSERT_AFTER(slistelm, elm, field) do {                   \
+        SLIST_NEXT((elm), field) = SLIST_NEXT((slistelm), field);       \
+        SLIST_NEXT((slistelm), field) = (elm);                          \
+} while (0)
+
+#define SLIST_INSERT_HEAD(head, elm, field) do {                        \
+        SLIST_NEXT((elm), field) = SLIST_FIRST((head));                 \
+        SLIST_FIRST((head)) = (elm);                                    \
+} while (0)
+
+#define SLIST_NEXT(elm, field)  ((elm)->field.sle_next)
+
+#define SLIST_REMOVE(head, elm, type, field) do {                       \
+        QMD_SAVELINK(oldnext, (elm)->field.sle_next);                   \
+        if (SLIST_FIRST((head)) == (elm)) {                             \
+                SLIST_REMOVE_HEAD((head), field);                       \
+        }                                                               \
+        else {                                                          \
+                struct type *curelm = SLIST_FIRST((head));              \
+                while (SLIST_NEXT(curelm, field) != (elm))              \
+                        curelm = SLIST_NEXT(curelm, field);             \
+                SLIST_REMOVE_AFTER(curelm, field);                      \
+        }                                                               \
+        TRASHIT(*oldnext);                                              \
+} while (0)
+
+#define SLIST_REMOVE_AFTER(elm, field) do {                             \
+        SLIST_NEXT(elm, field) =                                        \
+            SLIST_NEXT(SLIST_NEXT(elm, field), field);                  \
+} while (0)
+
+#define SLIST_REMOVE_HEAD(head, field) do {                             \
+        SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field);   \
+} while (0)
+
+#define SLIST_SWAP(head1, head2, type) do {                             \
+        struct type *swap_first = SLIST_FIRST(head1);                   \
+        SLIST_FIRST(head1) = SLIST_FIRST(head2);                        \
+        SLIST_FIRST(head2) = swap_first;                                \
+} while (0)
+
+/*
+ * Singly-linked Tail queue declarations.
+ */
+#define STAILQ_HEAD(name, type)                                         \
+struct name {                                                           \
+        struct type *stqh_first;/* first element */                     \
+        struct type **stqh_last;/* addr of last next element */         \
+}
+
+#define STAILQ_HEAD_INITIALIZER(head)                                   \
+        { NULL, &(head).stqh_first }
+
+#define STAILQ_ENTRY(type)                                              \
+struct {                                                                \
+        struct type *stqe_next; /* next element */                      \
+}
+
+/*
+ * Singly-linked Tail queue functions.
+ */
+#define STAILQ_CONCAT(head1, head2) do {                                \
+        if (!STAILQ_EMPTY((head2))) {                                   \
+                *(head1)->stqh_last = (head2)->stqh_first;              \
+                (head1)->stqh_last = (head2)->stqh_last;                \
+                STAILQ_INIT((head2));                                   \
+        }                                                               \
+} while (0)
+
+#define STAILQ_EMPTY(head)      ((head)->stqh_first == NULL)
+
+#define STAILQ_FIRST(head)      ((head)->stqh_first)
+
+#define STAILQ_FOREACH(var, head, field)                                \
+        for((var) = STAILQ_FIRST((head));                               \
+           (var);                                                       \
+           (var) = STAILQ_NEXT((var), field))
+
+
+#define STAILQ_FOREACH_SAFE(var, head, field, tvar)                     \
+        for ((var) = STAILQ_FIRST((head));                              \
+            (var) && ((tvar) = STAILQ_NEXT((var), field), 1);           \
+            (var) = (tvar))
+
+#define STAILQ_INIT(head) do {                                          \
+        STAILQ_FIRST((head)) = NULL;                                    \
+        (head)->stqh_last = &STAILQ_FIRST((head));                      \
+} while (0)
+
+#define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {               \
+        if ((STAILQ_NEXT((elm), field) = STAILQ_NEXT((tqelm), field)) == NULL)\
+                (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
+        STAILQ_NEXT((tqelm), field) = (elm);                            \
+} while (0)
+
+#define STAILQ_INSERT_HEAD(head, elm, field) do {                       \
+        if ((STAILQ_NEXT((elm), field) = STAILQ_FIRST((head))) == NULL) \
+                (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
+        STAILQ_FIRST((head)) = (elm);                                   \
+} while (0)
+
+#define STAILQ_INSERT_TAIL(head, elm, field) do {                       \
+        STAILQ_NEXT((elm), field) = NULL;                               \
+        *(head)->stqh_last = (elm);                                     \
+        (head)->stqh_last = &STAILQ_NEXT((elm), field);                 \
+} while (0)
+
+#define STAILQ_LAST(head, type, field)                                  \
+        (STAILQ_EMPTY((head)) ? NULL :                                  \
+            __containerof((head)->stqh_last, struct type, field.stqe_next))
+
+#define STAILQ_NEXT(elm, field) ((elm)->field.stqe_next)
+
+#define STAILQ_REMOVE(head, elm, type, field) do {                      \
+        QMD_SAVELINK(oldnext, (elm)->field.stqe_next);                  \
+        if (STAILQ_FIRST((head)) == (elm)) {                            \
+                STAILQ_REMOVE_HEAD((head), field);                      \
+        }                                                               \
+        else {                                                          \
+                struct type *curelm = STAILQ_FIRST((head));             \
+                while (STAILQ_NEXT(curelm, field) != (elm))             \
+                        curelm = STAILQ_NEXT(curelm, field);            \
+                STAILQ_REMOVE_AFTER(head, curelm, field);               \
+        }                                                               \
+        TRASHIT(*oldnext);                                              \
+} while (0)
+
+#define STAILQ_REMOVE_AFTER(head, elm, field) do {                      \
+        if ((STAILQ_NEXT(elm, field) =                                  \
+             STAILQ_NEXT(STAILQ_NEXT(elm, field), field)) == NULL)      \
+                (head)->stqh_last = &STAILQ_NEXT((elm), field);         \
+} while (0)
+
+#define STAILQ_REMOVE_HEAD(head, field) do {                            \
+        if ((STAILQ_FIRST((head)) =                                     \
+             STAILQ_NEXT(STAILQ_FIRST((head)), field)) == NULL)         \
+                (head)->stqh_last = &STAILQ_FIRST((head));              \
+} while (0)
+
+#define STAILQ_SWAP(head1, head2, type) do {                            \
+        struct type *swap_first = STAILQ_FIRST(head1);                  \
+        struct type **swap_last = (head1)->stqh_last;                   \
+        STAILQ_FIRST(head1) = STAILQ_FIRST(head2);                      \
+        (head1)->stqh_last = (head2)->stqh_last;                        \
+        STAILQ_FIRST(head2) = swap_first;                               \
+        (head2)->stqh_last = swap_last;                                 \
+        if (STAILQ_EMPTY(head1))                                        \
+                (head1)->stqh_last = &STAILQ_FIRST(head1);              \
+        if (STAILQ_EMPTY(head2))                                        \
+                (head2)->stqh_last = &STAILQ_FIRST(head2);              \
+} while (0)
+
+
+/*
+ * List declarations.
+ */
+#define LIST_HEAD(name, type)                                           \
+struct name {                                                           \
+        struct type *lh_first;  /* first element */                     \
+}
+
+#define LIST_HEAD_INITIALIZER(head)                                     \
+        { NULL }
+
+#define LIST_ENTRY(type)                                                \
+struct {                                                                \
+        struct type *le_next;   /* next element */                      \
+        struct type **le_prev;  /* address of previous next element */  \
+}
+
+/*
+ * List functions.
+ */
+
+#if (defined(_KERNEL) && defined(INVARIANTS))
+#define QMD_LIST_CHECK_HEAD(head, field) do {                           \
+        if (LIST_FIRST((head)) != NULL &&                               \
+            LIST_FIRST((head))->field.le_prev !=                        \
+             &LIST_FIRST((head)))                                       \
+                panic("Bad list head %p first->prev != head", (head));  \
+} while (0)
+
+#define QMD_LIST_CHECK_NEXT(elm, field) do {                            \
+        if (LIST_NEXT((elm), field) != NULL &&                          \
+            LIST_NEXT((elm), field)->field.le_prev !=                   \
+             &((elm)->field.le_next))                                   \
+                panic("Bad link elm %p next->prev != elm", (elm));      \
+} while (0)
+
+#define QMD_LIST_CHECK_PREV(elm, field) do {                            \
+        if (*(elm)->field.le_prev != (elm))                             \
+                panic("Bad link elm %p prev->next != elm", (elm));      \
+} while (0)
+#else
+#define QMD_LIST_CHECK_HEAD(head, field)
+#define QMD_LIST_CHECK_NEXT(elm, field)
+#define QMD_LIST_CHECK_PREV(elm, field)
+#endif /* (_KERNEL && INVARIANTS) */
+
+#define LIST_EMPTY(head)        ((head)->lh_first == NULL)
+
+#define LIST_FIRST(head)        ((head)->lh_first)
+
+#define LIST_FOREACH(var, head, field)                                  \
+        for ((var) = LIST_FIRST((head));                                \
+            (var);                                                      \
+            (var) = LIST_NEXT((var), field))
+
+#define LIST_FOREACH_SAFE(var, head, field, tvar)                       \
+        for ((var) = LIST_FIRST((head));                                \
+            (var) && ((tvar) = LIST_NEXT((var), field), 1);             \
+            (var) = (tvar))
+
+#define LIST_INIT(head) do {                                            \
+        LIST_FIRST((head)) = NULL;                                      \
+} while (0)
+
+#define LIST_INSERT_AFTER(listelm, elm, field) do {                     \
+        QMD_LIST_CHECK_NEXT(listelm, field);                            \
+        if ((LIST_NEXT((elm), field) = LIST_NEXT((listelm), field)) != NULL)\
+                LIST_NEXT((listelm), field)->field.le_prev =            \
+                    &LIST_NEXT((elm), field);                           \
+        LIST_NEXT((listelm), field) = (elm);                            \
+        (elm)->field.le_prev = &LIST_NEXT((listelm), field);            \
+} while (0)
+
+#define LIST_INSERT_BEFORE(listelm, elm, field) do {                    \
+        QMD_LIST_CHECK_PREV(listelm, field);                            \
+        (elm)->field.le_prev = (listelm)->field.le_prev;                \
+        LIST_NEXT((elm), field) = (listelm);                            \
+        *(listelm)->field.le_prev = (elm);                              \
+        (listelm)->field.le_prev = &LIST_NEXT((elm), field);            \
+} while (0)
+
+#define LIST_INSERT_HEAD(head, elm, field) do {                         \
+        QMD_LIST_CHECK_HEAD((head), field);                             \
+        if ((LIST_NEXT((elm), field) = LIST_FIRST((head))) != NULL)     \
+                LIST_FIRST((head))->field.le_prev = &LIST_NEXT((elm), field);\
+        LIST_FIRST((head)) = (elm);                                     \
+        (elm)->field.le_prev = &LIST_FIRST((head));                     \
+} while (0)
+
+#define LIST_NEXT(elm, field)   ((elm)->field.le_next)
+
+#define LIST_PREV(elm, head, type, field)                               \
+        ((elm)->field.le_prev == &LIST_FIRST((head)) ? NULL :           \
+            __containerof((elm)->field.le_prev, struct type, field.le_next))
+
+#define LIST_REMOVE(elm, field) do {                                    \
+        QMD_SAVELINK(oldnext, (elm)->field.le_next);                    \
+        QMD_SAVELINK(oldprev, (elm)->field.le_prev);                    \
+        QMD_LIST_CHECK_NEXT(elm, field);                                \
+        QMD_LIST_CHECK_PREV(elm, field);                                \
+        if (LIST_NEXT((elm), field) != NULL)                            \
+                LIST_NEXT((elm), field)->field.le_prev =                \
+                    (elm)->field.le_prev;                               \
+        *(elm)->field.le_prev = LIST_NEXT((elm), field);                \
+        TRASHIT(*oldnext);                                              \
+        TRASHIT(*oldprev);                                              \
+} while (0)
+
+#define LIST_SWAP(head1, head2, type, field) do {                       \
+        struct type *swap_tmp = LIST_FIRST((head1));                    \
+        LIST_FIRST((head1)) = LIST_FIRST((head2));                      \
+        LIST_FIRST((head2)) = swap_tmp;                                 \
+        if ((swap_tmp = LIST_FIRST((head1))) != NULL)                   \
+                swap_tmp->field.le_prev = &LIST_FIRST((head1));         \
+        if ((swap_tmp = LIST_FIRST((head2))) != NULL)                   \
+                swap_tmp->field.le_prev = &LIST_FIRST((head2));         \
+} while (0)
+
+/*
+ * Tail queue declarations.
+ */
+#define TAILQ_HEAD(name, type)                                          \
+struct name {                                                           \
+        struct type *tqh_first; /* first element */                     \
+        struct type **tqh_last; /* addr of last next element */         \
+        TRACEBUF                                                        \
+}
+
+#define TAILQ_HEAD_INITIALIZER(head)                                    \
+        { NULL, &(head).tqh_first }
+
+#define TAILQ_ENTRY(type)                                               \
+struct {                                                                \
+        struct type *tqe_next;  /* next element */                      \
+        struct type **tqe_prev; /* address of previous next element */  \
+        TRACEBUF                                                        \
+}
+
+/*
+ * Tail queue functions.
+ */
+#if (defined(_KERNEL) && defined(INVARIANTS))
+#define QMD_TAILQ_CHECK_HEAD(head, field) do {                          \
+        if (!TAILQ_EMPTY(head) &&                                       \
+            TAILQ_FIRST((head))->field.tqe_prev !=                      \
+             &TAILQ_FIRST((head)))                                      \
+                panic("Bad tailq head %p first->prev != head", (head)); \
+} while (0)
+
+#define QMD_TAILQ_CHECK_TAIL(head, field) do {                          \
+        if (*(head)->tqh_last != NULL)                                  \
+                panic("Bad tailq NEXT(%p->tqh_last) != NULL", (head));  \
+} while (0)
+
+#define QMD_TAILQ_CHECK_NEXT(elm, field) do {                           \
+        if (TAILQ_NEXT((elm), field) != NULL &&                         \
+            TAILQ_NEXT((elm), field)->field.tqe_prev !=                 \
+             &((elm)->field.tqe_next))                                  \
+                panic("Bad link elm %p next->prev != elm", (elm));      \
+} while (0)
+
+#define QMD_TAILQ_CHECK_PREV(elm, field) do {                           \
+        if (*(elm)->field.tqe_prev != (elm))                            \
+                panic("Bad link elm %p prev->next != elm", (elm));      \
+} while (0)
+#else
+#define QMD_TAILQ_CHECK_HEAD(head, field)
+#define QMD_TAILQ_CHECK_TAIL(head, headname)
+#define QMD_TAILQ_CHECK_NEXT(elm, field)
+#define QMD_TAILQ_CHECK_PREV(elm, field)
+#endif /* (_KERNEL && INVARIANTS) */
+
+#define TAILQ_CONCAT(head1, head2, field) do {                          \
+        if (!TAILQ_EMPTY(head2)) {                                      \
+                *(head1)->tqh_last = (head2)->tqh_first;                \
+                (head2)->tqh_first->field.tqe_prev = (head1)->tqh_last; \
+                (head1)->tqh_last = (head2)->tqh_last;                  \
+                TAILQ_INIT((head2));                                    \
+                QMD_TRACE_HEAD(head1);                                  \
+                QMD_TRACE_HEAD(head2);                                  \
+        }                                                               \
+} while (0)
+
+#define TAILQ_EMPTY(head)       ((head)->tqh_first == NULL)
+
+#define TAILQ_FIRST(head)       ((head)->tqh_first)
+
+#define TAILQ_FOREACH(var, head, field)                                 \
+        for ((var) = TAILQ_FIRST((head));                               \
+            (var);                                                      \
+            (var) = TAILQ_NEXT((var), field))
+
+#define TAILQ_FOREACH_SAFE(var, head, field, tvar)                      \
+        for ((var) = TAILQ_FIRST((head));                               \
+            (var) && ((tvar) = TAILQ_NEXT((var), field), 1);            \
+            (var) = (tvar))
+
+#define TAILQ_FOREACH_REVERSE(var, head, headname, field)               \
+        for ((var) = TAILQ_LAST((head), headname);                      \
+            (var);                                                      \
+            (var) = TAILQ_PREV((var), headname, field))
+
+#define TAILQ_FOREACH_REVERSE_SAFE(var, head, headname, field, tvar)    \
+        for ((var) = TAILQ_LAST((head), headname);                      \
+            (var) && ((tvar) = TAILQ_PREV((var), headname, field), 1);  \
+            (var) = (tvar))
+
+#define TAILQ_INIT(head) do {                                           \
+        TAILQ_FIRST((head)) = NULL;                                     \
+        (head)->tqh_last = &TAILQ_FIRST((head));                        \
+        QMD_TRACE_HEAD(head);                                           \
+} while (0)
+
+#define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {              \
+        QMD_TAILQ_CHECK_NEXT(listelm, field);                           \
+        if ((TAILQ_NEXT((elm), field) = TAILQ_NEXT((listelm), field)) != NULL)\
+                TAILQ_NEXT((elm), field)->field.tqe_prev =              \
+                    &TAILQ_NEXT((elm), field);                          \
+        else {                                                          \
+                (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
+                QMD_TRACE_HEAD(head);                                   \
+        }                                                               \
+        TAILQ_NEXT((listelm), field) = (elm);                           \
+        (elm)->field.tqe_prev = &TAILQ_NEXT((listelm), field);          \
+        QMD_TRACE_ELEM(&(elm)->field);                                  \
+        QMD_TRACE_ELEM(&listelm->field);                                \
+} while (0)
+
+#define TAILQ_INSERT_BEFORE(listelm, elm, field) do {                   \
+        QMD_TAILQ_CHECK_PREV(listelm, field);                           \
+        (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
+        TAILQ_NEXT((elm), field) = (listelm);                           \
+        *(listelm)->field.tqe_prev = (elm);                             \
+        (listelm)->field.tqe_prev = &TAILQ_NEXT((elm), field);          \
+        QMD_TRACE_ELEM(&(elm)->field);                                  \
+        QMD_TRACE_ELEM(&listelm->field);                                \
+} while (0)
+
+#define TAILQ_INSERT_HEAD(head, elm, field) do {                        \
+        QMD_TAILQ_CHECK_HEAD(head, field);                              \
+        if ((TAILQ_NEXT((elm), field) = TAILQ_FIRST((head))) != NULL)   \
+                TAILQ_FIRST((head))->field.tqe_prev =                   \
+                    &TAILQ_NEXT((elm), field);                          \
+        else                                                            \
+                (head)->tqh_last = &TAILQ_NEXT((elm), field);           \
+        TAILQ_FIRST((head)) = (elm);                                    \
+        (elm)->field.tqe_prev = &TAILQ_FIRST((head));                   \
+        QMD_TRACE_HEAD(head);                                           \
+        QMD_TRACE_ELEM(&(elm)->field);                                  \
+} while (0)
+
+#define TAILQ_INSERT_TAIL(head, elm, field) do {                        \
+        QMD_TAILQ_CHECK_TAIL(head, field);                              \
+        TAILQ_NEXT((elm), field) = NULL;                                \
+        (elm)->field.tqe_prev = (head)->tqh_last;                       \
+        *(head)->tqh_last = (elm);                                      \
+        (head)->tqh_last = &TAILQ_NEXT((elm), field);                   \
+        QMD_TRACE_HEAD(head);                                           \
+        QMD_TRACE_ELEM(&(elm)->field);                                  \
+} while (0)
+
+#define TAILQ_LAST(head, headname)                                      \
+        (*(((struct headname *)((head)->tqh_last))->tqh_last))
+
+#define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
+
+#define TAILQ_PREV(elm, headname, field)                                \
+        (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
+
+#define TAILQ_REMOVE(head, elm, field) do {                             \
+        QMD_SAVELINK(oldnext, (elm)->field.tqe_next);                   \
+        QMD_SAVELINK(oldprev, (elm)->field.tqe_prev);                   \
+        QMD_TAILQ_CHECK_NEXT(elm, field);                               \
+        QMD_TAILQ_CHECK_PREV(elm, field);                               \
+        if ((TAILQ_NEXT((elm), field)) != NULL)                         \
+                TAILQ_NEXT((elm), field)->field.tqe_prev =              \
+                    (elm)->field.tqe_prev;                              \
+        else {                                                          \
+                (head)->tqh_last = (elm)->field.tqe_prev;               \
+                QMD_TRACE_HEAD(head);                                   \
+        }                                                               \
+        *(elm)->field.tqe_prev = TAILQ_NEXT((elm), field);              \
+        TRASHIT(*oldnext);                                              \
+        TRASHIT(*oldprev);                                              \
+        QMD_TRACE_ELEM(&(elm)->field);                                  \
+} while (0)
+
+#define TAILQ_SWAP(head1, head2, type, field) do {                      \
+        struct type *swap_first = (head1)->tqh_first;                   \
+        struct type **swap_last = (head1)->tqh_last;                    \
+        (head1)->tqh_first = (head2)->tqh_first;                        \
+        (head1)->tqh_last = (head2)->tqh_last;                          \
+        (head2)->tqh_first = swap_first;                                \
+        (head2)->tqh_last = swap_last;                                  \
+        if ((swap_first = (head1)->tqh_first) != NULL)                  \
+                swap_first->field.tqe_prev = &(head1)->tqh_first;       \
+        else                                                            \
+                (head1)->tqh_last = &(head1)->tqh_first;                \
+        if ((swap_first = (head2)->tqh_first) != NULL)                  \
+                swap_first->field.tqe_prev = &(head2)->tqh_first;       \
+        else                                                            \
+                (head2)->tqh_last = &(head2)->tqh_first;                \
+} while (0)
+
+#endif /* !_SYS_QUEUE_H_ */

src/async_nif.hrl

@@ -0,0 +1,43 @@
+%% -------------------------------------------------------------------
+%%
+%% async_nif: An async thread-pool layer for Erlang's NIF API
+%%
+%% Copyright (c) 2012 Basho Technologies, Inc. All Rights Reserved.
+%% Author: Gregory Burd <greg@basho.com> <greg@burd.me>
+%%
+%% This file is provided to you under the Apache License,
+%% Version 2.0 (the "License"); you may not use this file
+%% except in compliance with the License.  You may obtain
+%% a copy of the License at
+%%
+%%   http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing,
+%% software distributed under the License is distributed on an
+%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+%% KIND, either express or implied.  See the License for the
+%% specific language governing permissions and limitations
+%% under the License.
+%%
+%% -------------------------------------------------------------------
+
+-define(ASYNC_NIF_CALL(Fun, Args),
+        begin
+            NIFRef = erlang:make_ref(),
+            case erlang:apply(Fun, [NIFRef|Args]) of
+                {ok, {enqueued, QDepth}} ->
+                    [erlang:bump_reductions(10 * QDepth) || is_integer(QDepth), QDepth > 100],
+                    receive
+                        {NIFRef, {error, shutdown}=Error} ->
+                            %% Work unit was queued, but not executed.
+                            Error;
+                        {NIFRef, {error, _Reason}=Error} ->
+                            %% Work unit returned an error.
+                            Error;
+                        {NIFRef, Reply} ->
+                            Reply
+                    end;
+                Other ->
+                    Other
+            end
+        end).

src/riak_kv_wterl_backend.erl

@@ -43,6 +43,7 @@
 
 -ifdef(TEST).
 -include_lib("eunit/include/eunit.hrl").
+-compiel(export_all).
 -endif.
 
 -define(API_VERSION, 1).
@@ -50,10 +51,13 @@
 %%-define(CAPABILITIES, [async_fold, indexes]).
 -define(CAPABILITIES, [async_fold]).
 
+-record(pass, {session :: wterl:session(),
+	       cursor  :: wterl:cursor()}).
+-type pass() :: #pass{}.
+
 -record(state, {table :: string(),
                 connection :: wterl:connection(),
-		cursors :: ets:tid(),
+		passes :: [pass()]}).
-                session :: wterl:session()}).
 
 -type state() :: #state{}.
 -type config() :: [{atom(), term()}].
@@ -81,6 +85,7 @@ capabilities(_, _) ->
 %% @doc Start the wterl backend
 -spec start(integer(), config()) -> {ok, state()} | {error, term()}.
 start(Partition, Config) ->
+    lager:start(),
     AppStart =
         case application:start(wterl) of
             ok ->
@@ -94,34 +99,30 @@ start(Partition, Config) ->
     case AppStart of
         ok ->
             Table = "lsm:wt" ++ integer_to_list(Partition),
-            establish_connection(Table, Config);
+            {ok, Connection} = establish_connection(Config),
+	    Passes = establish_passes(erlang:system_info(schedulers), Connection, Table),
+	    {ok, #state{table=Table, connection=Connection, passes=Passes}};
         {error, Reason2} ->
             {error, Reason2}
     end.
 
 %% @doc Stop the wterl backend
 -spec stop(state()) -> ok.
-stop(#state{session=undefined, cursors=undefined}) ->
+stop(#state{passes=Passes}) ->
-    ok;
+    lists:foreach(fun({Session, Cursor}) ->
-stop(#state{session=Session, cursors=undefined}) ->
+			  ok = wterl:cursor_close(Cursor),
-    ok = wterl:session_close(Session);
+			  ok = wterl:session_close(Session)
-stop(#state{session=Session, cursors=Cursors}=State) ->
+		  end, Passes),
-    ets:foldl(fun({_Table, Cursor}, _) ->
+    ok.
-		      ok = wterl:cursor_close(Cursor)
-              end, true, Cursors),
-    ets:delete(Cursors),
-    stop(State#state{session=Session, cursors=undefined}).
 
 %% @doc Retrieve an object from the wterl backend
 -spec get(riak_object:bucket(), riak_object:key(), state()) ->
                  {ok, any(), state()} |
                  {ok, not_found, state()} |
                  {error, term(), state()}.
-get(Bucket, Key, #state{session=undefined}=State) ->
+get(Bucket, Key, #state{passes=Passes}=State) ->
-    get(Bucket, Key, establish_session(State));
-get(Bucket, Key, #state{session=Session, table=Table}=State0) ->
     WTKey = to_object_key(Bucket, Key),
-    {Cursor, State} = cursor(Session, Table, get, State0),
+    {_Session, Cursor} = lists:nth(erlang:system_info(scheduler_id), Passes),
     case wterl:cursor_search(Cursor, WTKey) of
         {ok, Value} ->
             {ok, Value, State};
@@ -139,11 +140,9 @@ get(Bucket, Key, #state{session=Session, table=Table}=State0) ->
 -spec put(riak_object:bucket(), riak_object:key(), [index_spec()], binary(), state()) ->
                  {ok, state()} |
                  {error, term(), state()}.
-put(Bucket, PrimaryKey, IndexSpecs, Val, #state{session=undefined}=State) ->
+put(Bucket, PrimaryKey, _IndexSpecs, Val, #state{passes=Passes}=State) ->
-    put(Bucket, PrimaryKey, IndexSpecs, Val, establish_session(State));
-put(Bucket, PrimaryKey, _IndexSpecs, Val, #state{session=Session, table=Table}=State0) ->
     WTKey = to_object_key(Bucket, PrimaryKey),
-    {Cursor, State} = cursor(Session, Table, put, State0),
+    {_Session, Cursor} = lists:nth(erlang:system_info(scheduler_id), Passes),
     case wterl:cursor_insert(Cursor, WTKey, Val) of
         ok ->
             {ok, State};
@@ -158,11 +157,9 @@ put(Bucket, PrimaryKey, _IndexSpecs, Val, #state{session=Session, table=Table}=S
 -spec delete(riak_object:bucket(), riak_object:key(), [index_spec()], state()) ->
                     {ok, state()} |
                     {error, term(), state()}.
-delete(Bucket, Key, IndexSpecs, #state{session=undefined}=State) ->
+delete(Bucket, Key, _IndexSpecs, #state{passes=Passes}=State) ->
-    delete(Bucket, Key, IndexSpecs, establish_session(State));
-delete(Bucket, Key, _IndexSpecs, #state{session=Session, table=Table}=State0) ->
     WTKey = to_object_key(Bucket, Key),
-    {Cursor, State} = cursor(Session, Table, delete, State0),
+    {_Session, Cursor} = lists:nth(erlang:system_info(scheduler_id), Passes),
     case wterl:cursor_remove(Cursor, WTKey) of
         ok ->
             {ok, State};
@@ -175,12 +172,12 @@ delete(Bucket, Key, _IndexSpecs, #state{session=Session, table=Table}=State0) ->
                    any(),
                    [],
                    state()) -> {ok, any()} | {async, fun()}.
-fold_buckets(FoldBucketsFun, Acc, Opts, #state{session=undefined}=State) ->
+fold_buckets(FoldBucketsFun, Acc, Opts, #state{table=Table}) ->
-    fold_buckets(FoldBucketsFun, Acc, Opts, establish_session(State));
+    {ok, Connection} = wterl_conn:get(),
-fold_buckets(FoldBucketsFun, Acc, Opts, #state{session=Session, table=Table}) ->
     FoldFun = fold_buckets_fun(FoldBucketsFun),
     BucketFolder =
         fun() ->
+                {ok, Session} = wterl:session_open(Connection),
                 case wterl:cursor_open(Session, Table) of
                     {error, "No such file or directory"} ->
                         Acc;
@@ -193,7 +190,8 @@ fold_buckets(FoldBucketsFun, Acc, Opts, #state{session=Session, table=Table}) ->
                             {break, AccFinal} ->
                                 AccFinal
                         after
-                            ok = wterl:cursor_close(Cursor)
+                            ok = wterl:cursor_close(Cursor),
+			    ok = wterl:session_close(Session)
                         end
                 end
         end,
@@ -209,9 +207,7 @@ fold_buckets(FoldBucketsFun, Acc, Opts, #state{session=Session, table=Table}) ->
                 any(),
                 [{atom(), term()}],
                 state()) -> {ok, term()} | {async, fun()}.
-fold_keys(FoldKeysFun, Acc, Opts, #state{session=undefined}=State) ->
+fold_keys(FoldKeysFun, Acc, Opts, #state{table=Table}) ->
-    fold_keys(FoldKeysFun, Acc, Opts, establish_session(State));
-fold_keys(FoldKeysFun, Acc, Opts, #state{session=Session, table=Table}) ->
     %% Figure out how we should limit the fold: by bucket, by
     %% secondary index, or neither (fold across everything.)
     Bucket = lists:keyfind(bucket, 1, Opts),
@@ -224,10 +220,13 @@ fold_keys(FoldKeysFun, Acc, Opts, #state{session=Session, table=Table}) ->
            true            -> undefined
         end,
 
+    {ok, Connection} = wterl_conn:get(),
+
     %% Set up the fold...
     FoldFun = fold_keys_fun(FoldKeysFun, Limiter),
     KeyFolder =
         fun() ->
+                {ok, Session} = wterl:session_open(Connection),
                 case wterl:cursor_open(Session, Table) of
                     {error, "No such file or directory"} ->
                         Acc;
@@ -238,7 +237,8 @@ fold_keys(FoldKeysFun, Acc, Opts, #state{session=Session, table=Table}) ->
                             {break, AccFinal} ->
                                 AccFinal
                         after
-                            ok = wterl:cursor_close(Cursor)
+                            ok = wterl:cursor_close(Cursor),
+			    ok = wterl:session_close(Session)
                         end
                 end
         end,
@@ -254,13 +254,13 @@ fold_keys(FoldKeysFun, Acc, Opts, #state{session=Session, table=Table}) ->
                    any(),
                    [{atom(), term()}],
                    state()) -> {ok, any()} | {async, fun()}.
-fold_objects(FoldObjectsFun, Acc, Opts, #state{session=undefined}=State) ->
+fold_objects(FoldObjectsFun, Acc, Opts, #state{table=Table}) ->
-    fold_objects(FoldObjectsFun, Acc, Opts, establish_session(State));
+    {ok, Connection} = wterl_conn:get(),
-fold_objects(FoldObjectsFun, Acc, Opts, #state{session=Session, table=Table}) ->
     Bucket =  proplists:get_value(bucket, Opts),
     FoldFun = fold_objects_fun(FoldObjectsFun, Bucket),
     ObjectFolder =
         fun() ->
+                {ok, Session} = wterl:session_open(Connection),
                 case wterl:cursor_open(Session, Table) of
                     {error, "No such file or directory"} ->
                         Acc;
@@ -271,7 +271,8 @@ fold_objects(FoldObjectsFun, Acc, Opts, #state{session=Session, table=Table}) ->
                             {break, AccFinal} ->
                                 AccFinal
                         after
-                            ok = wterl:cursor_close(Cursor)
+                            ok = wterl:cursor_close(Cursor),
+			    ok = wterl:session_close(Session)
                         end
                 end
         end,
@@ -284,9 +285,8 @@ fold_objects(FoldObjectsFun, Acc, Opts, #state{session=Session, table=Table}) ->
 
 %% @doc Delete all objects from this wterl backend
 -spec drop(state()) -> {ok, state()} | {error, term(), state()}.
-drop(#state{session=undefined}=State) ->
+drop(#state{passes=Passes, table=Table}=State) ->
-    drop(establish_session(State));
+    {Session, _Cursor} = lists:nth(erlang:system_info(scheduler_id), Passes),
-drop(#state{table=Table, session=Session}=State) ->
     case wterl:session_truncate(Session, Table) of
         ok ->
             {ok, State};
@@ -297,10 +297,9 @@ drop(#state{table=Table, session=Session}=State) ->
 %% @doc Returns true if this wterl backend contains any
 %% non-tombstone values; otherwise returns false.
 -spec is_empty(state()) -> boolean().
-is_empty(#state{session=undefined}=State) ->
+is_empty(#state{passes=Passes}) ->
-    is_empty(establish_session(State));
+    {_Session, Cursor} = lists:nth(erlang:system_info(scheduler_id), Passes),
-is_empty(#state{table=Table, session=Session}) ->
+    wterl:cursor_reset(Cursor),
-    {ok, Cursor} = wterl:cursor_open(Session, Table),
     try
         not_found =:= wterl:cursor_next(Cursor)
     after
@@ -309,10 +308,8 @@ is_empty(#state{table=Table, session=Session}) ->
 
 %% @doc Get the status information for this wterl backend
 -spec status(state()) -> [{atom(), term()}].
-status(#state{session=undefined}=State) ->
+status(#state{passes=Passes}) ->
-    status(establish_session(State));
+    {_Session, Cursor} = lists:nth(erlang:system_info(scheduler_id), Passes),
-status(#state{table=Table, session=Session}) ->
-    {ok, Cursor} = wterl:cursor_open(Session, "statistics:"++Table),
     try
         Stats = fetch_status(Cursor),
         [{stats, Stats}]
@@ -330,21 +327,8 @@ callback(_Ref, _Msg, State) ->
 %% Internal functions
 %% ===================================================================
 
-cursor(Session, Table, Type, #state{cursors=undefined}=State) ->
-    Cursors = ets:new(?MODULE, [{read_concurrency, true}]),
-    cursor(Session, Table, Type, State#state{cursors=Cursors});
-cursor(Session, Table, Type, #state{cursors=Cursors}=State) ->
-    case ets:lookup(Cursors, {Type, Table}) of
-	[{{_Type, Table}, Cursor}] ->
-	    {Cursor, State};
-	_ ->
-	    {ok, Cursor} = wterl:cursor_open(Session, Table),
-	    ets:insert(Cursors, {Table, Cursor}),
-	    {Cursor, State}
-    end.
-
 %% @private
-establish_connection(Table, Config) ->
+establish_connection(Config) ->
     %% Get the data root directory
     case app_helper:get_prop_or_env(data_root, Config, wterl) of
         undefined ->
@@ -373,19 +357,33 @@ establish_connection(Table, Config) ->
 			  %"salvage", "verify", "write", "evict", "lsm"
 			])
 		     ] ++ proplists:get_value(wterl, Config, [])), % sec
-            %%lager:info("WiredTiger connection:open(~s, ~s)", [DataRoot, wterl:config_to_bin(Opts)]),
+            lager:info("WiredTiger connection:open(~s, ~s)", [DataRoot, wterl:config_to_bin(Opts)]),
             case wterl_conn:open(DataRoot, Opts) of
                 {ok, Connection} ->
-                    {ok, #state{table=Table, connection=Connection}};
+                    {ok, Connection};
                 {error, Reason2} ->
 		    lager:error("Failed to establish a WiredTiger connection, wterl backend unable to start: ~p\n", [Reason2]),
                     {error, Reason2}
             end
     end.
 
+establish_passes(Count, Connection, Table)
+  when is_number(Count), Count > 0 ->
+    establish_passes(Count, Connection, Table, []).
+
+establish_passes(Count, Connection, Table, Acc)
+  when Count > 0 ->
+    case Count > 1 of
+	true ->
+	    {ok, Session} = establish_session(Connection, Table),
+	    {ok, Cursor} = wterl:cursor_open(Session, Table),
+	    [{Session, Cursor} | establish_passes(Count - 1, Connection, Table, Acc)];
+	false ->
+	    Acc
+    end.
+
 %% @private
-establish_session(#state{table=Table, session=undefined}=State) ->
+establish_session(Connection, Table) ->
-    {ok, Connection} = wterl_conn:get(),
     case wterl:session_open(Connection, wterl:config_to_bin([{isolation, "snapshot"}])) of
         {ok, Session} ->
             SessionOpts =
@@ -398,17 +396,15 @@ establish_session(#state{table=Table, session=undefined}=State) ->
                  {lsm_bloom_config, [{leaf_page_max, "10MB"}]} ],
             case wterl:session_create(Session, Table, wterl:config_to_bin(SessionOpts)) of
                 ok ->
-                    State#state{session=Session};
+		    {ok, Session};
                 {error, Reason} ->
                     lager:error("Failed to start wterl backend: ~p\n", [Reason]),
-                    State
+		    {error, Reason}
             end;
         {error, Reason} ->
             lager:error("Failed to open a WiredTiger session: ~p\n", [Reason]),
-            State
+	    {error, Reason}
-    end;
+    end.
-establish_session(State) ->
-    State.
 
 %% @private
 %% Return a function to fold over the buckets on this backend
@@ -555,7 +551,7 @@ size_cache(RequestedSize) ->
                             "1GB"
                     end,
                 application:set_env(wterl, cache_size, FinalGuess),
-                lager:info("Using cache size of ~p for WiredTiger storage backend.", [FinalGuess]),
+		lager:info("Using cache size of ~p for WiredTiger storage backend.", [FinalGuess]),
                 FinalGuess;
             Value when is_list(Value) ->
                 Value;

src/temp_riak_kv_backend.erl

@@ -272,13 +272,16 @@ empty_check({Backend, State}) ->
     }.
 
 setup({BackendMod, Config}) ->
-    lager:start(),
+    application:start(lager),
     application:start(sasl),
     application:start(os_mon),
     {ok, S} = BackendMod:start(42, Config),
     {BackendMod, S}.
 
 cleanup({BackendMod, S}) ->
-    ok = BackendMod:stop(S).
+    ok = BackendMod:stop(S),
+    application:stop(lager),
+    application:stop(sasl),
+    application:stop(os_mon).
 
 -endif. % TEST

src/wterl.erl

@@ -63,6 +63,8 @@
          fold_keys/3,
          fold/3]).
 
+-include("async_nif.hrl").
+
 -ifdef(TEST).
 -ifdef(EQC).
 -include_lib("eqc/include/eqc.hrl").
@@ -103,147 +105,262 @@ init() ->
     erlang:load_nif(filename:join(PrivDir, atom_to_list(?MODULE)), 0).
 
 -spec conn_open(string(), config()) -> {ok, connection()} | {error, term()}.
-conn_open(_HomeDir, _Config) ->
+conn_open(HomeDir, Config) ->
+    ?ASYNC_NIF_CALL(fun conn_open_nif/3, [HomeDir, Config]).
+
+-spec conn_open_nif(reference(), string(), config()) -> {ok, connection()} | {error, term()}.
+conn_open_nif(_AsyncRef, _HomeDir, _Config) ->
     ?nif_stub.
 
 -spec conn_close(connection()) -> ok | {error, term()}.
-conn_close(_ConnRef) ->
+conn_close(ConnRef) ->
+    ?ASYNC_NIF_CALL(fun conn_close_nif/2, [ConnRef]).
+
+-spec conn_close_nif(reference(), connection()) -> ok | {error, term()}.
+conn_close_nif(_AsyncRef, _ConnRef) ->
     ?nif_stub.
 
 -spec session_open(connection()) -> {ok, session()} | {error, term()}.
+-spec session_open(connection(), config()) -> {ok, session()} | {error, term()}.
 session_open(ConnRef) ->
     session_open(ConnRef, ?EMPTY_CONFIG).
+session_open(ConnRef, Config) ->
+    ?ASYNC_NIF_CALL(fun session_open_nif/3, [ConnRef, Config]).
 
--spec session_open(connection(), config()) -> {ok, session()} | {error, term()}.
+-spec session_open_nif(reference(), connection(), config()) -> {ok, session()} | {error, term()}.
-session_open(_ConnRef, _Config) ->
+session_open_nif(_AsyncRef, _ConnRef, _Config) ->
     ?nif_stub.
 
 -spec session_close(session()) -> ok | {error, term()}.
-session_close(_Ref) ->
+session_close(Ref) ->
+    ?ASYNC_NIF_CALL(fun session_close_nif/2, [Ref]).
+
+-spec session_close_nif(reference(), session()) -> ok | {error, term()}.
+session_close_nif(_AsyncRef, _Ref) ->
     ?nif_stub.
 
 -spec session_create(session(), string()) -> ok | {error, term()}.
 -spec session_create(session(), string(), config()) -> ok | {error, term()}.
 session_create(Ref, Name) ->
     session_create(Ref, Name, ?EMPTY_CONFIG).
-session_create(_Ref, _Name, _Config) ->
+session_create(Ref, Name, Config) ->
+    ?ASYNC_NIF_CALL(fun session_create_nif/4, [Ref, Name, Config]).
+
+-spec session_create_nif(reference(), session(), string(), config()) -> ok | {error, term()}.
+session_create_nif(_AsyncNif, _Ref, _Name, _Config) ->
     ?nif_stub.
 
 -spec session_drop(session(), string()) -> ok | {error, term()}.
 -spec session_drop(session(), string(), config()) -> ok | {error, term()}.
 session_drop(Ref, Name) ->
     session_drop(Ref, Name, ?EMPTY_CONFIG).
-session_drop(_Ref, _Name, _Config) ->
+session_drop(Ref, Name, Config) ->
+    ?ASYNC_NIF_CALL(fun session_drop_nif/4, [Ref, Name, Config]).
+
+-spec session_drop_nif(reference(), session(), string(), config()) -> ok | {error, term()}.
+session_drop_nif(_AsyncRef, _Ref, _Name, _Config) ->
     ?nif_stub.
 
 -spec session_delete(session(), string(), key()) -> ok | {error, term()}.
-session_delete(_Ref, _Table, _Key) ->
+session_delete(Ref, Table, Key) ->
+    ?ASYNC_NIF_CALL(fun session_delete_nif/4, [Ref, Table, Key]).
+
+-spec session_delete_nif(reference(), session(), string(), key()) -> ok | {error, term()}.
+session_delete_nif(_AsyncRef, _Ref, _Table, _Key) ->
     ?nif_stub.
 
 -spec session_get(session(), string(), key()) -> {ok, value()} | not_found | {error, term()}.
-session_get(_Ref, _Table, _Key) ->
+session_get(Ref, Table, Key) ->
+    ?ASYNC_NIF_CALL(fun session_get_nif/4, [Ref, Table, Key]).
+
+-spec session_get_nif(reference(), session(), string(), key()) -> {ok, value()} | not_found | {error, term()}.
+session_get_nif(_AsyncRef, _Ref, _Table, _Key) ->
     ?nif_stub.
 
 -spec session_put(session(), string(), key(), value()) -> ok | {error, term()}.
-session_put(_Ref, _Table, _Key, _Value) ->
+session_put(Ref, Table, Key, Value) ->
+    ?ASYNC_NIF_CALL(fun session_put_nif/5, [Ref, Table, Key, Value]).
+
+-spec session_put_nif(reference(), session(), string(), key(), value()) -> ok | {error, term()}.
+session_put_nif(_AsyncRef, _Ref, _Table, _Key, _Value) ->
     ?nif_stub.
 
 -spec session_rename(session(), string(), string()) -> ok | {error, term()}.
 -spec session_rename(session(), string(), string(), config()) -> ok | {error, term()}.
 session_rename(Ref, OldName, NewName) ->
     session_rename(Ref, OldName, NewName, ?EMPTY_CONFIG).
-session_rename(_Ref, _OldName, _NewName, _Config) ->
+session_rename(Ref, OldName, NewName, Config) ->
+    ?ASYNC_NIF_CALL(fun session_rename_nif/5, [Ref, OldName, NewName, Config]).
+
+-spec session_rename_nif(reference(), session(), string(), string(), config()) -> ok | {error, term()}.
+session_rename_nif(_AsyncRef, _Ref, _OldName, _NewName, _Config) ->
     ?nif_stub.
 
 -spec session_salvage(session(), string()) -> ok | {error, term()}.
 -spec session_salvage(session(), string(), config()) -> ok | {error, term()}.
 session_salvage(Ref, Name) ->
     session_salvage(Ref, Name, ?EMPTY_CONFIG).
-session_salvage(_Ref, _Name, _Config) ->
+session_salvage(Ref, Name, Config) ->
+    ?ASYNC_NIF_CALL(fun session_salvage_nif/4, [Ref, Name, Config]).
+
+-spec session_salvage_nif(reference(), session(), string(), config()) -> ok | {error, term()}.
+session_salvage_nif(_AsyncRef, _Ref, _Name, _Config) ->
     ?nif_stub.
 
 -spec session_checkpoint(session()) -> ok | {error, term()}.
 -spec session_checkpoint(session(), config()) -> ok | {error, term()}.
 session_checkpoint(_Ref) ->
     session_checkpoint(_Ref, ?EMPTY_CONFIG).
-session_checkpoint(_Ref, _Config) ->
+session_checkpoint(Ref, Config) ->
+    ?ASYNC_NIF_CALL(fun session_checkpoint_nif/3, [Ref, Config]).
+
+-spec session_checkpoint_nif(reference(), session(), config()) -> ok | {error, term()}.
+session_checkpoint_nif(_AsyncRef, _Ref, _Config) ->
     ?nif_stub.
 
 -spec session_truncate(session(), string()) -> ok | {error, term()}.
 -spec session_truncate(session(), string(), config()) -> ok | {error, term()}.
 session_truncate(Ref, Name) ->
     session_truncate(Ref, Name, ?EMPTY_CONFIG).
-session_truncate(_Ref, _Name, _Config) ->
+session_truncate(Ref, Name, Config) ->
+    ?ASYNC_NIF_CALL(fun session_truncate_nif/4, [Ref, Name, Config]).
+
+-spec session_truncate_nif(reference(), session(), string(), config()) -> ok | {error, term()}.
+session_truncate_nif(_AsyncRef, _Ref, _Name, _Config) ->
     ?nif_stub.
 
 -spec session_upgrade(session(), string()) -> ok | {error, term()}.
 -spec session_upgrade(session(), string(), config()) -> ok | {error, term()}.
 session_upgrade(Ref, Name) ->
     session_upgrade(Ref, Name, ?EMPTY_CONFIG).
-session_upgrade(_Ref, _Name, _Config) ->
+session_upgrade(Ref, Name, Config) ->
+    ?ASYNC_NIF_CALL(fun session_upgrade_nif/4, [Ref, Name, Config]).
+
+-spec session_upgrade_nif(reference(), session(), string(), config()) -> ok | {error, term()}.
+session_upgrade_nif(_AsyncRef, _Ref, _Name, _Config) ->
     ?nif_stub.
 
 -spec session_verify(session(), string()) -> ok | {error, term()}.
 -spec session_verify(session(), string(), config()) -> ok | {error, term()}.
 session_verify(Ref, Name) ->
     session_verify(Ref, Name, ?EMPTY_CONFIG).
-session_verify(_Ref, _Name, _Config) ->
+session_verify(Ref, Name, Config) ->
+    ?ASYNC_NIF_CALL(fun session_verify_nif/4, [Ref, Name, Config]).
+
+-spec session_verify_nif(reference(), session(), string(), config()) -> ok | {error, term()}.
+session_verify_nif(_AsyncRef, _Ref, _Name, _Config) ->
     ?nif_stub.
 
 -spec cursor_open(session(), string()) -> {ok, cursor()} | {error, term()}.
-cursor_open(_Ref, _Table) ->
+cursor_open(Ref, Table) ->
+    ?ASYNC_NIF_CALL(fun cursor_open_nif/3, [Ref, Table]).
+
+-spec cursor_open_nif(reference(), session(), string()) -> {ok, cursor()} | {error, term()}.
+cursor_open_nif(_AsyncRef, _Ref, _Table) ->
     ?nif_stub.
 
 -spec cursor_close(cursor()) -> ok | {error, term()}.
-cursor_close(_Cursor) ->
+cursor_close(Cursor) ->
+    ?ASYNC_NIF_CALL(fun cursor_close_nif/2, [Cursor]).
+
+-spec cursor_close_nif(reference(), cursor()) -> ok | {error, term()}.
+cursor_close_nif(_AsyncRef, _Cursor) ->
     ?nif_stub.
 
 -spec cursor_next(cursor()) -> {ok, key(), value()} | not_found | {error, term()}.
-cursor_next(_Cursor) ->
+cursor_next(Cursor) ->
+    ?ASYNC_NIF_CALL(fun cursor_next_nif/2, [Cursor]).
+
+-spec cursor_next_nif(reference(), cursor()) -> {ok, key(), value()} | not_found | {error, term()}.
+cursor_next_nif(_AsyncRef, _Cursor) ->
     ?nif_stub.
 
 -spec cursor_next_key(cursor()) -> {ok, key()} | not_found | {error, term()}.
-cursor_next_key(_Cursor) ->
+cursor_next_key(Cursor) ->
+    ?ASYNC_NIF_CALL(fun cursor_next_key_nif/2, [Cursor]).
+
+-spec cursor_next_key_nif(reference(), cursor()) -> {ok, key()} | not_found | {error, term()}.
+cursor_next_key_nif(_AsyncRef, _Cursor) ->
     ?nif_stub.
 
 -spec cursor_next_value(cursor()) -> {ok, value()} | not_found | {error, term()}.
-cursor_next_value(_Cursor) ->
+cursor_next_value(Cursor) ->
+    ?ASYNC_NIF_CALL(fun cursor_next_value_nif/2, [Cursor]).
+
+-spec cursor_next_value_nif(reference(), cursor()) -> {ok, value()} | not_found | {error, term()}.
+cursor_next_value_nif(_AsyncRef, _Cursor) ->
     ?nif_stub.
 
 -spec cursor_prev(cursor()) -> {ok, key(), value()} | not_found | {error, term()}.
-cursor_prev(_Cursor) ->
+cursor_prev(Cursor) ->
+    ?ASYNC_NIF_CALL(fun cursor_prev_nif/2, [Cursor]).
+
+-spec cursor_prev_nif(reference(), cursor()) -> {ok, key(), value()} | not_found | {error, term()}.
+cursor_prev_nif(_AsyncRef, _Cursor) ->
     ?nif_stub.
 
 -spec cursor_prev_key(cursor()) -> {ok, key()} | not_found | {error, term()}.
-cursor_prev_key(_Cursor) ->
+cursor_prev_key(Cursor) ->
+    ?ASYNC_NIF_CALL(fun cursor_prev_key_nif/2, [Cursor]).
+
+-spec cursor_prev_key_nif(reference(), cursor()) -> {ok, key()} | not_found | {error, term()}.
+cursor_prev_key_nif(_AsyncRef, _Cursor) ->
     ?nif_stub.
 
 -spec cursor_prev_value(cursor()) -> {ok, value()} | not_found | {error, term()}.
-cursor_prev_value(_Cursor) ->
+cursor_prev_value(Cursor) ->
+    ?ASYNC_NIF_CALL(fun cursor_prev_value_nif/2, [Cursor]).
+
+-spec cursor_prev_value_nif(reference(), cursor()) -> {ok, value()} | not_found | {error, term()}.
+cursor_prev_value_nif(_AsyncRef, _Cursor) ->
     ?nif_stub.
 
 -spec cursor_search(cursor(), key()) -> {ok, value()} | {error, term()}.
-cursor_search(_Cursor, _Key) ->
+cursor_search(Cursor, Key) ->
+    ?ASYNC_NIF_CALL(fun cursor_search_nif/3, [Cursor, Key]).
+
+-spec cursor_search_nif(reference(), cursor(), key()) -> {ok, value()} | {error, term()}.
+cursor_search_nif(_AsyncRef, _Cursor, _Key) ->
     ?nif_stub.
 
 -spec cursor_search_near(cursor(), key()) -> {ok, value()} | {error, term()}.
-cursor_search_near(_Cursor, _Key) ->
+cursor_search_near(Cursor, Key) ->
+    ?ASYNC_NIF_CALL(fun cursor_search_near_nif/3, [Cursor, Key]).
+
+-spec cursor_search_near_nif(reference(), cursor(), key()) -> {ok, value()} | {error, term()}.
+cursor_search_near_nif(_AsyncRef, _Cursor, _Key) ->
     ?nif_stub.
 
 -spec cursor_reset(cursor()) -> ok | {error, term()}.
-cursor_reset(_Cursor) ->
+cursor_reset(Cursor) ->
+    ?ASYNC_NIF_CALL(fun cursor_reset_nif/2, [Cursor]).
+
+-spec cursor_reset_nif(reference(), cursor()) -> ok | {error, term()}.
+cursor_reset_nif(_AsyncRef, _Cursor) ->
     ?nif_stub.
 
 -spec cursor_insert(cursor(), key(), value()) -> ok | {error, term()}.
-cursor_insert(_Cursor, _Key, _Value) ->
+cursor_insert(Cursor, Key, Value) ->
+    ?ASYNC_NIF_CALL(fun cursor_insert_nif/4, [Cursor, Key, Value]).
+
+-spec cursor_insert_nif(reference(), cursor(), key(), value()) -> ok | {error, term()}.
+cursor_insert_nif(_AsyncRef, _Cursor, _Key, _Value) ->
     ?nif_stub.
 
 -spec cursor_update(cursor(), key(), value()) -> ok | {error, term()}.
-cursor_update(_Cursor, _Key, _Value) ->
+cursor_update(Cursor, Key, Value) ->
+    ?ASYNC_NIF_CALL(fun cursor_update_nif/4, [Cursor, Key, Value]).
+
+-spec cursor_update_nif(reference(), cursor(), key(), value()) -> ok | {error, term()}.
+cursor_update_nif(_AsyncRef, _Cursor, _Key, _Value) ->
     ?nif_stub.
 
 -spec cursor_remove(cursor(), key()) -> ok | {error, term()}.
-cursor_remove(_Cursor, _Key) ->
+cursor_remove(Cursor, Key) ->
+    ?ASYNC_NIF_CALL(fun cursor_remove_nif/3, [Cursor, Key]).
+
+-spec cursor_remove_nif(reference(), cursor(), key()) -> ok | {error, term()}.
+cursor_remove_nif(_AsyncRef, _Cursor, _Key) ->
     ?nif_stub.
 
 -type fold_keys_fun() :: fun((Key::binary(), any()) -> any()).
@@ -371,7 +488,9 @@ config_to_bin([{Key, Value} | Rest], Acc) ->
 -define(TEST_DATA_DIR, "test/wterl.basic").
 
 open_test_conn(DataDir) ->
-    ?assertCmd("rm -rf "++DataDir),
+    {ok, CWD} = file:get_cwd(),
+    ?assertMatch(true, lists:suffix("wterl/.eunit", CWD)),
+    ?cmd("rm -rf "++DataDir),
     ?assertMatch(ok, filelib:ensure_dir(filename:join(DataDir, "x"))),
     OpenConfig = config_to_bin([{create,true},{cache_size,"100MB"}]),
     {ok, ConnRef} = conn_open(DataDir, OpenConfig),
@@ -637,9 +756,11 @@ prop_put_delete() ->
     ?LET({Keys, Values}, {keys(), values()},
          ?FORALL(Ops, eqc_gen:non_empty(list(ops(Keys, Values))),
                  begin
-                     DataDir = "/tmp/wterl.putdelete.qc",
+                     DataDir = "test/wterl.putdelete.qc",
                      Table = "table:eqc",
-                     ?cmd("rm -rf "++DataDir),
+		     {ok, CWD} = file:get_cwd(),
+		     ?assertMatch(true, lists:suffix("wterl/.eunit", CWD)),
+		     ?cmd("rm -rf "++DataDir),
                      ok = filelib:ensure_dir(filename:join(DataDir, "x")),
                      Cfg = wterl:config_to_bin([{create,true}]),
                      {ok, Conn} = wterl:conn_open(DataDir, Cfg),