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