533 lines
20 KiB
C
533 lines
20 KiB
C
/*
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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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#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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#include <assert.h>
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#include "fifo_q.h"
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#include "stats.h"
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#ifndef __UNUSED
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#define __UNUSED(v) ((void)(v))
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#endif
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#define ASYNC_NIF_MAX_WORKERS 128
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#define ASYNC_NIF_WORKER_QUEUE_SIZE 500
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#define ASYNC_NIF_MAX_QUEUED_REQS 1000 * ASYNC_NIF_MAX_WORKERS
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STAT_DECL(qwait, 1000);
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struct async_nif_req_entry {
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ERL_NIF_TERM ref;
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ErlNifEnv *env;
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ErlNifPid pid;
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void *args;
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void (*fn_work)(ErlNifEnv*, ERL_NIF_TERM, ErlNifPid*, unsigned int, void *);
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void (*fn_post)(void *);
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};
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DECL_FIFO_QUEUE(reqs, struct async_nif_req_entry);
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struct async_nif_work_queue {
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STAT_DEF(qwait);
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ErlNifMutex *reqs_mutex;
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ErlNifCond *reqs_cnd;
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FIFO_QUEUE_TYPE(reqs) reqs;
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};
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struct async_nif_worker_entry {
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ErlNifTid tid;
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unsigned int worker_id;
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struct async_nif_state *async_nif;
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struct async_nif_work_queue *q;
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};
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struct async_nif_state {
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STAT_DEF(qwait);
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unsigned int shutdown;
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unsigned int num_workers;
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struct async_nif_worker_entry worker_entries[ASYNC_NIF_MAX_WORKERS];
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unsigned int num_queues;
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unsigned int next_q;
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FIFO_QUEUE_TYPE(reqs) recycled_reqs;
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unsigned int num_reqs;
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ErlNifMutex *recycled_req_mutex;
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struct async_nif_work_queue queues[];
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};
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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, ErlNifPid *pid, unsigned int worker_id, struct decl ## _args *args) { \
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__UNUSED(worker_id); \
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do work_block while(0); \
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} \
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static void fn_post_ ## decl (struct decl ## _args *args) { \
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__UNUSED(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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const char *affinity = 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 -= 1; \
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/* Note: !!! this assumes that the first element of priv_data is ours */ \
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struct async_nif_state *async_nif = *(struct async_nif_state**)enif_priv_data(env); \
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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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req = async_nif_reuse_req(async_nif); \
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new_env = req->env; \
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if (!req) \
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return enif_make_tuple2(env, enif_make_atom(env, "error"), \
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enif_make_atom(env, "eagain")); \
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do pre_block while(0); \
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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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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->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->fn_work = (void (*)(ErlNifEnv *, ERL_NIF_TERM, ErlNifPid*, unsigned int, void *))fn_work_ ## decl ; \
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req->fn_post = (void (*)(void *))fn_post_ ## decl; \
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int h = -1; \
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if (affinity) \
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h = async_nif_str_hash_func(affinity) % async_nif->num_queues; \
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ERL_NIF_TERM reply = async_nif_enqueue_req(async_nif, req, h); \
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if (!reply) { \
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fn_post_ ## decl (args); \
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enif_free(copy_of_args); \
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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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} \
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return reply; \
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}
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#define ASYNC_NIF_INIT(name) \
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static ErlNifMutex *name##_async_nif_coord = NULL;
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#define ASYNC_NIF_LOAD(name, priv) do { \
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if (!name##_async_nif_coord) \
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name##_async_nif_coord = enif_mutex_create(NULL); \
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enif_mutex_lock(name##_async_nif_coord); \
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priv = async_nif_load(); \
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enif_mutex_unlock(name##_async_nif_coord); \
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} while(0);
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#define ASYNC_NIF_UNLOAD(name, env, priv) do { \
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if (!name##_async_nif_coord) \
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name##_async_nif_coord = enif_mutex_create(NULL); \
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enif_mutex_lock(name##_async_nif_coord); \
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async_nif_unload(env, priv); \
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enif_mutex_unlock(name##_async_nif_coord); \
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enif_mutex_destroy(name##_async_nif_coord); \
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name##_async_nif_coord = NULL; \
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} while(0);
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#define ASYNC_NIF_UPGRADE(name, env) do { \
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if (!name##_async_nif_coord) \
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name##_async_nif_coord = enif_mutex_create(NULL); \
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enif_mutex_lock(name##_async_nif_coord); \
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async_nif_upgrade(env); \
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enif_mutex_unlock(name##_async_nif_coord); \
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} while(0);
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#define ASYNC_NIF_RETURN_BADARG() do { \
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async_nif_recycle_req(req, async_nif); \
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return enif_make_badarg(env); \
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} while(0);
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#define ASYNC_NIF_WORK_ENV new_env
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#define ASYNC_NIF_REPLY(msg) enif_send(NULL, pid, env, enif_make_tuple2(env, ref, msg))
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/**
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* Return a request structure from the recycled req queue if one exists,
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* otherwise create one.
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*/
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struct async_nif_req_entry *
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async_nif_reuse_req(struct async_nif_state *async_nif)
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{
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struct async_nif_req_entry *req = NULL;
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ErlNifEnv *env = NULL;
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enif_mutex_lock(async_nif->recycled_req_mutex);
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if (fifo_q_empty(reqs, async_nif->recycled_reqs)) {
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if (async_nif->num_reqs < ASYNC_NIF_MAX_QUEUED_REQS) {
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req = enif_alloc(sizeof(struct async_nif_req_entry));
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if (req) {
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memset(req, 0, sizeof(struct async_nif_req_entry));
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env = enif_alloc_env();
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if (!env) {
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enif_free(req);
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req = NULL;
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} else {
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req->env = env;
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async_nif->num_reqs++;
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}
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}
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}
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} else {
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req = fifo_q_get(reqs, async_nif->recycled_reqs);
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}
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enif_mutex_unlock(async_nif->recycled_req_mutex);
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STAT_TICK(async_nif, qwait);
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return req;
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}
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/**
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* Store the request for future re-use.
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*
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* req a request entry with an ErlNifEnv* which will be cleared
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* before reuse, but not until then.
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* async_nif a handle to our state so that we can find and use the mutex
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*/
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void
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async_nif_recycle_req(struct async_nif_req_entry *req, struct async_nif_state *async_nif)
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{
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STAT_TOCK(async_nif, qwait);
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enif_mutex_lock(async_nif->recycled_req_mutex);
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fifo_q_put(reqs, async_nif->recycled_reqs, req);
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enif_mutex_unlock(async_nif->recycled_req_mutex);
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}
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/**
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* A string hash function.
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*
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* A basic hash function for strings of characters used during the
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* affinity association.
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*
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* s a NULL terminated set of bytes to be hashed
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* -> an integer hash encoding of the bytes
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*/
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static inline unsigned int
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async_nif_str_hash_func(const char *s)
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{
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unsigned int h = (unsigned int)*s;
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if (h) for (++s ; *s; ++s) h = (h << 5) - h + (unsigned int)*s;
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return h;
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}
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/**
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* Enqueue a request for processing by a worker thread.
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*
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* Places the request into a work queue determined either by the
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* provided affinity or by iterating through the available queues.
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*/
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static ERL_NIF_TERM
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async_nif_enqueue_req(struct async_nif_state* async_nif, struct async_nif_req_entry *req, int hint)
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{
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/* Identify the most appropriate worker for this request. */
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unsigned int qid = 0;
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struct async_nif_work_queue *q = NULL;
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unsigned int n = async_nif->num_queues;
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/* Either we're choosing a queue based on some affinity/hinted value or we
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need to select the next queue in the rotation and atomically update that
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global value (next_q is shared across worker threads) . */
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if (hint >= 0) {
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qid = (unsigned int)hint;
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} else {
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qid = async_nif->next_q;
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qid = (qid + 1) % async_nif->num_queues;
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async_nif->next_q = qid;
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}
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/* Now we inspect and interate across the set of queues trying to select one
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that isn't too full or too slow. */
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do {
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q = &async_nif->queues[qid];
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enif_mutex_lock(q->reqs_mutex);
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/* Now that we hold the lock, check for shutdown. As long as we hold
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this lock either a) we're shutting down so exit now or b) this queue
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will be valid until we release the lock. */
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if (async_nif->shutdown) {
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enif_mutex_unlock(q->reqs_mutex);
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return 0;
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}
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double await = STAT_MEAN_LOG2_SAMPLE(async_nif, qwait);
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double await_inthisq = STAT_MEAN_LOG2_SAMPLE(q, qwait);
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if (fifo_q_full(reqs, q->reqs) || await_inthisq > await) {
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enif_mutex_unlock(q->reqs_mutex);
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qid = (qid + 1) % async_nif->num_queues;
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q = &async_nif->queues[qid];
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} else {
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break;
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}
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// TODO: at some point add in work sheading/stealing
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} while(n-- > 0);
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/* We hold the queue's lock, and we've seletect a reasonable queue for this
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new request so add the request. */
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STAT_TICK(q, qwait);
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fifo_q_put(reqs, q->reqs, req);
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/* Build the term before releasing the lock so as not to race on the use of
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the req pointer (which will soon become invalid in another thread
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performing the request). */
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ERL_NIF_TERM reply = enif_make_tuple2(req->env, enif_make_atom(req->env, "ok"),
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enif_make_atom(req->env, "enqueued"));
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enif_mutex_unlock(q->reqs_mutex);
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enif_cond_signal(q->reqs_cnd);
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return reply;
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}
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/**
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* TODO:
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*/
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static void *
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async_nif_worker_fn(void *arg)
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{
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struct async_nif_worker_entry *we = (struct async_nif_worker_entry *)arg;
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unsigned int worker_id = we->worker_id;
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struct async_nif_state *async_nif = we->async_nif;
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struct async_nif_work_queue *q = we->q;
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struct async_nif_req_entry *req = NULL;
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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(q->reqs_mutex);
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check_again_for_work:
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if (async_nif->shutdown) {
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enif_mutex_unlock(q->reqs_mutex);
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break;
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}
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if (fifo_q_empty(reqs, q->reqs)) {
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/* Queue is empty so we wait for more work to arrive. */
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STAT_RESET(q, qwait);
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enif_cond_wait(q->reqs_cnd, q->reqs_mutex);
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goto check_again_for_work;
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} else {
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assert(fifo_q_size(reqs, q->reqs) > 0);
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assert(fifo_q_size(reqs, q->reqs) < fifo_q_capacity(reqs, q->reqs));
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/* At this point the next req is ours to process and we hold the
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reqs_mutex lock. Take the request off the queue. */
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req = fifo_q_get(reqs, q->reqs);
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enif_mutex_unlock(q->reqs_mutex);
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/* Ensure that there is at least one other worker thread watching this
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queue. */
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enif_cond_signal(q->reqs_cnd);
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/* Perform the work. */
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req->fn_work(req->env, req->ref, &req->pid, worker_id, req->args);
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STAT_TOCK(q, qwait);
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/* Now call the post-work cleanup function. */
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req->fn_post(req->args);
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/* Clean up req for reuse. */
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req->ref = 0;
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req->fn_work = 0;
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req->fn_post = 0;
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enif_free(req->args);
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req->args = NULL;
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enif_clear_env(req->env);
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async_nif_recycle_req(req, async_nif);
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req = NULL;
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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
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async_nif_unload(ErlNifEnv *env, struct async_nif_state *async_nif)
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{
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unsigned int i;
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unsigned int num_queues = async_nif->num_queues;
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struct async_nif_work_queue *q = NULL;
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struct async_nif_req_entry *req = NULL;
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__UNUSED(env);
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STAT_PRINT(async_nif, qwait, "wterl");
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/* Signal the worker threads, stop what you're doing and exit. To
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ensure that we don't race with the enqueue() process we first
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lock all the worker queues, then set shutdown to true, then
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unlock. The enqueue function will take the queue mutex, then
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test for shutdown condition, then enqueue only if not shutting
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down. */
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for (i = 0; i < num_queues; i++) {
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q = &async_nif->queues[i];
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enif_mutex_lock(q->reqs_mutex);
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}
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async_nif->shutdown = 1;
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for (i = 0; i < num_queues; i++) {
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q = &async_nif->queues[i];
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enif_cond_broadcast(q->reqs_cnd);
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enif_mutex_unlock(q->reqs_mutex);
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}
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/* Join for the now exiting worker threads. */
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for (i = 0; i < async_nif->num_workers; ++i) {
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void *exit_value = 0; /* We ignore the thread_join's exit value. */
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enif_thread_join(async_nif->worker_entries[i].tid, &exit_value);
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}
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/* Free req structres sitting on the recycle queue. */
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enif_mutex_lock(async_nif->recycled_req_mutex);
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req = NULL;
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fifo_q_foreach(reqs, async_nif->recycled_reqs, req, {
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enif_free_env(req->env);
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enif_free(req);
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});
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fifo_q_free(reqs, async_nif->recycled_reqs);
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/* Cleanup in-flight requests, mutexes and conditions in each work queue. */
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for (i = 0; i < num_queues; i++) {
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q = &async_nif->queues[i];
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/* Worker threads are stopped, now toss anything left in the queue. */
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req = NULL;
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fifo_q_foreach(reqs, q->reqs, req, {
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enif_clear_env(req->env);
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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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req->fn_post(req->args);
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enif_free_env(req->env);
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enif_free(req->args);
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enif_free(req);
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});
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fifo_q_free(reqs, q->reqs);
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enif_mutex_destroy(q->reqs_mutex);
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enif_cond_destroy(q->reqs_cnd);
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}
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enif_mutex_unlock(async_nif->recycled_req_mutex);
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enif_mutex_destroy(async_nif->recycled_req_mutex);
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memset(async_nif, 0, sizeof(struct async_nif_state) + (sizeof(struct async_nif_work_queue) * async_nif->num_queues));
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enif_free(async_nif);
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}
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static void *
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async_nif_load()
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{
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static int has_init = 0;
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unsigned int i, j, num_queues;
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ErlNifSysInfo info;
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struct async_nif_state *async_nif;
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/* Don't init more than once. */
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if (has_init) return 0;
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else has_init = 1;
|
|
|
|
/* Find out how many schedulers there are. */
|
|
enif_system_info(&info, sizeof(ErlNifSysInfo));
|
|
|
|
/* Size the number of work queues according to schedulers. */
|
|
if (info.scheduler_threads > ASYNC_NIF_MAX_WORKERS / 2) {
|
|
num_queues = ASYNC_NIF_MAX_WORKERS / 2;
|
|
} else {
|
|
int remainder = ASYNC_NIF_MAX_WORKERS % info.scheduler_threads;
|
|
if (remainder != 0)
|
|
num_queues = info.scheduler_threads - remainder;
|
|
else
|
|
num_queues = info.scheduler_threads;
|
|
if (num_queues < 2)
|
|
num_queues = 2;
|
|
}
|
|
|
|
/* Init our portion of priv_data's module-specific state. */
|
|
async_nif = enif_alloc(sizeof(struct async_nif_state) +
|
|
sizeof(struct async_nif_work_queue) * num_queues);
|
|
if (!async_nif)
|
|
return NULL;
|
|
memset(async_nif, 0, sizeof(struct async_nif_state) +
|
|
sizeof(struct async_nif_work_queue) * num_queues);
|
|
|
|
async_nif->num_queues = num_queues;
|
|
async_nif->num_workers = 2 * num_queues;
|
|
async_nif->next_q = 0;
|
|
async_nif->shutdown = 0;
|
|
async_nif->recycled_reqs = fifo_q_new(reqs, ASYNC_NIF_MAX_QUEUED_REQS);
|
|
async_nif->recycled_req_mutex = enif_mutex_create(NULL);
|
|
STAT_INIT(async_nif, qwait);
|
|
|
|
for (i = 0; i < async_nif->num_queues; i++) {
|
|
struct async_nif_work_queue *q = &async_nif->queues[i];
|
|
q->reqs = fifo_q_new(reqs, ASYNC_NIF_WORKER_QUEUE_SIZE);
|
|
q->reqs_mutex = enif_mutex_create(NULL);
|
|
q->reqs_cnd = enif_cond_create(NULL);
|
|
STAT_INIT(q, qwait);
|
|
}
|
|
|
|
/* Setup the thread pool management. */
|
|
memset(async_nif->worker_entries, 0, sizeof(struct async_nif_worker_entry) * ASYNC_NIF_MAX_WORKERS);
|
|
|
|
/* Start the worker threads. */
|
|
for (i = 0; i < async_nif->num_workers; i++) {
|
|
struct async_nif_worker_entry *we = &async_nif->worker_entries[i];
|
|
we->async_nif = async_nif;
|
|
we->worker_id = i;
|
|
we->q = &async_nif->queues[i % async_nif->num_queues];
|
|
if (enif_thread_create(NULL, &async_nif->worker_entries[i].tid,
|
|
&async_nif_worker_fn, (void*)we, NULL) != 0) {
|
|
async_nif->shutdown = 1;
|
|
|
|
for (j = 0; j < async_nif->num_queues; j++) {
|
|
struct async_nif_work_queue *q = &async_nif->queues[j];
|
|
enif_cond_broadcast(q->reqs_cnd);
|
|
}
|
|
|
|
while(i-- > 0) {
|
|
void *exit_value = 0; /* Ignore this. */
|
|
enif_thread_join(async_nif->worker_entries[i].tid, &exit_value);
|
|
}
|
|
|
|
for (j = 0; j < async_nif->num_queues; j++) {
|
|
struct async_nif_work_queue *q = &async_nif->queues[j];
|
|
enif_mutex_destroy(q->reqs_mutex);
|
|
enif_cond_destroy(q->reqs_cnd);
|
|
}
|
|
|
|
memset(async_nif->worker_entries, 0, sizeof(struct async_nif_worker_entry) * ASYNC_NIF_MAX_WORKERS);
|
|
enif_free(async_nif);
|
|
return NULL;
|
|
}
|
|
}
|
|
return async_nif;
|
|
}
|
|
|
|
static void
|
|
async_nif_upgrade(ErlNifEnv *env)
|
|
{
|
|
__UNUSED(env);
|
|
// TODO:
|
|
}
|
|
|
|
|
|
#if defined(__cplusplus)
|
|
}
|
|
#endif
|
|
|
|
#endif // __ASYNC_NIF_H__
|