Update workqueue implementation to use a single queue for the work
Previously I used one queue per worker; now I use one queue for everyone. The "broadcast" code is gone, replaced with an idempotent 'update' operation.
This commit is contained in:
Nick Mathewson
parent
051ad788e0
commit
a52e549124
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@ -5,6 +5,7 @@
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#include "orconfig.h"
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#include <pthread.h>
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#include <signal.h>
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#include "compat.h"
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#include "torlog.h"
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@ -1,4 +1,4 @@
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/* Copyright (c) 2013, The Tor Project, Inc. */
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/* Copyright (c) 2013-2015, The Tor Project, Inc. */
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/* See LICENSE for licensing information */
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#include "orconfig.h"
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@ -13,8 +13,23 @@ struct threadpool_s {
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/** An array of pointers to workerthread_t: one for each running worker
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* thread. */
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struct workerthread_s **threads;
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/** Index of the next thread that we'll give work to.*/
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int next_for_work;
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/** Condition variable that we wait on when we have no work, and which
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* gets signaled when our queue becomes nonempty. */
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tor_cond_t condition;
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/** Queue of pending work that we have to do. */
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TOR_TAILQ_HEAD(, workqueue_entry_s) work;
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/** The current 'update generation' of the threadpool. Any thread that is
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* at an earlier generation needs to run the update function. */
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unsigned generation;
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/** Function that should be run for updates on each thread. */
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int (*update_fn)(void *, void *);
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/** Function to free update arguments if they can't be run. */
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void (*free_update_arg_fn)(void *);
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/** Array of n_threads update arguments. */
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void **update_args;
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/** Number of elements in threads. */
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int n_threads;
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@ -34,10 +49,10 @@ struct workqueue_entry_s {
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/** The next workqueue_entry_t that's pending on the same thread or
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* reply queue. */
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TOR_TAILQ_ENTRY(workqueue_entry_s) next_work;
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/** The thread to which this workqueue_entry_t was assigned. This field
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/** The threadpool to which this workqueue_entry_t was assigned. This field
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* is set when the workqueue_entry_t is created, and won't be cleared until
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* after it's handled in the main thread. */
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struct workerthread_s *on_thread;
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struct threadpool_s *on_pool;
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/** True iff this entry is waiting for a worker to start processing it. */
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uint8_t pending;
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/** Function to run in the worker thread. */
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@ -62,13 +77,10 @@ struct replyqueue_s {
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* contention, each gets its own queue. This breaks the guarantee that that
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* queued work will get executed strictly in order. */
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typedef struct workerthread_s {
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/** Lock to protect all fields of this thread and its queue. */
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tor_mutex_t lock;
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/** Condition variable that we wait on when we have no work, and which
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* gets signaled when our queue becomes nonempty. */
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tor_cond_t condition;
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/** Queue of pending work that we have to do. */
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TOR_TAILQ_HEAD(, workqueue_entry_s) work;
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/** Which thread it this? In range 0..in_pool->n_threads-1 */
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int index;
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/** The pool this thread is a part of. */
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struct threadpool_s *in_pool;
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/** True iff this thread is currently in its loop. (Not currently used.) */
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unsigned is_running;
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/** True iff this thread has crashed or is shut down for some reason. (Not
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@ -81,6 +93,8 @@ typedef struct workerthread_s {
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void *state;
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/** Reply queue to which we pass our results. */
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replyqueue_t *reply_queue;
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/** The current update generation of this thread */
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unsigned generation;
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} workerthread_t;
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static void queue_reply(replyqueue_t *queue, workqueue_entry_t *work);
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@ -132,13 +146,13 @@ workqueue_entry_cancel(workqueue_entry_t *ent)
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{
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int cancelled = 0;
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void *result = NULL;
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tor_mutex_acquire(&ent->on_thread->lock);
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tor_mutex_acquire(&ent->on_pool->lock);
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if (ent->pending) {
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TOR_TAILQ_REMOVE(&ent->on_thread->work, ent, next_work);
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TOR_TAILQ_REMOVE(&ent->on_pool->work, ent, next_work);
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cancelled = 1;
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result = ent->arg;
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}
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tor_mutex_release(&ent->on_thread->lock);
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tor_mutex_release(&ent->on_pool->lock);
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if (cancelled) {
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tor_free(ent);
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@ -146,6 +160,16 @@ workqueue_entry_cancel(workqueue_entry_t *ent)
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return result;
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}
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/**DOCDOC
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must hold lock */
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static int
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worker_thread_has_work(workerthread_t *thread)
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{
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return !TOR_TAILQ_EMPTY(&thread->in_pool->work) ||
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thread->generation != thread->in_pool->generation;
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}
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/**
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* Main function for the worker thread.
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*/
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@ -153,20 +177,39 @@ static void
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worker_thread_main(void *thread_)
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{
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workerthread_t *thread = thread_;
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threadpool_t *pool = thread->in_pool;
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workqueue_entry_t *work;
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int result;
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tor_mutex_acquire(&thread->lock);
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thread->is_running = 1;
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tor_mutex_acquire(&pool->lock);
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while (1) {
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/* lock must be held at this point. */
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while (!TOR_TAILQ_EMPTY(&thread->work)) {
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while (worker_thread_has_work(thread)) {
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/* lock must be held at this point. */
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if (thread->in_pool->generation != thread->generation) {
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void *arg = thread->in_pool->update_args[thread->index];
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thread->in_pool->update_args[thread->index] = NULL;
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int (*update_fn)(void*,void*) = thread->in_pool->update_fn;
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thread->generation = thread->in_pool->generation;
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tor_mutex_release(&pool->lock);
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work = TOR_TAILQ_FIRST(&thread->work);
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TOR_TAILQ_REMOVE(&thread->work, work, next_work);
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int r = update_fn(thread->state, arg);
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if (r < 0) {
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thread->is_running = 0;
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thread->is_shut_down = 1;
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return;
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}
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tor_mutex_acquire(&pool->lock);
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continue;
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}
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work = TOR_TAILQ_FIRST(&pool->work);
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TOR_TAILQ_REMOVE(&pool->work, work, next_work);
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work->pending = 0;
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tor_mutex_release(&thread->lock);
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tor_mutex_release(&pool->lock);
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/* We run the work function without holding the thread lock. This
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* is the main thread's first opportunity to give us more work. */
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@ -175,25 +218,23 @@ worker_thread_main(void *thread_)
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/* Queue the reply for the main thread. */
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queue_reply(thread->reply_queue, work);
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tor_mutex_acquire(&thread->lock);
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/* We may need to exit the thread. */
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if (result >= WQ_RPL_ERROR) {
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thread->is_running = 0;
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thread->is_shut_down = 1;
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tor_mutex_release(&thread->lock);
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return;
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}
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tor_mutex_acquire(&pool->lock);
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}
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/* At this point the lock is held, and there is no work in this thread's
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* queue. */
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/* TODO: Try work-stealing. */
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/* TODO: support an idle-function */
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/* Okay. Now, wait till somebody has work for us. */
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/* XXXX we could just omit waiting and instead */
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thread->waiting = 1;
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if (tor_cond_wait(&thread->condition, &thread->lock, NULL) < 0) {
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if (tor_cond_wait(&pool->condition, &pool->lock, NULL) < 0) {
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/* XXXX ERROR */
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}
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thread->waiting = 0;
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@ -221,14 +262,12 @@ queue_reply(replyqueue_t *queue, workqueue_entry_t *work)
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/** Allocate and start a new worker thread to use state object <b>state</b>,
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* and send responses to <b>replyqueue</b>. */
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static workerthread_t *
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workerthread_new(void *state, replyqueue_t *replyqueue)
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workerthread_new(void *state, threadpool_t *pool, replyqueue_t *replyqueue)
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{
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workerthread_t *thr = tor_malloc_zero(sizeof(workerthread_t));
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tor_mutex_init_for_cond(&thr->lock);
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tor_cond_init(&thr->condition);
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TOR_TAILQ_INIT(&thr->work);
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thr->state = state;
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thr->reply_queue = replyqueue;
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thr->in_pool = pool;
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if (spawn_func(worker_thread_main, thr) < 0) {
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log_err(LD_GENERAL, "Can't launch worker thread.");
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@ -238,30 +277,6 @@ workerthread_new(void *state, replyqueue_t *replyqueue)
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return thr;
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}
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/**
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* Add an item of work to a single worker thread. See threadpool_queue_work(*)
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* for arguments.
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*/
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static workqueue_entry_t *
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workerthread_queue_work(workerthread_t *worker,
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int (*fn)(void *, void *),
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void (*reply_fn)(void *),
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void *arg)
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{
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workqueue_entry_t *ent = workqueue_entry_new(fn, reply_fn, arg);
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tor_mutex_acquire(&worker->lock);
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ent->on_thread = worker;
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ent->pending = 1;
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TOR_TAILQ_INSERT_TAIL(&worker->work, ent, next_work);
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if (worker->waiting) /* XXXX inside or outside of lock?? */
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tor_cond_signal_one(&worker->condition);
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tor_mutex_release(&worker->lock);
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return ent;
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}
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/**
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* Queue an item of work for a thread in a thread pool. The function
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* <b>fn</b> will be run in a worker thread, and will receive as arguments the
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@ -285,20 +300,19 @@ threadpool_queue_work(threadpool_t *pool,
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void (*reply_fn)(void *),
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void *arg)
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{
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workerthread_t *worker;
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workqueue_entry_t *ent = workqueue_entry_new(fn, reply_fn, arg);
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ent->on_pool = pool;
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ent->pending = 1;
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tor_mutex_acquire(&pool->lock);
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/* Pick the next thread in random-access order. */
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worker = pool->threads[pool->next_for_work++];
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if (!worker) {
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tor_mutex_release(&pool->lock);
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return NULL;
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}
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if (pool->next_for_work >= pool->n_threads)
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pool->next_for_work = 0;
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TOR_TAILQ_INSERT_TAIL(&pool->work, ent, next_work);
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tor_mutex_release(&pool->lock);
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return workerthread_queue_work(worker, fn, reply_fn, arg);
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tor_cond_signal_one(&pool->condition);
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return ent;
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}
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/**
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@ -309,30 +323,56 @@ threadpool_queue_work(threadpool_t *pool,
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* <b>arg</b> value is passed to <b>dup_fn</b> once per each thread to
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* make a copy of it.
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*
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* UPDATE FUNCTIONS MUST BE IDEMPOTENT. We do not guarantee that every update
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* will be run. If a new update is scheduled before the old update finishes
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* running, then the new will replace the old in any threads that haven't run
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* it yet.
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*
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* Return 0 on success, -1 on failure.
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*/
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int
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threadpool_queue_for_all(threadpool_t *pool,
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threadpool_queue_update(threadpool_t *pool,
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void *(*dup_fn)(void *),
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int (*fn)(void *, void *),
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void (*reply_fn)(void *),
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void (*free_fn)(void *),
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void *arg)
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{
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int i = 0;
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workerthread_t *worker;
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void *arg_copy;
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while (1) {
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tor_mutex_acquire(&pool->lock);
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if (i >= pool->n_threads) {
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tor_mutex_release(&pool->lock);
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return 0;
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}
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worker = pool->threads[i++];
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tor_mutex_release(&pool->lock);
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int i, n_threads;
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void (*old_args_free_fn)(void *arg);
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void **old_args;
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void **new_args;
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arg_copy = dup_fn ? dup_fn(arg) : arg;
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/* CHECK*/ workerthread_queue_work(worker, fn, reply_fn, arg_copy);
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tor_mutex_acquire(&pool->lock);
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n_threads = pool->n_threads;
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old_args = pool->update_args;
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old_args_free_fn = pool->free_update_arg_fn;
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new_args = tor_calloc(n_threads, sizeof(void*));
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for (i = 0; i < n_threads; ++i) {
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if (dup_fn)
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new_args[i] = dup_fn(arg);
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else
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new_args[i] = arg;
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}
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pool->update_args = new_args;
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pool->free_update_arg_fn = free_fn;
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pool->update_fn = fn;
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++pool->generation;
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tor_mutex_release(&pool->lock);
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tor_cond_signal_all(&pool->condition);
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if (old_args) {
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for (i = 0; i < n_threads; ++i) {
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if (old_args[i] && old_args_free_fn)
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old_args_free_fn(old_args[i]);
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}
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tor_free(old_args);
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}
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return 0;
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}
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/** Launch threads until we have <b>n</b>. */
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@ -346,7 +386,8 @@ threadpool_start_threads(threadpool_t *pool, int n)
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while (pool->n_threads < n) {
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void *state = pool->new_thread_state_fn(pool->new_thread_state_arg);
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workerthread_t *thr = workerthread_new(state, pool->reply_queue);
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workerthread_t *thr = workerthread_new(state, pool, pool->reply_queue);
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thr->index = pool->n_threads;
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if (!thr) {
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tor_mutex_release(&pool->lock);
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@ -375,7 +416,10 @@ threadpool_new(int n_threads,
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{
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threadpool_t *pool;
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pool = tor_malloc_zero(sizeof(threadpool_t));
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tor_mutex_init(&pool->lock);
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tor_mutex_init_nonrecursive(&pool->lock);
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tor_cond_init(&pool->condition);
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TOR_TAILQ_INIT(&pool->work);
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pool->new_thread_state_fn = new_thread_state_fn;
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pool->new_thread_state_arg = arg;
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pool->free_thread_state_fn = free_thread_state_fn;
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@ -447,7 +491,7 @@ replyqueue_process(replyqueue_t *queue)
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workqueue_entry_t *work = TOR_TAILQ_FIRST(&queue->answers);
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TOR_TAILQ_REMOVE(&queue->answers, work, next_work);
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tor_mutex_release(&queue->lock);
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work->on_thread = NULL;
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work->on_pool = NULL;
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work->reply_fn(work->arg);
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workqueue_entry_free(work);
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@ -27,11 +27,11 @@ workqueue_entry_t *threadpool_queue_work(threadpool_t *pool,
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int (*fn)(void *, void *),
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void (*reply_fn)(void *),
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void *arg);
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int threadpool_queue_for_all(threadpool_t *pool,
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void *(*dup_fn)(void *),
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int (*fn)(void *, void *),
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void (*reply_fn)(void *),
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void *arg);
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int threadpool_queue_update(threadpool_t *pool,
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void *(*dup_fn)(void *),
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int (*fn)(void *, void *),
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void (*free_fn)(void *),
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void *arg);
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void *workqueue_entry_cancel(workqueue_entry_t *pending_work);
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threadpool_t *threadpool_new(int n_threads,
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replyqueue_t *replyqueue,
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@ -170,11 +170,6 @@ update_state_threadfn(void *state_, void *work_)
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++state->generation;
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return WQ_RPL_REPLY;
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}
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static void
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update_state_replyfn(void *work_)
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{
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tor_free(work_);
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}
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/** Called when the onion key has changed and we need to spawn new
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* cpuworkers. Close all currently idle cpuworkers, and mark the last
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@ -183,11 +178,11 @@ update_state_replyfn(void *work_)
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void
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cpuworkers_rotate_keyinfo(void)
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{
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if (threadpool_queue_for_all(threadpool,
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worker_state_new,
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update_state_threadfn,
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update_state_replyfn,
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NULL)) {
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if (threadpool_queue_update(threadpool,
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worker_state_new,
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update_state_threadfn,
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worker_state_free,
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NULL)) {
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log_warn(LD_OR, "Failed to queue key update for worker threads.");
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}
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}
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@ -132,7 +132,6 @@ new_state(void *arg)
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/* Every thread gets its own keys. not a problem for benchmarking */
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st->rsa = crypto_pk_new();
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if (crypto_pk_generate_key_with_bits(st->rsa, 1024) < 0) {
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puts("keygen failed");
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crypto_pk_free(st->rsa);
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tor_free(st);
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return NULL;
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@ -213,7 +212,6 @@ add_n_work_items(threadpool_t *tp, int n)
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while (n_queued++ < n) {
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ent = add_work(tp);
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if (! ent) {
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puts("Couldn't add work.");
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tor_event_base_loopexit(tor_libevent_get_base(), NULL);
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return -1;
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}
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@ -238,18 +236,6 @@ add_n_work_items(threadpool_t *tp, int n)
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}
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static int shutting_down = 0;
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static int n_shutdowns_done = 0;
|
||||
|
||||
static void
|
||||
shutdown_reply(void *arg)
|
||||
{
|
||||
(void)arg;
|
||||
tor_assert(shutting_down);
|
||||
++n_shutdowns_done;
|
||||
if (n_shutdowns_done == opt_n_threads) {
|
||||
tor_event_base_loopexit(tor_libevent_get_base(), NULL);
|
||||
}
|
||||
}
|
||||
|
||||
static void
|
||||
replysock_readable_cb(tor_socket_t sock, short what, void *arg)
|
||||
|
|
@ -297,8 +283,8 @@ replysock_readable_cb(tor_socket_t sock, short what, void *arg)
|
|||
n_received+n_successful_cancel == n_sent &&
|
||||
n_sent >= opt_n_items) {
|
||||
shutting_down = 1;
|
||||
threadpool_queue_for_all(tp, NULL,
|
||||
workqueue_do_shutdown, shutdown_reply, NULL);
|
||||
threadpool_queue_update(tp, NULL,
|
||||
workqueue_do_shutdown, NULL, NULL);
|
||||
}
|
||||
}
|
||||
|
||||
|
|
@ -410,8 +396,9 @@ main(int argc, char **argv)
|
|||
|
||||
event_base_loop(tor_libevent_get_base(), 0);
|
||||
|
||||
if (n_sent != opt_n_items || n_received+n_successful_cancel != n_sent ||
|
||||
n_shutdowns_done != opt_n_threads) {
|
||||
if (n_sent != opt_n_items || n_received+n_successful_cancel != n_sent) {
|
||||
printf("%d vs %d\n", n_sent, opt_n_items);
|
||||
printf("%d+%d vs %d\n", n_received, n_successful_cancel, n_sent);
|
||||
puts("FAIL");
|
||||
return 1;
|
||||
} else {
|
||||
|
|
|
|||
Loading…
Reference in New Issue