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Update to latest async work.

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This commit is contained in:
Gregory Burd 2013-07-26 14:33:40 -04:00
parent 69a850737e
commit 73e071eabe
1 changed files with 39 additions and 26 deletions
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65
c_src/async_nif.h
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@ -53,6 +53,7 @@ struct async_nif_work_queue {
unsigned int depth;
ErlNifMutex *reqs_mutex;
ErlNifCond *reqs_cnd;
struct async_nif_work_queue *next;
STAILQ_HEAD(reqs, async_nif_req_entry) reqs;
};
@ -148,14 +149,14 @@ struct async_nif_state {
#define ASYNC_NIF_LOAD(name, priv) do { \
if (!name##_async_nif_coord) \
name##_async_nif_coord = enif_mutex_create(NULL); \
name##_async_nif_coord = enif_mutex_create("nif_coord load"); \
enif_mutex_lock(name##_async_nif_coord); \
priv = async_nif_load(); \
enif_mutex_unlock(name##_async_nif_coord); \
} while(0);
#define ASYNC_NIF_UNLOAD(name, env, priv) do { \
if (!name##_async_nif_coord) \
name##_async_nif_coord = enif_mutex_create(NULL); \
name##_async_nif_coord = enif_mutex_create("nif_coord unload"); \
enif_mutex_lock(name##_async_nif_coord); \
async_nif_unload(env, priv); \
enif_mutex_unlock(name##_async_nif_coord); \
@ -164,7 +165,7 @@ struct async_nif_state {
} while(0);
#define ASYNC_NIF_UPGRADE(name, env) do { \
if (!name##_async_nif_coord) \
name##_async_nif_coord = enif_mutex_create(NULL); \
name##_async_nif_coord = enif_mutex_create("nif_coord upgrade"); \
enif_mutex_lock(name##_async_nif_coord); \
async_nif_upgrade(env); \
enif_mutex_unlock(name##_async_nif_coord); \
@ -197,7 +198,7 @@ async_nif_reuse_req(struct async_nif_state *async_nif)
env = enif_alloc_env();
if (env) {
req->env = env;
async_nif->num_reqs++;
__sync_fetch_and_add(&async_nif->num_reqs, 1);
} else {
enif_free(req);
req = NULL;
@ -287,9 +288,9 @@ static ERL_NIF_TERM
async_nif_enqueue_req(struct async_nif_state* async_nif, struct async_nif_req_entry *req, int hint)
{
/* Identify the most appropriate worker for this request. */
unsigned int i, qid = 0;
unsigned int i, last_qid, qid = 0;
struct async_nif_work_queue *q = NULL;
double avg_depth = 0.0;
double avg_depth;
/* Either we're choosing a queue based on some affinity/hinted value or we
need to select the next queue in the rotation and atomically update that
@ -297,9 +298,10 @@ async_nif_enqueue_req(struct async_nif_state* async_nif, struct async_nif_req_en
if (hint >= 0) {
qid = (unsigned int)hint;
} else {
qid = async_nif->next_q;
qid = (qid + 1) % async_nif->num_queues;
async_nif->next_q = qid;
do {
last_qid = __sync_fetch_and_add(&async_nif->next_q, 0);
qid = (last_qid + 1) % async_nif->num_queues;
} while (!__sync_bool_compare_and_swap(&async_nif->next_q, last_qid, qid));
}
/* Now we inspect and interate across the set of queues trying to select one
@ -314,8 +316,7 @@ async_nif_enqueue_req(struct async_nif_state* async_nif, struct async_nif_req_en
avg_depth += async_nif->queues[j].depth;
}
}
if (avg_depth != 0)
avg_depth /= n;
if (avg_depth) avg_depth /= n;
/* Lock this queue under consideration, then check for shutdown. While
we hold this lock either a) we're shutting down so exit now or b) this
@ -337,20 +338,23 @@ async_nif_enqueue_req(struct async_nif_state* async_nif, struct async_nif_req_en
}
/* If the for loop finished then we didn't find a suitable queue for this
request, meaning we're backed up so trigger eagain. */
if (i == async_nif->num_queues) {
enif_mutex_unlock(q->reqs_mutex);
return 0;
}
request, meaning we're backed up so trigger eagain. Note that if we left
the loop in this way we hold no lock. */
if (i == async_nif->num_queues) return 0;
/* Add the request to the queue. */
STAILQ_INSERT_TAIL(&q->reqs, req, entries);
q->depth++;
__sync_fetch_and_add(&q->depth, 1);
/* We've selected a queue for this new request now check to make sure there are
enough workers actively processing requests on this queue. */
if (q->depth > q->num_workers)
if (async_nif_start_worker(async_nif, q) == 0) q->num_workers++;
while (q->depth > q->num_workers) {
switch(async_nif_start_worker(async_nif, q)) {
case EINVAL: case ENOMEM: default: return 0;
case EAGAIN: continue;
case 0: __sync_fetch_and_add(&q->num_workers, 1); goto done;
}
}done:;
/* Build the term before releasing the lock so as not to race on the use of
the req pointer (which will soon become invalid in another thread
@ -375,6 +379,7 @@ async_nif_worker_fn(void *arg)
struct async_nif_state *async_nif = we->async_nif;
struct async_nif_work_queue *q = we->q;
struct async_nif_req_entry *req = NULL;
unsigned int tries = async_nif->num_queues;
for(;;) {
/* Examine the request queue, are there things to be done? */
@ -388,7 +393,14 @@ async_nif_worker_fn(void *arg)
/* Queue is empty so we wait for more work to arrive. */
if (q->num_workers > ASYNC_NIF_MIN_WORKERS) {
enif_mutex_unlock(q->reqs_mutex);
break;
if (tries == 0 && q == we->q) break; // we've tried all queues, thread exit
else {
tries--;
__sync_fetch_and_add(&q->num_workers, -1);
q = q->next;
__sync_fetch_and_add(&q->num_workers, 1);
continue; // try another queue
}
} else {
enif_cond_wait(q->reqs_cnd, q->reqs_mutex);
goto check_again_for_work;
@ -398,7 +410,7 @@ async_nif_worker_fn(void *arg)
reqs_mutex lock. Take the request off the queue. */
req = STAILQ_FIRST(&q->reqs);
STAILQ_REMOVE(&q->reqs, req, async_nif_req_entry, entries);
q->depth--;
__sync_fetch_and_add(&q->depth, -1);
/* Ensure that there is at least one other worker thread watching this
queue. */
@ -424,7 +436,7 @@ async_nif_worker_fn(void *arg)
enif_mutex_lock(async_nif->we_mutex);
SLIST_INSERT_HEAD(&async_nif->we_joining, we, entries);
enif_mutex_unlock(async_nif->we_mutex);
q->num_workers--;
__sync_fetch_and_add(&q->num_workers, -1);
enif_thread_exit(0);
return 0;
}
@ -556,15 +568,16 @@ async_nif_load()
async_nif->next_q = 0;
async_nif->shutdown = 0;
STAILQ_INIT(&async_nif->recycled_reqs);
async_nif->recycled_req_mutex = enif_mutex_create(NULL);
async_nif->we_mutex = enif_mutex_create(NULL);
async_nif->recycled_req_mutex = enif_mutex_create("recycled_req");
async_nif->we_mutex = enif_mutex_create("we");
SLIST_INIT(&async_nif->we_joining);
for (i = 0; i < async_nif->num_queues; i++) {
struct async_nif_work_queue *q = &async_nif->queues[i];
STAILQ_INIT(&q->reqs);
q->reqs_mutex = enif_mutex_create(NULL);
q->reqs_cnd = enif_cond_create(NULL);
q->reqs_mutex = enif_mutex_create("reqs");
q->reqs_cnd = enif_cond_create("reqs");
q->next = &async_nif->queues[(i + 1) % num_queues];
}
return async_nif;
}