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|
/*
*
* Copyright 2015-2016 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
#include "src/core/lib/surface/completion_queue.h"
#include <stdio.h>
#include <string.h>
#include <grpc/support/alloc.h>
#include <grpc/support/atm.h>
#include <grpc/support/log.h>
#include <grpc/support/string_util.h>
#include <grpc/support/time.h>
#include "src/core/lib/iomgr/pollset.h"
#include "src/core/lib/iomgr/timer.h"
#include "src/core/lib/profiling/timers.h"
#include "src/core/lib/support/spinlock.h"
#include "src/core/lib/support/string.h"
#include "src/core/lib/surface/api_trace.h"
#include "src/core/lib/surface/call.h"
#include "src/core/lib/surface/event_string.h"
grpc_tracer_flag grpc_trace_operation_failures =
GRPC_TRACER_INITIALIZER(false, "op_failure");
#ifndef NDEBUG
grpc_tracer_flag grpc_trace_pending_tags =
GRPC_TRACER_INITIALIZER(false, "pending_tags");
grpc_tracer_flag grpc_trace_cq_refcount =
GRPC_TRACER_INITIALIZER(false, "cq_refcount");
#endif
typedef struct {
grpc_pollset_worker **worker;
void *tag;
} plucker;
typedef struct {
bool can_get_pollset;
bool can_listen;
size_t (*size)(void);
void (*init)(grpc_pollset *pollset, gpr_mu **mu);
grpc_error *(*kick)(grpc_pollset *pollset,
grpc_pollset_worker *specific_worker);
grpc_error *(*work)(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
grpc_pollset_worker **worker, gpr_timespec now,
gpr_timespec deadline);
void (*shutdown)(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
grpc_closure *closure);
void (*destroy)(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset);
} cq_poller_vtable;
typedef struct non_polling_worker {
gpr_cv cv;
bool kicked;
struct non_polling_worker *next;
struct non_polling_worker *prev;
} non_polling_worker;
typedef struct {
gpr_mu mu;
non_polling_worker *root;
grpc_closure *shutdown;
} non_polling_poller;
static size_t non_polling_poller_size(void) {
return sizeof(non_polling_poller);
}
static void non_polling_poller_init(grpc_pollset *pollset, gpr_mu **mu) {
non_polling_poller *npp = (non_polling_poller *)pollset;
gpr_mu_init(&npp->mu);
*mu = &npp->mu;
}
static void non_polling_poller_destroy(grpc_exec_ctx *exec_ctx,
grpc_pollset *pollset) {
non_polling_poller *npp = (non_polling_poller *)pollset;
gpr_mu_destroy(&npp->mu);
}
static grpc_error *non_polling_poller_work(grpc_exec_ctx *exec_ctx,
grpc_pollset *pollset,
grpc_pollset_worker **worker,
gpr_timespec now,
gpr_timespec deadline) {
non_polling_poller *npp = (non_polling_poller *)pollset;
if (npp->shutdown) return GRPC_ERROR_NONE;
non_polling_worker w;
gpr_cv_init(&w.cv);
if (worker != NULL) *worker = (grpc_pollset_worker *)&w;
if (npp->root == NULL) {
npp->root = w.next = w.prev = &w;
} else {
w.next = npp->root;
w.prev = w.next->prev;
w.next->prev = w.prev->next = &w;
}
w.kicked = false;
while (!npp->shutdown && !w.kicked && !gpr_cv_wait(&w.cv, &npp->mu, deadline))
;
if (&w == npp->root) {
npp->root = w.next;
if (&w == npp->root) {
if (npp->shutdown) {
GRPC_CLOSURE_SCHED(exec_ctx, npp->shutdown, GRPC_ERROR_NONE);
}
npp->root = NULL;
}
}
w.next->prev = w.prev;
w.prev->next = w.next;
gpr_cv_destroy(&w.cv);
if (worker != NULL) *worker = NULL;
return GRPC_ERROR_NONE;
}
static grpc_error *non_polling_poller_kick(
grpc_pollset *pollset, grpc_pollset_worker *specific_worker) {
non_polling_poller *p = (non_polling_poller *)pollset;
if (specific_worker == NULL) specific_worker = (grpc_pollset_worker *)p->root;
if (specific_worker != NULL) {
non_polling_worker *w = (non_polling_worker *)specific_worker;
if (!w->kicked) {
w->kicked = true;
gpr_cv_signal(&w->cv);
}
}
return GRPC_ERROR_NONE;
}
static void non_polling_poller_shutdown(grpc_exec_ctx *exec_ctx,
grpc_pollset *pollset,
grpc_closure *closure) {
non_polling_poller *p = (non_polling_poller *)pollset;
GPR_ASSERT(closure != NULL);
p->shutdown = closure;
if (p->root == NULL) {
GRPC_CLOSURE_SCHED(exec_ctx, closure, GRPC_ERROR_NONE);
} else {
non_polling_worker *w = p->root;
do {
gpr_cv_signal(&w->cv);
w = w->next;
} while (w != p->root);
}
}
static const cq_poller_vtable g_poller_vtable_by_poller_type[] = {
/* GRPC_CQ_DEFAULT_POLLING */
{.can_get_pollset = true,
.can_listen = true,
.size = grpc_pollset_size,
.init = grpc_pollset_init,
.kick = grpc_pollset_kick,
.work = grpc_pollset_work,
.shutdown = grpc_pollset_shutdown,
.destroy = grpc_pollset_destroy},
/* GRPC_CQ_NON_LISTENING */
{.can_get_pollset = true,
.can_listen = false,
.size = grpc_pollset_size,
.init = grpc_pollset_init,
.kick = grpc_pollset_kick,
.work = grpc_pollset_work,
.shutdown = grpc_pollset_shutdown,
.destroy = grpc_pollset_destroy},
/* GRPC_CQ_NON_POLLING */
{.can_get_pollset = false,
.can_listen = false,
.size = non_polling_poller_size,
.init = non_polling_poller_init,
.kick = non_polling_poller_kick,
.work = non_polling_poller_work,
.shutdown = non_polling_poller_shutdown,
.destroy = non_polling_poller_destroy},
};
typedef struct cq_vtable {
grpc_cq_completion_type cq_completion_type;
size_t data_size;
void (*init)(void *data);
void (*shutdown)(grpc_exec_ctx *exec_ctx, grpc_completion_queue *cq);
void (*destroy)(void *data);
bool (*begin_op)(grpc_completion_queue *cq, void *tag);
void (*end_op)(grpc_exec_ctx *exec_ctx, grpc_completion_queue *cq, void *tag,
grpc_error *error,
void (*done)(grpc_exec_ctx *exec_ctx, void *done_arg,
grpc_cq_completion *storage),
void *done_arg, grpc_cq_completion *storage);
grpc_event (*next)(grpc_completion_queue *cq, gpr_timespec deadline,
void *reserved);
grpc_event (*pluck)(grpc_completion_queue *cq, void *tag,
gpr_timespec deadline, void *reserved);
} cq_vtable;
/* Queue that holds the cq_completion_events. Internally uses gpr_mpscq queue
* (a lockfree multiproducer single consumer queue). It uses a queue_lock
* to support multiple consumers.
* Only used in completion queues whose completion_type is GRPC_CQ_NEXT */
typedef struct grpc_cq_event_queue {
/* Spinlock to serialize consumers i.e pop() operations */
gpr_spinlock queue_lock;
gpr_mpscq queue;
/* A lazy counter of number of items in the queue. This is NOT atomically
incremented/decremented along with push/pop operations and hence is only
eventually consistent */
gpr_atm num_queue_items;
} grpc_cq_event_queue;
typedef struct cq_next_data {
/** Completed events for completion-queues of type GRPC_CQ_NEXT */
grpc_cq_event_queue queue;
/** Counter of how many things have ever been queued on this completion queue
useful for avoiding locks to check the queue */
gpr_atm things_queued_ever;
/* Number of outstanding events (+1 if not shut down) */
gpr_atm pending_events;
/** 0 initially. 1 once we initiated shutdown */
bool shutdown_called;
} cq_next_data;
typedef struct cq_pluck_data {
/** Completed events for completion-queues of type GRPC_CQ_PLUCK */
grpc_cq_completion completed_head;
grpc_cq_completion *completed_tail;
/** Number of pending events (+1 if we're not shutdown) */
gpr_atm pending_events;
/** Counter of how many things have ever been queued on this completion queue
useful for avoiding locks to check the queue */
gpr_atm things_queued_ever;
/** 0 initially. 1 once we completed shutting */
/* TODO: (sreek) This is not needed since (shutdown == 1) if and only if
* (pending_events == 0). So consider removing this in future and use
* pending_events */
gpr_atm shutdown;
/** 0 initially. 1 once we initiated shutdown */
bool shutdown_called;
int num_pluckers;
plucker pluckers[GRPC_MAX_COMPLETION_QUEUE_PLUCKERS];
} cq_pluck_data;
/* Completion queue structure */
struct grpc_completion_queue {
/** Once owning_refs drops to zero, we will destroy the cq */
gpr_refcount owning_refs;
gpr_mu *mu;
const cq_vtable *vtable;
const cq_poller_vtable *poller_vtable;
#ifndef NDEBUG
void **outstanding_tags;
size_t outstanding_tag_count;
size_t outstanding_tag_capacity;
#endif
grpc_closure pollset_shutdown_done;
int num_polls;
};
/* Forward declarations */
static void cq_finish_shutdown_next(grpc_exec_ctx *exec_ctx,
grpc_completion_queue *cq);
static void cq_finish_shutdown_pluck(grpc_exec_ctx *exec_ctx,
grpc_completion_queue *cq);
static void cq_shutdown_next(grpc_exec_ctx *exec_ctx,
grpc_completion_queue *cq);
static void cq_shutdown_pluck(grpc_exec_ctx *exec_ctx,
grpc_completion_queue *cq);
static bool cq_begin_op_for_next(grpc_completion_queue *cq, void *tag);
static bool cq_begin_op_for_pluck(grpc_completion_queue *cq, void *tag);
static void cq_end_op_for_next(grpc_exec_ctx *exec_ctx,
grpc_completion_queue *cq, void *tag,
grpc_error *error,
void (*done)(grpc_exec_ctx *exec_ctx,
void *done_arg,
grpc_cq_completion *storage),
void *done_arg, grpc_cq_completion *storage);
static void cq_end_op_for_pluck(grpc_exec_ctx *exec_ctx,
grpc_completion_queue *cq, void *tag,
grpc_error *error,
void (*done)(grpc_exec_ctx *exec_ctx,
void *done_arg,
grpc_cq_completion *storage),
void *done_arg, grpc_cq_completion *storage);
static grpc_event cq_next(grpc_completion_queue *cq, gpr_timespec deadline,
void *reserved);
static grpc_event cq_pluck(grpc_completion_queue *cq, void *tag,
gpr_timespec deadline, void *reserved);
static void cq_init_next(void *data);
static void cq_init_pluck(void *data);
static void cq_destroy_next(void *data);
static void cq_destroy_pluck(void *data);
/* Completion queue vtables based on the completion-type */
static const cq_vtable g_cq_vtable[] = {
/* GRPC_CQ_NEXT */
{.data_size = sizeof(cq_next_data),
.cq_completion_type = GRPC_CQ_NEXT,
.init = cq_init_next,
.shutdown = cq_shutdown_next,
.destroy = cq_destroy_next,
.begin_op = cq_begin_op_for_next,
.end_op = cq_end_op_for_next,
.next = cq_next,
.pluck = NULL},
/* GRPC_CQ_PLUCK */
{.data_size = sizeof(cq_pluck_data),
.cq_completion_type = GRPC_CQ_PLUCK,
.init = cq_init_pluck,
.shutdown = cq_shutdown_pluck,
.destroy = cq_destroy_pluck,
.begin_op = cq_begin_op_for_pluck,
.end_op = cq_end_op_for_pluck,
.next = NULL,
.pluck = cq_pluck},
};
#define DATA_FROM_CQ(cq) ((void *)(cq + 1))
#define POLLSET_FROM_CQ(cq) \
((grpc_pollset *)(cq->vtable->data_size + (char *)DATA_FROM_CQ(cq)))
grpc_tracer_flag grpc_cq_pluck_trace =
GRPC_TRACER_INITIALIZER(true, "queue_pluck");
grpc_tracer_flag grpc_cq_event_timeout_trace =
GRPC_TRACER_INITIALIZER(true, "queue_timeout");
#define GRPC_SURFACE_TRACE_RETURNED_EVENT(cq, event) \
if (GRPC_TRACER_ON(grpc_api_trace) && \
(GRPC_TRACER_ON(grpc_cq_pluck_trace) || \
(event)->type != GRPC_QUEUE_TIMEOUT)) { \
char *_ev = grpc_event_string(event); \
gpr_log(GPR_INFO, "RETURN_EVENT[%p]: %s", cq, _ev); \
gpr_free(_ev); \
}
static void on_pollset_shutdown_done(grpc_exec_ctx *exec_ctx, void *cq,
grpc_error *error);
static void cq_event_queue_init(grpc_cq_event_queue *q) {
gpr_mpscq_init(&q->queue);
q->queue_lock = GPR_SPINLOCK_INITIALIZER;
gpr_atm_no_barrier_store(&q->num_queue_items, 0);
}
static void cq_event_queue_destroy(grpc_cq_event_queue *q) {
gpr_mpscq_destroy(&q->queue);
}
static bool cq_event_queue_push(grpc_cq_event_queue *q, grpc_cq_completion *c) {
gpr_mpscq_push(&q->queue, (gpr_mpscq_node *)c);
return gpr_atm_no_barrier_fetch_add(&q->num_queue_items, 1) == 0;
}
static grpc_cq_completion *cq_event_queue_pop(grpc_cq_event_queue *q) {
grpc_cq_completion *c = NULL;
if (gpr_spinlock_trylock(&q->queue_lock)) {
c = (grpc_cq_completion *)gpr_mpscq_pop(&q->queue);
gpr_spinlock_unlock(&q->queue_lock);
}
if (c) {
gpr_atm_no_barrier_fetch_add(&q->num_queue_items, -1);
}
return c;
}
/* Note: The counter is not incremented/decremented atomically with push/pop.
* The count is only eventually consistent */
static long cq_event_queue_num_items(grpc_cq_event_queue *q) {
return (long)gpr_atm_no_barrier_load(&q->num_queue_items);
}
grpc_completion_queue *grpc_completion_queue_create_internal(
grpc_cq_completion_type completion_type,
grpc_cq_polling_type polling_type) {
grpc_completion_queue *cq;
GPR_TIMER_BEGIN("grpc_completion_queue_create_internal", 0);
GRPC_API_TRACE(
"grpc_completion_queue_create_internal(completion_type=%d, "
"polling_type=%d)",
2, (completion_type, polling_type));
const cq_vtable *vtable = &g_cq_vtable[completion_type];
const cq_poller_vtable *poller_vtable =
&g_poller_vtable_by_poller_type[polling_type];
cq = (grpc_completion_queue *)gpr_zalloc(sizeof(grpc_completion_queue) +
vtable->data_size +
poller_vtable->size());
cq->vtable = vtable;
cq->poller_vtable = poller_vtable;
/* One for destroy(), one for pollset_shutdown */
gpr_ref_init(&cq->owning_refs, 2);
poller_vtable->init(POLLSET_FROM_CQ(cq), &cq->mu);
vtable->init(DATA_FROM_CQ(cq));
GRPC_CLOSURE_INIT(&cq->pollset_shutdown_done, on_pollset_shutdown_done, cq,
grpc_schedule_on_exec_ctx);
GPR_TIMER_END("grpc_completion_queue_create_internal", 0);
return cq;
}
static void cq_init_next(void *ptr) {
cq_next_data *cqd = (cq_next_data *)ptr;
/* Initial count is dropped by grpc_completion_queue_shutdown */
gpr_atm_no_barrier_store(&cqd->pending_events, 1);
cqd->shutdown_called = false;
gpr_atm_no_barrier_store(&cqd->things_queued_ever, 0);
cq_event_queue_init(&cqd->queue);
}
static void cq_destroy_next(void *ptr) {
cq_next_data *cqd = (cq_next_data *)ptr;
GPR_ASSERT(cq_event_queue_num_items(&cqd->queue) == 0);
cq_event_queue_destroy(&cqd->queue);
}
static void cq_init_pluck(void *ptr) {
cq_pluck_data *cqd = (cq_pluck_data *)ptr;
/* Initial count is dropped by grpc_completion_queue_shutdown */
gpr_atm_no_barrier_store(&cqd->pending_events, 1);
cqd->completed_tail = &cqd->completed_head;
cqd->completed_head.next = (uintptr_t)cqd->completed_tail;
gpr_atm_no_barrier_store(&cqd->shutdown, 0);
cqd->shutdown_called = false;
cqd->num_pluckers = 0;
gpr_atm_no_barrier_store(&cqd->things_queued_ever, 0);
}
static void cq_destroy_pluck(void *ptr) {
cq_pluck_data *cqd = (cq_pluck_data *)ptr;
GPR_ASSERT(cqd->completed_head.next == (uintptr_t)&cqd->completed_head);
}
grpc_cq_completion_type grpc_get_cq_completion_type(grpc_completion_queue *cq) {
return cq->vtable->cq_completion_type;
}
int grpc_get_cq_poll_num(grpc_completion_queue *cq) {
int cur_num_polls;
gpr_mu_lock(cq->mu);
cur_num_polls = cq->num_polls;
gpr_mu_unlock(cq->mu);
return cur_num_polls;
}
#ifndef NDEBUG
void grpc_cq_internal_ref(grpc_completion_queue *cq, const char *reason,
const char *file, int line) {
if (GRPC_TRACER_ON(grpc_trace_cq_refcount)) {
gpr_atm val = gpr_atm_no_barrier_load(&cq->owning_refs.count);
gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG,
"CQ:%p ref %" PRIdPTR " -> %" PRIdPTR " %s", cq, val, val + 1,
reason);
}
#else
void grpc_cq_internal_ref(grpc_completion_queue *cq) {
#endif
gpr_ref(&cq->owning_refs);
}
static void on_pollset_shutdown_done(grpc_exec_ctx *exec_ctx, void *arg,
grpc_error *error) {
grpc_completion_queue *cq = (grpc_completion_queue *)arg;
GRPC_CQ_INTERNAL_UNREF(exec_ctx, cq, "pollset_destroy");
}
#ifndef NDEBUG
void grpc_cq_internal_unref(grpc_exec_ctx *exec_ctx, grpc_completion_queue *cq,
const char *reason, const char *file, int line) {
if (GRPC_TRACER_ON(grpc_trace_cq_refcount)) {
gpr_atm val = gpr_atm_no_barrier_load(&cq->owning_refs.count);
gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG,
"CQ:%p unref %" PRIdPTR " -> %" PRIdPTR " %s", cq, val, val - 1,
reason);
}
#else
void grpc_cq_internal_unref(grpc_exec_ctx *exec_ctx,
grpc_completion_queue *cq) {
#endif
if (gpr_unref(&cq->owning_refs)) {
cq->vtable->destroy(DATA_FROM_CQ(cq));
cq->poller_vtable->destroy(exec_ctx, POLLSET_FROM_CQ(cq));
#ifndef NDEBUG
gpr_free(cq->outstanding_tags);
#endif
gpr_free(cq);
}
}
#ifndef NDEBUG
static void cq_check_tag(grpc_completion_queue *cq, void *tag, bool lock_cq) {
int found = 0;
if (lock_cq) {
gpr_mu_lock(cq->mu);
}
for (int i = 0; i < (int)cq->outstanding_tag_count; i++) {
if (cq->outstanding_tags[i] == tag) {
cq->outstanding_tag_count--;
GPR_SWAP(void *, cq->outstanding_tags[i],
cq->outstanding_tags[cq->outstanding_tag_count]);
found = 1;
break;
}
}
if (lock_cq) {
gpr_mu_unlock(cq->mu);
}
GPR_ASSERT(found);
}
#else
static void cq_check_tag(grpc_completion_queue *cq, void *tag, bool lock_cq) {}
#endif
/* Atomically increments a counter only if the counter is not zero. Returns
* true if the increment was successful; false if the counter is zero */
static bool atm_inc_if_nonzero(gpr_atm *counter) {
while (true) {
gpr_atm count = gpr_atm_no_barrier_load(counter);
/* If zero, we are done. If not, we must to a CAS (instead of an atomic
* increment) to maintain the contract: do not increment the counter if it
* is zero. */
if (count == 0) {
return false;
} else if (gpr_atm_no_barrier_cas(counter, count, count + 1)) {
break;
}
}
return true;
}
static bool cq_begin_op_for_next(grpc_completion_queue *cq, void *tag) {
cq_next_data *cqd = DATA_FROM_CQ(cq);
return atm_inc_if_nonzero(&cqd->pending_events);
}
static bool cq_begin_op_for_pluck(grpc_completion_queue *cq, void *tag) {
cq_pluck_data *cqd = DATA_FROM_CQ(cq);
return atm_inc_if_nonzero(&cqd->pending_events);
}
bool grpc_cq_begin_op(grpc_completion_queue *cq, void *tag) {
#ifndef NDEBUG
gpr_mu_lock(cq->mu);
if (cq->outstanding_tag_count == cq->outstanding_tag_capacity) {
cq->outstanding_tag_capacity = GPR_MAX(4, 2 * cq->outstanding_tag_capacity);
cq->outstanding_tags = (void **)gpr_realloc(
cq->outstanding_tags,
sizeof(*cq->outstanding_tags) * cq->outstanding_tag_capacity);
}
cq->outstanding_tags[cq->outstanding_tag_count++] = tag;
gpr_mu_unlock(cq->mu);
#endif
return cq->vtable->begin_op(cq, tag);
}
/* Queue a GRPC_OP_COMPLETED operation to a completion queue (with a
* completion
* type of GRPC_CQ_NEXT) */
static void cq_end_op_for_next(grpc_exec_ctx *exec_ctx,
grpc_completion_queue *cq, void *tag,
grpc_error *error,
void (*done)(grpc_exec_ctx *exec_ctx,
void *done_arg,
grpc_cq_completion *storage),
void *done_arg, grpc_cq_completion *storage) {
GPR_TIMER_BEGIN("cq_end_op_for_next", 0);
if (GRPC_TRACER_ON(grpc_api_trace) ||
(GRPC_TRACER_ON(grpc_trace_operation_failures) &&
error != GRPC_ERROR_NONE)) {
const char *errmsg = grpc_error_string(error);
GRPC_API_TRACE(
"cq_end_op_for_next(exec_ctx=%p, cq=%p, tag=%p, error=%s, "
"done=%p, done_arg=%p, storage=%p)",
7, (exec_ctx, cq, tag, errmsg, done, done_arg, storage));
if (GRPC_TRACER_ON(grpc_trace_operation_failures) &&
error != GRPC_ERROR_NONE) {
gpr_log(GPR_ERROR, "Operation failed: tag=%p, error=%s", tag, errmsg);
}
}
cq_next_data *cqd = DATA_FROM_CQ(cq);
int is_success = (error == GRPC_ERROR_NONE);
storage->tag = tag;
storage->done = done;
storage->done_arg = done_arg;
storage->next = (uintptr_t)(is_success);
cq_check_tag(cq, tag, true); /* Used in debug builds only */
/* Add the completion to the queue */
bool is_first = cq_event_queue_push(&cqd->queue, storage);
gpr_atm_no_barrier_fetch_add(&cqd->things_queued_ever, 1);
bool will_definitely_shutdown =
gpr_atm_no_barrier_load(&cqd->pending_events) == 1;
if (!will_definitely_shutdown) {
/* Only kick if this is the first item queued */
if (is_first) {
gpr_mu_lock(cq->mu);
grpc_error *kick_error =
cq->poller_vtable->kick(POLLSET_FROM_CQ(cq), NULL);
gpr_mu_unlock(cq->mu);
if (kick_error != GRPC_ERROR_NONE) {
const char *msg = grpc_error_string(kick_error);
gpr_log(GPR_ERROR, "Kick failed: %s", msg);
GRPC_ERROR_UNREF(kick_error);
}
}
if (gpr_atm_full_fetch_add(&cqd->pending_events, -1) == 1) {
GRPC_CQ_INTERNAL_REF(cq, "shutting_down");
gpr_mu_lock(cq->mu);
cq_finish_shutdown_next(exec_ctx, cq);
gpr_mu_unlock(cq->mu);
GRPC_CQ_INTERNAL_UNREF(exec_ctx, cq, "shutting_down");
}
} else {
GRPC_CQ_INTERNAL_REF(cq, "shutting_down");
gpr_atm_rel_store(&cqd->pending_events, 0);
gpr_mu_lock(cq->mu);
cq_finish_shutdown_next(exec_ctx, cq);
gpr_mu_unlock(cq->mu);
GRPC_CQ_INTERNAL_UNREF(exec_ctx, cq, "shutting_down");
}
GPR_TIMER_END("cq_end_op_for_next", 0);
GRPC_ERROR_UNREF(error);
}
/* Queue a GRPC_OP_COMPLETED operation to a completion queue (with a
* completion
* type of GRPC_CQ_PLUCK) */
static void cq_end_op_for_pluck(grpc_exec_ctx *exec_ctx,
grpc_completion_queue *cq, void *tag,
grpc_error *error,
void (*done)(grpc_exec_ctx *exec_ctx,
void *done_arg,
grpc_cq_completion *storage),
void *done_arg, grpc_cq_completion *storage) {
cq_pluck_data *cqd = DATA_FROM_CQ(cq);
int is_success = (error == GRPC_ERROR_NONE);
GPR_TIMER_BEGIN("cq_end_op_for_pluck", 0);
if (GRPC_TRACER_ON(grpc_api_trace) ||
(GRPC_TRACER_ON(grpc_trace_operation_failures) &&
error != GRPC_ERROR_NONE)) {
const char *errmsg = grpc_error_string(error);
GRPC_API_TRACE(
"cq_end_op_for_pluck(exec_ctx=%p, cq=%p, tag=%p, error=%s, "
"done=%p, done_arg=%p, storage=%p)",
7, (exec_ctx, cq, tag, errmsg, done, done_arg, storage));
if (GRPC_TRACER_ON(grpc_trace_operation_failures) &&
error != GRPC_ERROR_NONE) {
gpr_log(GPR_ERROR, "Operation failed: tag=%p, error=%s", tag, errmsg);
}
}
storage->tag = tag;
storage->done = done;
storage->done_arg = done_arg;
storage->next = ((uintptr_t)&cqd->completed_head) | ((uintptr_t)(is_success));
gpr_mu_lock(cq->mu);
cq_check_tag(cq, tag, false); /* Used in debug builds only */
/* Add to the list of completions */
gpr_atm_no_barrier_fetch_add(&cqd->things_queued_ever, 1);
cqd->completed_tail->next =
((uintptr_t)storage) | (1u & (uintptr_t)cqd->completed_tail->next);
cqd->completed_tail = storage;
if (gpr_atm_full_fetch_add(&cqd->pending_events, -1) == 1) {
cq_finish_shutdown_pluck(exec_ctx, cq);
gpr_mu_unlock(cq->mu);
} else {
grpc_pollset_worker *pluck_worker = NULL;
for (int i = 0; i < cqd->num_pluckers; i++) {
if (cqd->pluckers[i].tag == tag) {
pluck_worker = *cqd->pluckers[i].worker;
break;
}
}
grpc_error *kick_error =
cq->poller_vtable->kick(POLLSET_FROM_CQ(cq), pluck_worker);
gpr_mu_unlock(cq->mu);
if (kick_error != GRPC_ERROR_NONE) {
const char *msg = grpc_error_string(kick_error);
gpr_log(GPR_ERROR, "Kick failed: %s", msg);
GRPC_ERROR_UNREF(kick_error);
}
}
GPR_TIMER_END("cq_end_op_for_pluck", 0);
GRPC_ERROR_UNREF(error);
}
void grpc_cq_end_op(grpc_exec_ctx *exec_ctx, grpc_completion_queue *cq,
void *tag, grpc_error *error,
void (*done)(grpc_exec_ctx *exec_ctx, void *done_arg,
grpc_cq_completion *storage),
void *done_arg, grpc_cq_completion *storage) {
cq->vtable->end_op(exec_ctx, cq, tag, error, done, done_arg, storage);
}
typedef struct {
gpr_atm last_seen_things_queued_ever;
grpc_completion_queue *cq;
gpr_timespec deadline;
grpc_cq_completion *stolen_completion;
void *tag; /* for pluck */
bool first_loop;
} cq_is_finished_arg;
static bool cq_is_next_finished(grpc_exec_ctx *exec_ctx, void *arg) {
cq_is_finished_arg *a = (cq_is_finished_arg *)arg;
grpc_completion_queue *cq = a->cq;
cq_next_data *cqd = DATA_FROM_CQ(cq);
GPR_ASSERT(a->stolen_completion == NULL);
gpr_atm current_last_seen_things_queued_ever =
gpr_atm_no_barrier_load(&cqd->things_queued_ever);
if (current_last_seen_things_queued_ever != a->last_seen_things_queued_ever) {
a->last_seen_things_queued_ever =
gpr_atm_no_barrier_load(&cqd->things_queued_ever);
/* Pop a cq_completion from the queue. Returns NULL if the queue is empty
* might return NULL in some cases even if the queue is not empty; but
* that
* is ok and doesn't affect correctness. Might effect the tail latencies a
* bit) */
a->stolen_completion = cq_event_queue_pop(&cqd->queue);
if (a->stolen_completion != NULL) {
return true;
}
}
return !a->first_loop &&
gpr_time_cmp(a->deadline, gpr_now(a->deadline.clock_type)) < 0;
}
#ifndef NDEBUG
static void dump_pending_tags(grpc_completion_queue *cq) {
if (!GRPC_TRACER_ON(grpc_trace_pending_tags)) return;
gpr_strvec v;
gpr_strvec_init(&v);
gpr_strvec_add(&v, gpr_strdup("PENDING TAGS:"));
gpr_mu_lock(cq->mu);
for (size_t i = 0; i < cq->outstanding_tag_count; i++) {
char *s;
gpr_asprintf(&s, " %p", cq->outstanding_tags[i]);
gpr_strvec_add(&v, s);
}
gpr_mu_unlock(cq->mu);
char *out = gpr_strvec_flatten(&v, NULL);
gpr_strvec_destroy(&v);
gpr_log(GPR_DEBUG, "%s", out);
gpr_free(out);
}
#else
static void dump_pending_tags(grpc_completion_queue *cq) {}
#endif
static grpc_event cq_next(grpc_completion_queue *cq, gpr_timespec deadline,
void *reserved) {
grpc_event ret;
gpr_timespec now;
cq_next_data *cqd = DATA_FROM_CQ(cq);
GPR_TIMER_BEGIN("grpc_completion_queue_next", 0);
GRPC_API_TRACE(
"grpc_completion_queue_next("
"cq=%p, "
"deadline=gpr_timespec { tv_sec: %" PRId64
", tv_nsec: %d, clock_type: %d }, "
"reserved=%p)",
5, (cq, deadline.tv_sec, deadline.tv_nsec, (int)deadline.clock_type,
reserved));
GPR_ASSERT(!reserved);
dump_pending_tags(cq);
deadline = gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC);
GRPC_CQ_INTERNAL_REF(cq, "next");
cq_is_finished_arg is_finished_arg = {
.last_seen_things_queued_ever =
gpr_atm_no_barrier_load(&cqd->things_queued_ever),
.cq = cq,
.deadline = deadline,
.stolen_completion = NULL,
.tag = NULL,
.first_loop = true};
grpc_exec_ctx exec_ctx =
GRPC_EXEC_CTX_INITIALIZER(0, cq_is_next_finished, &is_finished_arg);
for (;;) {
gpr_timespec iteration_deadline = deadline;
if (is_finished_arg.stolen_completion != NULL) {
grpc_cq_completion *c = is_finished_arg.stolen_completion;
is_finished_arg.stolen_completion = NULL;
ret.type = GRPC_OP_COMPLETE;
ret.success = c->next & 1u;
ret.tag = c->tag;
c->done(&exec_ctx, c->done_arg, c);
break;
}
grpc_cq_completion *c = cq_event_queue_pop(&cqd->queue);
if (c != NULL) {
ret.type = GRPC_OP_COMPLETE;
ret.success = c->next & 1u;
ret.tag = c->tag;
c->done(&exec_ctx, c->done_arg, c);
break;
} else {
/* If c == NULL it means either the queue is empty OR in an transient
inconsistent state. If it is the latter, we shold do a 0-timeout poll
so that the thread comes back quickly from poll to make a second
attempt at popping. Not doing this can potentially deadlock this
thread forever (if the deadline is infinity) */
if (cq_event_queue_num_items(&cqd->queue) > 0) {
iteration_deadline = gpr_time_0(GPR_CLOCK_MONOTONIC);
}
}
if (gpr_atm_no_barrier_load(&cqd->pending_events) == 0) {
/* Before returning, check if the queue has any items left over (since
gpr_mpscq_pop() can sometimes return NULL even if the queue is not
empty. If so, keep retrying but do not return GRPC_QUEUE_SHUTDOWN */
if (cq_event_queue_num_items(&cqd->queue) > 0) {
/* Go to the beginning of the loop. No point doing a poll because
(cq->shutdown == true) is only possible when there is no pending
work (i.e cq->pending_events == 0) and any outstanding completion
events should have already been queued on this cq */
continue;
}
memset(&ret, 0, sizeof(ret));
ret.type = GRPC_QUEUE_SHUTDOWN;
break;
}
now = gpr_now(GPR_CLOCK_MONOTONIC);
if (!is_finished_arg.first_loop && gpr_time_cmp(now, deadline) >= 0) {
memset(&ret, 0, sizeof(ret));
ret.type = GRPC_QUEUE_TIMEOUT;
dump_pending_tags(cq);
break;
}
/* The main polling work happens in grpc_pollset_work */
gpr_mu_lock(cq->mu);
cq->num_polls++;
grpc_error *err = cq->poller_vtable->work(&exec_ctx, POLLSET_FROM_CQ(cq),
NULL, now, iteration_deadline);
gpr_mu_unlock(cq->mu);
if (err != GRPC_ERROR_NONE) {
const char *msg = grpc_error_string(err);
gpr_log(GPR_ERROR, "Completion queue next failed: %s", msg);
GRPC_ERROR_UNREF(err);
memset(&ret, 0, sizeof(ret));
ret.type = GRPC_QUEUE_TIMEOUT;
dump_pending_tags(cq);
break;
}
is_finished_arg.first_loop = false;
}
if (cq_event_queue_num_items(&cqd->queue) > 0 &&
gpr_atm_no_barrier_load(&cqd->pending_events) > 0) {
gpr_mu_lock(cq->mu);
cq->poller_vtable->kick(POLLSET_FROM_CQ(cq), NULL);
gpr_mu_unlock(cq->mu);
}
GRPC_SURFACE_TRACE_RETURNED_EVENT(cq, &ret);
GRPC_CQ_INTERNAL_UNREF(&exec_ctx, cq, "next");
grpc_exec_ctx_finish(&exec_ctx);
GPR_ASSERT(is_finished_arg.stolen_completion == NULL);
GPR_TIMER_END("grpc_completion_queue_next", 0);
return ret;
}
/* Finishes the completion queue shutdown. This means that there are no more
completion events / tags expected from the completion queue
- Must be called under completion queue lock
- Must be called only once in completion queue's lifetime
- grpc_completion_queue_shutdown() MUST have been called before calling
this function */
static void cq_finish_shutdown_next(grpc_exec_ctx *exec_ctx,
grpc_completion_queue *cq) {
cq_next_data *cqd = DATA_FROM_CQ(cq);
GPR_ASSERT(cqd->shutdown_called);
GPR_ASSERT(gpr_atm_no_barrier_load(&cqd->pending_events) == 0);
cq->poller_vtable->shutdown(exec_ctx, POLLSET_FROM_CQ(cq),
&cq->pollset_shutdown_done);
}
static void cq_shutdown_next(grpc_exec_ctx *exec_ctx,
grpc_completion_queue *cq) {
cq_next_data *cqd = DATA_FROM_CQ(cq);
/* Need an extra ref for cq here because:
* We call cq_finish_shutdown_next() below, that would call pollset shutdown.
* Pollset shutdown decrements the cq ref count which can potentially destroy
* the cq (if that happens to be the last ref).
* Creating an extra ref here prevents the cq from getting destroyed while
* this function is still active */
GRPC_CQ_INTERNAL_REF(cq, "shutting_down");
gpr_mu_lock(cq->mu);
if (cqd->shutdown_called) {
gpr_mu_unlock(cq->mu);
GRPC_CQ_INTERNAL_UNREF(exec_ctx, cq, "shutting_down");
return;
}
cqd->shutdown_called = true;
if (gpr_atm_full_fetch_add(&cqd->pending_events, -1) == 1) {
cq_finish_shutdown_next(exec_ctx, cq);
}
gpr_mu_unlock(cq->mu);
GRPC_CQ_INTERNAL_UNREF(exec_ctx, cq, "shutting_down");
}
grpc_event grpc_completion_queue_next(grpc_completion_queue *cq,
gpr_timespec deadline, void *reserved) {
return cq->vtable->next(cq, deadline, reserved);
}
static int add_plucker(grpc_completion_queue *cq, void *tag,
grpc_pollset_worker **worker) {
cq_pluck_data *cqd = DATA_FROM_CQ(cq);
if (cqd->num_pluckers == GRPC_MAX_COMPLETION_QUEUE_PLUCKERS) {
return 0;
}
cqd->pluckers[cqd->num_pluckers].tag = tag;
cqd->pluckers[cqd->num_pluckers].worker = worker;
cqd->num_pluckers++;
return 1;
}
static void del_plucker(grpc_completion_queue *cq, void *tag,
grpc_pollset_worker **worker) {
cq_pluck_data *cqd = DATA_FROM_CQ(cq);
for (int i = 0; i < cqd->num_pluckers; i++) {
if (cqd->pluckers[i].tag == tag && cqd->pluckers[i].worker == worker) {
cqd->num_pluckers--;
GPR_SWAP(plucker, cqd->pluckers[i], cqd->pluckers[cqd->num_pluckers]);
return;
}
}
GPR_UNREACHABLE_CODE(return );
}
static bool cq_is_pluck_finished(grpc_exec_ctx *exec_ctx, void *arg) {
cq_is_finished_arg *a = (cq_is_finished_arg *)arg;
grpc_completion_queue *cq = a->cq;
cq_pluck_data *cqd = DATA_FROM_CQ(cq);
GPR_ASSERT(a->stolen_completion == NULL);
gpr_atm current_last_seen_things_queued_ever =
gpr_atm_no_barrier_load(&cqd->things_queued_ever);
if (current_last_seen_things_queued_ever != a->last_seen_things_queued_ever) {
gpr_mu_lock(cq->mu);
a->last_seen_things_queued_ever =
gpr_atm_no_barrier_load(&cqd->things_queued_ever);
grpc_cq_completion *c;
grpc_cq_completion *prev = &cqd->completed_head;
while ((c = (grpc_cq_completion *)(prev->next & ~(uintptr_t)1)) !=
&cqd->completed_head) {
if (c->tag == a->tag) {
prev->next = (prev->next & (uintptr_t)1) | (c->next & ~(uintptr_t)1);
if (c == cqd->completed_tail) {
cqd->completed_tail = prev;
}
gpr_mu_unlock(cq->mu);
a->stolen_completion = c;
return true;
}
prev = c;
}
gpr_mu_unlock(cq->mu);
}
return !a->first_loop &&
gpr_time_cmp(a->deadline, gpr_now(a->deadline.clock_type)) < 0;
}
static grpc_event cq_pluck(grpc_completion_queue *cq, void *tag,
gpr_timespec deadline, void *reserved) {
grpc_event ret;
grpc_cq_completion *c;
grpc_cq_completion *prev;
grpc_pollset_worker *worker = NULL;
gpr_timespec now;
cq_pluck_data *cqd = DATA_FROM_CQ(cq);
GPR_TIMER_BEGIN("grpc_completion_queue_pluck", 0);
if (GRPC_TRACER_ON(grpc_cq_pluck_trace)) {
GRPC_API_TRACE(
"grpc_completion_queue_pluck("
"cq=%p, tag=%p, "
"deadline=gpr_timespec { tv_sec: %" PRId64
", tv_nsec: %d, clock_type: %d }, "
"reserved=%p)",
6, (cq, tag, deadline.tv_sec, deadline.tv_nsec,
(int)deadline.clock_type, reserved));
}
GPR_ASSERT(!reserved);
dump_pending_tags(cq);
deadline = gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC);
GRPC_CQ_INTERNAL_REF(cq, "pluck");
gpr_mu_lock(cq->mu);
cq_is_finished_arg is_finished_arg = {
.last_seen_things_queued_ever =
gpr_atm_no_barrier_load(&cqd->things_queued_ever),
.cq = cq,
.deadline = deadline,
.stolen_completion = NULL,
.tag = tag,
.first_loop = true};
grpc_exec_ctx exec_ctx =
GRPC_EXEC_CTX_INITIALIZER(0, cq_is_pluck_finished, &is_finished_arg);
for (;;) {
if (is_finished_arg.stolen_completion != NULL) {
gpr_mu_unlock(cq->mu);
c = is_finished_arg.stolen_completion;
is_finished_arg.stolen_completion = NULL;
ret.type = GRPC_OP_COMPLETE;
ret.success = c->next & 1u;
ret.tag = c->tag;
c->done(&exec_ctx, c->done_arg, c);
break;
}
prev = &cqd->completed_head;
while ((c = (grpc_cq_completion *)(prev->next & ~(uintptr_t)1)) !=
&cqd->completed_head) {
if (c->tag == tag) {
prev->next = (prev->next & (uintptr_t)1) | (c->next & ~(uintptr_t)1);
if (c == cqd->completed_tail) {
cqd->completed_tail = prev;
}
gpr_mu_unlock(cq->mu);
ret.type = GRPC_OP_COMPLETE;
ret.success = c->next & 1u;
ret.tag = c->tag;
c->done(&exec_ctx, c->done_arg, c);
goto done;
}
prev = c;
}
if (gpr_atm_no_barrier_load(&cqd->shutdown)) {
gpr_mu_unlock(cq->mu);
memset(&ret, 0, sizeof(ret));
ret.type = GRPC_QUEUE_SHUTDOWN;
break;
}
if (!add_plucker(cq, tag, &worker)) {
gpr_log(GPR_DEBUG,
"Too many outstanding grpc_completion_queue_pluck calls: maximum "
"is %d",
GRPC_MAX_COMPLETION_QUEUE_PLUCKERS);
gpr_mu_unlock(cq->mu);
memset(&ret, 0, sizeof(ret));
/* TODO(ctiller): should we use a different result here */
ret.type = GRPC_QUEUE_TIMEOUT;
dump_pending_tags(cq);
break;
}
now = gpr_now(GPR_CLOCK_MONOTONIC);
if (!is_finished_arg.first_loop && gpr_time_cmp(now, deadline) >= 0) {
del_plucker(cq, tag, &worker);
gpr_mu_unlock(cq->mu);
memset(&ret, 0, sizeof(ret));
ret.type = GRPC_QUEUE_TIMEOUT;
dump_pending_tags(cq);
break;
}
cq->num_polls++;
grpc_error *err = cq->poller_vtable->work(&exec_ctx, POLLSET_FROM_CQ(cq),
&worker, now, deadline);
if (err != GRPC_ERROR_NONE) {
del_plucker(cq, tag, &worker);
gpr_mu_unlock(cq->mu);
const char *msg = grpc_error_string(err);
gpr_log(GPR_ERROR, "Completion queue pluck failed: %s", msg);
GRPC_ERROR_UNREF(err);
memset(&ret, 0, sizeof(ret));
ret.type = GRPC_QUEUE_TIMEOUT;
dump_pending_tags(cq);
break;
}
is_finished_arg.first_loop = false;
del_plucker(cq, tag, &worker);
}
done:
GRPC_SURFACE_TRACE_RETURNED_EVENT(cq, &ret);
GRPC_CQ_INTERNAL_UNREF(&exec_ctx, cq, "pluck");
grpc_exec_ctx_finish(&exec_ctx);
GPR_ASSERT(is_finished_arg.stolen_completion == NULL);
GPR_TIMER_END("grpc_completion_queue_pluck", 0);
return ret;
}
grpc_event grpc_completion_queue_pluck(grpc_completion_queue *cq, void *tag,
gpr_timespec deadline, void *reserved) {
return cq->vtable->pluck(cq, tag, deadline, reserved);
}
static void cq_finish_shutdown_pluck(grpc_exec_ctx *exec_ctx,
grpc_completion_queue *cq) {
cq_pluck_data *cqd = DATA_FROM_CQ(cq);
GPR_ASSERT(cqd->shutdown_called);
GPR_ASSERT(!gpr_atm_no_barrier_load(&cqd->shutdown));
gpr_atm_no_barrier_store(&cqd->shutdown, 1);
cq->poller_vtable->shutdown(exec_ctx, POLLSET_FROM_CQ(cq),
&cq->pollset_shutdown_done);
}
/* NOTE: This function is almost exactly identical to cq_shutdown_next() but
* merging them is a bit tricky and probably not worth it */
static void cq_shutdown_pluck(grpc_exec_ctx *exec_ctx,
grpc_completion_queue *cq) {
cq_pluck_data *cqd = DATA_FROM_CQ(cq);
/* Need an extra ref for cq here because:
* We call cq_finish_shutdown_pluck() below, that would call pollset shutdown.
* Pollset shutdown decrements the cq ref count which can potentially destroy
* the cq (if that happens to be the last ref).
* Creating an extra ref here prevents the cq from getting destroyed while
* this function is still active */
GRPC_CQ_INTERNAL_REF(cq, "shutting_down (pluck cq)");
gpr_mu_lock(cq->mu);
if (cqd->shutdown_called) {
gpr_mu_unlock(cq->mu);
GRPC_CQ_INTERNAL_UNREF(exec_ctx, cq, "shutting_down (pluck cq)");
return;
}
cqd->shutdown_called = true;
if (gpr_atm_full_fetch_add(&cqd->pending_events, -1) == 1) {
cq_finish_shutdown_pluck(exec_ctx, cq);
}
gpr_mu_unlock(cq->mu);
GRPC_CQ_INTERNAL_UNREF(exec_ctx, cq, "shutting_down (pluck cq)");
}
/* Shutdown simply drops a ref that we reserved at creation time; if we drop
to zero here, then enter shutdown mode and wake up any waiters */
void grpc_completion_queue_shutdown(grpc_completion_queue *cq) {
grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
GPR_TIMER_BEGIN("grpc_completion_queue_shutdown", 0);
GRPC_API_TRACE("grpc_completion_queue_shutdown(cq=%p)", 1, (cq));
cq->vtable->shutdown(&exec_ctx, cq);
grpc_exec_ctx_finish(&exec_ctx);
GPR_TIMER_END("grpc_completion_queue_shutdown", 0);
}
void grpc_completion_queue_destroy(grpc_completion_queue *cq) {
GRPC_API_TRACE("grpc_completion_queue_destroy(cq=%p)", 1, (cq));
GPR_TIMER_BEGIN("grpc_completion_queue_destroy", 0);
grpc_completion_queue_shutdown(cq);
grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
GRPC_CQ_INTERNAL_UNREF(&exec_ctx, cq, "destroy");
grpc_exec_ctx_finish(&exec_ctx);
GPR_TIMER_END("grpc_completion_queue_destroy", 0);
}
grpc_pollset *grpc_cq_pollset(grpc_completion_queue *cq) {
return cq->poller_vtable->can_get_pollset ? POLLSET_FROM_CQ(cq) : NULL;
}
bool grpc_cq_can_listen(grpc_completion_queue *cq) {
return cq->poller_vtable->can_listen;
}
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