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/*
*
* Copyright 2016, Google Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include "src/core/lib/iomgr/combiner.h"
#include <string.h>
#include <grpc/support/alloc.h>
#include <grpc/support/log.h>
#include "src/core/lib/iomgr/workqueue.h"
#include "src/core/lib/profiling/timers.h"
int grpc_combiner_trace = 0;
#define GRPC_COMBINER_TRACE(fn) \
do { \
if (grpc_combiner_trace) { \
fn; \
} \
} while (0)
struct grpc_combiner {
grpc_workqueue *optional_workqueue;
gpr_mpscq queue;
// state is:
// lower bit - zero if orphaned
// other bits - number of items queued on the lock
gpr_atm state;
bool take_async_break_before_final_list;
grpc_closure_list final_list;
grpc_closure continue_finishing;
};
grpc_combiner *grpc_combiner_create(grpc_workqueue *optional_workqueue) {
grpc_combiner *lock = gpr_malloc(sizeof(*lock));
lock->optional_workqueue = optional_workqueue;
gpr_atm_no_barrier_store(&lock->state, 1);
gpr_mpscq_init(&lock->queue);
lock->take_async_break_before_final_list = false;
grpc_closure_list_init(&lock->final_list);
GRPC_COMBINER_TRACE(gpr_log(GPR_DEBUG, "C:%p create", lock));
return lock;
}
static void really_destroy(grpc_exec_ctx *exec_ctx, grpc_combiner *lock) {
GRPC_COMBINER_TRACE(gpr_log(GPR_DEBUG, "C:%p really_destroy", lock));
GPR_ASSERT(gpr_atm_no_barrier_load(&lock->state) == 0);
gpr_mpscq_destroy(&lock->queue);
GRPC_WORKQUEUE_UNREF(exec_ctx, lock->optional_workqueue, "combiner");
gpr_free(lock);
}
void grpc_combiner_destroy(grpc_exec_ctx *exec_ctx, grpc_combiner *lock) {
gpr_atm old_state = gpr_atm_full_fetch_add(&lock->state, -1);
GRPC_COMBINER_TRACE(gpr_log(
GPR_DEBUG, "C:%p really_destroy old_state=%" PRIdPTR, lock, old_state));
if (old_state == 1) {
really_destroy(exec_ctx, lock);
}
}
static bool maybe_finish_one(grpc_exec_ctx *exec_ctx, grpc_combiner *lock);
static void finish(grpc_exec_ctx *exec_ctx, grpc_combiner *lock);
static void continue_finishing_mainline(grpc_exec_ctx *exec_ctx, void *arg,
grpc_error *error) {
GPR_TIMER_BEGIN("combiner.continue_executing_mainline", 0);
grpc_combiner *lock = arg;
GRPC_COMBINER_TRACE(
gpr_log(GPR_DEBUG, "C:%p continue_finishing_mainline", lock));
GPR_ASSERT(exec_ctx->active_combiner == NULL);
exec_ctx->active_combiner = lock;
if (maybe_finish_one(exec_ctx, lock)) finish(exec_ctx, lock);
GPR_ASSERT(exec_ctx->active_combiner == lock);
exec_ctx->active_combiner = NULL;
GPR_TIMER_END("combiner.continue_executing_mainline", 0);
}
static void execute_final(grpc_exec_ctx *exec_ctx, grpc_combiner *lock) {
GPR_TIMER_BEGIN("combiner.execute_final", 0);
grpc_closure *c = lock->final_list.head;
GPR_ASSERT(c != NULL);
grpc_closure_list_init(&lock->final_list);
lock->take_async_break_before_final_list = false;
int loops = 0;
while (c != NULL) {
GRPC_COMBINER_TRACE(
gpr_log(GPR_DEBUG, "C:%p execute_final[%d] c=%p", lock, loops, c));
grpc_closure *next = c->next_data.next;
grpc_error *error = c->error;
c->cb(exec_ctx, c->cb_arg, error);
GRPC_ERROR_UNREF(error);
c = next;
loops++;
}
GPR_TIMER_END("combiner.execute_final", 0);
}
static void continue_executing_final(grpc_exec_ctx *exec_ctx, void *arg,
grpc_error *error) {
GPR_TIMER_BEGIN("combiner.continue_executing_final", 0);
grpc_combiner *lock = arg;
GRPC_COMBINER_TRACE(
gpr_log(GPR_DEBUG, "C:%p continue_executing_final", lock));
GPR_ASSERT(exec_ctx->active_combiner == NULL);
exec_ctx->active_combiner = lock;
// quick peek to see if new things have turned up on the queue: if so, go back
// to executing them before the final list
if ((gpr_atm_acq_load(&lock->state) >> 1) > 1) {
if (maybe_finish_one(exec_ctx, lock)) finish(exec_ctx, lock);
} else {
execute_final(exec_ctx, lock);
finish(exec_ctx, lock);
}
GPR_ASSERT(exec_ctx->active_combiner == lock);
exec_ctx->active_combiner = NULL;
GPR_TIMER_END("combiner.continue_executing_final", 0);
}
static bool start_execute_final(grpc_exec_ctx *exec_ctx, grpc_combiner *lock) {
GPR_TIMER_BEGIN("combiner.start_execute_final", 0);
GPR_ASSERT(exec_ctx->active_combiner == lock);
GRPC_COMBINER_TRACE(
gpr_log(GPR_DEBUG,
"C:%p start_execute_final take_async_break_before_final_list=%d",
lock, lock->take_async_break_before_final_list));
if (lock->take_async_break_before_final_list) {
grpc_closure_init(&lock->continue_finishing, continue_executing_final,
lock);
grpc_exec_ctx_sched(exec_ctx, &lock->continue_finishing, GRPC_ERROR_NONE,
GRPC_WORKQUEUE_REF(lock->optional_workqueue, "sched"));
GPR_TIMER_END("combiner.start_execute_final", 0);
return false;
} else {
execute_final(exec_ctx, lock);
GPR_TIMER_END("combiner.start_execute_final", 0);
return true;
}
}
static bool maybe_finish_one(grpc_exec_ctx *exec_ctx, grpc_combiner *lock) {
GPR_TIMER_BEGIN("combiner.maybe_finish_one", 0);
gpr_mpscq_node *n = gpr_mpscq_pop(&lock->queue);
GRPC_COMBINER_TRACE(
gpr_log(GPR_DEBUG, "C:%p maybe_finish_one n=%p", lock, n));
GPR_ASSERT(exec_ctx->active_combiner == lock);
if (n == NULL) {
// queue is in an inconsistant state: use this as a cue that we should
// go off and do something else for a while (and come back later)
grpc_closure_init(&lock->continue_finishing, continue_finishing_mainline,
lock);
grpc_exec_ctx_sched(exec_ctx, &lock->continue_finishing, GRPC_ERROR_NONE,
GRPC_WORKQUEUE_REF(lock->optional_workqueue, "sched"));
GPR_TIMER_END("combiner.maybe_finish_one", 0);
return false;
}
grpc_closure *cl = (grpc_closure *)n;
grpc_error *error = cl->error;
cl->cb(exec_ctx, cl->cb_arg, error);
GRPC_ERROR_UNREF(error);
GPR_TIMER_END("combiner.maybe_finish_one", 0);
return true;
}
static void finish(grpc_exec_ctx *exec_ctx, grpc_combiner *lock) {
bool (*executor)(grpc_exec_ctx * exec_ctx, grpc_combiner * lock);
GPR_TIMER_BEGIN("combiner.finish", 0);
int loops = 0;
do {
executor = maybe_finish_one;
gpr_atm old_state = gpr_atm_full_fetch_add(&lock->state, -2);
GRPC_COMBINER_TRACE(gpr_log(GPR_DEBUG,
"C:%p finish[%d] old_state=%" PRIdPTR, lock,
loops, old_state));
switch (old_state) {
case 5: // we're down to one queued item: if it's the final list we
case 4: // should do that
if (!grpc_closure_list_empty(lock->final_list)) {
executor = start_execute_final;
}
break;
case 3: // had one count, one unorphaned --> unlocked unorphaned
GPR_TIMER_END("combiner.finish", 0);
return;
case 2: // and one count, one orphaned --> unlocked and orphaned
really_destroy(exec_ctx, lock);
GPR_TIMER_END("combiner.finish", 0);
return;
case 1:
case 0:
// these values are illegal - representing an already unlocked or
// deleted lock
GPR_UNREACHABLE_CODE(return );
}
loops++;
} while (executor(exec_ctx, lock));
GPR_TIMER_END("combiner.finish", 0);
}
void grpc_combiner_execute(grpc_exec_ctx *exec_ctx, grpc_combiner *lock,
grpc_closure *cl, grpc_error *error) {
GRPC_COMBINER_TRACE(
gpr_log(GPR_DEBUG, "C:%p grpc_combiner_execute c=%p", lock, cl));
GPR_TIMER_BEGIN("combiner.execute", 0);
gpr_atm last = gpr_atm_full_fetch_add(&lock->state, 2);
GPR_ASSERT(last & 1); // ensure lock has not been destroyed
if (last == 1) {
exec_ctx->active_combiner = lock;
GPR_TIMER_BEGIN("combiner.execute_first_cb", 0);
cl->cb(exec_ctx, cl->cb_arg, error);
GPR_TIMER_END("combiner.execute_first_cb", 0);
GRPC_ERROR_UNREF(error);
finish(exec_ctx, lock);
GPR_ASSERT(exec_ctx->active_combiner == lock);
exec_ctx->active_combiner = NULL;
} else {
cl->error = error;
gpr_mpscq_push(&lock->queue, &cl->next_data.atm_next);
}
GPR_TIMER_END("combiner.execute", 0);
}
static void enqueue_finally(grpc_exec_ctx *exec_ctx, void *closure,
grpc_error *error) {
grpc_combiner_execute_finally(exec_ctx, exec_ctx->active_combiner, closure,
GRPC_ERROR_REF(error), false);
}
void grpc_combiner_execute_finally(grpc_exec_ctx *exec_ctx, grpc_combiner *lock,
grpc_closure *closure, grpc_error *error,
bool force_async_break) {
GRPC_COMBINER_TRACE(gpr_log(
GPR_DEBUG,
"C:%p grpc_combiner_execute_finally c=%p force_async_break=%d; ac=%p",
lock, closure, force_async_break, exec_ctx->active_combiner));
GPR_TIMER_BEGIN("combiner.execute_finally", 0);
if (exec_ctx->active_combiner != lock) {
GPR_TIMER_MARK("slowpath", 0);
grpc_combiner_execute(exec_ctx, lock,
grpc_closure_create(enqueue_finally, closure), error);
GPR_TIMER_END("combiner.execute_finally", 0);
return;
}
if (force_async_break) {
lock->take_async_break_before_final_list = true;
}
if (grpc_closure_list_empty(lock->final_list)) {
gpr_atm_full_fetch_add(&lock->state, 2);
}
grpc_closure_list_append(&lock->final_list, closure, error);
GPR_TIMER_END("combiner.execute_finally", 0);
}
void grpc_combiner_force_async_finally(grpc_combiner *lock) {
lock->take_async_break_before_final_list = true;
}
|