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/*
*
* Copyright 2017 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 <grpc/support/port_platform.h>
#include "src/core/ext/filters/client_channel/backup_poller.h"
#include <grpc/grpc.h>
#include <grpc/support/alloc.h>
#include <grpc/support/log.h>
#include <grpc/support/sync.h>
#include "src/core/ext/filters/client_channel/client_channel.h"
#include "src/core/lib/gpr/env.h"
#include "src/core/lib/gpr/string.h"
#include "src/core/lib/iomgr/error.h"
#include "src/core/lib/iomgr/pollset.h"
#include "src/core/lib/iomgr/timer.h"
#include "src/core/lib/surface/channel.h"
#include "src/core/lib/surface/completion_queue.h"
#define DEFAULT_POLL_INTERVAL_MS 5000
namespace {
struct backup_poller {
grpc_timer polling_timer;
grpc_closure run_poller_closure;
grpc_closure shutdown_closure;
gpr_mu* pollset_mu;
grpc_pollset* pollset; // guarded by pollset_mu
bool shutting_down; // guarded by pollset_mu
gpr_refcount refs;
gpr_refcount shutdown_refs;
};
} // namespace
static gpr_once g_once = GPR_ONCE_INIT;
static gpr_mu g_poller_mu;
static backup_poller* g_poller = nullptr; // guarded by g_poller_mu
// g_poll_interval_ms is set only once at the first time
// grpc_client_channel_start_backup_polling() is called, after that it is
// treated as const.
static int g_poll_interval_ms = DEFAULT_POLL_INTERVAL_MS;
static void init_globals() {
gpr_mu_init(&g_poller_mu);
char* env = gpr_getenv("GRPC_CLIENT_CHANNEL_BACKUP_POLL_INTERVAL_MS");
if (env != nullptr) {
int poll_interval_ms = gpr_parse_nonnegative_int(env);
if (poll_interval_ms == -1) {
gpr_log(GPR_ERROR,
"Invalid GRPC_CLIENT_CHANNEL_BACKUP_POLL_INTERVAL_MS: %s, "
"default value %d will be used.",
env, g_poll_interval_ms);
} else {
g_poll_interval_ms = poll_interval_ms;
}
}
gpr_free(env);
}
static void backup_poller_shutdown_unref(backup_poller* p) {
if (gpr_unref(&p->shutdown_refs)) {
grpc_pollset_destroy(p->pollset);
gpr_free(p->pollset);
gpr_free(p);
}
}
static void done_poller(void* arg, grpc_error* error) {
backup_poller_shutdown_unref(static_cast<backup_poller*>(arg));
}
static void g_poller_unref() {
gpr_mu_lock(&g_poller_mu);
if (gpr_unref(&g_poller->refs)) {
backup_poller* p = g_poller;
g_poller = nullptr;
gpr_mu_unlock(&g_poller_mu);
gpr_mu_lock(p->pollset_mu);
p->shutting_down = true;
grpc_pollset_shutdown(
p->pollset, GRPC_CLOSURE_INIT(&p->shutdown_closure, done_poller, p,
grpc_schedule_on_exec_ctx));
gpr_mu_unlock(p->pollset_mu);
grpc_timer_cancel(&p->polling_timer);
} else {
gpr_mu_unlock(&g_poller_mu);
}
}
static void run_poller(void* arg, grpc_error* error) {
backup_poller* p = static_cast<backup_poller*>(arg);
if (error != GRPC_ERROR_NONE) {
if (error != GRPC_ERROR_CANCELLED) {
GRPC_LOG_IF_ERROR("run_poller", GRPC_ERROR_REF(error));
}
backup_poller_shutdown_unref(p);
return;
}
gpr_mu_lock(p->pollset_mu);
if (p->shutting_down) {
gpr_mu_unlock(p->pollset_mu);
backup_poller_shutdown_unref(p);
return;
}
grpc_error* err =
grpc_pollset_work(p->pollset, nullptr, grpc_core::ExecCtx::Get()->Now());
gpr_mu_unlock(p->pollset_mu);
GRPC_LOG_IF_ERROR("Run client channel backup poller", err);
grpc_timer_init(&p->polling_timer,
grpc_core::ExecCtx::Get()->Now() + g_poll_interval_ms,
&p->run_poller_closure);
}
static void g_poller_init_locked() {
if (g_poller == nullptr) {
g_poller = static_cast<backup_poller*>(gpr_zalloc(sizeof(backup_poller)));
g_poller->pollset =
static_cast<grpc_pollset*>(gpr_zalloc(grpc_pollset_size()));
g_poller->shutting_down = false;
grpc_pollset_init(g_poller->pollset, &g_poller->pollset_mu);
gpr_ref_init(&g_poller->refs, 0);
// one for timer cancellation, one for pollset shutdown
gpr_ref_init(&g_poller->shutdown_refs, 2);
GRPC_CLOSURE_INIT(&g_poller->run_poller_closure, run_poller, g_poller,
grpc_schedule_on_exec_ctx);
grpc_timer_init(&g_poller->polling_timer,
grpc_core::ExecCtx::Get()->Now() + g_poll_interval_ms,
&g_poller->run_poller_closure);
}
}
void grpc_client_channel_start_backup_polling(
grpc_pollset_set* interested_parties) {
gpr_once_init(&g_once, init_globals);
if (g_poll_interval_ms == 0) {
return;
}
gpr_mu_lock(&g_poller_mu);
g_poller_init_locked();
gpr_ref(&g_poller->refs);
/* Get a reference to g_poller->pollset before releasing g_poller_mu to make
* TSAN happy. Otherwise, reading from g_poller (i.e g_poller->pollset) after
* releasing the lock and setting g_poller to NULL in g_poller_unref() is
* being flagged as a data-race by TSAN */
grpc_pollset* pollset = g_poller->pollset;
gpr_mu_unlock(&g_poller_mu);
grpc_pollset_set_add_pollset(interested_parties, pollset);
}
void grpc_client_channel_stop_backup_polling(
grpc_pollset_set* interested_parties) {
if (g_poll_interval_ms == 0) {
return;
}
grpc_pollset_set_del_pollset(interested_parties, g_poller->pollset);
g_poller_unref();
}
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