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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "net/dns/serial_worker.h"
#include "base/bind.h"
#include "base/location.h"
#include "base/message_loop/message_loop_proxy.h"
#include "base/threading/worker_pool.h"
namespace net {
namespace {
// Delay between calls to WorkerPool::PostTask
const int kWorkerPoolRetryDelayMs = 100;
}
SerialWorker::SerialWorker()
: message_loop_(base::MessageLoopProxy::current()),
state_(IDLE) {}
SerialWorker::~SerialWorker() {}
void SerialWorker::WorkNow() {
DCHECK(message_loop_->BelongsToCurrentThread());
switch (state_) {
case IDLE:
if (!base::WorkerPool::PostTask(FROM_HERE, base::Bind(
&SerialWorker::DoWorkJob, this), false)) {
#if defined(OS_POSIX)
// See worker_pool_posix.cc.
NOTREACHED() << "WorkerPool::PostTask is not expected to fail on posix";
#else
LOG(WARNING) << "Failed to WorkerPool::PostTask, will retry later";
message_loop_->PostDelayedTask(
FROM_HERE,
base::Bind(&SerialWorker::RetryWork, this),
base::TimeDelta::FromMilliseconds(kWorkerPoolRetryDelayMs));
state_ = WAITING;
return;
#endif
}
state_ = WORKING;
return;
case WORKING:
// Remember to re-read after |DoRead| finishes.
state_ = PENDING;
return;
case CANCELLED:
case PENDING:
case WAITING:
return;
default:
NOTREACHED() << "Unexpected state " << state_;
}
}
void SerialWorker::Cancel() {
DCHECK(message_loop_->BelongsToCurrentThread());
state_ = CANCELLED;
}
void SerialWorker::DoWorkJob() {
this->DoWork();
// If this fails, the loop is gone, so there is no point retrying.
message_loop_->PostTask(FROM_HERE, base::Bind(
&SerialWorker::OnWorkJobFinished, this));
}
void SerialWorker::OnWorkJobFinished() {
DCHECK(message_loop_->BelongsToCurrentThread());
switch (state_) {
case CANCELLED:
return;
case WORKING:
state_ = IDLE;
this->OnWorkFinished();
return;
case PENDING:
state_ = IDLE;
WorkNow();
return;
default:
NOTREACHED() << "Unexpected state " << state_;
}
}
void SerialWorker::RetryWork() {
DCHECK(message_loop_->BelongsToCurrentThread());
switch (state_) {
case CANCELLED:
return;
case WAITING:
state_ = IDLE;
WorkNow();
return;
default:
NOTREACHED() << "Unexpected state " << state_;
}
}
} // namespace net
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