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// Copyright (c) 2011 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/watching_file_reader.h"
#include "base/bind.h"
#include "base/message_loop_proxy.h"
#include "base/threading/worker_pool.h"
namespace net {
FilePathWatcherShim::FilePathWatcherShim()
: watcher_(new base::files::FilePathWatcher()) {}
FilePathWatcherShim::~FilePathWatcherShim() {}
bool FilePathWatcherShim::Watch(
const FilePath& path,
base::files::FilePathWatcher::Delegate* delegate) {
DCHECK(CalledOnValidThread());
return watcher_->Watch(path, delegate);
}
FilePathWatcherShim*
FilePathWatcherFactory::CreateFilePathWatcher() {
DCHECK(CalledOnValidThread());
return new FilePathWatcherShim();
}
WatchingFileReader::WatchingFileReader()
: message_loop_(base::MessageLoopProxy::current()),
factory_(new FilePathWatcherFactory()),
reading_(false),
read_pending_(false),
cancelled_(false) {}
void WatchingFileReader::StartWatch(const FilePath& path) {
DCHECK(message_loop_->BelongsToCurrentThread());
DCHECK(!watcher_.get());
DCHECK(path_.empty());
path_ = path;
RestartWatch();
}
void WatchingFileReader::Cancel() {
DCHECK(message_loop_->BelongsToCurrentThread());
cancelled_ = true;
// Let go of the watcher to break the reference cycle.
watcher_.reset();
}
void WatchingFileReader::OnFilePathChanged(const FilePath& path) {
DCHECK(message_loop_->BelongsToCurrentThread());
ReadNow();
}
void WatchingFileReader::OnFilePathError(const FilePath& path) {
DCHECK(message_loop_->BelongsToCurrentThread());
RestartWatch();
}
WatchingFileReader::~WatchingFileReader() {}
void WatchingFileReader::RescheduleWatch() {
DCHECK(message_loop_->BelongsToCurrentThread());
message_loop_->PostDelayedTask(
FROM_HERE,
base::Bind(&WatchingFileReader::RestartWatch, this),
kWatchRetryDelayMs);
}
void WatchingFileReader::RestartWatch() {
if (cancelled_)
return;
watcher_.reset(factory_->CreateFilePathWatcher());
if (watcher_->Watch(path_, this)) {
ReadNow();
} else {
LOG(WARNING) << "Watch on " <<
path_.LossyDisplayName() <<
" failed, scheduling restart";
RescheduleWatch();
}
}
void WatchingFileReader::ReadNow() {
if (cancelled_)
return;
if (reading_) {
// Remember to re-read after DoRead posts results.
read_pending_ = true;
} else {
if (!base::WorkerPool::PostTask(FROM_HERE, base::Bind(
&WatchingFileReader::DoReadJob, 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(&WatchingFileReader::ReadNow, this),
kWorkerPoolRetryDelayMs);
return;
#endif
}
reading_ = true;
read_pending_ = false;
}
}
void WatchingFileReader::DoReadJob() {
this->DoRead();
// If this fails, the loop is gone, so there is no point retrying.
message_loop_->PostTask(FROM_HERE, base::Bind(
&WatchingFileReader::OnReadJobFinished, this));
}
void WatchingFileReader::OnReadJobFinished() {
DCHECK(message_loop_->BelongsToCurrentThread());
if (cancelled_)
return;
reading_ = false;
if (read_pending_) {
// Discard this result and re-read.
ReadNow();
return;
}
this->OnReadFinished();
}
} // namespace net
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