diff options
Diffstat (limited to 'chrome/browser/file_watcher_inotify.cc')
-rw-r--r-- | chrome/browser/file_watcher_inotify.cc | 302 |
1 files changed, 302 insertions, 0 deletions
diff --git a/chrome/browser/file_watcher_inotify.cc b/chrome/browser/file_watcher_inotify.cc new file mode 100644 index 0000000..20321d5 --- /dev/null +++ b/chrome/browser/file_watcher_inotify.cc @@ -0,0 +1,302 @@ +// Copyright (c) 2010 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 "chrome/browser/file_watcher.h" + +#include <errno.h> +#include <string.h> +#include <sys/inotify.h> +#include <sys/ioctl.h> +#include <sys/select.h> +#include <unistd.h> + +#include <algorithm> +#include <set> +#include <utility> +#include <vector> + +#include "base/eintr_wrapper.h" +#include "base/file_path.h" +#include "base/file_util.h" +#include "base/hash_tables.h" +#include "base/lock.h" +#include "base/logging.h" +#include "base/message_loop.h" +#include "base/scoped_ptr.h" +#include "base/singleton.h" +#include "base/task.h" +#include "base/thread.h" + +namespace { + +class FileWatcherImpl; + +// Singleton to manage all inotify watches. +// TODO(tony): It would be nice if this wasn't a singleton. +// http://crbug.com/38174 +class InotifyReader { + public: + typedef int Watch; // Watch descriptor used by AddWatch and RemoveWatch. + static const Watch kInvalidWatch = -1; + + // Watch |path| for changes. |watcher| will be notified on each change. + // Returns kInvalidWatch on failure. + Watch AddWatch(const FilePath& path, FileWatcherImpl* watcher); + + // Remove |watch|. Returns true on success. + bool RemoveWatch(Watch watch, FileWatcherImpl* watcher); + + // Callback for InotifyReaderTask. + void OnInotifyEvent(const inotify_event* event); + + private: + friend struct DefaultSingletonTraits<InotifyReader>; + + typedef std::set<FileWatcherImpl*> WatcherSet; + + InotifyReader(); + ~InotifyReader(); + + // We keep track of which delegates want to be notified on which watches. + base::hash_map<Watch, WatcherSet> watchers_; + + // Lock to protect watchers_. + Lock lock_; + + // Separate thread on which we run blocking read for inotify events. + base::Thread thread_; + + // File descriptor returned by inotify_init. + const int inotify_fd_; + + // Use self-pipe trick to unblock select during shutdown. + int shutdown_pipe_[2]; + + // Flag set to true when startup was successful. + bool valid_; + + DISALLOW_COPY_AND_ASSIGN(InotifyReader); +}; + +class FileWatcherImpl : public FileWatcher::PlatformDelegate { + public: + FileWatcherImpl(); + ~FileWatcherImpl(); + + // Called for each event coming from the watch. + void OnInotifyEvent(const inotify_event* event); + + // Start watching |path| for changes and notify |delegate| on each change. + // Returns true if watch for |path| has been added successfully. + virtual bool Watch(const FilePath& path, FileWatcher::Delegate* delegate); + + private: + // Delegate to notify upon changes. + scoped_refptr<FileWatcher::Delegate> delegate_; + + // Watch returned by InotifyReader. + InotifyReader::Watch watch_; + + // The file we're watching. + FilePath path_; + + DISALLOW_COPY_AND_ASSIGN(FileWatcherImpl); +}; + +class InotifyReaderTask : public Task { + public: + InotifyReaderTask(InotifyReader* reader, int inotify_fd, int shutdown_fd) + : reader_(reader), + inotify_fd_(inotify_fd), + shutdown_fd_(shutdown_fd) { + } + + virtual void Run() { + while (true) { + fd_set rfds; + FD_ZERO(&rfds); + FD_SET(inotify_fd_, &rfds); + FD_SET(shutdown_fd_, &rfds); + + // Wait until some inotify events are available. + int select_result = + HANDLE_EINTR(select(std::max(inotify_fd_, shutdown_fd_) + 1, + &rfds, NULL, NULL, NULL)); + if (select_result < 0) { + DPLOG(WARNING) << "select failed"; + return; + } + + if (FD_ISSET(shutdown_fd_, &rfds)) + return; + + // Adjust buffer size to current event queue size. + int buffer_size; + int ioctl_result = HANDLE_EINTR(ioctl(inotify_fd_, FIONREAD, + &buffer_size)); + + if (ioctl_result != 0) { + DPLOG(WARNING) << "ioctl failed"; + return; + } + + std::vector<char> buffer(buffer_size); + + ssize_t bytes_read = HANDLE_EINTR(read(inotify_fd_, &buffer[0], + buffer_size)); + + if (bytes_read < 0) { + DPLOG(WARNING) << "read from inotify fd failed"; + return; + } + + ssize_t i = 0; + while (i < bytes_read) { + inotify_event* event = reinterpret_cast<inotify_event*>(&buffer[i]); + size_t event_size = sizeof(inotify_event) + event->len; + DCHECK(i + event_size <= static_cast<size_t>(bytes_read)); + reader_->OnInotifyEvent(event); + i += event_size; + } + } + } + + private: + InotifyReader* reader_; + int inotify_fd_; + int shutdown_fd_; + + DISALLOW_COPY_AND_ASSIGN(InotifyReaderTask); +}; + +InotifyReader::InotifyReader() + : thread_("inotify_reader"), + inotify_fd_(inotify_init()), + valid_(false) { + shutdown_pipe_[0] = -1; + shutdown_pipe_[1] = -1; + if (inotify_fd_ >= 0 && pipe(shutdown_pipe_) == 0 && thread_.Start()) { + thread_.message_loop()->PostTask( + FROM_HERE, new InotifyReaderTask(this, inotify_fd_, shutdown_pipe_[0])); + valid_ = true; + } +} + +InotifyReader::~InotifyReader() { + if (valid_) { + // Write to the self-pipe so that the select call in InotifyReaderTask + // returns. + ssize_t ret = HANDLE_EINTR(write(shutdown_pipe_[1], "", 1)); + DPCHECK(ret > 0); + DCHECK_EQ(ret, 1); + thread_.Stop(); + } + if (inotify_fd_ >= 0) + close(inotify_fd_); + if (shutdown_pipe_[0] >= 0) + close(shutdown_pipe_[0]); + if (shutdown_pipe_[1] >= 0) + close(shutdown_pipe_[1]); +} + +InotifyReader::Watch InotifyReader::AddWatch( + const FilePath& path, FileWatcherImpl* watcher) { + if (!valid_) + return kInvalidWatch; + + AutoLock auto_lock(lock_); + + Watch watch = inotify_add_watch(inotify_fd_, path.value().c_str(), + IN_CREATE | IN_DELETE | + IN_CLOSE_WRITE | IN_MOVE); + + if (watch == kInvalidWatch) + return kInvalidWatch; + + watchers_[watch].insert(watcher); + + return watch; +} + +bool InotifyReader::RemoveWatch(Watch watch, + FileWatcherImpl* watcher) { + if (!valid_) + return false; + + AutoLock auto_lock(lock_); + + watchers_[watch].erase(watcher); + + if (watchers_[watch].empty()) { + watchers_.erase(watch); + return (inotify_rm_watch(inotify_fd_, watch) == 0); + } + + return true; +} + +void InotifyReader::OnInotifyEvent(const inotify_event* event) { + if (event->mask & IN_IGNORED) + return; + + // In case you want to limit the scope of this lock, it's not sufficient + // to just copy things under the lock, and then run the notifications + // without holding the lock. FileWatcherImpl's dtor removes its watches, + // and to do that obtains the lock. After it finishes removing watches, + // it's destroyed. So, if you copy under the lock and notify without the lock, + // it's possible you'll copy the FileWatcherImpl which is being + // destroyed, then it will destroy itself, and then you'll try to notify it. + AutoLock auto_lock(lock_); + + for (WatcherSet::iterator watcher = watchers_[event->wd].begin(); + watcher != watchers_[event->wd].end(); + ++watcher) { + (*watcher)->OnInotifyEvent(event); + } +} + +FileWatcherImpl::FileWatcherImpl() + : delegate_(NULL), + watch_(InotifyReader::kInvalidWatch) { +} + +FileWatcherImpl::~FileWatcherImpl() { + if (watch_ == InotifyReader::kInvalidWatch) + return; + + Singleton<InotifyReader>::get()->RemoveWatch(watch_, this); +} + +void FileWatcherImpl::OnInotifyEvent(const inotify_event* event) { + // Since we're watching the directory, filter out inotify events + // if it's not related to the file we're watching. + if (path_ != path_.DirName().Append(event->name)) + return; + + ChromeThread::PostTask(ChromeThread::FILE, FROM_HERE, + NewRunnableMethod(delegate_.get(), &FileWatcher::Delegate::OnFileChanged, + path_)); +} + +bool FileWatcherImpl::Watch(const FilePath& path, + FileWatcher::Delegate* delegate) { + // Each FileWatcherImpl can only watch one file. + DCHECK(watch_ == InotifyReader::kInvalidWatch); + + // It's not possible to watch a file that doesn't exist, so instead, + // watch the parent directory. + if (!file_util::PathExists(path.DirName())) + return false; + + delegate_ = delegate; + path_ = path; + watch_ = Singleton<InotifyReader>::get()->AddWatch(path.DirName(), this); + return watch_ != InotifyReader::kInvalidWatch; +} + +} // namespace + +FileWatcher::FileWatcher() { + impl_ = new FileWatcherImpl(); +} |