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athena/system/device_socket_listener.cc

Index: athena/system/device_socket_listener.cc
diff --git a/athena/system/device_socket_listener.cc b/athena/system/device_socket_listener.cc
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index 0000000000000000000000000000000000000000..e041e44c5413d38bfdedcc53eb3781a8c7668e27
--- /dev/null
+++ b/athena/system/device_socket_listener.cc
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+// Copyright 2014 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 "athena/system/device_socket_listener.h"
+
+#include <errno.h>
+#include <map>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <vector>
+
+#include "base/bind.h"
+#include "base/files/file_path.h"
+#include "base/memory/singleton.h"
+#include "base/message_loop/message_loop.h"
+#include "base/observer_list.h"
+#include "base/stl_util.h"
+#include "ipc/unix_domain_socket_util.h"
+
+namespace athena {
+
+namespace {
+
+typedef ObserverList<DeviceSocketListener> DeviceSocketListeners;
+
+// Reads from a device socket blocks of a particular size. When that amount of
+// data is read DeviceSocketManager::OnDataAvailable is called on the singleton
+// instance which then informs all of the listeners on that socket.
+class DeviceSocketReader : public base::MessagePumpLibevent::Watcher {
+ public:
+  DeviceSocketReader(const std::string& socket_path,
+                      size_t data_size)
+      : socket_path_(socket_path),
+        data_size_(data_size),
+        data_(new char[data_size]) {
+  }
+  virtual ~DeviceSocketReader() {}
+
+ private:
+  // Overidden from base::MessagePumpLibevent::Watcher.
+  virtual void OnFileCanReadWithoutBlocking(int fd) OVERRIDE;
+  virtual void OnFileCanWriteWithoutBlocking(int fd) OVERRIDE;
+
+  std::string socket_path_;
+  size_t data_size_;
+  scoped_ptr<char[]> data_;
+
+  DISALLOW_COPY_AND_ASSIGN(DeviceSocketReader);
+};
+
+class DeviceSocketManager;
+DeviceSocketManager* device_socket_manager_instance_ = NULL;
+
+// A singleton instance for managing all connections to sockets.
+class DeviceSocketManager {
+ public:
+  static void Create(scoped_refptr<base::TaskRunner> io_task_runner) {
+    device_socket_manager_instance_ =
+        new DeviceSocketManager(io_task_runner);
+  }
+
+  static void Shutdown() {
+    CHECK(device_socket_manager_instance_);
+    delete device_socket_manager_instance_;
+    device_socket_manager_instance_ = NULL;
+  }
+
+  static DeviceSocketManager* GetInstance() {
+    CHECK(device_socket_manager_instance_);
+    return device_socket_manager_instance_;
+  }
+
+  // If there isn't an existing connection to |socket_path|, then opens a
+  // connection to |socket_path| and starts listening for data. All listeners
+  // for |socket_path| receives data when data is available on the socket.
+  void StartListening(const std::string& socket_path,
+                      size_t data_size,
+                      DeviceSocketListener* listener);
+
+  // Removes |listener| from the list of listeners that receive data from
+  // |socket_path|. If this is the last listener, then this closes the
+  // connection to the socket.
+  void StopListening(const std::string& socket_path,
+                     DeviceSocketListener* listener);
+
+  // Sends data to all the listeners registered to receive data from
+  // |socket_path|.
+  void OnDataAvailable(const std::string& socket_path,
+                       const void* data);
+
+  // Notifies listeners of errors reading from the socket and closes it.
+  void OnError(const std::string& socket_path, int err);
+  void OnEOF(const std::string& socket_path);
+
+ private:
+  friend struct DefaultSingletonTraits<DeviceSocketManager>;
+
+  struct SocketData {
+    SocketData()
+        : fd(-1) {
+    }
+
+    int fd;
+    DeviceSocketListeners observers;
+    scoped_ptr<base::MessagePumpLibevent::FileDescriptorWatcher> controller;
+    scoped_ptr<DeviceSocketReader> watcher;
+  };
+
+  DeviceSocketManager(scoped_refptr<base::TaskRunner> io_task_runner)
+      : io_task_runner_(io_task_runner) {
+  }
+
+  ~DeviceSocketManager() {
+    STLDeleteContainerPairSecondPointers(socket_data_.begin(),
+                                         socket_data_.end());
+  }
+
+  void StartListeningOnIO(const std::string& socket_path,
+                          size_t data_size,
+                          DeviceSocketListener* listener);
+
+  void StopListeningOnIO(const std::string& socket_path,
+                         DeviceSocketListener* listener);
+
+  void CloseSocket(const std::string& socket_path);
+
+  std::map<std::string, SocketData*> socket_data_;
+  scoped_refptr<base::TaskRunner> io_task_runner_;
+
+  DISALLOW_COPY_AND_ASSIGN(DeviceSocketManager);
+};
+
+////////////////////////////////////////////////////////////////////////////////
+// DeviceSocketReader
+
+void DeviceSocketReader::OnFileCanReadWithoutBlocking(int fd) {
+  ssize_t read_size = recv(fd, data_.get(), data_size_, 0);
+  if (read_size < 0) {
+    if (errno == EINTR)
+      return;
+    DeviceSocketManager::GetInstance()->OnError(socket_path_, errno);
+    return;
+  }
+  if (read_size == 0) {
+    DeviceSocketManager::GetInstance()->OnEOF(socket_path_);
+    return;
+  }
+  if (read_size != static_cast<ssize_t>(data_size_))
+    return;
+  DeviceSocketManager::GetInstance()->OnDataAvailable(socket_path_,
+                                                      data_.get());
+}
+
+void DeviceSocketReader::OnFileCanWriteWithoutBlocking(int fd) {
+  NOTREACHED();
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// DeviceSocketManager
+
+void DeviceSocketManager::StartListening(const std::string& socket_path,
+                                         size_t data_size,
+                                         DeviceSocketListener* listener) {
+  io_task_runner_->PostTask(FROM_HERE,
+      base::Bind(&DeviceSocketManager::StartListeningOnIO,
+                 base::Unretained(this), socket_path, data_size, listener));
+}
+
+void DeviceSocketManager::StopListening(const std::string& socket_path,
+                                        DeviceSocketListener* listener) {
+  io_task_runner_->PostTask(FROM_HERE,
+      base::Bind(&DeviceSocketManager::StopListeningOnIO,
+                 base::Unretained(this), socket_path, listener));
+}
+
+void DeviceSocketManager::OnDataAvailable(const std::string& socket_path,
+                                          const void* data) {
+  CHECK_GT(socket_data_.count(socket_path), 0UL);
+  DeviceSocketListeners& listeners = socket_data_[socket_path]->observers;
+  FOR_EACH_OBSERVER(DeviceSocketListener, listeners, OnDataAvailableOnIO(data));
+}
+
+void DeviceSocketManager::CloseSocket(const std::string& socket_path) {
+  if (!socket_data_.count(socket_path))
+    return;
+  SocketData* socket_data = socket_data_[socket_path];
+  close(socket_data->fd);
+  delete socket_data;
+  socket_data_.erase(socket_path);
+}
+
+void DeviceSocketManager::OnError(const std::string& socket_path, int err) {
+  LOG(ERROR) << "Error reading from socket: " << socket_path << ": "
+             << strerror(err);
+  CloseSocket(socket_path);
+  // TODO(flackr): Notify listeners that the socket was closed unexpectedly.
+}
+
+void DeviceSocketManager::OnEOF(const std::string& socket_path) {
+  LOG(ERROR) << "EOF reading from socket: " << socket_path;
+  CloseSocket(socket_path);
+}
+
+void DeviceSocketManager::StartListeningOnIO(const std::string& socket_path,
+                                             size_t data_size,
+                                             DeviceSocketListener* listener) {
+  CHECK(io_task_runner_->RunsTasksOnCurrentThread());
+  SocketData* socket_data = NULL;
+  if (!socket_data_.count(socket_path)) {
+    int socket_fd = -1;
+    if (!IPC::CreateClientUnixDomainSocket(base::FilePath(socket_path),
+                                           &socket_fd)) {
+      LOG(ERROR) << "Error connecting to socket: " << socket_path;
+      return;
+    }
+
+    socket_data = new SocketData;
+    socket_data_[socket_path] = socket_data;
+
+    socket_data->fd = socket_fd;
+
+    socket_data->controller.reset(
+        new base::MessagePumpLibevent::FileDescriptorWatcher());
+    socket_data->watcher.reset(
+        new DeviceSocketReader(socket_path, data_size));
+
+    base::MessageLoopForIO::current()->WatchFileDescriptor(
+        socket_fd,
+        true,
+        base::MessageLoopForIO::WATCH_READ,
+        socket_data->controller.get(),
+        socket_data->watcher.get());
+  } else {
+    socket_data = socket_data_[socket_path];
+  }
+  socket_data->observers.AddObserver(listener);
+}
+
+void DeviceSocketManager::StopListeningOnIO(const std::string& socket_path,
+                                            DeviceSocketListener* listener) {
+  if (!socket_data_.count(socket_path))
+    return;  // Happens if unable to create a socket.
+
+  CHECK(io_task_runner_->RunsTasksOnCurrentThread());
+  DeviceSocketListeners& listeners = socket_data_[socket_path]->observers;
+  listeners.RemoveObserver(listener);
+  if (!listeners.might_have_observers()) {
+    // All listeners for this socket has been removed. Close the socket.
+    CloseSocket(socket_path);
+  }
+}
+
+}  // namespace
+
+DeviceSocketListener::DeviceSocketListener(const std::string& socket_path,
+                                           size_t data_size)
+  : socket_path_(socket_path),
+    data_size_(data_size) {
+}
+
+DeviceSocketListener::~DeviceSocketListener() {
+  StopListening();
+}
+
+// static
+void DeviceSocketListener::CreateSocketManager(
+    scoped_refptr<base::TaskRunner> io_task_runner) {
+  DeviceSocketManager::Create(io_task_runner);
+}
+
+// static
+void DeviceSocketListener::ShutdownSocketManager() {
+  DeviceSocketManager::Shutdown();
+}
+
+void DeviceSocketListener::StartListening() {
+  DeviceSocketManager::GetInstance()->StartListening(socket_path_,
+                                                     data_size_,
+                                                     this);
+}
+
+void DeviceSocketListener::StopListening() {
+  DeviceSocketManager::GetInstance()->StopListening(socket_path_, this);
+}
+
+}  // namespace athena