1/*
2 * Copyright (C) 2017 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef CHRE_HOST_SOCKET_CLIENT_H_
18#define CHRE_HOST_SOCKET_CLIENT_H_
19
20#include <atomic>
21#include <condition_variable>
22#include <mutex>
23#include <thread>
24
25#include <cutils/sockets.h>
26#include <utils/RefBase.h>
27#include <utils/StrongPointer.h>
28
29namespace android {
30namespace chre {
31
32class SocketClient {
33 public:
34  SocketClient();
35  ~SocketClient();
36
37  /**
38   * Represents the callback interface used for handling events that occur on
39   * the receive thread. Note that it is *not* safe to call connect(),
40   * connectInBackground(), or disconnect() from the context of these callbacks.
41   */
42  class ICallbacks : public VirtualLightRefBase {
43   public:
44    /**
45     * Invoked from within the context of the read thread when a message is
46     * received on the socket.
47     *
48     * @param data Buffer containing received message data
49     * @param length Size of the message in bytes
50     */
51    virtual void onMessageReceived(const void *data, size_t length) = 0;
52
53    /**
54     * Called when the socket is successfully (re-)connected.
55     */
56    virtual void onConnected() {};
57
58    /**
59     * Called when we have failed to (re-)connect the socket after many attempts
60     * and are giving up.
61     */
62    virtual void onConnectionAborted() {};
63
64    /**
65     * Invoked when the socket is disconnected, and this connection loss was not
66     * the result of an explicit call to disconnect(), i.e. the connection was
67     * terminated on the remote end.
68     */
69    virtual void onDisconnected() {};
70  };
71
72  /**
73   * Synchronously attempts to connect to the Android reserved namespace socket
74   * with the given name. If this connection attempt is successful, starts a
75   * receive thread to handle messages received on the socket, and uses this
76   * thread to automatically reconnect if disconnected by the remote end.
77   *
78   * @param socketName Name of the Android domain socket to connect to
79   * @param callbacks
80   *
81   * @return true if the connection was successful
82   */
83  bool connect(const char *socketName,
84               const ::android::sp<ICallbacks>& callbacks);
85
86  /**
87   * Starts up the receive thread and attempts to connect to the socket in the
88   * background. The onConnected() callback will be invoked when the socket is
89   * connected successfully, or onConnectionAborted() will be invoked if the
90   * connection could not be made after many retries and the client is giving
91   * up.
92   *
93   * @param socketName Name of the Android domain socket to connect to
94   * @param callbacks
95   *
96   * @return true if the receive thread was started and will attempt to connect
97   *         the socket asynchronously
98   */
99  bool connectInBackground(const char *socketName,
100                           const ::android::sp<ICallbacks>& callbacks);
101
102  /**
103   * Performs graceful teardown of the socket. After this function returns, this
104   * object will no longer invoke any callbacks or hold a reference to the
105   * callbacks object provided to connect().
106   */
107  void disconnect();
108
109  /**
110   * @return true if the socket is currently connected
111   */
112  bool isConnected() const;
113
114  /**
115   * Send a message on the connected socket. Safe to call from any thread.
116   *
117   * @param data Buffer containing message data
118   * @param length Size of the message to send in bytes
119   *
120   * @return true if the message was successfully sent
121   */
122  bool sendMessage(const void *data, size_t length);
123
124 private:
125  static constexpr size_t kMaxSocketNameLen = 64;
126  char mSocketName[kMaxSocketNameLen];
127  sp<ICallbacks> mCallbacks;
128
129  std::atomic<int> mSockFd;
130  std::thread mRxThread;
131
132  //! Set to true when we initiate the graceful socket shutdown procedure, so we
133  //! know not to invoke onSocketDisconnectedByRemote()
134  std::atomic<bool> mGracefulShutdown;
135
136  //! Condition variable used as the method to wake the RX thread when we want
137  //! to disconnect, but it's trying to reconnect automatically
138  std::condition_variable mShutdownCond;
139  std::mutex mShutdownMutex;
140
141  bool doConnect(const char *socketName,
142                 const ::android::sp<ICallbacks>& callbacks,
143                 bool connectInBackground);
144  bool inReceiveThread() const;
145  void receiveThread();
146  bool receiveThreadRunning() const;
147  bool reconnect();
148  void startReceiveThread();
149  bool tryConnect(bool suppressErrorLogs = false);
150};
151
152}  // namespace chre
153}  // namespace android
154
155#endif  // CHRE_HOST_SOCKET_CLIENT_H_
156