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_PLATFORM_PLATFORM_LOG_BASE_H_
18#define CHRE_PLATFORM_PLATFORM_LOG_BASE_H_
19
20#include <cstddef>
21#include <cstdint>
22
23#include "chre/platform/mutex.h"
24
25namespace chre {
26
27/**
28 * Storage for the SLPI implementation of PlatformLog.
29 */
30class PlatformLogBase {
31 public:
32  typedef void (FlushLogBufferCallback)(const char *buffer, size_t bufferSize,
33                                        void *context);
34
35  /**
36   * Flushes the log buffer by invoking a provided callback, passing in the log
37   * buffer and size, then resetting the log buffer. The callback is invoked
38   * within the context of the logging lock which guarantees exclusive access to
39   * the buffer. The callback should not attempt to use the PlatformLog::log()
40   * method or else a deadlock will occur.
41   *
42   * @param callback the callback to invoke within the context of a lock on the
43   *        log buffer.
44   * @param context a context pointer to provide to the callback.
45   */
46  void flushLogBuffer(FlushLogBufferCallback callback, void *context);
47
48 protected:
49  //! The maximum size of a formatted log message.
50  static constexpr size_t kMaxLogMessageSize = 160;
51
52  //! The size of the logging buffer, in bytes. Assuming an average log message
53  //! has a length of 60, this allows for ~70 log messages. Some messages may
54  //! be longer, some may be shorter. YMMV but this should be a good balance
55  //! between AP wakeups and memory usage.
56  static constexpr size_t kLogBufferSize = (1 * 1024);
57
58  //! The watermark point at which log buffers should be sent to the host. This
59  //! cannot be zero or else an infinite loop may be caused. It must be large
60  //! enough to hold a few messages.
61  static constexpr size_t kLogBufferWatermarkSize = (kLogBufferSize * 20) / 100;
62
63  //! A mutex for acquiring exclusive control over the log buffer and other
64  //! internal state.
65  Mutex mMutex;
66
67  //! The buffer to log messages into.
68  char mLogBuffer[kLogBufferSize];
69
70  //! The current size of messages logged in the buffer.
71  size_t mLogBufferSize = 0;
72
73  //! Set to true when a log flush is pending. Do not request another log flush
74  //! if this is set to true.
75  bool mLogFlushPending = false;
76};
77
78}  // namespace chre
79
80#endif  // CHRE_PLATFORM_PLATFORM_LOG_BASE_H_
81