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 25 namespace chre { 26 27 /** 28 * Storage for the SLPI implementation of PlatformLog. 29 */ 30 class 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