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 #include "chre/platform/shared/platform_log.h"
18 
19 #include <cstdarg>
20 #include <cstdio>
21 #include <iostream>
22 
23 #include "chre/platform/fatal_error.h"
24 
25 namespace chre {
26 
27 void PlatformLogBase::logLooper() {
28   while (1) {
29     char *logMessage = nullptr;
30 
31     {
32       std::unique_lock<std::mutex> lock(mMutex);
33       mConditionVariable.wait(
34           lock, [this] { return (!mLogQueue.empty() || mStopLogger); });
35 
36       if (!mLogQueue.empty()) {
37         // Move the log message to avoid holding a lock for longer than
38         // required.
39         logMessage = mLogQueue.front();
40         mLogQueue.pop();
41       } else if (mStopLogger) {
42         // The stop logger is checked in an else-if to allow the main log queue
43         // to drain when the logger is stopping.
44         break;
45       }
46     }
47 
48     // If we get here, there must be a log message to output. This is outside of
49     // the context of the lock which means that the logging thread will only be
50     // blocked for the minimum amount of time.
51     std::cerr << logMessage << std::endl;
52     free(logMessage);
53   }
54 }
55 
56 PlatformLog::PlatformLog() {
57   mLoggerThread = std::thread(&PlatformLog::logLooper, this);
58 }
59 
60 PlatformLog::~PlatformLog() {
61   {
62     std::unique_lock<std::mutex> lock(mMutex);
63     mStopLogger = true;
64     mConditionVariable.notify_one();
65   }
66 
67   mLoggerThread.join();
68 }
69 
70 void PlatformLog::log(const char *formatStr, ...) {
71   char *formattedStr;
72   va_list argList;
73   va_start(argList, formatStr);
74   int result = vasprintf(&formattedStr, formatStr, argList);
75   va_end(argList);
76 
77   if (result >= 0) {
78     std::unique_lock<std::mutex> lock(mMutex);
79     mLogQueue.push(formattedStr);
80     mConditionVariable.notify_one();
81   } else {
82     FATAL_ERROR("Failed to allocate log message");
83   }
84 }
85 
86 }  // namespace chre
87