Add audio watchdog thread

Change-Id: I4ed62087bd6554179abb8258d2da606050e762c0

1 files changed, 88 insertions, 0 deletions

diff --git a/services/audioflinger/AudioWatchdog.h b/services/audioflinger/AudioWatchdog.h
new file mode 100644
index 0000000..4657530
--- /dev/null
+++ b/services/audioflinger/AudioWatchdog.h
@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// The watchdog thread runs periodically.  It has two functions:
+//   (a) verify that adequate CPU time is available, and log
+//       as soon as possible when there appears to be a CPU shortage
+//   (b) monitor the other threads [not yet implemented]
+
+#ifndef AUDIO_WATCHDOG_H
+#define AUDIO_WATCHDOG_H
+
+#include <time.h>
+#include <utils/Thread.h>
+
+namespace android {
+
+// Keeps a cache of AudioWatchdog statistics that can be logged by dumpsys.
+// The usual caveats about atomicity of information apply.
+struct AudioWatchdogDump {
+    AudioWatchdogDump() : mUnderruns(0), mLogs(0), mMostRecent(0) { }
+    /*virtual*/ ~AudioWatchdogDump() { }
+    uint32_t mUnderruns;    // total number of underruns
+    uint32_t mLogs;         // total number of log messages
+    time_t   mMostRecent;   // time of most recent log
+    void     dump(int fd);  // should only be called on a stable copy, not the original
+};
+
+class AudioWatchdog : public Thread {
+
+public:
+    AudioWatchdog(unsigned periodMs = 50) : Thread(false /*canCallJava*/), mPaused(false),
+            mPeriodNs(periodMs * 1000000), mMaxCycleNs(mPeriodNs * 2),
+            // mOldTs
+            // mLogTs initialized below
+            mOldTsValid(false), mUnderruns(0), mLogs(0), mDump(&mDummyDump)
+        {
+#define MIN_TIME_BETWEEN_LOGS_SEC 60
+            // force an immediate log on first underrun
+            mLogTs.tv_sec = MIN_TIME_BETWEEN_LOGS_SEC;
+            mLogTs.tv_nsec = 0;
+        }
+    virtual         ~AudioWatchdog() { }
+
+     // Do not call Thread::requestExitAndWait() without first calling requestExit().
+    // Thread::requestExitAndWait() is not virtual, and the implementation doesn't do enough.
+    virtual void        requestExit();
+
+    // FIXME merge API and implementation with AudioTrackThread
+    void            pause();        // suspend thread from execution at next loop boundary
+    void            resume();       // allow thread to execute, if not requested to exit
+
+    // Where to store the dump, or NULL to not update
+    void            setDump(AudioWatchdogDump* dump);
+
+private:
+    virtual bool    threadLoop();
+
+    Mutex           mMyLock;        // Thread::mLock is private
+    Condition       mMyCond;        // Thread::mThreadExitedCondition is private
+    bool            mPaused;        // whether thread is currently paused
+
+    uint32_t        mPeriodNs;      // nominal period
+    uint32_t        mMaxCycleNs;    // maximum allowed time of one cycle before declaring underrun
+    struct timespec mOldTs;         // monotonic time when threadLoop last ran
+    struct timespec mLogTs;         // time since last log
+    bool            mOldTsValid;    // whether mOldTs is valid
+    uint32_t        mUnderruns;     // total number of underruns
+    uint32_t        mLogs;          // total number of logs
+    AudioWatchdogDump*  mDump;      // where to store the dump, always non-NULL
+    AudioWatchdogDump   mDummyDump; // default area for dump in case setDump() is not called
+};
+
+}   // namespace android
+
+#endif  // AUDIO_WATCHDOG_H