Add AutoPark template class and use to control FastMixer

Bug: 24667895
Change-Id: Id739a109aca13664b9390d2f9d9616fa2f88d188
diff --git a/services/audioflinger/AutoPark.h b/services/audioflinger/AutoPark.h
new file mode 100644
index 0000000..e539e47
--- /dev/null
+++ b/services/audioflinger/AutoPark.h
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2016 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.
+ */
+
+namespace android {
+
+// T is FastMixer or FastCapture
+template<typename T> class AutoPark {
+public:
+
+    // Park the specific FastThread, which can be nullptr, in hot idle if not currently idling
+    AutoPark(const sp<T>& fastThread) : mFastThread(fastThread)
+    {
+        mPreviousCommand = FastThreadState::HOT_IDLE;
+        if (fastThread != nullptr) {
+            auto sq = mFastThread->sq();
+            FastThreadState *state = sq->begin();
+            if (!(state->mCommand & FastThreadState::IDLE)) {
+                mPreviousCommand = state->mCommand;
+                state->mCommand = FastThreadState::HOT_IDLE;
+                sq->end();
+                sq->push(sq->BLOCK_UNTIL_ACKED);
+            } else {
+                sq->end(false /*didModify*/);
+            }
+        }
+    }
+
+    // Remove the FastThread from hot idle if necessary
+    ~AutoPark()
+    {
+        if (!(mPreviousCommand & FastThreadState::IDLE)) {
+            ALOG_ASSERT(mFastThread != nullptr);
+            auto sq = mFastThread->sq();
+            FastThreadState *state = sq->begin();
+            ALOG_ASSERT(state->mCommand == FastThreadState::HOT_IDLE);
+            state->mCommand = mPreviousCommand;
+            sq->end();
+            sq->push(sq->BLOCK_UNTIL_PUSHED);
+        }
+    }
+
+private:
+    const sp<T>                 mFastThread;
+    // if !&IDLE, holds the FastThread state to restore after new parameters processed
+    FastThreadState::Command    mPreviousCommand;
+};  // class AutoPark
+
+}   // namespace
diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index 973c983..bc17339 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -71,6 +71,8 @@
 #include <cpustats/ThreadCpuUsage.h>
 #endif
 
+#include "AutoPark.h"
+
 // ----------------------------------------------------------------------------
 
 // Note: the following macro is used for extremely verbose logging message.  In
@@ -3283,31 +3285,9 @@
 status_t AudioFlinger::MixerThread::createAudioPatch_l(const struct audio_patch *patch,
                                                           audio_patch_handle_t *handle)
 {
-    // if !&IDLE, holds the FastMixer state to restore after new parameters processed
-    FastMixerState::Command previousCommand = FastMixerState::HOT_IDLE;
-    if (mFastMixer != 0) {
-        FastMixerStateQueue *sq = mFastMixer->sq();
-        FastMixerState *state = sq->begin();
-        if (!(state->mCommand & FastMixerState::IDLE)) {
-            previousCommand = state->mCommand;
-            state->mCommand = FastMixerState::HOT_IDLE;
-            sq->end();
-            sq->push(FastMixerStateQueue::BLOCK_UNTIL_ACKED);
-        } else {
-            sq->end(false /*didModify*/);
-        }
-    }
-    status_t status = PlaybackThread::createAudioPatch_l(patch, handle);
+    AutoPark<FastMixer> park(mFastMixer);
 
-    if (!(previousCommand & FastMixerState::IDLE)) {
-        ALOG_ASSERT(mFastMixer != 0);
-        FastMixerStateQueue *sq = mFastMixer->sq();
-        FastMixerState *state = sq->begin();
-        ALOG_ASSERT(state->mCommand == FastMixerState::HOT_IDLE);
-        state->mCommand = previousCommand;
-        sq->end();
-        sq->push(FastMixerStateQueue::BLOCK_UNTIL_PUSHED);
-    }
+    status_t status = PlaybackThread::createAudioPatch_l(patch, handle);
 
     return status;
 }
@@ -3390,33 +3370,10 @@
 
 status_t AudioFlinger::MixerThread::releaseAudioPatch_l(const audio_patch_handle_t handle)
 {
-    // if !&IDLE, holds the FastMixer state to restore after new parameters processed
-    FastMixerState::Command previousCommand = FastMixerState::HOT_IDLE;
-    if (mFastMixer != 0) {
-        FastMixerStateQueue *sq = mFastMixer->sq();
-        FastMixerState *state = sq->begin();
-        if (!(state->mCommand & FastMixerState::IDLE)) {
-            previousCommand = state->mCommand;
-            state->mCommand = FastMixerState::HOT_IDLE;
-            sq->end();
-            sq->push(FastMixerStateQueue::BLOCK_UNTIL_ACKED);
-        } else {
-            sq->end(false /*didModify*/);
-        }
-    }
+    AutoPark<FastMixer> park(mFastMixer);
 
     status_t status = PlaybackThread::releaseAudioPatch_l(handle);
 
-    if (!(previousCommand & FastMixerState::IDLE)) {
-        ALOG_ASSERT(mFastMixer != 0);
-        FastMixerStateQueue *sq = mFastMixer->sq();
-        FastMixerState *state = sq->begin();
-        ALOG_ASSERT(state->mCommand == FastMixerState::HOT_IDLE);
-        state->mCommand = previousCommand;
-        sq->end();
-        sq->push(FastMixerStateQueue::BLOCK_UNTIL_PUSHED);
-    }
-
     return status;
 }
 
@@ -4464,20 +4421,7 @@
 
     status = NO_ERROR;
 
-    // if !&IDLE, holds the FastMixer state to restore after new parameters processed
-    FastMixerState::Command previousCommand = FastMixerState::HOT_IDLE;
-    if (mFastMixer != 0) {
-        FastMixerStateQueue *sq = mFastMixer->sq();
-        FastMixerState *state = sq->begin();
-        if (!(state->mCommand & FastMixerState::IDLE)) {
-            previousCommand = state->mCommand;
-            state->mCommand = FastMixerState::HOT_IDLE;
-            sq->end();
-            sq->push(FastMixerStateQueue::BLOCK_UNTIL_ACKED);
-        } else {
-            sq->end(false /*didModify*/);
-        }
-    }
+    AutoPark<FastMixer> park(mFastMixer);
 
     AudioParameter param = AudioParameter(keyValuePair);
     int value;
@@ -4572,16 +4516,6 @@
         }
     }
 
-    if (!(previousCommand & FastMixerState::IDLE)) {
-        ALOG_ASSERT(mFastMixer != 0);
-        FastMixerStateQueue *sq = mFastMixer->sq();
-        FastMixerState *state = sq->begin();
-        ALOG_ASSERT(state->mCommand == FastMixerState::HOT_IDLE);
-        state->mCommand = previousCommand;
-        sq->end();
-        sq->push(FastMixerStateQueue::BLOCK_UNTIL_PUSHED);
-    }
-
     return reconfig || a2dpDeviceChanged;
 }