1/*
2 * Copyright (C) 2016 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
17namespace android {
18
19// T is FastMixer or FastCapture
20template<typename T> class AutoPark {
21public:
22
23    // Park the specific FastThread, which can be nullptr, in hot idle if not currently idling
24    AutoPark(const sp<T>& fastThread) : mFastThread(fastThread)
25    {
26        mPreviousCommand = FastThreadState::HOT_IDLE;
27        if (fastThread != nullptr) {
28            auto sq = mFastThread->sq();
29            FastThreadState *state = sq->begin();
30            if (!(state->mCommand & FastThreadState::IDLE)) {
31                mPreviousCommand = state->mCommand;
32                state->mCommand = FastThreadState::HOT_IDLE;
33                sq->end();
34                sq->push(sq->BLOCK_UNTIL_ACKED);
35            } else {
36                sq->end(false /*didModify*/);
37            }
38        }
39    }
40
41    // Remove the FastThread from hot idle if necessary
42    ~AutoPark()
43    {
44        if (!(mPreviousCommand & FastThreadState::IDLE)) {
45            ALOG_ASSERT(mFastThread != nullptr);
46            auto sq = mFastThread->sq();
47            FastThreadState *state = sq->begin();
48            ALOG_ASSERT(state->mCommand == FastThreadState::HOT_IDLE);
49            state->mCommand = mPreviousCommand;
50            sq->end();
51            sq->push(sq->BLOCK_UNTIL_PUSHED);
52        }
53    }
54
55private:
56    const sp<T>                 mFastThread;
57    // if !&IDLE, holds the FastThread state to restore after new parameters processed
58    FastThreadState::Command    mPreviousCommand;
59};  // class AutoPark
60
61}   // namespace
62