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author | Glenn Kasten <gkasten@google.com> | 2012-11-26 10:40:24 -0800 |
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committer | Glenn Kasten <gkasten@google.com> | 2013-03-05 08:26:50 -0800 |
commit | 538f498bbd5a2da51c9037a2689afc97f8bded8f (patch) | |
tree | 1c9197aff7f824310044a6b88148e04c20c85552 /include/media | |
parent | 0c57461f2c19f3a271c66f52cf8c9b2a82b13518 (diff) | |
download | frameworks_av-538f498bbd5a2da51c9037a2689afc97f8bded8f.zip frameworks_av-538f498bbd5a2da51c9037a2689afc97f8bded8f.tar.gz frameworks_av-538f498bbd5a2da51c9037a2689afc97f8bded8f.tar.bz2 |
Add template class SingleStateQueue
Change-Id: If7e2bc9b2a216524ee9cbb68682e2634933b4973
Diffstat (limited to 'include/media')
-rw-r--r-- | include/media/SingleStateQueue.h | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/include/media/SingleStateQueue.h b/include/media/SingleStateQueue.h new file mode 100644 index 0000000..04c5fd0 --- /dev/null +++ b/include/media/SingleStateQueue.h @@ -0,0 +1,97 @@ +/* + * 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. + */ + +#ifndef SINGLE_STATE_QUEUE_H +#define SINGLE_STATE_QUEUE_H + +// Non-blocking single element state queue, or +// Non-blocking single-reader / single-writer multi-word atomic load / store + +#include <stdint.h> + +namespace android { + +template<typename T> class SingleStateQueue { + +public: + + class Mutator; + class Observer; + + struct Shared { + // needs to be part of a union so don't define constructor or destructor + + friend class Mutator; + friend class Observer; + +private: + void init() { mAck = 0; mSequence = 0; } + + volatile int32_t mAck; +#if 0 + int mPad[7]; + // cache line boundary +#endif + volatile int32_t mSequence; + T mValue; + }; + + class Mutator { + public: + Mutator(Shared *shared); + /*virtual*/ ~Mutator() { } + + // push new value onto state queue, overwriting previous value; + // returns a sequence number which can be used with ack() + int32_t push(const T& value); + + // return true if most recent push has been observed + bool ack(); + + // return true if a push with specified sequence number or later has been observed + bool ack(int32_t sequence); + + private: + int32_t mSequence; + Shared * const mShared; + }; + + class Observer { + public: + Observer(Shared *shared); + /*virtual*/ ~Observer() { } + + // return true if value has changed + bool poll(T& value); + + private: + int32_t mSequence; + int mSeed; // for PRNG + Shared * const mShared; + }; + +#if 0 + SingleStateQueue(void /*Shared*/ *shared); + /*virtual*/ ~SingleStateQueue() { } + + static size_t size() { return sizeof(Shared); } +#endif + +}; + +} // namespace android + +#endif // SINGLE_STATE_QUEUE_H |