1dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten/* 2dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten * Copyright (C) 2012 The Android Open Source Project 3dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten * 4dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten * Licensed under the Apache License, Version 2.0 (the "License"); 5dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten * you may not use this file except in compliance with the License. 6dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten * You may obtain a copy of the License at 7dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten * 8dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten * http://www.apache.org/licenses/LICENSE-2.0 9dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten * 10dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten * Unless required by applicable law or agreed to in writing, software 11dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten * distributed under the License is distributed on an "AS IS" BASIS, 12dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten * See the License for the specific language governing permissions and 14dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten * limitations under the License. 15dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten */ 16dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten 17dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten#ifndef ANDROID_AUDIO_STATE_QUEUE_H 18dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten#define ANDROID_AUDIO_STATE_QUEUE_H 19dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten 20dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kastennamespace android { 21dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten 22399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten#ifdef STATE_QUEUE_DUMP 23399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten// The StateQueueObserverDump and StateQueueMutatorDump keep 24399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten// a cache of StateQueue statistics that can be logged by dumpsys. 25399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten// Each individual native word-sized field is accessed atomically. But the 26399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten// overall structure is non-atomic, that is there may be an inconsistency between fields. 27399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten// No barriers or locks are used for either writing or reading. 28399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten// Only POD types are permitted, and the contents shouldn't be trusted (i.e. do range checks). 29399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten// It has a different lifetime than the StateQueue, and so it can't be a member of StateQueue. 30399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten 31399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kastenstruct StateQueueObserverDump { 32399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten StateQueueObserverDump() : mStateChanges(0) { } 33399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten /*virtual*/ ~StateQueueObserverDump() { } 34399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten unsigned mStateChanges; // incremented each time poll() detects a state change 35399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten void dump(int fd); 36399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten}; 37399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten 38399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kastenstruct StateQueueMutatorDump { 39399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten StateQueueMutatorDump() : mPushDirty(0), mPushAck(0), mBlockedSequence(0) { } 40399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten /*virtual*/ ~StateQueueMutatorDump() { } 41399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten unsigned mPushDirty; // incremented each time push() is called with a dirty state 42399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten unsigned mPushAck; // incremented each time push(BLOCK_UNTIL_ACKED) is called 43399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten unsigned mBlockedSequence; // incremented before and after each time that push() 44399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten // blocks for more than one PUSH_BLOCK_ACK_NS; 45399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten // if odd, then mutator is currently blocked inside push() 46399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten void dump(int fd); 47399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten}; 48399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten#endif 49399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten 50dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten// manages a FIFO queue of states 51dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kastentemplate<typename T> class StateQueue { 52dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten 53dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kastenpublic: 54dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten StateQueue(); 55dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten virtual ~StateQueue(); 56dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten 57dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // Observer APIs 58dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten 59dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // Poll for a state change. Returns a pointer to a read-only state, 60dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // or NULL if the state has not been initialized yet. 61dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // If a new state has not pushed by mutator since the previous poll, 62dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // then the returned pointer will be unchanged. 63dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // The previous state pointer is guaranteed to still be valid; 64dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // this allows the observer to diff the previous and new states. 65dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten const T* poll(); 66dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten 67dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // Mutator APIs 68dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten 69dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // Begin a mutation. Returns a pointer to a read/write state, except the 70dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // first time it is called the state is write-only and _must_ be initialized. 71dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // Mutations cannot be nested. 72dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // If the state is dirty and has not been pushed onto the state queue yet, then 73dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // this new mutation will be squashed together with the previous one. 74dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten T* begin(); 75dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten 76dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // End the current mutation and indicate whether caller modified the state. 77dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // If didModify is true, then the state is marked dirty (in need of pushing). 78dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // There is no rollback option because modifications are done in place. 79dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // Does not automatically push the new state onto the state queue. 80dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten void end(bool didModify = true); 81dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten 82dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // Push a new state, if any, out to the observer via the state queue. 83dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // For BLOCK_NEVER, returns: 84dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // true if not dirty, or dirty and pushed successfully 85dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // false if dirty and not pushed because that would block; remains dirty 86dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // For BLOCK_UNTIL_PUSHED and BLOCK_UNTIL_ACKED, always returns true. 87dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // No-op if there are no pending modifications (not dirty), except 88dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // for BLOCK_UNTIL_ACKED it will wait until a prior push has been acknowledged. 89dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // Must not be called in the middle of a mutation. 90dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten enum block_t { 91dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten BLOCK_NEVER, // do not block 92dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten BLOCK_UNTIL_PUSHED, // block until there's a slot available for the push 93dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten BLOCK_UNTIL_ACKED, // also block until the push is acknowledged by the observer 94dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten }; 95dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten bool push(block_t block = BLOCK_NEVER); 96dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten 97dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // Return whether the current state is dirty (modified and not pushed). 98dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten bool isDirty() const { return mIsDirty; } 99dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten 100399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten#ifdef STATE_QUEUE_DUMP 101399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten // Register location of observer dump area 102399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten void setObserverDump(StateQueueObserverDump *dump) 103399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten { mObserverDump = dump != NULL ? dump : &mObserverDummyDump; } 104399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten 105399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten // Register location of mutator dump area 106399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten void setMutatorDump(StateQueueMutatorDump *dump) 107399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten { mMutatorDump = dump != NULL ? dump : &mMutatorDummyDump; } 108399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten#endif 109399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten 110dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kastenprivate: 111dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten static const unsigned kN = 4; // values != 4 are not supported by this code 112dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten T mStates[kN]; // written by mutator, read by observer 113dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten 114dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // "volatile" is meaningless with SMP, but here it indicates that we're using atomic ops 115dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten volatile const T* mNext; // written by mutator to advance next, read by observer 116dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten volatile const T* mAck; // written by observer to acknowledge advance of next, read by mutator 117dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten 118dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // only used by observer 119dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten const T* mCurrent; // most recent value returned by poll() 120dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten 121dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten // only used by mutator 122dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten T* mMutating; // where updates by mutator are done in place 123dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten const T* mExpecting; // what the mutator expects mAck to be set to 124dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten bool mInMutation; // whether we're currently in the middle of a mutation 125dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten bool mIsDirty; // whether mutating state has been modified since last push 126dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten bool mIsInitialized; // whether mutating state has been initialized yet 127dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten 128399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten#ifdef STATE_QUEUE_DUMP 129399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten StateQueueObserverDump mObserverDummyDump; // default area for observer dump if not set 130399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten StateQueueObserverDump* mObserverDump; // pointer to active observer dump, always non-NULL 131399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten StateQueueMutatorDump mMutatorDummyDump; // default area for mutator dump if not set 132399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten StateQueueMutatorDump* mMutatorDump; // pointer to active mutator dump, always non-NULL 133399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten#endif 134399930859a75d806ce0ef124ac22025ae4ef0549Glenn Kasten 135dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten}; // class StateQueue 136dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten 137dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten} // namespace android 138dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten 139dc998c809e084b617990b281e2ed5271830cc2e0Glenn Kasten#endif // ANDROID_AUDIO_STATE_QUEUE_H 140