Home | History | Annotate | Download | only in audio_utils 
      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 
     17 #include <errno.h>
     18 #include <limits.h>
     19 #include <audio_utils/fifo_index.h>
     20 #include <audio_utils/futex.h>
     21 
     22 // These are not implemented within <audio_utils/fifo_index.h>
     23 // so that we don't expose futex.
     24 
     25 uint32_t audio_utils_fifo_index::loadAcquire()
     26 {
     27     return atomic_load_explicit(&mIndex, std::memory_order_acquire);
     28 }
     29 
     30 void audio_utils_fifo_index::storeRelease(uint32_t value)
     31 {
     32     atomic_store_explicit(&mIndex, value, std::memory_order_release);
     33 }
     34 
     35 int audio_utils_fifo_index::wait(int op, uint32_t expected, const struct timespec *timeout)
     36 {
     37     return sys_futex(&mIndex, op, expected, timeout, NULL, 0);
     38 }
     39 
     40 int audio_utils_fifo_index::wake(int op, int waiters)
     41 {
     42     return sys_futex(&mIndex, op, waiters, NULL, NULL, 0);
     43 }
     44 
     45 uint32_t audio_utils_fifo_index::loadConsume()
     46 {
     47     return atomic_load_explicit(&mIndex, std::memory_order_consume);
     48 }
     49 
     50 ////
     51 
     52 RefIndexDeferredStoreReleaseDeferredWake::RefIndexDeferredStoreReleaseDeferredWake(
     53         audio_utils_fifo_index& index)
     54     : mIndex(index), mValue(0), mWriteback(false), mWaiters(0), mWakeOp(FUTEX_WAIT_PRIVATE)
     55 {
     56 }
     57 
     58 RefIndexDeferredStoreReleaseDeferredWake::~RefIndexDeferredStoreReleaseDeferredWake()
     59 {
     60     writeback();
     61     wakeNowIfNeeded();
     62 }
     63 
     64 void RefIndexDeferredStoreReleaseDeferredWake::set(uint32_t value) {
     65     mValue = value;
     66     mWriteback = true;
     67 }
     68 
     69 void RefIndexDeferredStoreReleaseDeferredWake::writeback()
     70 {
     71     if (mWriteback) {
     72         // TODO When part of a collection, should use relaxed for all but the last writeback
     73         mIndex.storeRelease(mValue);
     74         mWriteback = false;
     75     }
     76 }
     77 
     78 void RefIndexDeferredStoreReleaseDeferredWake::writethrough(uint32_t value) {
     79     set(value);
     80     writeback();
     81 }
     82 
     83 void RefIndexDeferredStoreReleaseDeferredWake::wakeDeferred(int op, int waiters)
     84 {
     85     if (waiters <= 0) {
     86         return;
     87     }
     88     // default is FUTEX_WAKE_PRIVATE
     89     if (op == FUTEX_WAKE) {
     90         mWakeOp = FUTEX_WAKE;
     91     }
     92     if (waiters < INT_MAX - mWaiters) {
     93         mWaiters += waiters;
     94     } else {
     95         mWaiters = INT_MAX;
     96     }
     97 }
     98 
     99 void RefIndexDeferredStoreReleaseDeferredWake::wakeNowIfNeeded()
    100 {
    101     if (mWaiters > 0) {
    102         mIndex.wake(mWakeOp, mWaiters);
    103         mWaiters = 0;
    104         mWakeOp = FUTEX_WAKE_PRIVATE;
    105     }
    106 }
    107 
    108 void RefIndexDeferredStoreReleaseDeferredWake::wakeNow(int op, int waiters)
    109 {
    110     wakeDeferred(op, waiters);
    111     wakeNowIfNeeded();
    112 }
    113 
    114 ////
    115 
    116 RefIndexCachedLoadAcquireDeferredWait::RefIndexCachedLoadAcquireDeferredWait(
    117         audio_utils_fifo_index& index)
    118     : mIndex(index), mValue(0), mLoaded(false)
    119 {
    120 }
    121 
    122 RefIndexCachedLoadAcquireDeferredWait::~RefIndexCachedLoadAcquireDeferredWait()
    123 {
    124 }
    125 
    126 uint32_t RefIndexCachedLoadAcquireDeferredWait::get()
    127 {
    128     prefetch();
    129     return mValue;
    130 }
    131 
    132 void RefIndexCachedLoadAcquireDeferredWait::prefetch()
    133 {
    134     if (!mLoaded) {
    135         // TODO When part of a collection, should use relaxed for all but the last load
    136         mValue = mIndex.loadAcquire();
    137         mLoaded = true;
    138     }
    139 }
    140 
    141 void RefIndexCachedLoadAcquireDeferredWait::invalidate()
    142 {
    143     mLoaded = false;
    144 }
    145 
    146 #if 0
    147 uint32_t RefIndexCachedLoadAcquireDeferredWait::readthrough()
    148 {
    149     invalidate();
    150     return get();
    151 }
    152 #endif
    153 
    154 int RefIndexCachedLoadAcquireDeferredWait::wait(int op, const struct timespec *timeout)
    155 {
    156     if (!mLoaded) {
    157         return -EINVAL;
    158     }
    159     int err = mIndex.wait(op, mValue /*expected*/, timeout);
    160     invalidate();
    161     return err;
    162 }
    163