/*
* Copyright (C) 2010 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.
*/
#include "sles_allinclusive.h"
// Use this macro to validate a pthread_t before passing it into pthread_gettid_np.
// One of the common reasons for deadlock is trying to lock a mutex for an object
// which has been destroyed (which does memset to 0x00 or 0x55 as the final step).
// To avoid crashing with a SIGSEGV right before we're about to log a deadlock warning,
// we check that the pthread_t is probably valid. Note that it is theoretically
// possible for something to look like a valid pthread_t but not actually be valid.
// So we might still crash, but only in the case where a deadlock was imminent anyway.
#define LIKELY_VALID(ptr) (((ptr) != (pthread_t) 0) && ((((size_t) (ptr)) & 3) == 0))
/** \brief Exclusively lock an object */
#ifdef USE_DEBUG
void init_time_spec(timespec* ts, long delta) {
clock_gettime(CLOCK_REALTIME, ts);
ts->tv_nsec += delta;
if (ts->tv_nsec >= 1000000000L) {
ts->tv_sec++;
ts->tv_nsec -= 1000000000L;
}
}
void object_lock_exclusive_(IObject *thiz, const char *file, int line)
{
int ok;
ok = pthread_mutex_trylock(&thiz->mMutex);
if (0 != ok) {
// not android_atomic_acquire_load because we don't care about relative load/load ordering
int32_t oldGeneration = thiz->mGeneration;
// wait up to a total of 250 ms
static const long nanoBackoffs[] = {
10 * 1000000, 20 * 1000000, 30 * 1000000, 40 * 1000000, 50 * 1000000, 100 * 1000000};
unsigned i = 0;
timespec ts;
memset(&ts, 0, sizeof(timespec));
for (;;) {
init_time_spec(&ts, nanoBackoffs[i]);
ok = pthread_mutex_timedlock(&thiz->mMutex, &ts);
if (0 == ok) {
break;
}
if (EBUSY == ok) {
// this is the expected return value for timeout, and will be handled below
} else if (EDEADLK == ok) {
// we don't use the kind of mutex that can return this error, but just in case
SL_LOGE("%s:%d: recursive lock detected", file, line);
} else {
// some other return value
SL_LOGE("%s:%d: pthread_mutex_lock_timeout_np returned %d", file, line, ok);
}
// is anyone else making forward progress?
int32_t newGeneration = thiz->mGeneration;
if (newGeneration != oldGeneration) {
// if we ever see forward progress then lock without timeout (more efficient)
goto forward_progress;
}
// no, then continue trying to lock but with increasing timeouts
if (++i >= (sizeof(nanoBackoffs) / sizeof(nanoBackoffs[0]))) {
// the extra block avoids a C++ compiler error about goto past initialization
{
pthread_t me = pthread_self();
pthread_t owner = thiz->mOwner;
// unlikely, but this could result in a memory fault if owner is corrupt
pid_t ownerTid = LIKELY_VALID(owner) ? pthread_gettid_np(owner) : -1;
SL_LOGW("%s:%d: pthread %p (tid %d) sees object %p was locked by pthread %p"
" (tid %d) at %s:%d\n", file, line, *(void **)&me, gettid(), thiz,
*(void **)&owner, ownerTid, thiz->mFile, thiz->mLine);
}
forward_progress:
// attempt one more time without timeout; maybe this time we will be successful
ok = pthread_mutex_lock(&thiz->mMutex);
assert(0 == ok);
break;
}
}
}
// here if mutex was successfully locked
pthread_t zero;
memset(&zero, 0, sizeof(pthread_t));
if (0 != memcmp(&zero, &thiz->mOwner, sizeof(pthread_t))) {
pthread_t me = pthread_self();
pthread_t owner = thiz->mOwner;
pid_t ownerTid = LIKELY_VALID(owner) ? pthread_gettid_np(owner) : -1;
if (pthread_equal(pthread_self(), owner)) {
SL_LOGE("%s:%d: pthread %p (tid %d) sees object %p was recursively locked by pthread"
" %p (tid %d) at %s:%d\n", file, line, *(void **)&me, gettid(), thiz,
*(void **)&owner, ownerTid, thiz->mFile, thiz->mLine);
} else {
SL_LOGE("%s:%d: pthread %p (tid %d) sees object %p was left unlocked in unexpected"
" state by pthread %p (tid %d) at %s:%d\n", file, line, *(void **)&me, gettid(),
thiz, *(void **)&owner, ownerTid, thiz->mFile, thiz->mLine);
}
assert(false);
}
thiz->mOwner = pthread_self();
thiz->mFile = file;
thiz->mLine = line;
// not android_atomic_inc because we are already holding a mutex
++thiz->mGeneration;
}
#else
void object_lock_exclusive(IObject *thiz)
{
int ok;
ok = pthread_mutex_lock(&thiz->mMutex);
assert(0 == ok);
}
#endif
/** \brief Exclusively unlock an object and do not report any updates */
#ifdef USE_DEBUG
void object_unlock_exclusive_(IObject *thiz, const char *file, int line)
{
assert(pthread_equal(pthread_self(), thiz->mOwner));
assert(NULL != thiz->mFile);
assert(0 != thiz->mLine);
memset(&thiz->mOwner, 0, sizeof(pthread_t));
thiz->mFile = file;
thiz->mLine = line;
int ok;
ok = pthread_mutex_unlock(&thiz->mMutex);
assert(0 == ok);
}
#else
void object_unlock_exclusive(IObject *thiz)
{
int ok;
ok = pthread_mutex_unlock(&thiz->mMutex);
assert(0 == ok);
}
#endif
/** \brief Exclusively unlock an object and report updates to the specified bit-mask of
* attributes
*/
#ifdef USE_DEBUG
void object_unlock_exclusive_attributes_(IObject *thiz, unsigned attributes,
const char *file, int line)
#else
void object_unlock_exclusive_attributes(IObject *thiz, unsigned attributes)
#endif
{
#ifdef USE_DEBUG
assert(pthread_equal(pthread_self(), thiz->mOwner));
assert(NULL != thiz->mFile);
assert(0 != thiz->mLine);
#endif
int ok;
// make SL object IDs be contiguous with XA object IDs
SLuint32 objectID = IObjectToObjectID(thiz);
SLuint32 index = objectID;
if ((XA_OBJECTID_ENGINE <= index) && (index <= XA_OBJECTID_CAMERADEVICE)) {
;
} else if ((SL_OBJECTID_ENGINE <= index) && (index <= SL_OBJECTID_METADATAEXTRACTOR)) {
index -= SL_OBJECTID_ENGINE - XA_OBJECTID_CAMERADEVICE - 1;
} else {
assert(false);
index = 0;
}
// first synchronously handle updates to attributes here, while object is still locked.
// This appears to be a loop, but actually typically runs through the loop only once.
unsigned asynchronous = attributes;
while (attributes) {
// this sequence is carefully crafted to be O(1); tread carefully when making changes
unsigned bit = ctz(attributes);
// ATTR_INDEX_MAX == next bit position after the last attribute
assert(ATTR_INDEX_MAX > bit);
// compute the entry in the handler table using object ID and bit number
AttributeHandler handler = handlerTable[index][bit];
if (NULL != handler) {
asynchronous &= ~(*handler)(thiz);
}
attributes &= ~(1 << bit);
}
// any remaining attributes are handled asynchronously in the sync thread
if (asynchronous) {
unsigned oldAttributesMask = thiz->mAttributesMask;
thiz->mAttributesMask = oldAttributesMask | asynchronous;
if (oldAttributesMask) {
asynchronous = ATTR_NONE;
}
}
#ifdef ANDROID
// FIXME hack to safely handle a post-unlock PrefetchStatus callback and/or AudioTrack::start()
slPrefetchCallback prefetchCallback = NULL;
void *prefetchContext = NULL;
SLuint32 prefetchEvents = SL_PREFETCHEVENT_NONE;
android::sp<android::AudioTrack> audioTrack;
if (SL_OBJECTID_AUDIOPLAYER == objectID) {
CAudioPlayer *ap = (CAudioPlayer *) thiz;
prefetchCallback = ap->mPrefetchStatus.mDeferredPrefetchCallback;
prefetchContext = ap->mPrefetchStatus.mDeferredPrefetchContext;
prefetchEvents = ap->mPrefetchStatus.mDeferredPrefetchEvents;
ap->mPrefetchStatus.mDeferredPrefetchCallback = NULL;
// clearing these next two fields is not required, but avoids stale data during debugging
ap->mPrefetchStatus.mDeferredPrefetchContext = NULL;
ap->mPrefetchStatus.mDeferredPrefetchEvents = SL_PREFETCHEVENT_NONE;
if (ap->mDeferredStart) {
audioTrack = ap->mAudioTrack;
ap->mDeferredStart = false;
}
}
#endif
#ifdef USE_DEBUG
memset(&thiz->mOwner, 0, sizeof(pthread_t));
thiz->mFile = file;
thiz->mLine = line;
#endif
ok = pthread_mutex_unlock(&thiz->mMutex);
assert(0 == ok);
#ifdef ANDROID
// FIXME call the prefetch status callback while not holding the mutex on AudioPlayer
if (NULL != prefetchCallback) {
// note these are synchronous by the application's thread as it is about to return from API
assert(prefetchEvents != SL_PREFETCHEVENT_NONE);
CAudioPlayer *ap = (CAudioPlayer *) thiz;
// spec requires separate callbacks for each event
if (SL_PREFETCHEVENT_STATUSCHANGE & prefetchEvents) {
(*prefetchCallback)(&ap->mPrefetchStatus.mItf, prefetchContext,
SL_PREFETCHEVENT_STATUSCHANGE);
}
if (SL_PREFETCHEVENT_FILLLEVELCHANGE & prefetchEvents) {
(*prefetchCallback)(&ap->mPrefetchStatus.mItf, prefetchContext,
SL_PREFETCHEVENT_FILLLEVELCHANGE);
}
}
// call AudioTrack::start() while not holding the mutex on AudioPlayer
if (audioTrack != 0) {
audioTrack->start();
audioTrack.clear();
}
#endif
// first update to this interface since previous sync
if (ATTR_NONE != asynchronous) {
unsigned id = thiz->mInstanceID;
if (0 != id) {
--id;
assert(MAX_INSTANCE > id);
IEngine *thisEngine = &thiz->mEngine->mEngine;
// FIXME atomic or here
interface_lock_exclusive(thisEngine);
thisEngine->mChangedMask |= 1 << id;
interface_unlock_exclusive(thisEngine);
}
}
}
/** \brief Wait on the condition variable associated with the object; see pthread_cond_wait */
#ifdef USE_DEBUG
void object_cond_wait_(IObject *thiz, const char *file, int line)
{
// note that this will unlock the mutex, so we have to clear the owner
assert(pthread_equal(pthread_self(), thiz->mOwner));
assert(NULL != thiz->mFile);
assert(0 != thiz->mLine);
memset(&thiz->mOwner, 0, sizeof(pthread_t));
thiz->mFile = file;
thiz->mLine = line;
// alas we don't know the new owner's identity
int ok;
ok = pthread_cond_wait(&thiz->mCond, &thiz->mMutex);
assert(0 == ok);
// restore my ownership
thiz->mOwner = pthread_self();
thiz->mFile = file;
thiz->mLine = line;
}
#else
void object_cond_wait(IObject *thiz)
{
int ok;
ok = pthread_cond_wait(&thiz->mCond, &thiz->mMutex);
assert(0 == ok);
}
#endif
/** \brief Signal the condition variable associated with the object; see pthread_cond_signal */
void object_cond_signal(IObject *thiz)
{
int ok;
ok = pthread_cond_signal(&thiz->mCond);
assert(0 == ok);
}
/** \brief Broadcast the condition variable associated with the object;
* see pthread_cond_broadcast
*/
void object_cond_broadcast(IObject *thiz)
{
int ok;
ok = pthread_cond_broadcast(&thiz->mCond);
assert(0 == ok);
}