New control block for AudioTrack and AudioRecord

Main differences between old and new control block:
 - removes the mutex, which was a potential source of priority inversion
 - circular indices into shared buffer, which is now always a power-of-2 size

Change-Id: I4e9b7fa99858b488ac98a441fa70e31dbba1b865
diff --git a/media/libmedia/AudioRecord.cpp b/media/libmedia/AudioRecord.cpp
index a2b8ae2..9faa497 100644
--- a/media/libmedia/AudioRecord.cpp
+++ b/media/libmedia/AudioRecord.cpp
@@ -19,18 +19,13 @@
 #define LOG_TAG "AudioRecord"
 
 #include <sys/resource.h>
-#include <sys/types.h>
-
 #include <binder/IPCThreadState.h>
-#include <cutils/atomic.h>
-#include <cutils/compiler.h>
 #include <media/AudioRecord.h>
-#include <media/AudioSystem.h>
-#include <system/audio.h>
 #include <utils/Log.h>
-
 #include <private/media/AudioTrackShared.h>
 
+#define WAIT_PERIOD_MS          10
+
 namespace android {
 // ---------------------------------------------------------------------------
 
@@ -41,7 +36,9 @@
         audio_format_t format,
         audio_channel_mask_t channelMask)
 {
-    if (frameCount == NULL) return BAD_VALUE;
+    if (frameCount == NULL) {
+        return BAD_VALUE;
+    }
 
     // default to 0 in case of error
     *frameCount = 0;
@@ -75,8 +72,7 @@
 
 AudioRecord::AudioRecord()
     : mStatus(NO_INIT), mSessionId(0),
-      mPreviousPriority(ANDROID_PRIORITY_NORMAL), mPreviousSchedulingGroup(SP_DEFAULT),
-      mProxy(NULL)
+      mPreviousPriority(ANDROID_PRIORITY_NORMAL), mPreviousSchedulingGroup(SP_DEFAULT)
 {
 }
 
@@ -89,14 +85,15 @@
         callback_t cbf,
         void* user,
         int notificationFrames,
-        int sessionId)
+        int sessionId,
+        transfer_type transferType)
     : mStatus(NO_INIT), mSessionId(0),
       mPreviousPriority(ANDROID_PRIORITY_NORMAL),
       mPreviousSchedulingGroup(SP_DEFAULT),
       mProxy(NULL)
 {
-    mStatus = set(inputSource, sampleRate, format, channelMask,
-            frameCount, cbf, user, notificationFrames, false /*threadCanCallJava*/, sessionId);
+    mStatus = set(inputSource, sampleRate, format, channelMask, frameCount, cbf, user,
+            notificationFrames, false /*threadCanCallJava*/, sessionId, transferType);
 }
 
 AudioRecord::~AudioRecord()
@@ -111,11 +108,13 @@
             mAudioRecordThread->requestExitAndWait();
             mAudioRecordThread.clear();
         }
-        mAudioRecord.clear();
+        if (mAudioRecord != 0) {
+            mAudioRecord->asBinder()->unlinkToDeath(mDeathNotifier, this);
+            mAudioRecord.clear();
+        }
         IPCThreadState::self()->flushCommands();
         AudioSystem::releaseAudioSessionId(mSessionId);
     }
-    delete mProxy;
 }
 
 status_t AudioRecord::set(
@@ -128,8 +127,32 @@
         void* user,
         int notificationFrames,
         bool threadCanCallJava,
-        int sessionId)
+        int sessionId,
+        transfer_type transferType)
 {
+    switch (transferType) {
+    case TRANSFER_DEFAULT:
+        if (cbf == NULL || threadCanCallJava) {
+            transferType = TRANSFER_SYNC;
+        } else {
+            transferType = TRANSFER_CALLBACK;
+        }
+        break;
+    case TRANSFER_CALLBACK:
+        if (cbf == NULL) {
+            ALOGE("Transfer type TRANSFER_CALLBACK but cbf == NULL");
+            return BAD_VALUE;
+        }
+        break;
+    case TRANSFER_OBTAIN:
+    case TRANSFER_SYNC:
+        break;
+    default:
+        ALOGE("Invalid transfer type %d", transferType);
+        return BAD_VALUE;
+    }
+    mTransfer = transferType;
+
     // FIXME "int" here is legacy and will be replaced by size_t later
     if (frameCountInt < 0) {
         ALOGE("Invalid frame count %d", frameCountInt);
@@ -143,6 +166,7 @@
     AutoMutex lock(mLock);
 
     if (mAudioRecord != 0) {
+        ALOGE("Track already in use");
         return INVALID_OPERATION;
     }
 
@@ -159,14 +183,16 @@
     if (format == AUDIO_FORMAT_DEFAULT) {
         format = AUDIO_FORMAT_PCM_16_BIT;
     }
+
     // validate parameters
     if (!audio_is_valid_format(format)) {
-        ALOGE("Invalid format");
+        ALOGE("Invalid format %d", format);
         return BAD_VALUE;
     }
     mFormat = format;
 
     if (!audio_is_input_channel(channelMask)) {
+        ALOGE("Invalid channel mask %#x", channelMask);
         return BAD_VALUE;
     }
     mChannelMask = channelMask;
@@ -200,6 +226,7 @@
     size_t minFrameCount = 0;
     status_t status = getMinFrameCount(&minFrameCount, sampleRate, format, channelMask);
     if (status != NO_ERROR) {
+        ALOGE("getMinFrameCount() failed; status %d", status);
         return status;
     }
     ALOGV("AudioRecord::set() minFrameCount = %d", minFrameCount);
@@ -207,6 +234,7 @@
     if (frameCount == 0) {
         frameCount = minFrameCount;
     } else if (frameCount < minFrameCount) {
+        ALOGE("frameCount %u < minFrameCount %u", frameCount, minFrameCount);
         return BAD_VALUE;
     }
 
@@ -215,7 +243,7 @@
     }
 
     // create the IAudioRecord
-    status = openRecord_l(sampleRate, format, frameCount, input);
+    status = openRecord_l(sampleRate, format, frameCount, input, 0 /*epoch*/);
     if (status != NO_ERROR) {
         return status;
     }
@@ -233,7 +261,7 @@
     mActive = false;
     mCbf = cbf;
     mNotificationFrames = notificationFrames;
-    mRemainingFrames = notificationFrames;
+    mRefreshRemaining = true;
     mUserData = user;
     // TODO: add audio hardware input latency here
     mLatency = (1000*mFrameCount) / sampleRate;
@@ -244,117 +272,78 @@
     mInputSource = inputSource;
     mInput = input;
     AudioSystem::acquireAudioSessionId(mSessionId);
+    mSequence = 1;
+    mObservedSequence = mSequence;
+    mInOverrun = false;
 
     return NO_ERROR;
 }
 
-status_t AudioRecord::initCheck() const
-{
-    return mStatus;
-}
-
-// -------------------------------------------------------------------------
-
-uint32_t AudioRecord::latency() const
-{
-    return mLatency;
-}
-
-audio_format_t AudioRecord::format() const
-{
-    return mFormat;
-}
-
-uint32_t AudioRecord::channelCount() const
-{
-    return mChannelCount;
-}
-
-size_t AudioRecord::frameCount() const
-{
-    return mFrameCount;
-}
-
-audio_source_t AudioRecord::inputSource() const
-{
-    return mInputSource;
-}
-
 // -------------------------------------------------------------------------
 
 status_t AudioRecord::start(AudioSystem::sync_event_t event, int triggerSession)
 {
-    status_t ret = NO_ERROR;
-    sp<AudioRecordThread> t = mAudioRecordThread;
-
     ALOGV("start, sync event %d trigger session %d", event, triggerSession);
 
     AutoMutex lock(mLock);
-    // acquire a strong reference on the IAudioRecord and IMemory so that they cannot be destroyed
-    // while we are accessing the cblk
-    sp<IAudioRecord> audioRecord = mAudioRecord;
-    sp<IMemory> iMem = mCblkMemory;
-    audio_track_cblk_t* cblk = mCblk;
+    if (mActive) {
+        return NO_ERROR;
+    }
 
-    if (!mActive) {
+    // reset current position as seen by client to 0
+    mProxy->setEpoch(mProxy->getEpoch() - mProxy->getPosition());
+
+    mNewPosition = mProxy->getPosition() + mUpdatePeriod;
+    int32_t flags = android_atomic_acquire_load(&mCblk->flags);
+
+    status_t status = NO_ERROR;
+    if (!(flags & CBLK_INVALID)) {
+        ALOGV("mAudioRecord->start()");
+        status = mAudioRecord->start(event, triggerSession);
+        if (status == DEAD_OBJECT) {
+            flags |= CBLK_INVALID;
+        }
+    }
+    if (flags & CBLK_INVALID) {
+        status = restoreRecord_l("start");
+    }
+
+    if (status != NO_ERROR) {
+        ALOGE("start() status %d", status);
+    } else {
         mActive = true;
-
-        cblk->lock.lock();
-        if (!(cblk->flags & CBLK_INVALID)) {
-            cblk->lock.unlock();
-            ALOGV("mAudioRecord->start()");
-            ret = mAudioRecord->start(event, triggerSession);
-            cblk->lock.lock();
-            if (ret == DEAD_OBJECT) {
-                android_atomic_or(CBLK_INVALID, &cblk->flags);
-            }
-        }
-        if (cblk->flags & CBLK_INVALID) {
-            audio_track_cblk_t* temp = cblk;
-            ret = restoreRecord_l(temp);
-            cblk = temp;
-        }
-        cblk->lock.unlock();
-        if (ret == NO_ERROR) {
-            mNewPosition = cblk->user + mUpdatePeriod;
-            cblk->bufferTimeoutMs = (event == AudioSystem::SYNC_EVENT_NONE) ? MAX_RUN_TIMEOUT_MS :
-                                            AudioSystem::kSyncRecordStartTimeOutMs;
-            cblk->waitTimeMs = 0;
-            if (t != 0) {
-                t->resume();
-            } else {
-                mPreviousPriority = getpriority(PRIO_PROCESS, 0);
-                get_sched_policy(0, &mPreviousSchedulingGroup);
-                androidSetThreadPriority(0, ANDROID_PRIORITY_AUDIO);
-            }
+        sp<AudioRecordThread> t = mAudioRecordThread;
+        if (t != 0) {
+            t->resume();
         } else {
-            mActive = false;
+            mPreviousPriority = getpriority(PRIO_PROCESS, 0);
+            get_sched_policy(0, &mPreviousSchedulingGroup);
+            androidSetThreadPriority(0, ANDROID_PRIORITY_AUDIO);
         }
     }
 
-    return ret;
+    return status;
 }
 
 void AudioRecord::stop()
 {
-    sp<AudioRecordThread> t = mAudioRecordThread;
-
-    ALOGV("stop");
-
     AutoMutex lock(mLock);
-    if (mActive) {
-        mActive = false;
-        mCblk->cv.signal();
-        mAudioRecord->stop();
-        // the record head position will reset to 0, so if a marker is set, we need
-        // to activate it again
-        mMarkerReached = false;
-        if (t != 0) {
-            t->pause();
-        } else {
-            setpriority(PRIO_PROCESS, 0, mPreviousPriority);
-            set_sched_policy(0, mPreviousSchedulingGroup);
-        }
+    if (!mActive) {
+        return;
+    }
+
+    mActive = false;
+    mProxy->interrupt();
+    mAudioRecord->stop();
+    // the record head position will reset to 0, so if a marker is set, we need
+    // to activate it again
+    mMarkerReached = false;
+    sp<AudioRecordThread> t = mAudioRecordThread;
+    if (t != 0) {
+        t->pause();
+    } else {
+        setpriority(PRIO_PROCESS, 0, mPreviousPriority);
+        set_sched_policy(0, mPreviousSchedulingGroup);
     }
 }
 
@@ -364,14 +353,11 @@
     return !mActive;
 }
 
-uint32_t AudioRecord::getSampleRate() const
-{
-    return mSampleRate;
-}
-
 status_t AudioRecord::setMarkerPosition(uint32_t marker)
 {
-    if (mCbf == NULL) return INVALID_OPERATION;
+    if (mCbf == NULL) {
+        return INVALID_OPERATION;
+    }
 
     AutoMutex lock(mLock);
     mMarkerPosition = marker;
@@ -382,7 +368,9 @@
 
 status_t AudioRecord::getMarkerPosition(uint32_t *marker) const
 {
-    if (marker == NULL) return BAD_VALUE;
+    if (marker == NULL) {
+        return BAD_VALUE;
+    }
 
     AutoMutex lock(mLock);
     *marker = mMarkerPosition;
@@ -392,13 +380,12 @@
 
 status_t AudioRecord::setPositionUpdatePeriod(uint32_t updatePeriod)
 {
-    if (mCbf == NULL) return INVALID_OPERATION;
-
-    uint32_t curPosition;
-    getPosition(&curPosition);
+    if (mCbf == NULL) {
+        return INVALID_OPERATION;
+    }
 
     AutoMutex lock(mLock);
-    mNewPosition = curPosition + updatePeriod;
+    mNewPosition = mProxy->getPosition() + updatePeriod;
     mUpdatePeriod = updatePeriod;
 
     return NO_ERROR;
@@ -406,7 +393,9 @@
 
 status_t AudioRecord::getPositionUpdatePeriod(uint32_t *updatePeriod) const
 {
-    if (updatePeriod == NULL) return BAD_VALUE;
+    if (updatePeriod == NULL) {
+        return BAD_VALUE;
+    }
 
     AutoMutex lock(mLock);
     *updatePeriod = mUpdatePeriod;
@@ -416,10 +405,12 @@
 
 status_t AudioRecord::getPosition(uint32_t *position) const
 {
-    if (position == NULL) return BAD_VALUE;
+    if (position == NULL) {
+        return BAD_VALUE;
+    }
 
     AutoMutex lock(mLock);
-    *position = mCblk->user;
+    *position = mProxy->getPosition();
 
     return NO_ERROR;
 }
@@ -427,7 +418,7 @@
 unsigned int AudioRecord::getInputFramesLost() const
 {
     // no need to check mActive, because if inactive this will return 0, which is what we want
-    return AudioSystem::getInputFramesLost(mInput);
+    return AudioSystem::getInputFramesLost(getInput());
 }
 
 // -------------------------------------------------------------------------
@@ -437,7 +428,8 @@
         uint32_t sampleRate,
         audio_format_t format,
         size_t frameCount,
-        audio_io_handle_t input)
+        audio_io_handle_t input,
+        size_t epoch)
 {
     status_t status;
     const sp<IAudioFlinger>& audioFlinger = AudioSystem::get_audio_flinger();
@@ -447,7 +439,7 @@
     }
 
     pid_t tid = -1;
-    // FIXME see similar logic at AudioTrack
+    // FIXME see similar logic at AudioTrack for tid
 
     int originalSessionId = mSessionId;
     sp<IAudioRecord> record = audioFlinger->openRecord(input,
@@ -470,133 +462,138 @@
         ALOGE("Could not get control block");
         return NO_INIT;
     }
-    mAudioRecord.clear();
+    if (mAudioRecord != 0) {
+        mAudioRecord->asBinder()->unlinkToDeath(mDeathNotifier, this);
+        mDeathNotifier.clear();
+    }
     mAudioRecord = record;
-    mCblkMemory.clear();
     mCblkMemory = iMem;
     audio_track_cblk_t* cblk = static_cast<audio_track_cblk_t*>(iMem->pointer());
     mCblk = cblk;
-    mBuffers = (char*)cblk + sizeof(audio_track_cblk_t);
-    cblk->bufferTimeoutMs = MAX_RUN_TIMEOUT_MS;
-    cblk->waitTimeMs = 0;
+
+    // starting address of buffers in shared memory
+    void *buffers = (char*)cblk + sizeof(audio_track_cblk_t);
 
     // update proxy
-    delete mProxy;
-    mProxy = new AudioRecordClientProxy(cblk, mBuffers, frameCount, mFrameSize);
+    mProxy = new AudioRecordClientProxy(cblk, buffers, frameCount, mFrameSize);
+    mProxy->setEpoch(epoch);
+    mProxy->setMinimum(mNotificationFrames);
+
+    mDeathNotifier = new DeathNotifier(this);
+    mAudioRecord->asBinder()->linkToDeath(mDeathNotifier, this);
 
     return NO_ERROR;
 }
 
 status_t AudioRecord::obtainBuffer(Buffer* audioBuffer, int32_t waitCount)
 {
-    ALOG_ASSERT(mStatus == NO_ERROR && mProxy != NULL);
+    if (audioBuffer == NULL) {
+        return BAD_VALUE;
+    }
+    if (mTransfer != TRANSFER_OBTAIN) {
+        audioBuffer->frameCount = 0;
+        audioBuffer->size = 0;
+        audioBuffer->raw = NULL;
+        return INVALID_OPERATION;
+    }
 
-    AutoMutex lock(mLock);
-    bool active;
-    status_t result = NO_ERROR;
-    audio_track_cblk_t* cblk = mCblk;
-    uint32_t framesReq = audioBuffer->frameCount;
-    uint32_t waitTimeMs = (waitCount < 0) ? cblk->bufferTimeoutMs : WAIT_PERIOD_MS;
+    const struct timespec *requested;
+    if (waitCount == -1) {
+        requested = &ClientProxy::kForever;
+    } else if (waitCount == 0) {
+        requested = &ClientProxy::kNonBlocking;
+    } else if (waitCount > 0) {
+        long long ms = WAIT_PERIOD_MS * (long long) waitCount;
+        struct timespec timeout;
+        timeout.tv_sec = ms / 1000;
+        timeout.tv_nsec = (int) (ms % 1000) * 1000000;
+        requested = &timeout;
+    } else {
+        ALOGE("%s invalid waitCount %d", __func__, waitCount);
+        requested = NULL;
+    }
+    return obtainBuffer(audioBuffer, requested);
+}
 
-    audioBuffer->frameCount  = 0;
-    audioBuffer->size        = 0;
+status_t AudioRecord::obtainBuffer(Buffer* audioBuffer, const struct timespec *requested,
+        struct timespec *elapsed, size_t *nonContig)
+{
+    // previous and new IAudioRecord sequence numbers are used to detect track re-creation
+    uint32_t oldSequence = 0;
+    uint32_t newSequence;
 
-    size_t framesReady = mProxy->framesReady();
+    Proxy::Buffer buffer;
+    status_t status = NO_ERROR;
 
-    if (framesReady == 0) {
-        cblk->lock.lock();
-        goto start_loop_here;
-        while (framesReady == 0) {
-            active = mActive;
-            if (CC_UNLIKELY(!active)) {
-                cblk->lock.unlock();
-                return NO_MORE_BUFFERS;
-            }
-            if (CC_UNLIKELY(!waitCount)) {
-                cblk->lock.unlock();
-                return WOULD_BLOCK;
-            }
-            if (!(cblk->flags & CBLK_INVALID)) {
-                mLock.unlock();
-                // this condition is in shared memory, so if IAudioRecord and control block
-                // are replaced due to mediaserver death or IAudioRecord invalidation then
-                // cv won't be signalled, but fortunately the timeout will limit the wait
-                result = cblk->cv.waitRelative(cblk->lock, milliseconds(waitTimeMs));
-                cblk->lock.unlock();
-                mLock.lock();
-                if (!mActive) {
-                    return status_t(STOPPED);
-                }
-                // IAudioRecord may have been re-created while mLock was unlocked
-                cblk = mCblk;
-                cblk->lock.lock();
-            }
-            if (cblk->flags & CBLK_INVALID) {
-                goto create_new_record;
-            }
-            if (CC_UNLIKELY(result != NO_ERROR)) {
-                cblk->waitTimeMs += waitTimeMs;
-                if (cblk->waitTimeMs >= cblk->bufferTimeoutMs) {
-                    ALOGW(   "obtainBuffer timed out (is the CPU pegged?) "
-                            "user=%08x, server=%08x", cblk->user, cblk->server);
-                    cblk->lock.unlock();
-                    // callback thread or sync event hasn't changed
-                    result = mAudioRecord->start(AudioSystem::SYNC_EVENT_SAME, 0);
-                    cblk->lock.lock();
-                    if (result == DEAD_OBJECT) {
-                        android_atomic_or(CBLK_INVALID, &cblk->flags);
-create_new_record:
-                        audio_track_cblk_t* temp = cblk;
-                        result = AudioRecord::restoreRecord_l(temp);
-                        cblk = temp;
+    static const int32_t kMaxTries = 5;
+    int32_t tryCounter = kMaxTries;
+
+    do {
+        // obtainBuffer() is called with mutex unlocked, so keep extra references to these fields to
+        // keep them from going away if another thread re-creates the track during obtainBuffer()
+        sp<AudioRecordClientProxy> proxy;
+        sp<IMemory> iMem;
+        {
+            // start of lock scope
+            AutoMutex lock(mLock);
+
+            newSequence = mSequence;
+            // did previous obtainBuffer() fail due to media server death or voluntary invalidation?
+            if (status == DEAD_OBJECT) {
+                // re-create track, unless someone else has already done so
+                if (newSequence == oldSequence) {
+                    status = restoreRecord_l("obtainBuffer");
+                    if (status != NO_ERROR) {
+                        break;
                     }
-                    if (result != NO_ERROR) {
-                        ALOGW("obtainBuffer create Track error %d", result);
-                        cblk->lock.unlock();
-                        return result;
-                    }
-                    cblk->waitTimeMs = 0;
-                }
-                if (--waitCount == 0) {
-                    cblk->lock.unlock();
-                    return TIMED_OUT;
                 }
             }
-            // read the server count again
-start_loop_here:
-            framesReady = mProxy->framesReady();
-        }
-        cblk->lock.unlock();
+            oldSequence = newSequence;
+
+            // Keep the extra references
+            proxy = mProxy;
+            iMem = mCblkMemory;
+
+            // Non-blocking if track is stopped
+            if (!mActive) {
+                requested = &ClientProxy::kNonBlocking;
+            }
+
+        }   // end of lock scope
+
+        buffer.mFrameCount = audioBuffer->frameCount;
+        // FIXME starts the requested timeout and elapsed over from scratch
+        status = proxy->obtainBuffer(&buffer, requested, elapsed);
+
+    } while ((status == DEAD_OBJECT) && (tryCounter-- > 0));
+
+    audioBuffer->frameCount = buffer.mFrameCount;
+    audioBuffer->size = buffer.mFrameCount * mFrameSize;
+    audioBuffer->raw = buffer.mRaw;
+    if (nonContig != NULL) {
+        *nonContig = buffer.mNonContig;
     }
-
-    cblk->waitTimeMs = 0;
-    // reset time out to running value after obtaining a buffer
-    cblk->bufferTimeoutMs = MAX_RUN_TIMEOUT_MS;
-
-    if (framesReq > framesReady) {
-        framesReq = framesReady;
-    }
-
-    uint32_t u = cblk->user;
-    uint32_t bufferEnd = cblk->userBase + mFrameCount;
-
-    if (framesReq > bufferEnd - u) {
-        framesReq = bufferEnd - u;
-    }
-
-    audioBuffer->frameCount  = framesReq;
-    audioBuffer->size        = framesReq * mFrameSize;
-    audioBuffer->raw         = mProxy->buffer(u);
-    active = mActive;
-    return active ? status_t(NO_ERROR) : status_t(STOPPED);
+    return status;
 }
 
 void AudioRecord::releaseBuffer(Buffer* audioBuffer)
 {
-    ALOG_ASSERT(mStatus == NO_ERROR && mProxy != NULL);
+    // all TRANSFER_* are valid
+
+    size_t stepCount = audioBuffer->size / mFrameSize;
+    if (stepCount == 0) {
+        return;
+    }
+
+    Proxy::Buffer buffer;
+    buffer.mFrameCount = stepCount;
+    buffer.mRaw = audioBuffer->raw;
 
     AutoMutex lock(mLock);
-    (void) mProxy->stepUser(audioBuffer->frameCount);
+    mInOverrun = false;
+    mProxy->releaseBuffer(&buffer);
+
+    // the server does not automatically disable recorder on overrun, so no need to restart
 }
 
 audio_io_handle_t AudioRecord::getInput() const
@@ -616,215 +613,304 @@
     return mInput;
 }
 
-int AudioRecord::getSessionId() const
-{
-    // no lock needed because session ID doesn't change after first set()
-    return mSessionId;
-}
-
 // -------------------------------------------------------------------------
 
 ssize_t AudioRecord::read(void* buffer, size_t userSize)
 {
-    ssize_t read = 0;
-    Buffer audioBuffer;
-    int8_t *dst = static_cast<int8_t*>(buffer);
+    if (mTransfer != TRANSFER_SYNC) {
+        return INVALID_OPERATION;
+    }
 
-    if (ssize_t(userSize) < 0) {
-        // sanity-check. user is most-likely passing an error code.
-        ALOGE("AudioRecord::read(buffer=%p, size=%u (%d)",
-                buffer, userSize, userSize);
+    if (ssize_t(userSize) < 0 || (buffer == NULL && userSize != 0)) {
+        // sanity-check. user is most-likely passing an error code, and it would
+        // make the return value ambiguous (actualSize vs error).
+        ALOGE("AudioRecord::read(buffer=%p, size=%u (%d)", buffer, userSize, userSize);
         return BAD_VALUE;
     }
 
-    mLock.lock();
-    // acquire a strong reference on the IAudioRecord and IMemory so that they cannot be destroyed
-    // while we are accessing the cblk
-    sp<IAudioRecord> audioRecord = mAudioRecord;
-    sp<IMemory> iMem = mCblkMemory;
-    mLock.unlock();
+    ssize_t read = 0;
+    Buffer audioBuffer;
 
-    do {
+    while (userSize >= mFrameSize) {
+        audioBuffer.frameCount = userSize / mFrameSize;
 
-        audioBuffer.frameCount = userSize/frameSize();
-
-        // By using a wait count corresponding to twice the timeout period in
-        // obtainBuffer() we give a chance to recover once for a read timeout
-        // (if media_server crashed for instance) before returning a length of
-        // 0 bytes read to the client
-        status_t err = obtainBuffer(&audioBuffer, ((2 * MAX_RUN_TIMEOUT_MS) / WAIT_PERIOD_MS));
+        status_t err = obtainBuffer(&audioBuffer, &ClientProxy::kForever);
         if (err < 0) {
-            // out of buffers, return #bytes written
-            if (err == status_t(NO_MORE_BUFFERS)) {
+            if (read > 0) {
                 break;
             }
-            if (err == status_t(TIMED_OUT)) {
-                // return partial transfer count
-                return read;
-            }
             return ssize_t(err);
         }
 
         size_t bytesRead = audioBuffer.size;
-        memcpy(dst, audioBuffer.i8, bytesRead);
-
-        dst += bytesRead;
+        memcpy(buffer, audioBuffer.i8, bytesRead);
+        buffer = ((char *) buffer) + bytesRead;
         userSize -= bytesRead;
         read += bytesRead;
 
         releaseBuffer(&audioBuffer);
-    } while (userSize);
+    }
 
     return read;
 }
 
 // -------------------------------------------------------------------------
 
-bool AudioRecord::processAudioBuffer(const sp<AudioRecordThread>& thread)
+nsecs_t AudioRecord::processAudioBuffer(const sp<AudioRecordThread>& thread)
 {
-    Buffer audioBuffer;
-    uint32_t frames = mRemainingFrames;
-    size_t readSize;
-
     mLock.lock();
-    // acquire a strong reference on the IAudioRecord and IMemory so that they cannot be destroyed
-    // while we are accessing the cblk
-    sp<IAudioRecord> audioRecord = mAudioRecord;
-    sp<IMemory> iMem = mCblkMemory;
-    audio_track_cblk_t* cblk = mCblk;
-    bool active = mActive;
-    uint32_t markerPosition = mMarkerPosition;
-    uint32_t newPosition = mNewPosition;
-    uint32_t user = cblk->user;
-    // determine whether a marker callback will be needed, while locked
-    bool needMarker = !mMarkerReached && (mMarkerPosition > 0) && (user >= mMarkerPosition);
-    if (needMarker) {
-        mMarkerReached = true;
+
+    // Can only reference mCblk while locked
+    int32_t flags = android_atomic_and(~CBLK_OVERRUN, &mCblk->flags);
+
+    // Check for track invalidation
+    if (flags & CBLK_INVALID) {
+        (void) restoreRecord_l("processAudioBuffer");
+        mLock.unlock();
+        // Run again immediately, but with a new IAudioRecord
+        return 0;
     }
-    // determine the number of new position callback(s) that will be needed, while locked
+
+    bool active = mActive;
+
+    // Manage overrun callback, must be done under lock to avoid race with releaseBuffer()
+    bool newOverrun = false;
+    if (flags & CBLK_OVERRUN) {
+        if (!mInOverrun) {
+            mInOverrun = true;
+            newOverrun = true;
+        }
+    }
+
+    // Get current position of server
+    size_t position = mProxy->getPosition();
+
+    // Manage marker callback
+    bool markerReached = false;
+    size_t markerPosition = mMarkerPosition;
+    // FIXME fails for wraparound, need 64 bits
+    if (!mMarkerReached && (markerPosition > 0) && (position >= markerPosition)) {
+        mMarkerReached = markerReached = true;
+    }
+
+    // Determine the number of new position callback(s) that will be needed, while locked
+    size_t newPosCount = 0;
+    size_t newPosition = mNewPosition;
     uint32_t updatePeriod = mUpdatePeriod;
-    uint32_t needNewPos = updatePeriod > 0 && user >= newPosition ?
-            ((user - newPosition) / updatePeriod) + 1 : 0;
-    mNewPosition = newPosition + updatePeriod * needNewPos;
+    // FIXME fails for wraparound, need 64 bits
+    if (updatePeriod > 0 && position >= newPosition) {
+        newPosCount = ((position - newPosition) / updatePeriod) + 1;
+        mNewPosition += updatePeriod * newPosCount;
+    }
+
+    // Cache other fields that will be needed soon
+    size_t notificationFrames = mNotificationFrames;
+    if (mRefreshRemaining) {
+        mRefreshRemaining = false;
+        mRemainingFrames = notificationFrames;
+        mRetryOnPartialBuffer = false;
+    }
+    size_t misalignment = mProxy->getMisalignment();
+    int32_t sequence = mSequence;
+
+    // These fields don't need to be cached, because they are assigned only by set():
+    //      mTransfer, mCbf, mUserData, mSampleRate
+
     mLock.unlock();
 
-    // perform marker callback, while unlocked
-    if (needMarker) {
+    // perform callbacks while unlocked
+    if (newOverrun) {
+        mCbf(EVENT_OVERRUN, mUserData, NULL);
+    }
+    if (markerReached) {
         mCbf(EVENT_MARKER, mUserData, &markerPosition);
     }
-
-    // perform new position callback(s), while unlocked
-    for (; needNewPos > 0; --needNewPos) {
-        uint32_t temp = newPosition;
+    while (newPosCount > 0) {
+        size_t temp = newPosition;
         mCbf(EVENT_NEW_POS, mUserData, &temp);
         newPosition += updatePeriod;
+        newPosCount--;
+    }
+    if (mObservedSequence != sequence) {
+        mObservedSequence = sequence;
+        mCbf(EVENT_NEW_IAUDIORECORD, mUserData, NULL);
     }
 
-    do {
-        audioBuffer.frameCount = frames;
-        // Calling obtainBuffer() with a wait count of 1
-        // limits wait time to WAIT_PERIOD_MS. This prevents from being
-        // stuck here not being able to handle timed events (position, markers).
-        status_t err = obtainBuffer(&audioBuffer, 1);
-        if (err < NO_ERROR) {
-            if (err != TIMED_OUT) {
-                ALOGE_IF(err != status_t(NO_MORE_BUFFERS),
-                        "Error obtaining an audio buffer, giving up.");
-                return false;
+    // if inactive, then don't run me again until re-started
+    if (!active) {
+        return NS_INACTIVE;
+    }
+
+    // Compute the estimated time until the next timed event (position, markers)
+    uint32_t minFrames = ~0;
+    if (!markerReached && position < markerPosition) {
+        minFrames = markerPosition - position;
+    }
+    if (updatePeriod > 0 && updatePeriod < minFrames) {
+        minFrames = updatePeriod;
+    }
+
+    // If > 0, poll periodically to recover from a stuck server.  A good value is 2.
+    static const uint32_t kPoll = 0;
+    if (kPoll > 0 && mTransfer == TRANSFER_CALLBACK && kPoll * notificationFrames < minFrames) {
+        minFrames = kPoll * notificationFrames;
+    }
+
+    // Convert frame units to time units
+    nsecs_t ns = NS_WHENEVER;
+    if (minFrames != (uint32_t) ~0) {
+        // This "fudge factor" avoids soaking CPU, and compensates for late progress by server
+        static const nsecs_t kFudgeNs = 10000000LL; // 10 ms
+        ns = ((minFrames * 1000000000LL) / mSampleRate) + kFudgeNs;
+    }
+
+    // If not supplying data by EVENT_MORE_DATA, then we're done
+    if (mTransfer != TRANSFER_CALLBACK) {
+        return ns;
+    }
+
+    struct timespec timeout;
+    const struct timespec *requested = &ClientProxy::kForever;
+    if (ns != NS_WHENEVER) {
+        timeout.tv_sec = ns / 1000000000LL;
+        timeout.tv_nsec = ns % 1000000000LL;
+        ALOGV("timeout %ld.%03d", timeout.tv_sec, (int) timeout.tv_nsec / 1000000);
+        requested = &timeout;
+    }
+
+    while (mRemainingFrames > 0) {
+
+        Buffer audioBuffer;
+        audioBuffer.frameCount = mRemainingFrames;
+        size_t nonContig;
+        status_t err = obtainBuffer(&audioBuffer, requested, NULL, &nonContig);
+        LOG_ALWAYS_FATAL_IF((err != NO_ERROR) != (audioBuffer.frameCount == 0),
+                "obtainBuffer() err=%d frameCount=%u", err, audioBuffer.frameCount);
+        requested = &ClientProxy::kNonBlocking;
+        size_t avail = audioBuffer.frameCount + nonContig;
+        ALOGV("obtainBuffer(%u) returned %u = %u + %u",
+                mRemainingFrames, avail, audioBuffer.frameCount, nonContig);
+        if (err != NO_ERROR) {
+            if (err == TIMED_OUT || err == WOULD_BLOCK || err == -EINTR) {
+                break;
             }
-            break;
+            ALOGE("Error %d obtaining an audio buffer, giving up.", err);
+            return NS_NEVER;
         }
-        if (err == status_t(STOPPED)) return false;
+
+        if (mRetryOnPartialBuffer) {
+            mRetryOnPartialBuffer = false;
+            if (avail < mRemainingFrames) {
+                int64_t myns = ((mRemainingFrames - avail) *
+                        1100000000LL) / mSampleRate;
+                if (ns < 0 || myns < ns) {
+                    ns = myns;
+                }
+                return ns;
+            }
+        }
 
         size_t reqSize = audioBuffer.size;
         mCbf(EVENT_MORE_DATA, mUserData, &audioBuffer);
-        readSize = audioBuffer.size;
+        size_t readSize = audioBuffer.size;
 
         // Sanity check on returned size
-        if (ssize_t(readSize) <= 0) {
-            // The callback is done filling buffers
-            // Keep this thread going to handle timed events and
-            // still try to get more data in intervals of WAIT_PERIOD_MS
-            // but don't just loop and block the CPU, so wait
-            usleep(WAIT_PERIOD_MS*1000);
-            break;
+        if (ssize_t(readSize) < 0 || readSize > reqSize) {
+            ALOGE("EVENT_MORE_DATA requested %u bytes but callback returned %d bytes",
+                    reqSize, (int) readSize);
+            return NS_NEVER;
         }
-        if (readSize > reqSize) readSize = reqSize;
 
-        audioBuffer.size = readSize;
-        audioBuffer.frameCount = readSize/frameSize();
-        frames -= audioBuffer.frameCount;
+        if (readSize == 0) {
+            // The callback is done consuming buffers
+            // Keep this thread going to handle timed events and
+            // still try to provide more data in intervals of WAIT_PERIOD_MS
+            // but don't just loop and block the CPU, so wait
+            return WAIT_PERIOD_MS * 1000000LL;
+        }
+
+        size_t releasedFrames = readSize / mFrameSize;
+        audioBuffer.frameCount = releasedFrames;
+        mRemainingFrames -= releasedFrames;
+        if (misalignment >= releasedFrames) {
+            misalignment -= releasedFrames;
+        } else {
+            misalignment = 0;
+        }
 
         releaseBuffer(&audioBuffer);
 
-    } while (frames);
-
-
-    // Manage overrun callback
-    if (active && (mProxy->framesAvailable() == 0)) {
-        // The value of active is stale, but we are almost sure to be active here because
-        // otherwise we would have exited when obtainBuffer returned STOPPED earlier.
-        ALOGV("Overrun user: %x, server: %x, flags %04x", cblk->user, cblk->server, cblk->flags);
-        if (!(android_atomic_or(CBLK_UNDERRUN, &cblk->flags) & CBLK_UNDERRUN)) {
-            mCbf(EVENT_OVERRUN, mUserData, NULL);
+        // FIXME here is where we would repeat EVENT_MORE_DATA again on same advanced buffer
+        // if callback doesn't like to accept the full chunk
+        if (readSize < reqSize) {
+            continue;
         }
-    }
 
-    if (frames == 0) {
-        mRemainingFrames = mNotificationFrames;
-    } else {
-        mRemainingFrames = frames;
+        // There could be enough non-contiguous frames available to satisfy the remaining request
+        if (mRemainingFrames <= nonContig) {
+            continue;
+        }
+
+#if 0
+        // This heuristic tries to collapse a series of EVENT_MORE_DATA that would total to a
+        // sum <= notificationFrames.  It replaces that series by at most two EVENT_MORE_DATA
+        // that total to a sum == notificationFrames.
+        if (0 < misalignment && misalignment <= mRemainingFrames) {
+            mRemainingFrames = misalignment;
+            return (mRemainingFrames * 1100000000LL) / mSampleRate;
+        }
+#endif
+
     }
-    return true;
+    mRemainingFrames = notificationFrames;
+    mRetryOnPartialBuffer = true;
+
+    // A lot has transpired since ns was calculated, so run again immediately and re-calculate
+    return 0;
 }
 
-// must be called with mLock and cblk.lock held. Callers must also hold strong references on
-// the IAudioRecord and IMemory in case they are recreated here.
-// If the IAudioRecord is successfully restored, the cblk pointer is updated
-status_t AudioRecord::restoreRecord_l(audio_track_cblk_t*& refCblk)
+status_t AudioRecord::restoreRecord_l(const char *from)
 {
+    ALOGW("dead IAudioRecord, creating a new one from %s()", from);
+    ++mSequence;
     status_t result;
 
-    audio_track_cblk_t* cblk = refCblk;
-    audio_track_cblk_t* newCblk = cblk;
-    ALOGW("dead IAudioRecord, creating a new one");
-
-    // signal old cblk condition so that other threads waiting for available buffers stop
-    // waiting now
-    cblk->cv.broadcast();
-    cblk->lock.unlock();
-
     // if the new IAudioRecord is created, openRecord_l() will modify the
     // following member variables: mAudioRecord, mCblkMemory and mCblk.
     // It will also delete the strong references on previous IAudioRecord and IMemory
-    result = openRecord_l(mSampleRate, mFormat, mFrameCount, getInput_l());
+    size_t position = mProxy->getPosition();
+    mNewPosition = position + mUpdatePeriod;
+    result = openRecord_l(mSampleRate, mFormat, mFrameCount, getInput_l(), position);
     if (result == NO_ERROR) {
-        newCblk = mCblk;
-        // callback thread or sync event hasn't changed
-        result = mAudioRecord->start(AudioSystem::SYNC_EVENT_SAME, 0);
+        if (mActive) {
+            // callback thread or sync event hasn't changed
+            // FIXME this fails if we have a new AudioFlinger instance
+            result = mAudioRecord->start(AudioSystem::SYNC_EVENT_SAME, 0);
+        }
     }
     if (result != NO_ERROR) {
+        ALOGW("restoreRecord_l() failed status %d", result);
         mActive = false;
     }
 
-    ALOGV("restoreRecord_l() status %d mActive %d cblk %p, old cblk %p flags %08x old flags %08x",
-        result, mActive, newCblk, cblk, newCblk->flags, cblk->flags);
-
-    if (result == NO_ERROR) {
-        // from now on we switch to the newly created cblk
-        refCblk = newCblk;
-    }
-    newCblk->lock.lock();
-
-    ALOGW_IF(result != NO_ERROR, "restoreRecord_l() error %d", result);
-
     return result;
 }
 
 // =========================================================================
 
+void AudioRecord::DeathNotifier::binderDied(const wp<IBinder>& who)
+{
+    sp<AudioRecord> audioRecord = mAudioRecord.promote();
+    if (audioRecord != 0) {
+        AutoMutex lock(audioRecord->mLock);
+        audioRecord->mProxy->binderDied();
+    }
+}
+
+// =========================================================================
+
 AudioRecord::AudioRecordThread::AudioRecordThread(AudioRecord& receiver, bool bCanCallJava)
-    : Thread(bCanCallJava), mReceiver(receiver), mPaused(true)
+    : Thread(bCanCallJava), mReceiver(receiver), mPaused(true), mResumeLatch(false)
 {
 }
 
@@ -842,10 +928,26 @@
             return true;
         }
     }
-    if (!mReceiver.processAudioBuffer(this)) {
-        pause();
+    nsecs_t ns =  mReceiver.processAudioBuffer(this);
+    switch (ns) {
+    case 0:
+        return true;
+    case NS_WHENEVER:
+        sleep(1);
+        return true;
+    case NS_INACTIVE:
+        pauseConditional();
+        return true;
+    case NS_NEVER:
+        return false;
+    default:
+        LOG_ALWAYS_FATAL_IF(ns < 0, "processAudioBuffer() returned %lld", ns);
+        struct timespec req;
+        req.tv_sec = ns / 1000000000LL;
+        req.tv_nsec = ns % 1000000000LL;
+        nanosleep(&req, NULL /*rem*/);
+        return true;
     }
-    return true;
 }
 
 void AudioRecord::AudioRecordThread::requestExit()
@@ -859,6 +961,17 @@
 {
     AutoMutex _l(mMyLock);
     mPaused = true;
+    mResumeLatch = false;
+}
+
+void AudioRecord::AudioRecordThread::pauseConditional()
+{
+    AutoMutex _l(mMyLock);
+    if (mResumeLatch) {
+        mResumeLatch = false;
+    } else {
+        mPaused = true;
+    }
 }
 
 void AudioRecord::AudioRecordThread::resume()
@@ -866,7 +979,10 @@
     AutoMutex _l(mMyLock);
     if (mPaused) {
         mPaused = false;
+        mResumeLatch = false;
         mMyCond.signal();
+    } else {
+        mResumeLatch = true;
     }
 }