stagefright: don't use ALooperRoster mutex for reply handling

Change replyID-s from uint32_t to an object
Move reply handling into the loopers (to reuse a common mutex)

Bug: 19607784
Change-Id: Iaa035b846c424c5687ed17ce1079b325e86c54be

3 files changed, 74 insertions, 43 deletions

diff --git a/media/libstagefright/foundation/ALooper.cpp b/media/libstagefright/foundation/ALooper.cpp
index 617d32b..90b5f68 100644
--- a/media/libstagefright/foundation/ALooper.cpp
+++ b/media/libstagefright/foundation/ALooper.cpp
@@ -16,6 +16,9 @@
 
 //#define LOG_NDEBUG 0
 #define LOG_TAG "ALooper"
+
+#include <media/stagefright/foundation/ADebug.h>
+
 #include <utils/Log.h>
 
 #include <sys/time.h>
@@ -220,4 +223,29 @@ bool ALooper::loop() {
     return true;
 }
 
+// to be called by AMessage::postAndAwaitResponse only
+sp<AReplyToken> ALooper::createReplyToken() {
+    return new AReplyToken(this);
+}
+
+// to be called by AMessage::postAndAwaitResponse only
+status_t ALooper::awaitResponse(const sp<AReplyToken> &replyToken, sp<AMessage> *response) {
+    // return status in case we want to handle an interrupted wait
+    Mutex::Autolock autoLock(mRepliesLock);
+    CHECK(replyToken != NULL);
+    while (!replyToken->retrieveReply(response)) {
+        mRepliesCondition.wait(mRepliesLock);
+    }
+    return OK;
+}
+
+status_t ALooper::postReply(const sp<AReplyToken> &replyToken, const sp<AMessage> &reply) {
+    Mutex::Autolock autoLock(mRepliesLock);
+    status_t err = replyToken->setReply(reply);
+    if (err == OK) {
+        mRepliesCondition.broadcast();
+    }
+    return err;
+}
+
 }  // namespace android
diff --git a/media/libstagefright/foundation/ALooperRoster.cpp b/media/libstagefright/foundation/ALooperRoster.cpp
index c4e6788..473ce1b 100644
--- a/media/libstagefright/foundation/ALooperRoster.cpp
+++ b/media/libstagefright/foundation/ALooperRoster.cpp
@@ -30,8 +30,7 @@ namespace android {
 static bool verboseStats = false;
 
 ALooperRoster::ALooperRoster()
-    : mNextHandlerID(1),
-      mNextReplyID(1) {
+    : mNextHandlerID(1) {
 }
 
 ALooper::handler_id ALooperRoster::registerHandler(
@@ -100,39 +99,6 @@ void ALooperRoster::unregisterStaleHandlers() {
     }
 }
 
-status_t ALooperRoster::postAndAwaitResponse(
-        const sp<AMessage> &msg, sp<AMessage> *response) {
-    Mutex::Autolock autoLock(mLock);
-
-    uint32_t replyID = mNextReplyID++;
-
-    msg->setInt32("replyID", replyID);
-
-    status_t err = msg->post(0 /* delayUs */);
-    if (err != OK) {
-        response->clear();
-        return err;
-    }
-
-    ssize_t index;
-    while ((index = mReplies.indexOfKey(replyID)) < 0) {
-        mRepliesCondition.wait(mLock);
-    }
-
-    *response = mReplies.valueAt(index);
-    mReplies.removeItemsAt(index);
-
-    return OK;
-}
-
-void ALooperRoster::postReply(uint32_t replyID, const sp<AMessage> &reply) {
-    Mutex::Autolock autoLock(mLock);
-
-    CHECK(mReplies.indexOfKey(replyID) < 0);
-    mReplies.add(replyID, reply);
-    mRepliesCondition.broadcast();
-}
-
 static void makeFourCC(uint32_t fourcc, char *s) {
     s[0] = (fourcc >> 24) & 0xff;
     if (s[0]) {
diff --git a/media/libstagefright/foundation/AMessage.cpp b/media/libstagefright/foundation/AMessage.cpp
index d4add15..e549ff6 100644
--- a/media/libstagefright/foundation/AMessage.cpp
+++ b/media/libstagefright/foundation/AMessage.cpp
@@ -37,6 +37,17 @@ namespace android {
 
 extern ALooperRoster gLooperRoster;
 
+status_t AReplyToken::setReply(const sp<AMessage> &reply) {
+    if (mReplied) {
+        ALOGE("trying to post a duplicate reply");
+        return -EBUSY;
+    }
+    CHECK(mReply == NULL);
+    mReply = reply;
+    mReplied = true;
+    return OK;
+}
+
 AMessage::AMessage(void)
     : mWhat(0),
       mTarget(0),
@@ -355,24 +366,50 @@ status_t AMessage::post(int64_t delayUs) {
 }
 
 status_t AMessage::postAndAwaitResponse(sp<AMessage> *response) {
-    return gLooperRoster.postAndAwaitResponse(this, response);
+    sp<ALooper> looper = mLooper.promote();
+    if (looper == NULL) {
+        ALOGW("failed to post message as target looper for handler %d is gone.", mTarget);
+        return -ENOENT;
+    }
+
+    sp<AReplyToken> token = looper->createReplyToken();
+    if (token == NULL) {
+        ALOGE("failed to create reply token");
+        return -ENOMEM;
+    }
+    setObject("replyID", token);
+
+    looper->post(this, 0 /* delayUs */);
+    return looper->awaitResponse(token, response);
 }
 
-void AMessage::postReply(uint32_t replyID) {
-    gLooperRoster.postReply(replyID, this);
+status_t AMessage::postReply(const sp<AReplyToken> &replyToken) {
+    if (replyToken == NULL) {
+        ALOGW("failed to post reply to a NULL token");
+        return -ENOENT;
+    }
+    sp<ALooper> looper = replyToken->getLooper();
+    if (looper == NULL) {
+        ALOGW("failed to post reply as target looper is gone.");
+        return -ENOENT;
+    }
+    return looper->postReply(replyToken, this);
 }
 
-bool AMessage::senderAwaitsResponse(uint32_t *replyID) const {
-    int32_t tmp;
-    bool found = findInt32("replyID", &tmp);
+bool AMessage::senderAwaitsResponse(sp<AReplyToken> *replyToken) {
+    sp<RefBase> tmp;
+    bool found = findObject("replyID", &tmp);
 
     if (!found) {
         return false;
     }
 
-    *replyID = static_cast<uint32_t>(tmp);
+    *replyToken = static_cast<AReplyToken *>(tmp.get());
+    tmp.clear();
+    setObject("replyID", tmp);
+    // TODO: delete Object instead of setting it to NULL
 
-    return true;
+    return *replyToken != NULL;
 }
 
 sp<AMessage> AMessage::dup() const {