Support for posting messages and synchronously waiting for a response.

Change-Id: Id6c7a08c34fd5cb6c4632f78ece9e7898b29e52c

2 files changed, 68 insertions, 6 deletions

diff --git a/media/libstagefright/foundation/ALooperRoster.cpp b/media/libstagefright/foundation/ALooperRoster.cpp
index 8aa1b15..e399f2f 100644
--- a/media/libstagefright/foundation/ALooperRoster.cpp
+++ b/media/libstagefright/foundation/ALooperRoster.cpp
@@ -27,7 +27,8 @@
 namespace android {
 
 ALooperRoster::ALooperRoster()
-    : mNextHandlerID(1) {
+    : mNextHandlerID(1),
+      mNextReplyID(1) {
 }
 
 ALooper::handler_id ALooperRoster::registerHandler(
@@ -70,15 +71,19 @@ void ALooperRoster::unregisterHandler(ALooper::handler_id handlerID) {
     mHandlers.removeItemsAt(index);
 }
 
-void ALooperRoster::postMessage(
+status_t ALooperRoster::postMessage(
         const sp<AMessage> &msg, int64_t delayUs) {
     Mutex::Autolock autoLock(mLock);
+    return postMessage_l(msg, delayUs);
+}
 
+status_t ALooperRoster::postMessage_l(
+        const sp<AMessage> &msg, int64_t delayUs) {
     ssize_t index = mHandlers.indexOfKey(msg->target());
 
     if (index < 0) {
         LOGW("failed to post message. Target handler not registered.");
-        return;
+        return -ENOENT;
     }
 
     const HandlerInfo &info = mHandlers.valueAt(index);
@@ -91,10 +96,12 @@ void ALooperRoster::postMessage(
              msg->target());
 
         mHandlers.removeItemsAt(index);
-        return;
+        return -ENOENT;
     }
 
     looper->post(msg, delayUs);
+
+    return OK;
 }
 
 void ALooperRoster::deliverMessage(const sp<AMessage> &msg) {
@@ -145,4 +152,38 @@ sp<ALooper> ALooperRoster::findLooper(ALooper::handler_id handlerID) {
     return looper;
 }
 
+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 = postMessage_l(msg, 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();
+}
+
 }  // namespace android
diff --git a/media/libstagefright/foundation/AMessage.cpp b/media/libstagefright/foundation/AMessage.cpp
index b592c3f..582bdba 100644
--- a/media/libstagefright/foundation/AMessage.cpp
+++ b/media/libstagefright/foundation/AMessage.cpp
@@ -27,6 +27,8 @@
 
 namespace android {
 
+extern ALooperRoster gLooperRoster;
+
 AMessage::AMessage(uint32_t what, ALooper::handler_id target)
     : mWhat(what),
       mTarget(target),
@@ -227,11 +229,30 @@ bool AMessage::findRect(
 }
 
 void AMessage::post(int64_t delayUs) {
-    extern ALooperRoster gLooperRoster;
-
     gLooperRoster.postMessage(this, delayUs);
 }
 
+status_t AMessage::postAndAwaitResponse(sp<AMessage> *response) {
+    return gLooperRoster.postAndAwaitResponse(this, response);
+}
+
+void AMessage::postReply(uint32_t replyID) {
+    gLooperRoster.postReply(replyID, this);
+}
+
+bool AMessage::senderAwaitsResponse(uint32_t *replyID) const {
+    int32_t tmp;
+    bool found = findInt32("replyID", &tmp);
+
+    if (!found) {
+        return false;
+    }
+
+    *replyID = static_cast<uint32_t>(tmp);
+
+    return true;
+}
+
 sp<AMessage> AMessage::dup() const {
     sp<AMessage> msg = new AMessage(mWhat, mTarget);
     msg->mNumItems = mNumItems;