media/libstagefright/foundation/ALooperRoster.cpp

/*
 * 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.
 */

//#define LOG_NDEBUG 0
#define LOG_TAG "ALooperRoster"
#include <utils/Log.h>

#include "ALooperRoster.h"

#include "ADebug.h"
#include "AHandler.h"
#include "AMessage.h"

namespace android {

ALooperRoster::ALooperRoster()
    : mNextHandlerID(1),
      mNextReplyID(1) {
}

ALooper::handler_id ALooperRoster::registerHandler(
        const sp<ALooper> looper, const sp<AHandler> &handler) {
    Mutex::Autolock autoLock(mLock);

    if (handler->id() != 0) {
        CHECK(!"A handler must only be registered once.");
        return INVALID_OPERATION;
    }

    HandlerInfo info;
    info.mLooper = looper;
    info.mHandler = handler;
    ALooper::handler_id handlerID = mNextHandlerID++;
    mHandlers.add(handlerID, info);

    handler->setID(handlerID);

    return handlerID;
}

void ALooperRoster::unregisterHandler(ALooper::handler_id handlerID) {
    Mutex::Autolock autoLock(mLock);

    ssize_t index = mHandlers.indexOfKey(handlerID);

    if (index < 0) {
        return;
    }

    const HandlerInfo &info = mHandlers.valueAt(index);

    sp<AHandler> handler = info.mHandler.promote();

    if (handler != NULL) {
        handler->setID(0);
    }

    mHandlers.removeItemsAt(index);
}

void ALooperRoster::unregisterStaleHandlers() {

    Vector<sp<ALooper> > activeLoopers;
    {
        Mutex::Autolock autoLock(mLock);

        for (size_t i = mHandlers.size(); i-- > 0;) {
            const HandlerInfo &info = mHandlers.valueAt(i);

            sp<ALooper> looper = info.mLooper.promote();
            if (looper == NULL) {
                ALOGV("Unregistering stale handler %d", mHandlers.keyAt(i));
                mHandlers.removeItemsAt(i);
            } else {
                // At this point 'looper' might be the only sp<> keeping
                // the object alive. To prevent it from going out of scope
                // and having ~ALooper call this method again recursively
                // and then deadlocking because of the Autolock above, add
                // it to a Vector which will go out of scope after the lock
                // has been released.
                activeLoopers.add(looper);
            }
        }
    }
}

status_t ALooperRoster::postMessage(
        const sp<AMessage> &msg, int64_t delayUs) {

    sp<ALooper> looper = findLooper(msg->target());

    if (looper == NULL) {
        return -ENOENT;
    }
    looper->post(msg, delayUs);
    return OK;
}

void ALooperRoster::deliverMessage(const sp<AMessage> &msg) {
    sp<AHandler> handler;

    {
        Mutex::Autolock autoLock(mLock);

        ssize_t index = mHandlers.indexOfKey(msg->target());

        if (index < 0) {
            ALOGW("failed to deliver message. Target handler not registered.");
            return;
        }

        const HandlerInfo &info = mHandlers.valueAt(index);
        handler = info.mHandler.promote();

        if (handler == NULL) {
            ALOGW("failed to deliver message. "
                 "Target handler %d registered, but object gone.",
                 msg->target());

            mHandlers.removeItemsAt(index);
            return;
        }
    }

    handler->onMessageReceived(msg);
}

sp<ALooper> ALooperRoster::findLooper(ALooper::handler_id handlerID) {
    Mutex::Autolock autoLock(mLock);

    ssize_t index = mHandlers.indexOfKey(handlerID);

    if (index < 0) {
        return NULL;
    }

    sp<ALooper> looper = mHandlers.valueAt(index).mLooper.promote();

    if (looper == NULL) {
        mHandlers.removeItemsAt(index);
        return NULL;
    }

    return looper;
}

status_t ALooperRoster::postAndAwaitResponse(
        const sp<AMessage> &msg, sp<AMessage> *response) {
    sp<ALooper> looper = findLooper(msg->target());

    if (looper == NULL) {
        ALOGW("failed to post message. "
                "Target handler %d still registered, but object gone.",
                msg->target());
        response->clear();
        return -ENOENT;
    }

    Mutex::Autolock autoLock(mLock);

    uint32_t replyID = mNextReplyID++;

    msg->setInt32("replyID", replyID);

    looper->post(msg, 0 /* delayUs */);

    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