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* 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
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#ifndef A_LOOPER_H_
#define A_LOOPER_H_
#include <media/stagefright/foundation/ABase.h>
#include <media/stagefright/foundation/AString.h>
#include <utils/Errors.h>
#include <utils/KeyedVector.h>
#include <utils/List.h>
#include <utils/RefBase.h>
#include <utils/threads.h>
namespace android {
struct AHandler;
struct AMessage;
struct AReplyToken;
struct ALooper : public RefBase {
typedef int32_t event_id;
typedef int32_t handler_id;
// Takes effect in a subsequent call to start().
void setName(const char *name);
handler_id registerHandler(const sp<AHandler> &handler);
void unregisterHandler(handler_id handlerID);
status_t start(
bool runOnCallingThread = false,
bool canCallJava = false,
int32_t priority = PRIORITY_DEFAULT
status_t stop();
static int64_t GetNowUs();
const char *getName() const {
return mName.c_str();
virtual ~ALooper();
friend struct AMessage; // post()
struct Event {
int64_t mWhenUs;
sp<AMessage> mMessage;
Mutex mLock;
Condition mQueueChangedCondition;
AString mName;
List<Event> mEventQueue;
struct LooperThread;
sp<LooperThread> mThread;
bool mRunningLocally;
// use a separate lock for reply handling, as it is always on another thread
// use a central lock, however, to avoid creating a mutex for each reply
Mutex mRepliesLock;
Condition mRepliesCondition;
// START --- methods used only by AMessage
// posts a message on this looper with the given timeout
void post(const sp<AMessage> &msg, int64_t delayUs);
// creates a reply token to be used with this looper
sp<AReplyToken> createReplyToken();
// waits for a response for the reply token. If status is OK, the response
// is stored into the supplied variable. Otherwise, it is unchanged.
status_t awaitResponse(const sp<AReplyToken> &replyToken, sp<AMessage> *response);
// posts a reply for a reply token. If the reply could be successfully posted,
// it returns OK. Otherwise, it returns an error value.
status_t postReply(const sp<AReplyToken> &replyToken, const sp<AMessage> &msg);
// END --- methods used only by AMessage
bool loop();
} // namespace android
#endif // A_LOOPER_H_