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Commit 326afd18 authored by Yifan Hong's avatar Yifan Hong
Browse files

Add RpcServer::start() 

start() starts a thread that runs join() in the background.

Because the thread can now be owned by RpcServer, shutdown() ensures
the thread is properly cleaned up.

Test: binderRpcTest
Bug: 182914638

Change-Id: I570d3d852e9eb4f6064dce934a2fdb3bc8f210f7
parent bb2cca75

libs/binder/RpcServer.cpp

+22 −0
Original line number Diff line number Diff line
@@ -128,6 +128,17 @@ sp<IBinder> RpcServer::getRootObject() { 
    return ret;

}



static void joinRpcServer(sp<RpcServer>&& thiz) {

    thiz->join();

}



void RpcServer::start() {

    LOG_ALWAYS_FATAL_IF(!mAgreedExperimental, "no!");

    std::lock_guard<std::mutex> _l(mLock);

    LOG_ALWAYS_FATAL_IF(mJoinThread.get(), "Already started!");

    mJoinThread = std::make_unique<std::thread>(&joinRpcServer, sp<RpcServer>::fromExisting(this));

}



void RpcServer::join() {

    LOG_ALWAYS_FATAL_IF(!mAgreedExperimental, "no!");
@@ -178,6 +189,17 @@ bool RpcServer::shutdown() { 
    mShutdownTrigger->trigger();

    while (mJoinThreadRunning) mShutdownCv.wait(_l);



    // At this point, we know join() is about to exit, but the thread that calls

    // join() may not have exited yet.

    // If RpcServer owns the join thread (aka start() is called), make sure the thread exits;

    // otherwise ~thread() may call std::terminate(), which may crash the process.

    // If RpcServer does not own the join thread (aka join() is called directly),

    // then the owner of RpcServer is responsible for cleaning up that thread.

    if (mJoinThread.get()) {

        mJoinThread->join();

        mJoinThread.reset();

    }



    mShutdownTrigger = nullptr;

    return true;

}

libs/binder/include/binder/RpcServer.h

+7 −1
Original line number Diff line number Diff line
@@ -116,6 +116,11 @@ public: 
    void setRootObjectWeak(const wp<IBinder>& binder);

    sp<IBinder> getRootObject();



    /**

     * Runs join() in a background thread. Immediately returns.

     */

    void start();



    /**

     * You must have at least one client session before calling this.

     *
@@ -159,12 +164,13 @@ private: 
    base::unique_fd mServer; // socket we are accepting sessions on



    std::mutex mLock; // for below

    std::unique_ptr<std::thread> mJoinThread;

    bool mJoinThreadRunning = false;

    std::map<std::thread::id, std::thread> mConnectingThreads;

    sp<IBinder> mRootObject;

    wp<IBinder> mRootObjectWeak;

    std::map<int32_t, sp<RpcSession>> mSessions;

    int32_t mSessionIdCounter = 0;

    bool mJoinThreadRunning = false;

    std::unique_ptr<RpcSession::FdTrigger> mShutdownTrigger;

    std::condition_variable mShutdownCv;

};