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Commit 0f9c5c7d authored by Yifan Hong's avatar Yifan Hong
Browse files

RpcSession attaches/detaches JVM for Java thread 

If javaAttachThread / javaDetachThread exists, run them before
and after the while loop in join. This ensures the
Java thread is attached / detached appropriately for
binder threads that handles RPC calls.

Test: run aservice on Java services
Bug: 190450693
Change-Id: I23f171dd1e08dfacfbbb46ecc9564cbf42d6f353
parent 7716e351

libs/binder/Android.bp

+1 −0
Original line number Diff line number Diff line
@@ -192,6 +192,7 @@ cc_library { 


    header_libs: [

        "libbinder_headers",

        "libandroid_runtime_threads_headers",

    ],



    export_header_lib_headers: [

libs/binder/RpcSession.cpp

+46 −0
Original line number Diff line number Diff line
@@ -18,13 +18,16 @@ 


#include <binder/RpcSession.h>



#include <dlfcn.h>

#include <inttypes.h>

#include <poll.h>

#include <pthread.h>

#include <unistd.h>



#include <string_view>



#include <android-base/macros.h>

#include <android_runtime/threads.h>

#include <binder/Parcel.h>

#include <binder/RpcServer.h>

#include <binder/Stability.h>
@@ -274,10 +277,53 @@ RpcSession::PreJoinSetupResult RpcSession::preJoinSetup(base::unique_fd fd) { 
    };

}



namespace {

// RAII object for attaching / detaching current thread to JVM if Android Runtime exists. If

// Android Runtime doesn't exist, no-op.

class JavaThreadAttacher {

public:

    JavaThreadAttacher() {

        // Use dlsym to find androidJavaAttachThread because libandroid_runtime is loaded after

        // libbinder.

        static auto attachFn = reinterpret_cast<decltype(&androidJavaAttachThread)>(

                dlsym(RTLD_DEFAULT, "androidJavaAttachThread"));

        if (attachFn == nullptr) return;



        char buf[16];

        const char* threadName = "UnknownRpcSessionThread"; // default thread name

        if (0 == pthread_getname_np(pthread_self(), buf, sizeof(buf))) {

            threadName = buf;

        }

        LOG_RPC_DETAIL("Attaching current thread %s to JVM", threadName);

        LOG_ALWAYS_FATAL_IF(!attachFn(threadName), "Cannot attach thread %s to JVM", threadName);

        mAttached = true;

    }

    ~JavaThreadAttacher() {

        if (!mAttached) return;

        static auto detachFn = reinterpret_cast<decltype(&androidJavaDetachThread)>(

                dlsym(RTLD_DEFAULT, "androidJavaDetachThread"));

        LOG_ALWAYS_FATAL_IF(detachFn == nullptr,

                            "androidJavaAttachThread exists but androidJavaDetachThread doesn't");



        LOG_RPC_DETAIL("Detaching current thread from JVM");

        if (detachFn()) {

            mAttached = false;

        } else {

            ALOGW("Unable to detach current thread from JVM");

        }

    }



private:

    DISALLOW_COPY_AND_ASSIGN(JavaThreadAttacher);

    bool mAttached = false;

};

} // namespace



void RpcSession::join(sp<RpcSession>&& session, PreJoinSetupResult&& setupResult) {

    sp<RpcConnection>& connection = setupResult.connection;



    if (setupResult.status == OK) {

        JavaThreadAttacher javaThreadAttacher;

        while (true) {

            status_t status = session->state()->getAndExecuteCommand(connection, session,

                                                                     RpcState::CommandType::ANY);

libs/binder/tests/binderRpcTest.cpp

+37 −0
Original line number Diff line number Diff line
@@ -1208,6 +1208,43 @@ TEST(BinderRpc, Shutdown) { 
            << "After server->shutdown() returns true, join() did not stop after 2s";

}



TEST(BinderRpc, Java) {

#if !defined(__ANDROID__)

    GTEST_SKIP() << "This test is only run on Android. Though it can technically run on host on"

                    "createRpcDelegateServiceManager() with a device attached, such test belongs "

                    "to binderHostDeviceTest. Hence, just disable this test on host.";

#endif // !__ANDROID__

    sp<IServiceManager> sm = defaultServiceManager();

    ASSERT_NE(nullptr, sm);

    // Any Java service with non-empty getInterfaceDescriptor() would do.

    // Let's pick batteryproperties.

    auto binder = sm->checkService(String16("batteryproperties"));

    ASSERT_NE(nullptr, binder);

    auto descriptor = binder->getInterfaceDescriptor();

    ASSERT_GE(descriptor.size(), 0);

    ASSERT_EQ(OK, binder->pingBinder());



    auto rpcServer = RpcServer::make();

    rpcServer->iUnderstandThisCodeIsExperimentalAndIWillNotUseItInProduction();

    unsigned int port;

    ASSERT_TRUE(rpcServer->setupInetServer(0, &port));

    auto socket = rpcServer->releaseServer();



    auto keepAlive = sp<BBinder>::make();

    ASSERT_EQ(OK, binder->setRpcClientDebug(std::move(socket), keepAlive));



    auto rpcSession = RpcSession::make();

    ASSERT_TRUE(rpcSession->setupInetClient("127.0.0.1", port));

    auto rpcBinder = rpcSession->getRootObject();

    ASSERT_NE(nullptr, rpcBinder);



    ASSERT_EQ(OK, rpcBinder->pingBinder());



    ASSERT_EQ(descriptor, rpcBinder->getInterfaceDescriptor())

            << "getInterfaceDescriptor should not crash system_server";

    ASSERT_EQ(OK, rpcBinder->pingBinder());

}



} // namespace android



int main(int argc, char** argv) {