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Commit e39ccd3c authored by Josh Gao's avatar Josh Gao
Browse files

adb: allow reentrant calls to fdevent_run_on_main_thread. 

Previously, reentrant calls to fdevent_run_on_main_thread would
deadlock.

Test: adb_test on host
Change-Id: I0783be0558dcaf61ddbe76d13ac6917fc2de0be0
parent d51c6df1

adb/fdevent.cpp

+28 −16
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ 
#include <unistd.h>



#include <atomic>

#include <deque>

#include <functional>

#include <list>

#include <mutex>
@@ -81,7 +82,7 @@ static unsigned long main_thread_id; 


static auto& run_queue_notify_fd = *new unique_fd();

static auto& run_queue_mutex = *new std::mutex();

static auto& run_queue GUARDED_BY(run_queue_mutex) = *new std::vector<std::function<void()>>();

static auto& run_queue GUARDED_BY(run_queue_mutex) = *new std::deque<std::function<void()>>();



void check_main_thread() {

    if (main_thread_valid) {
@@ -359,11 +360,21 @@ static void fdevent_subproc_setup() { 
}

#endif // !ADB_HOST



static void fdevent_run_flush() REQUIRES(run_queue_mutex) {

    for (auto& f : run_queue) {

        f();

static void fdevent_run_flush() EXCLUDES(run_queue_mutex) {

    // We need to be careful around reentrancy here, since a function we call can queue up another

    // function.

    while (true) {

        std::function<void()> fn;

        {

            std::lock_guard<std::mutex> lock(run_queue_mutex);

            if (run_queue.empty()) {

                break;

            }

            fn = run_queue.front();

            run_queue.pop_front();

        }

        fn();

    }

    run_queue.clear();

}



static void fdevent_run_func(int fd, unsigned ev, void* /* userdata */) {
@@ -377,11 +388,11 @@ static void fdevent_run_func(int fd, unsigned ev, void* /* userdata */) { 
        PLOG(FATAL) << "failed to empty run queue notify fd";

    }



    std::lock_guard<std::mutex> lock(run_queue_mutex);

    fdevent_run_flush();

}



static void fdevent_run_setup() {

    {

        std::lock_guard<std::mutex> lock(run_queue_mutex);

        CHECK(run_queue_notify_fd.get() == -1);

        int s[2];
@@ -393,6 +404,7 @@ static void fdevent_run_setup() { 
        fdevent* fde = fdevent_create(s[1], fdevent_run_func, nullptr);

        CHECK(fde != nullptr);

        fdevent_add(fde, FDE_READ);

    }



    fdevent_run_flush();

}

adb/fdevent_test.cpp

+28 −0
Original line number Diff line number Diff line
@@ -194,3 +194,31 @@ TEST_F(FdeventTest, run_on_main_thread) { 
        ASSERT_EQ(i, vec[i]);

    }

}



static std::function<void()> make_appender(std::vector<int>* vec, int value) {

    return [vec, value]() {

        check_main_thread();

        if (value == 100) {

            return;

        }



        vec->push_back(value);

        fdevent_run_on_main_thread(make_appender(vec, value + 1));

    };

}



TEST_F(FdeventTest, run_on_main_thread_reentrant) {

    std::vector<int> vec;



    PrepareThread();

    std::thread thread(fdevent_loop);



    fdevent_run_on_main_thread(make_appender(&vec, 0));



    TerminateThread(thread);



    ASSERT_EQ(100u, vec.size());

    for (int i = 0; i < 100; ++i) {

        ASSERT_EQ(i, vec[i]);

    }

}