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Commit bc4dbfaf authored by Josh Gao's avatar Josh Gao
Browse files

adb: fix NonblockingFdConnection's behavior with large writes. 

Large opportunistic writes would perform a write without updating
writable_ or waking up the polling thread, which resulted in the worker
thread never polling with POLLOUT.

Test: adb_benchmark
Change-Id: Ifed3b97a4b647b539dcd2df858572fa7da9a22d0
parent 10d079a3

adb/transport_fd.cpp

+15 −17
Original line number Diff line number Diff line
@@ -85,18 +85,9 @@ struct NonblockingFdConnection : public Connection { 
            if (pfds[0].revents) {

                if ((pfds[0].revents & POLLOUT)) {

                    std::lock_guard<std::mutex> lock(this->write_mutex_);

                    WriteResult result = DispatchWrites();

                    switch (result) {

                        case WriteResult::Error:

                    if (DispatchWrites() == WriteResult::Error) {

                        *error = "write failed";

                        return;



                        case WriteResult::Completed:

                            writable_ = true;

                            break;



                        case WriteResult::TryAgain:

                            break;

                    }

                }
@@ -179,13 +170,14 @@ struct NonblockingFdConnection : public Connection { 


    WriteResult DispatchWrites() REQUIRES(write_mutex_) {

        CHECK(!write_buffer_.empty());

        if (!writable_) {

            return WriteResult::TryAgain;

        }



        auto iovs = write_buffer_.iovecs();

        ssize_t rc = adb_writev(fd_.get(), iovs.data(), iovs.size());

        if (rc == -1) {

            if (errno == EAGAIN || errno == EWOULDBLOCK) {

                writable_ = false;

                return WriteResult::TryAgain;

            }



            return WriteResult::Error;

        } else if (rc == 0) {

            errno = 0;
@@ -194,6 +186,7 @@ struct NonblockingFdConnection : public Connection { 


        // TODO: Implement a more efficient drop_front?

        write_buffer_.take_front(rc);

        writable_ = write_buffer_.empty();

        if (write_buffer_.empty()) {

            return WriteResult::Completed;

        }
@@ -211,7 +204,12 @@ struct NonblockingFdConnection : public Connection { 
        if (!packet->payload.empty()) {

            write_buffer_.append(std::make_unique<IOVector::block_type>(std::move(packet->payload)));

        }

        return DispatchWrites() != WriteResult::Error;



        WriteResult result = DispatchWrites();

        if (result == WriteResult::TryAgain) {

            WakeThread();

        }

        return result != WriteResult::Error;

    }



    std::thread thread_;