+/**
+ * Test that bytes written is correctly computed in case of write failure
+ */
+TEST(AsyncSocketTest, WriteErrorCallbackBytesWritten) {
+ // Send and receive buffer sizes for the sockets.
+ const int sockBufSize = 8 * 1024;
+
+ TestServer server(false, sockBufSize);
+
+ AsyncSocket::OptionMap options{
+ {{SOL_SOCKET, SO_SNDBUF}, sockBufSize},
+ {{SOL_SOCKET, SO_RCVBUF}, sockBufSize},
+ {{IPPROTO_TCP, TCP_NODELAY}, 1},
+ };
+
+ // The current thread will be used by the receiver - use a separate thread
+ // for the sender.
+ EventBase senderEvb;
+ std::thread senderThread([&]() { senderEvb.loopForever(); });
+
+ ConnCallback ccb;
+ std::shared_ptr<AsyncSocket> socket;
+
+ senderEvb.runInEventBaseThreadAndWait([&]() {
+ socket = AsyncSocket::newSocket(&senderEvb);
+ socket->connect(&ccb, server.getAddress(), 30, options);
+ });
+
+ // accept the socket on the server side
+ std::shared_ptr<BlockingSocket> acceptedSocket = server.accept();
+
+ // Send a big (45KB) write so that it is partially written. The first write
+ // is 16KB (8KB on both sides) and subsequent writes are 8KB each. Reading
+ // just under 24KB would cause 3-4 writes for the total of 32-40KB in the
+ // following sequence: 16KB + 8KB + 8KB (+ 8KB). This ensures that not all
+ // bytes are written when the socket is reset. Having at least 3 writes
+ // ensures that the total size (45KB) would be exceeed in case of overcounting
+ // based on the initial write size of 16KB.
+ constexpr size_t sendSize = 45 * 1024;
+ auto const sendBuf = std::vector<char>(sendSize, 'a');
+
+ WriteCallback wcb;
+
+ senderEvb.runInEventBaseThreadAndWait(
+ [&]() { socket->write(&wcb, sendBuf.data(), sendSize); });
+
+ // Reading 20KB would cause three additional writes of 8KB, but less
+ // than 45KB total, so the socket is reset before all bytes are written.
+ constexpr size_t recvSize = 20 * 1024;
+ uint8_t recvBuf[recvSize];
+ int bytesRead = acceptedSocket->readAll(recvBuf, sizeof(recvBuf));
+
+ acceptedSocket->closeWithReset();
+
+ senderEvb.terminateLoopSoon();
+ senderThread.join();
+
+ LOG(INFO) << "Bytes written: " << wcb.bytesWritten;
+
+ ASSERT_EQ(STATE_FAILED, wcb.state);
+ ASSERT_GE(wcb.bytesWritten, bytesRead);
+ ASSERT_LE(wcb.bytesWritten, sendSize);
+ ASSERT_EQ(recvSize, bytesRead);
+ ASSERT(32 * 1024 == wcb.bytesWritten || 40 * 1024 == wcb.bytesWritten);
+}
+