Started working on network hang fix.

Reviewers: buda

Reviewed By: buda

Subscribers: pullbot, mislav.bradac

Differential Revision: https://phabricator.memgraph.io/D228

tests/concurrent/network_read_hang.cpp

@@ -0,0 +1,127 @@
+#ifndef NDEBUG
+#define NDEBUG
+#endif
+
+#include <array>
+#include <cassert>
+#include <cstring>
+#include <iostream>
+#include <vector>
+#include <chrono>
+#include <thread>
+
+#include "gtest/gtest.h"
+
+#include "logging/default.hpp"
+#include "logging/streams/stdout.hpp"
+
+#include "communication/server.hpp"
+#include "dbms/dbms.hpp"
+#include "io/network/epoll.hpp"
+#include "io/network/socket.hpp"
+#include "query/engine.hpp"
+
+static constexpr const char interface[] = "127.0.0.1";
+
+using endpoint_t = io::network::NetworkEndpoint;
+using socket_t = io::network::Socket;
+
+class TestOutputStream {};
+
+class TestSession {
+ public:
+  TestSession(socket_t&& socket, Dbms& dbms,
+              QueryEngine<TestOutputStream>& query_engine)
+        : socket_(std::move(socket)) {
+    event_.data.ptr = this;
+  }
+
+  bool Alive() { return socket_.IsOpen(); }
+
+  int Id() const { return socket_.id(); }
+
+  void Execute(const byte* data, size_t len) {
+    this->socket_.Write(data, len);
+  }
+
+  void Close() {
+    this->socket_.Close();
+  }
+
+  socket_t socket_;
+  io::network::Epoll::Event event_;
+};
+
+using test_server_t =
+    communication::Server<TestSession, TestOutputStream, socket_t>;
+
+test_server_t *serverptr;
+std::atomic<bool> run{true};
+
+void client_run(int num, const char* interface, const char* port) {
+  endpoint_t endpoint(interface, port);
+  socket_t socket;
+  uint8_t data = 0x00;
+  ASSERT_TRUE(socket.Connect(endpoint));
+  ASSERT_TRUE(socket.SetTimeout(1, 0));
+  // set socket timeout to 1s
+  ASSERT_TRUE(socket.Write((uint8_t *)"\xAA", 1));
+  ASSERT_TRUE(socket.Read(&data, 1));
+  fprintf(stderr, "CLIENT %d READ 0x%02X!\n", num, data);
+  ASSERT_EQ(data, 0xAA);
+  while (run)
+    std::this_thread::sleep_for(std::chrono::milliseconds(100));
+  socket.Close();
+}
+
+void server_run(void* serverptr, int num) {
+  ((test_server_t*)serverptr)->Start(num);
+}
+
+TEST(Network, SocketReadHangOnConcurrentConnections) {
+  // initialize listen socket
+  endpoint_t endpoint(interface, "0");
+  socket_t socket;
+  ASSERT_TRUE(socket.Bind(endpoint));
+  ASSERT_TRUE(socket.SetNonBlocking());
+  ASSERT_TRUE(socket.Listen(1024));
+
+  // get bound address
+  auto ep = socket.endpoint();
+  printf("ADDRESS: %s, PORT: %d\n", ep.address(), ep.port());
+
+  // initialize server
+  Dbms dbms;
+  QueryEngine<TestOutputStream> query_engine;
+  test_server_t server(std::move(socket), dbms, query_engine);
+  serverptr = &server;
+
+  // start server
+  int N = (std::thread::hardware_concurrency() + 1) / 2;
+  int Nc = N * 3;
+  std::thread server_thread(server_run, serverptr, N);
+
+  // start clients
+  std::vector<std::thread> clients;
+  for (int i = 0; i < Nc; ++i)
+    clients.push_back(
+        std::thread(client_run, i, interface, ep.port_str()));
+
+  // wait for 2s and stop clients
+  std::this_thread::sleep_for(std::chrono::seconds(2));
+  run = false;
+
+  // cleanup clients
+  for (int i = 0; i < Nc; ++i) clients[i].join();
+
+  // stop server
+  server.Shutdown();
+  server_thread.join();
+}
+
+int main(int argc, char **argv) {
+  logging::init_async();
+  logging::log->pipe(std::make_unique<Stdout>());
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}