Fix dead loop of HttpClient on Linux; Allow to call Request() multiple times on the same HttpClient object.

example/rest_book_client/main.cc

@@ -215,28 +215,33 @@ int main(int argc, char* argv[]) {
   PrintSeparator();
 
   std::list<Book> books;
-  list_client.ListBooks(&books);
+  if (list_client.ListBooks(&books)) {
     PrintBookList(books);
+  }
 
   PrintSeparator();
 
   std::string id;
-  if (!list_client.CreateBook("1984", 12.3, &id)) {
-    return 1;
-  }
+  if (list_client.CreateBook("1984", 12.3, &id)) {
     std::cout << "Book ID: " << id << std::endl;
+  } else {
+    id = "1";
+    std::cout << "Book ID: " << id << " (faked)"<< std::endl;
+  }
 
   PrintSeparator();
 
   books.clear();
-  list_client.ListBooks(&books);
+  if (list_client.ListBooks(&books)) {
     PrintBookList(books);
+  }
 
   PrintSeparator();
 
   Book book;
-  detail_client.GetBook(id, &book);
+  if (detail_client.GetBook(id, &book)) {
     PrintBook(book);
+  }
 
   PrintSeparator();
 
@@ -244,8 +249,9 @@ int main(int argc, char* argv[]) {
 
   PrintSeparator();
 
-  detail_client.GetBook(id, &book);
+  if (detail_client.GetBook(id, &book)) {
     PrintBook(book);
+  }
 
   PrintSeparator();
 
@@ -254,8 +260,9 @@ int main(int argc, char* argv[]) {
   PrintSeparator();
 
   books.clear();
-  list_client.ListBooks(&books);
+  if (list_client.ListBooks(&books)) {
     PrintBookList(books);
+  }
 
   return 0;
 }

webcc/http_client.cc

@@ -34,6 +34,8 @@ void HttpClient::SetTimeout(int seconds) {
 }
 
 bool HttpClient::Request(const HttpRequest& request) {
+  io_context_.restart();
+
   response_.reset(new HttpResponse());
   response_parser_.reset(new HttpResponseParser(response_.get()));
 
@@ -72,22 +74,8 @@ Error HttpClient::Connect(const HttpRequest& request) {
 
   LOG_VERB("Connect to server...");
 
-  ec = boost::asio::error::would_block;
-
-  // ConnectHandler: void (boost::system::error_code, tcp::endpoint)
-  // Using |boost::lambda::var()| is identical to:
-  //   boost::asio::async_connect(
-  //       socket_, endpoints,
-  //       [this, &ec](boost::system::error_code inner_ec, tcp::endpoint) {
-  //         ec = inner_ec;
-  //       });
-  boost::asio::async_connect(socket_, endpoints,
-                             boost::lambda::var(ec) = boost::lambda::_1);
-
-  // Block until the asynchronous operation has completed.
-  do {
-    io_context_.run_one();
-  } while (ec == boost::asio::error::would_block);
+  // Use sync API directly since we don't need timeout control.
+  boost::asio::connect(socket_, endpoints, ec);
 
   // Determine whether a connection was successfully established.
   if (ec) {
@@ -98,11 +86,6 @@ Error HttpClient::Connect(const HttpRequest& request) {
 
   LOG_VERB("Socket connected.");
 
-  // ISSUE: |async_connect| reports success on failure.
-  // See the following bugs:
-  //   - https://svn.boost.org/trac10/ticket/8795
-  //   - https://svn.boost.org/trac10/ticket/8995
-
   return kNoError;
 }
 
@@ -114,16 +97,10 @@ Error HttpClient::SendReqeust(const HttpRequest& request) {
   // I find that it's almost impossible to simulate a situation in the server
   // side to test this timeout.
 
-  boost::system::error_code ec = boost::asio::error::would_block;
-
-  // WriteHandler: void (boost::system::error_code, std::size_t)
-  boost::asio::async_write(socket_, request.ToBuffers(),
-                           boost::lambda::var(ec) = boost::lambda::_1);
+  boost::system::error_code ec;
 
-  // Block until the asynchronous operation has completed.
-  do {
-    io_context_.run_one();
-  } while (ec == boost::asio::error::would_block);
+  // Use sync API directly since we don't need timeout control.
+  boost::asio::write(socket_, request.ToBuffers(), ec);
 
   if (ec) {
     LOG_ERRO("Socket write error (%s).", ec.message().c_str());
@@ -140,7 +117,7 @@ Error HttpClient::ReadResponse() {
   LOG_VERB("Read response (timeout: %ds)...", timeout_seconds_);
 
   deadline_.expires_from_now(boost::posix_time::seconds(timeout_seconds_));
-  AsyncWaitDeadline();
+  DoWaitDeadline();
 
   Error error = kNoError;
   DoReadResponse(&error);
@@ -208,23 +185,37 @@ void HttpClient::DoReadResponse(Error* error) {
   } while (ec == boost::asio::error::would_block);
 }
 
-void HttpClient::AsyncWaitDeadline() {
-  deadline_.async_wait(std::bind(&HttpClient::DeadlineHandler, this,
+void HttpClient::DoWaitDeadline() {
+  deadline_.async_wait(std::bind(&HttpClient::OnDeadline, this,
                                  std::placeholders::_1));
 }
 
-void HttpClient::DeadlineHandler(boost::system::error_code ec) {
-  LOG_VERB("Deadline handler.");
-
-  if (ec == boost::asio::error::operation_aborted) {
-    LOG_VERB("Deadline timer canceled.");
+void HttpClient::OnDeadline(boost::system::error_code ec) {
+  if (stopped_) {
     return;
   }
 
+  LOG_VERB("OnDeadline.");
+
+  // NOTE: Can't check this:
+  // if (ec == boost::asio::error::operation_aborted) {
+  //   LOG_VERB("Deadline timer canceled.");
+  //   return;
+  // }
+
+  if (deadline_.expires_at() <=
+      boost::asio::deadline_timer::traits_type::now()) {
+    // The deadline has passed.
+    // The socket is closed so that any outstanding asynchronous operations
+    // are canceled.
     LOG_WARN("HTTP client timed out.");
     timed_out_ = true;
-
     Stop();
+    return;
+  }
+
+  // Put the actor back to sleep.
+  DoWaitDeadline();
 }
 
 void HttpClient::Stop() {

webcc/http_client.h

@@ -48,8 +48,8 @@ class HttpClient {
 
   void DoReadResponse(Error* error);
 
-  void AsyncWaitDeadline();
-  void DeadlineHandler(boost::system::error_code ec);
+  void DoWaitDeadline();
+  void OnDeadline(boost::system::error_code ec);
 
   void Stop();