THRIFT-923. cpp: Implement a fully nonblocking server and client

There are three major parts of this:
1/ New callback-style interfaces for for a few key Thrift components:
   TAsyncProcessor for servers and TAsyncChannel for clients.
2/ Concrete implementations of TAsyncChannel and a server for
   TAsyncProcessor based on evhttp.
3/ Async-style code generation for C++

git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@1005127 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/lib/cpp/src/async/TEvhttpClientChannel.cpp b/lib/cpp/src/async/TEvhttpClientChannel.cpp
new file mode 100644
index 0000000..54676a1
--- /dev/null
+++ b/lib/cpp/src/async/TEvhttpClientChannel.cpp
@@ -0,0 +1,124 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#include "TEvhttpClientChannel.h"
+#include <evhttp.h>
+
+namespace apache { namespace thrift { namespace async {
+
+
+TEvhttpClientChannel::TEvhttpClientChannel(
+    const std::string& host,
+    const std::string& path,
+    const char* address,
+    int port,
+    struct event_base* eb)
+  : host_(host)
+  , path_(path)
+  , recvBuf_(NULL)
+  , conn_(NULL)
+{
+  conn_ = evhttp_connection_new(address, port);
+  if (conn_ == NULL) {
+    abort(); // XXX
+  }
+  evhttp_connection_set_base(conn_, eb);
+}
+
+
+TEvhttpClientChannel::~TEvhttpClientChannel() {
+  if (conn_ != NULL) {
+    evhttp_connection_free(conn_);
+  }
+}
+
+
+bool TEvhttpClientChannel::sendAndRecvMessage(
+    const VoidCallback& cob,
+    apache::thrift::transport::TMemoryBuffer* sendBuf,
+    apache::thrift::transport::TMemoryBuffer* recvBuf) {
+  cob_ = cob;
+  recvBuf_ = recvBuf;
+
+  struct evhttp_request* req = evhttp_request_new(response, this);
+  if (req == NULL) {
+    abort(); // XXX
+  }
+
+  int rv;
+
+  rv = evhttp_add_header(req->output_headers, "Host", host_.c_str());
+  if (rv != 0) {
+    abort(); // XXX
+  }
+
+  rv = evhttp_add_header(req->output_headers, "Content-Type", "application/x-thrift");
+  if (rv != 0) {
+    abort(); // XXX
+  }
+
+  uint8_t* obuf;
+  uint32_t sz;
+  sendBuf->getBuffer(&obuf, &sz);
+  rv = evbuffer_add(req->output_buffer, obuf, sz);
+  if (rv != 0) {
+    abort(); // XXX
+  }
+
+  rv = evhttp_make_request(conn_, req, EVHTTP_REQ_POST, path_.c_str());
+  if (rv != 0) {
+    abort(); // XXX
+  }
+
+  return true;
+}
+
+
+bool TEvhttpClientChannel::sendMessage(
+    const VoidCallback& cob, apache::thrift::transport::TMemoryBuffer* message) {
+  abort(); // XXX
+}
+
+
+bool TEvhttpClientChannel::recvMessage(
+    const VoidCallback& cob, apache::thrift::transport::TMemoryBuffer* message) {
+  abort(); // XXX
+}
+
+
+void TEvhttpClientChannel::finish(struct evhttp_request* req) {
+  if (req == NULL) {
+    return cob_();
+  } else if (req->response_code != 200) {
+    return cob_();
+  }
+  recvBuf_->resetBuffer(
+      EVBUFFER_DATA(req->input_buffer),
+      EVBUFFER_LENGTH(req->input_buffer));
+  return cob_();
+}
+
+
+/* static */ void TEvhttpClientChannel::response(struct evhttp_request* req, void* arg) {
+  TEvhttpClientChannel* self = (TEvhttpClientChannel*)arg;
+  self->finish(req);
+}
+
+
+}}} // apache::thrift::async