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/TAsyncProcessor.h b/lib/cpp/src/async/TAsyncProcessor.h
new file mode 100644
index 0000000..abf5816
--- /dev/null
+++ b/lib/cpp/src/async/TAsyncProcessor.h
@@ -0,0 +1,58 @@
+/*
+ * 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.
+ */
+
+#ifndef _THRIFT_TASYNCPROCESSOR_H_
+#define _THRIFT_TASYNCPROCESSOR_H_ 1
+
+#include <tr1/functional>
+#include <boost/shared_ptr.hpp>
+#include <protocol/TProtocol.h>
+#include <TProcessor.h>
+
+namespace apache { namespace thrift { namespace async {
+
+/**
+ * Async version of a TProcessor.  It is not expected to complete by the time
+ * the call to process returns.  Instead, it calls a cob to signal completion.
+ */
+class TAsyncProcessor {
+ public:
+  virtual ~TAsyncProcessor() {}
+
+  virtual void process(std::tr1::function<void(bool success)> _return,
+                       boost::shared_ptr<protocol::TProtocol> in,
+                       boost::shared_ptr<protocol::TProtocol> out) = 0;
+
+  void process(std::tr1::function<void(bool success)> _return,
+               boost::shared_ptr<apache::thrift::protocol::TProtocol> io) {
+    return process(_return, io, io);
+  }
+
+ protected:
+  TAsyncProcessor() {}
+};
+
+}}} // apache::thrift::async
+
+// XXX I'm lazy for now
+namespace apache { namespace thrift {
+using apache::thrift::async::TAsyncProcessor;
+}}
+
+#endif // #ifndef _THRIFT_TASYNCPROCESSOR_H_