Initial checkin of gRPC to third_party/

third_party/grpc/examples/cpp/helloworld/greeter_async_client.cc

+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include <iostream>
+#include <memory>
+#include <string>
+
+#include <grpc++/grpc++.h>
+
+#include "helloworld.grpc.pb.h"
+
+using grpc::Channel;
+using grpc::ClientAsyncResponseReader;
+using grpc::ClientContext;
+using grpc::CompletionQueue;
+using grpc::Status;
+using helloworld::HelloRequest;
+using helloworld::HelloReply;
+using helloworld::Greeter;
+
+class GreeterClient {
+ public:
+  explicit GreeterClient(std::shared_ptr<Channel> channel)
+      : stub_(Greeter::NewStub(channel)) {}
+
+  // Assambles the client's payload, sends it and presents the response back
+  // from the server.
+  std::string SayHello(const std::string& user) {
+    // Data we are sending to the server.
+    HelloRequest request;
+    request.set_name(user);
+
+    // Container for the data we expect from the server.
+    HelloReply reply;
+
+    // Context for the client. It could be used to convey extra information to
+    // the server and/or tweak certain RPC behaviors.
+    ClientContext context;
+
+    // The producer-consumer queue we use to communicate asynchronously with the
+    // gRPC runtime.
+    CompletionQueue cq;
+
+    // Storage for the status of the RPC upon completion.
+    Status status;
+
+    // stub_->AsyncSayHello() perform the RPC call, returning an instance we
+    // store in "rpc". Because we are using the asynchronous API, we need the
+    // hold on to the "rpc" instance in order to get updates on the ongoig RPC.
+    std::unique_ptr<ClientAsyncResponseReader<HelloReply> > rpc(
+        stub_->AsyncSayHello(&context, request, &cq));
+
+    // Request that, upon completion of the RPC, "reply" be updated with the
+    // server's response; "status" with the indication of whether the operation
+    // was successful. Tag the request with the integer 1.
+    rpc->Finish(&reply, &status, (void*)1);
+    void* got_tag;
+    bool ok = false;
+    // Block until the next result is available in the completion queue "cq".
+    cq.Next(&got_tag, &ok);
+
+    // Verify that the result from "cq" corresponds, by its tag, our previous
+    // request.
+    GPR_ASSERT(got_tag == (void*)1);
+    // ... and that the request was completed successfully. Note that "ok"
+    // corresponds solely to the request for updates introduced by Finish().
+    GPR_ASSERT(ok);
+
+    // Act upon the status of the actual RPC.
+    if (status.ok()) {
+      return reply.message();
+    } else {
+      return "RPC failed";
+    }
+  }
+
+ private:
+  // Out of the passed in Channel comes the stub, stored here, our view of the
+  // server's exposed services.
+  std::unique_ptr<Greeter::Stub> stub_;
+};
+
+int main(int argc, char** argv) {
+  // Instantiate the client. It requires a channel, out of which the actual RPCs
+  // are created. This channel models a connection to an endpoint (in this case,
+  // localhost at port 50051). We indicate that the channel isn't authenticated
+  // (use of InsecureChannelCredentials()).
+  GreeterClient greeter(grpc::CreateChannel(
+      "localhost:50051", grpc::InsecureChannelCredentials()));
+  std::string user("world");
+  std::string reply = greeter.SayHello(user);  // The actual RPC call!
+  std::cout << "Greeter received: " << reply << std::endl;
+
+  return 0;
+}