Created a new sample async client that is non-blocking. A reader thre…

…ad is spawned to handle all the RPC results.
tmatsuo · May 4, 2016 · 470cbd1 · 470cbd1
1 parent 2df7d40
commit 470cbd1
Show file tree

Hide file tree

Showing 3 changed files with 189 additions and 59 deletions.
diff --git a/examples/cpp/helloworld/Makefile b/examples/cpp/helloworld/Makefile
@@ -41,7 +41,7 @@ PROTOS_PATH = ../../protos
 
 vpath %.proto $(PROTOS_PATH)
 
-all: system-check greeter_client greeter_server greeter_async_client greeter_async_server
+all: system-check greeter_client greeter_server greeter_async_client greeter_async_client2 greeter_async_server
 
 greeter_client: helloworld.pb.o helloworld.grpc.pb.o greeter_client.o
 	$(CXX) $^ $(LDFLAGS) -o $@
@@ -52,6 +52,9 @@ greeter_server: helloworld.pb.o helloworld.grpc.pb.o greeter_server.o
 greeter_async_client: helloworld.pb.o helloworld.grpc.pb.o greeter_async_client.o
 	$(CXX) $^ $(LDFLAGS) -o $@
 
+greeter_async_client2: helloworld.pb.o helloworld.grpc.pb.o greeter_async_client2.o
+	$(CXX) $^ $(LDFLAGS) -o $@
+
 greeter_async_server: helloworld.pb.o helloworld.grpc.pb.o greeter_async_server.o
 	$(CXX) $^ $(LDFLAGS) -o $@
 
@@ -64,7 +67,7 @@ greeter_async_server: helloworld.pb.o helloworld.grpc.pb.o greeter_async_server.
 	$(PROTOC) -I $(PROTOS_PATH) --cpp_out=. $<
 
 clean:
-	rm -f *.o *.pb.cc *.pb.h greeter_client greeter_server greeter_async_client greeter_async_server
+	rm -f *.o *.pb.cc *.pb.h greeter_client greeter_server greeter_async_client greeter_async_client2 greeter_async_server
 
 
 # The following is to test your system and ensure a smoother experience.

diff --git a/examples/cpp/helloworld/greeter_async_client.cc b/examples/cpp/helloworld/greeter_async_client.cc
@@ -36,7 +36,6 @@
 #include <string>
 
 #include <grpc++/grpc++.h>
-#include <thread>
 
 #include "helloworld.grpc.pb.h"
 
@@ -56,91 +55,71 @@ class GreeterClient {
 
   // Assambles the client's payload, sends it and presents the response back
   // from the server.
-  void SayHello(const std::string& user) {
+  std::string SayHello(const std::string& user) {
     // Data we are sending to the server.
     HelloRequest request;
     request.set_name(user);
 
-    AsyncClientCall* call = new AsyncClientCall;
+    // 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 ongoing RPC.
-    call->response_reader = stub_->AsyncSayHello(&call->context, request, &cq_);
-
+    // 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 memory address of call object.
-    call->response_reader->Finish(&call->reply, &call->status, (void*)call);
-
-  }
-  void AsyncCompleteRpc()
-  {
+    // 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".
-    while (cq_.Next(&got_tag, &ok))
-    {
-      AsyncClientCall* call = static_cast<AsyncClientCall*>(got_tag);
-      if (ok)
-        std::cout << "Greeter received: " << call->reply.message() << std::endl;
-      else
-        std::cout << "RPC failed" << std::endl;
-      delete call;
+    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:
-
-  // Structure for keeping state and data information
-  struct AsyncClientCall
-  {
-      // 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;
-
-      // Storage for the status of the RPC upon completion.
-      Status status;
-
-
-      std::unique_ptr<ClientAsyncResponseReader<HelloReply>> response_reader;
-  };
-
   // 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_;
-
-  // The producer-consumer queue we use to communicate asynchronously with the
-  // gRPC runtime.
-  CompletionQueue cq_;
 };
 
 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()));
-
-  // Spawn reader thread that loops indefinitely
-  std::thread thread_ = std::thread(&GreeterClient::AsyncCompleteRpc, &greeter);
-
-  for (int i = 0; i < 100; i++)
-  {
-    std::string user("world " + std::to_string(i));
-    greeter.SayHello(user);  // The actual RPC call!
-  }
-
-  std::cout << "Press control-c to quit" << std::endl << std::endl;
-  thread_.join();  //blocks forever
+  std::string user("world");
+  std::string reply = greeter.SayHello(user);  // The actual RPC call!
+  std::cout << "Greeter received: " << reply << std::endl;
 
   return 0;
 }
diff --git a/examples/cpp/helloworld/greeter_async_client2.cc b/examples/cpp/helloworld/greeter_async_client2.cc
@@ -0,0 +1,148 @@
+/*
+ *
+ * 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 <thread>
+
+#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.
+    void SayHello(const std::string& user) {
+        // Data we are sending to the server.
+        HelloRequest request;
+        request.set_name(user);
+
+        AsyncClientCall* call = new AsyncClientCall;
+
+        // 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 ongoing RPC.
+        call->response_reader = stub_->AsyncSayHello(&call->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 memory address of call object.
+        call->response_reader->Finish(&call->reply, &call->status, (void*)call);
+
+    }
+
+    // Loop while listening for completed responses
+    void AsyncCompleteRpc()
+    {
+        void* got_tag;
+        bool ok = false;
+
+        // Block until the next result is available in the completion queue "cq".
+        while (cq_.Next(&got_tag, &ok))
+        {
+            AsyncClientCall* call = static_cast<AsyncClientCall*>(got_tag);
+            if (ok)
+                std::cout << "Greeter received: " << call->reply.message() << std::endl;
+            else
+                std::cout << "RPC failed" << std::endl;
+            delete call;
+        }
+    }
+
+  private:
+
+    // struct for keeping state and data information
+    struct AsyncClientCall
+    {
+        // 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;
+
+        // Storage for the status of the RPC upon completion.
+        Status status;
+
+
+        std::unique_ptr<ClientAsyncResponseReader<HelloReply>> response_reader;
+    };
+
+    // 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_;
+
+    // The producer-consumer queue we use to communicate asynchronously with the
+    // gRPC runtime.
+    CompletionQueue cq_;
+};
+
+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()));
+
+    // Spawn reader thread that loops indefinitely
+    std::thread thread_ = std::thread(&GreeterClient::AsyncCompleteRpc, &greeter);
+
+    for (int i = 0; i < 100; i++)
+    {
+        std::string user("world " + std::to_string(i));
+        greeter.SayHello(user);  // The actual RPC call!
+    }
+
+    std::cout << "Press control-c to quit" << std::endl << std::endl;
+    thread_.join();  //blocks forever
+
+    return 0;
+}