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/*
*
* Copyright 2018 gRPC authors.
*
* Licensed 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 <atomic>
#include <grpc++/grpc++.h>
#include <jni.h>
#include "helloworld.grpc.pb.h"
using grpc::Channel;
using grpc::ClientContext;
using grpc::Server;
using grpc::ServerBuilder;
using grpc::ServerContext;
using grpc::Status;
using helloworld::Greeter;
using helloworld::HelloReply;
using helloworld::HelloRequest;
std::atomic<bool> stop_server(false);
// Logic and data behind the server's behavior.
class GreeterServiceImpl final : public Greeter::Service {
Status SayHello(ServerContext* context, const HelloRequest* request,
HelloReply* reply) override {
std::string prefix("Hello ");
reply->set_message(prefix + request->name());
return Status::OK;
}
};
void StartServer(JNIEnv* env, jobject obj, jmethodID is_cancelled_mid,
int port) {
const int host_port_buf_size = 1024;
char host_port[host_port_buf_size];
snprintf(host_port, host_port_buf_size, "0.0.0.0:%d", port);
GreeterServiceImpl service;
ServerBuilder builder;
// Listen on the given address without any authentication mechanism.
builder.AddListeningPort(host_port, grpc::InsecureServerCredentials());
// Register "service" as the instance through which we'll communicate with
// clients. In this case it corresponds to an *synchronous* service.
builder.RegisterService(&service);
// Finally assemble the server.
std::unique_ptr<Server> server(builder.BuildAndStart());
while (!stop_server.load()) {
// Check with the Java code to see if the user has requested the server stop or the app is no
// longer in the foreground.
jboolean is_cancelled = env->CallBooleanMethod(obj, is_cancelled_mid);
if (is_cancelled == JNI_TRUE) {
stop_server = true;
}
}
}
class GreeterClient {
public:
GreeterClient(std::shared_ptr<Channel> channel)
: stub_(Greeter::NewStub(channel)) {}
// Assembles 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 actual RPC.
Status status = stub_->SayHello(&context, request, &reply);
if (status.ok()) {
return reply.message();
} else {
return status.error_message();
}
}
private:
std::unique_ptr<Greeter::Stub> stub_;
};
// Send an RPC and return the response. Invoked from Java code.
extern "C" JNIEXPORT jstring JNICALL
Java_io_grpc_helloworldexample_cpp_HelloworldActivity_sayHello(
JNIEnv* env, jobject obj_unused, jstring host_raw, jint port_raw,
jstring message_raw) {
const char* host_chars = env->GetStringUTFChars(host_raw, (jboolean*)0);
std::string host(host_chars, env->GetStringUTFLength(host_raw));
int port = static_cast<int>(port_raw);
const char* message_chars = env->GetStringUTFChars(message_raw, (jboolean*)0);
std::string message(message_chars, env->GetStringUTFLength(message_raw));
const int host_port_buf_size = 1024;
char host_port[host_port_buf_size];
snprintf(host_port, host_port_buf_size, "%s:%d", host.c_str(), port);
GreeterClient greeter(
grpc::CreateChannel(host_port, grpc::InsecureChannelCredentials()));
std::string reply = greeter.SayHello(message);
return env->NewStringUTF(reply.c_str());
}
// Start the server. Invoked from Java code.
extern "C" JNIEXPORT void JNICALL
Java_io_grpc_helloworldexample_cpp_HelloworldActivity_startServer(
JNIEnv* env, jobject obj_this, jint port_raw) {
int port = static_cast<int>(port_raw);
jclass cls = env->GetObjectClass(obj_this);
jmethodID is_cancelled_mid =
env->GetMethodID(cls, "isRunServerTaskCancelled", "()Z");
stop_server = false;
StartServer(env, obj_this, is_cancelled_mid, port);
}
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