grpc/include/grpc++/stream.h

/*
 *
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 * modification, are permitted provided that the following conditions are
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 *
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 * notice, this list of conditions and the following disclaimer.
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 * in the documentation and/or other materials provided with the
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 * this software without specific prior written permission.
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#ifndef __GRPCPP_STREAM_H__
#define __GRPCPP_STREAM_H__

#include <grpc++/call.h>
#include <grpc++/channel_interface.h>
#include <grpc++/completion_queue.h>
#include <grpc++/stream_context_interface.h>
#include <grpc++/status.h>
#include <grpc/support/log.h>

namespace grpc {

// Common interface for all client side streaming.
class ClientStreamingInterface {
 public:
  virtual ~ClientStreamingInterface() {}

  // Wait until the stream finishes, and return the final status. When the
  // client side declares it has no more message to send, either implicitly or
  // by calling WritesDone, it needs to make sure there is no more message to
  // be received from the server, either implicitly or by getting a false from
  // a Read(). Otherwise, this implicitly cancels the stream.
  virtual Status Finish() = 0;
};

// An interface that yields a sequence of R messages.
template <class R>
class ReaderInterface {
 public:
  virtual ~ReaderInterface() {}

  // Blocking read a message and parse to msg. Returns true on success.
  // The method returns false when there will be no more incoming messages,
  // either because the other side has called WritesDone or the stream has
  // failed (or been cancelled).
  virtual bool Read(R* msg) = 0;
};

// An interface that can be fed a sequence of W messages.
template <class W>
class WriterInterface {
 public:
  virtual ~WriterInterface() {}

  // Blocking write msg to the stream. Returns true on success.
  // Returns false when the stream has been closed.
  virtual bool Write(const W& msg) = 0;
};

template <class R>
class ClientReader final : public ClientStreamingInterface,
                           public ReaderInterface<R> {
 public:
  // Blocking create a stream and write the first request out.
  explicit ClientReader(ChannelInterface *channel, const RpcMethod &method,
                        ClientContext *context,
                        const google::protobuf::Message &request)
      : call_(channel->CreateCall(method, context, &cq_)) {
    CallOpBuffer buf;
    buf.AddSendMessage(request);
    buf.AddClientSendClose();
    call_.PerformOps(&buf, (void *)1);
    cq_.Pluck((void *)1);
  }

  virtual bool Read(R *msg) {
    CallOpBuffer buf;
    buf.AddRecvMessage(msg);
    call_.PerformOps(&buf, (void *)2);
    return cq_.Pluck((void *)2);
  }

  virtual Status Finish() override {
    CallOpBuffer buf;
    Status status;
    buf.AddClientRecvStatus(&status);
    call_.PerformOps(&buf, (void *)3);
    GPR_ASSERT(cq_.Pluck((void *)3));
    return status;
  }

 private:
  CompletionQueue cq_;
  Call call_;
};

template <class W>
class ClientWriter final : public ClientStreamingInterface,
                           public WriterInterface<W> {
 public:
  // Blocking create a stream.
  explicit ClientWriter(ChannelInterface *channel, const RpcMethod &method,
                        ClientContext *context,
                        google::protobuf::Message *response)
      : response_(response),
        call_(channel->CreateCall(method, context, &cq_)) {}

  virtual bool Write(const W& msg) {
    CallOpBuffer buf;
    buf.AddSendMessage(msg);
    call_.PerformOps(&buf, (void *)2);
    return cq_.Pluck((void *)2);
  }

  virtual bool WritesDone() {
    CallOpBuffer buf;
    buf.AddClientSendClose();
    call_.PerformOps(&buf, (void *)3);
    return cq_.Pluck((void *)3);
  }

  // Read the final response and wait for the final status.
  virtual Status Finish() override {
    CallOpBuffer buf;
    Status status;
    buf.AddClientRecvStatus(&status);
    call_.PerformOps(&buf, (void *)4);
    GPR_ASSERT(cq_.Pluck((void *)4));
    return status;
  }

 private:
  google::protobuf::Message *const response_;
  CompletionQueue cq_;
  Call call_;
};

// Client-side interface for bi-directional streaming.
template <class W, class R>
class ClientReaderWriter final : public ClientStreamingInterface,
                                 public WriterInterface<W>,
                                 public ReaderInterface<R> {
 public:
  // Blocking create a stream.
  explicit ClientReaderWriter(ChannelInterface *channel,
                              const RpcMethod &method, ClientContext *context)
      : call_(channel->CreateCall(method, context, &cq_)) {}

  virtual bool Read(R *msg) {
    CallOpBuffer buf;
    buf.AddRecvMessage(msg);
    call_.PerformOps(&buf, (void *)2);
    return cq_.Pluck((void *)2);
  }

  virtual bool Write(const W& msg) {
    CallOpBuffer buf;
    buf.AddSendMessage(msg);
    call_.PerformOps(&buf, (void *)3);
    return cq_.Pluck((void *)3);
  }

  virtual bool WritesDone() {
    CallOpBuffer buf;
    buf.AddClientSendClose();
    call_.PerformOps(&buf, (void *)4);
    return cq_.Pluck((void *)4);
  }

  virtual Status Finish() override {
    CallOpBuffer buf;
    Status status;
    buf.AddClientRecvStatus(&status);
    call_.PerformOps(&buf, (void *)5);
    GPR_ASSERT(cq_.Pluck((void *)5));
    return status;
  }

 private:
  CompletionQueue cq_;
  Call call_;
};

template <class R>
class ServerReader : public ReaderInterface<R> {
 public:
  explicit ServerReader(StreamContextInterface* context) : context_(context) {
    GPR_ASSERT(context_);
    context_->Start(true);
  }

  virtual bool Read(R* msg) { return context_->Read(msg); }

 private:
  StreamContextInterface* const context_;  // not owned
};

template <class W>
class ServerWriter : public WriterInterface<W> {
 public:
  explicit ServerWriter(StreamContextInterface* context) : context_(context) {
    GPR_ASSERT(context_);
    context_->Start(true);
    context_->Read(context_->request());
  }

  virtual bool Write(const W& msg) {
    return context_->Write(const_cast<W*>(&msg), false);
  }

 private:
  StreamContextInterface* const context_;  // not owned
};

// Server-side interface for bi-directional streaming.
template <class W, class R>
class ServerReaderWriter : public WriterInterface<W>,
                           public ReaderInterface<R> {
 public:
  explicit ServerReaderWriter(StreamContextInterface* context)
      : context_(context) {
    GPR_ASSERT(context_);
    context_->Start(true);
  }

  virtual bool Read(R* msg) { return context_->Read(msg); }

  virtual bool Write(const W& msg) {
    return context_->Write(const_cast<W*>(&msg), false);
  }

 private:
  StreamContextInterface* const context_;  // not owned
};

template <class W>
class ServerAsyncResponseWriter {
 public:
  explicit ServerAsyncResponseWriter(StreamContextInterface* context) : context_(context) {
    GPR_ASSERT(context_);
    context_->Start(true);
    context_->Read(context_->request());
  }

  virtual bool Write(const W& msg) {
    return context_->Write(const_cast<W*>(&msg), false);
  }

 private:
  StreamContextInterface* const context_;  // not owned
};

template <class R>
class ServerAsyncReader : public ReaderInterface<R> {
 public:
  explicit ServerAsyncReader(StreamContextInterface* context) : context_(context) {
    GPR_ASSERT(context_);
    context_->Start(true);
  }

  virtual bool Read(R* msg) { return context_->Read(msg); }

 private:
  StreamContextInterface* const context_;  // not owned
};

template <class W>
class ServerAsyncWriter : public WriterInterface<W> {
 public:
  explicit ServerAsyncWriter(StreamContextInterface* context) : context_(context) {
    GPR_ASSERT(context_);
    context_->Start(true);
    context_->Read(context_->request());
  }

  virtual bool Write(const W& msg) {
    return context_->Write(const_cast<W*>(&msg), false);
  }

 private:
  StreamContextInterface* const context_;  // not owned
};

// Server-side interface for bi-directional streaming.
template <class W, class R>
class ServerAsyncReaderWriter : public WriterInterface<W>,
                           public ReaderInterface<R> {
 public:
  explicit ServerAsyncReaderWriter(StreamContextInterface* context)
      : context_(context) {
    GPR_ASSERT(context_);
    context_->Start(true);
  }

  virtual bool Read(R* msg) { return context_->Read(msg); }

  virtual bool Write(const W& msg) {
    return context_->Write(const_cast<W*>(&msg), false);
  }

 private:
  StreamContextInterface* const context_;  // not owned
};

}  // namespace grpc

#endif  // __GRPCPP_STREAM_H__