chromium/third_party/grpc/src/include/grpcpp/support/interceptor.h

//
//
// Copyright 2015 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.
//
//

#ifndef GRPCPP_SUPPORT_INTERCEPTOR_H
#define GRPCPP_SUPPORT_INTERCEPTOR_H

#include <map>
#include <memory>
#include <string>

#include <grpc/impl/grpc_types.h>
#include <grpcpp/impl/metadata_map.h>
#include <grpcpp/support/byte_buffer.h>
#include <grpcpp/support/config.h>
#include <grpcpp/support/string_ref.h>

namespace grpc {

class ChannelInterface;
class Status;

namespace experimental {

/// An enumeration of different possible points at which the \a Intercept
/// method of the \a Interceptor interface may be called. Any given call
/// to \a Intercept will include one or more of these hook points, and
/// each hook point makes certain types of information available to the
/// interceptor.
/// In these enumeration names, PRE_SEND means that an interception has taken
/// place between the time the application provided a certain type of data
/// (e.g., initial metadata, status) and the time that that data goes to the
/// other side. POST_SEND means that the data has been committed for going to
/// the other side (even if it has not yet been received at the other side).
/// PRE_RECV means an interception between the time that a certain
/// operation has been requested and it is available. POST_RECV means that a
/// result is available but has not yet been passed back to the application.
/// A batch of interception points will only contain either PRE or POST hooks
/// but not both types. For example, a batch with PRE_SEND hook points will not
/// contain POST_RECV or POST_SEND ops. Likewise, a batch with POST_* ops can
/// not contain PRE_* ops.
enum class InterceptionHookPoints { … };

/// Class that is passed as an argument to the \a Intercept method
/// of the application's \a Interceptor interface implementation. It has five
/// purposes:
///   1. Indicate which hook points are present at a specific interception
///   2. Allow an interceptor to inform the library that an RPC should
///      continue to the next stage of its processing (which may be another
///      interceptor or the main path of the library)
///   3. Allow an interceptor to hijack the processing of the RPC (only for
///      client-side RPCs with PRE_SEND_INITIAL_METADATA) so that it does not
///      proceed with normal processing beyond that stage
///   4. Access the relevant fields of an RPC at each interception point
///   5. Set some fields of an RPC at each interception point, when possible
class InterceptorBatchMethods { … };

/// Interface for an interceptor. Interceptor authors must create a class
/// that derives from this parent class.
class Interceptor { … };

}  // namespace experimental
}  // namespace grpc

#endif  // GRPCPP_SUPPORT_INTERCEPTOR_H