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//
//
// Copyright 2016 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 GRPC_SRC_CORE_LIB_SURFACE_CHANNEL_INIT_H
#define GRPC_SRC_CORE_LIB_SURFACE_CHANNEL_INIT_H
#include <grpc/support/port_platform.h>
#include <utility>
#include <vector>
#include "absl/functional/any_invocable.h"
#include "src/core/lib/channel/channel_stack_builder.h"
#include "src/core/lib/surface/channel_stack_type.h"
#define GRPC_CHANNEL_INIT_BUILTIN_PRIORITY 10000
/// This module provides a way for plugins (and the grpc core library itself)
/// to register mutators for channel stacks.
/// It also provides a universal entry path to run those mutators to build
/// a channel stack for various subsystems.
namespace grpc_core {
class ChannelInit {
public:
/// One stage of mutation: call functions against \a builder to influence the
/// finally constructed channel stack
using Stage = absl::AnyInvocable<bool(ChannelStackBuilder* builder) const>;
class Builder {
public:
/// Register one stage of mutators.
/// Stages are run in priority order (lowest to highest), and then in
/// registration order (in the case of a tie).
/// Stages are registered against one of the pre-determined channel stack
/// types.
/// If the channel stack type is GRPC_CLIENT_SUBCHANNEL, the caller should
/// ensure that subchannels with different filter lists will always have
/// different channel args. This requires setting a channel arg in case the
/// registration function relies on some condition other than channel args
/// to decide whether to add a filter or not.
void RegisterStage(grpc_channel_stack_type type, int priority, Stage stage);
/// Finalize registration. No more calls to grpc_channel_init_register_stage
/// are allowed.
ChannelInit Build();
private:
struct Slot {
Slot(Stage stage, int priority)
: stage(std::move(stage)), priority(priority) {}
Stage stage;
int priority;
};
std::vector<Slot> slots_[GRPC_NUM_CHANNEL_STACK_TYPES];
};
/// Construct a channel stack of some sort: see channel_stack.h for details
/// \a builder is the channel stack builder to build into.
bool CreateStack(ChannelStackBuilder* builder) const;
private:
std::vector<Stage> slots_[GRPC_NUM_CHANNEL_STACK_TYPES];
};
} // namespace grpc_core
#endif // GRPC_SRC_CORE_LIB_SURFACE_CHANNEL_INIT_H
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