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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_CORE_LIB_CHANNEL_CHANNEL_STACK_BUILDER_H
#define GRPC_CORE_LIB_CHANNEL_CHANNEL_STACK_BUILDER_H
#include <grpc/support/port_platform.h>
#include <string>
#include <vector>
#include "absl/status/statusor.h"
#include "absl/strings/string_view.h"
#include <grpc/support/log.h>
#include "src/core/lib/channel/channel_args.h"
#include "src/core/lib/channel/channel_fwd.h"
#include "src/core/lib/gprpp/ref_counted_ptr.h"
#include "src/core/lib/surface/channel_stack_type.h"
#include "src/core/lib/transport/transport_fwd.h"
namespace grpc_core {
// Build a channel stack.
// Allows interested parties to add filters to the stack, and to query an
// in-progress build.
// Carries some useful context for the channel stack, such as a target string
// and a transport.
class ChannelStackBuilder {
public:
// Initialize with a name.
ChannelStackBuilder(const char* name, grpc_channel_stack_type type)
: name_(name), type_(type) {}
const char* name() const { return name_; }
// Set the target string.
ChannelStackBuilder& SetTarget(const char* target);
// Query the target.
absl::string_view target() const { return target_; }
// Set the transport.
ChannelStackBuilder& SetTransport(grpc_transport* transport) {
GPR_ASSERT(transport_ == nullptr);
transport_ = transport;
return *this;
}
// Query the transport.
grpc_transport* transport() const { return transport_; }
// Set channel args (takes a copy of them).
ChannelStackBuilder& SetChannelArgs(ChannelArgs args);
// Query the channel args.
const ChannelArgs& channel_args() const { return args_; }
// Mutable vector of proposed stack entries.
std::vector<const grpc_channel_filter*>* mutable_stack() { return &stack_; }
// The type of channel stack being built.
grpc_channel_stack_type channel_stack_type() const { return type_; }
// Helper to add a filter to the front of the stack.
void PrependFilter(const grpc_channel_filter* filter);
// Helper to add a filter to the end of the stack.
void AppendFilter(const grpc_channel_filter* filter);
// Build the channel stack.
// After success, *result holds the new channel stack,
// prefix_bytes are allocated before the channel stack,
// destroy is as per grpc_channel_stack_init
// On failure, *result is nullptr.
virtual absl::StatusOr<RefCountedPtr<grpc_channel_stack>> Build() = 0;
protected:
~ChannelStackBuilder();
private:
static std::string unknown_target() { return "unknown"; }
// The name of the stack
const char* const name_;
// The type of stack being built
const grpc_channel_stack_type type_;
// The target
std::string target_{unknown_target()};
// The transport
grpc_transport* transport_ = nullptr;
// Channel args
ChannelArgs args_;
// The in-progress stack
std::vector<const grpc_channel_filter*> stack_;
};
} // namespace grpc_core
#endif // GRPC_CORE_LIB_CHANNEL_CHANNEL_STACK_BUILDER_H