| // 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. |
| ChannelStackBuilder& SetChannelArgs(const 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_; } |
| |
| // Immutable vector of proposed stack entries. |
| const std::vector<const grpc_channel_filter*>& stack() const { |
| 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); |
| |
| // Determine whether a promise-based call stack is able to be built. |
| // Iterates each filter and ensures that there's a promise factory there. |
| // This will go away once the promise conversion is completed. |
| virtual bool IsPromising() const = 0; |
| |
| // 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 |