THUAI6/CAPI/cpp/grpc/include/grpcpp/support/channel_arguments.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_CHANNEL_ARGUMENTS_H
#define GRPCPP_SUPPORT_CHANNEL_ARGUMENTS_H

#include <list>
#include <vector>

#include <grpc/compression.h>
#include <grpc/grpc.h>
#include <grpcpp/resource_quota.h>
#include <grpcpp/support/config.h>

namespace grpc
{
    class SecureChannelCredentials;
    namespace testing
    {
        class ChannelArgumentsTest;
    }  // namespace testing

    /// Options for channel creation. The user can use generic setters to pass
    /// key value pairs down to C channel creation code. For gRPC related options,
    /// concrete setters are provided.
    class ChannelArguments
    {
    public:
        ChannelArguments();
        ~ChannelArguments();

        ChannelArguments(const ChannelArguments& other);
        ChannelArguments& operator=(ChannelArguments other)
        {
            Swap(other);
            return *this;
        }

        void Swap(ChannelArguments& other);

        /// Dump arguments in this instance to \a channel_args. Does not take
        /// ownership of \a channel_args.
        ///
        /// Note that the underlying arguments are shared. Changes made to either \a
        /// channel_args or this instance would be reflected on both.
        void SetChannelArgs(grpc_channel_args* channel_args) const;

        // gRPC specific channel argument setters
        /// Set target name override for SSL host name checking. This option should
        /// be used with caution in production.
        void SetSslTargetNameOverride(const std::string& name);
        // TODO(yangg) add flow control options
        /// Set the compression algorithm for the channel.
        void SetCompressionAlgorithm(grpc_compression_algorithm algorithm);

        /// Set the grpclb fallback timeout (in ms) for the channel. If this amount
        /// of time has passed but we have not gotten any non-empty \a serverlist from
        /// the balancer, we will fall back to use the backend address(es) returned by
        /// the resolver.
        void SetGrpclbFallbackTimeout(int fallback_timeout);

        /// Set a mutator for the underlying socket.
        void SetSocketMutator(grpc_socket_mutator* mutator);

        /// Set the string to prepend to the user agent.
        void SetUserAgentPrefix(const std::string& user_agent_prefix);

        /// Set the buffer pool to be attached to the constructed channel.
        void SetResourceQuota(const grpc::ResourceQuota& resource_quota);

        /// Set the max receive and send message sizes.
        void SetMaxReceiveMessageSize(int size);
        void SetMaxSendMessageSize(int size);

        /// Set LB policy name.
        /// Note that if the name resolver returns only balancer addresses, the
        /// grpclb LB policy will be used, regardless of what is specified here.
        void SetLoadBalancingPolicyName(const std::string& lb_policy_name);

        /// Set service config in JSON form.
        /// Primarily meant for use in unit tests.
        void SetServiceConfigJSON(const std::string& service_config_json);

        // Generic channel argument setter. Only for advanced use cases.
        /// Set an integer argument \a value under \a key.
        void SetInt(const std::string& key, int value);

        // Generic channel argument setter. Only for advanced use cases.
        /// Set a pointer argument \a value under \a key. Ownership is not
        /// transferred.
        void SetPointer(const std::string& key, void* value);

        /// Set a pointer argument \a value under \a key, transferring ownership of
        /// \a value to the \a ChannelArguments object. The \a vtable::Delete function
        /// is responsible for \a value cleanup/destruction when called.
        void SetPointerWithVtable(const std::string& key, void* value, const grpc_arg_pointer_vtable* vtable);

        /// Set a textual argument \a value under \a key.
        void SetString(const std::string& key, const std::string& value);

        /// Return (by value) a C \a grpc_channel_args structure which points to
        /// arguments owned by this \a ChannelArguments instance
        grpc_channel_args c_channel_args() const
        {
            grpc_channel_args out;
            out.num_args = args_.size();
            out.args = args_.empty() ? nullptr : const_cast<grpc_arg*>(&args_[0]);
            return out;
        }

    private:
        friend class grpc::SecureChannelCredentials;
        friend class grpc::testing::ChannelArgumentsTest;

        /// Default pointer argument operations.
        struct PointerVtableMembers
        {
            static void* Copy(void* in)
            {
                return in;
            }
            static void Destroy(void* /*in*/)
            {
            }
            static int Compare(void* a, void* b)
            {
                if (a < b)
                    return -1;
                if (a > b)
                    return 1;
                return 0;
            }
        };

        // Returns empty string when it is not set.
        std::string GetSslTargetNameOverride() const;

        std::vector<grpc_arg> args_;
        std::list<std::string> strings_;
    };

}  // namespace grpc

#endif  // GRPCPP_SUPPORT_CHANNEL_ARGUMENTS_H