Question

如果我想在cmake中重新创建以下protoc命令：

protoc -I ../proto/ --cpp_out=. service.proto

我在cmake中使用以下行：

file(GLOB ProtoFiles "${CMAKE_CURRENT_SOURCE_DIR}/*.proto")
PROTOBUF_GENERATE_CPP(ProtoSources ProtoHeaders ${ProtoFiles})

如果我想重新创建下面的protoc命令：

protoc -I ../proto/ --grpc_out=. --plugin=protoc-gen-grpc=`which grpc_cpp_plugin` service.proto

在上述情况下，我无法确定如何更改cmake文件，请帮忙！

问题是如何解决：

--plugin=EXECUTABLE           Specifies a plugin executable to use.
                              Normally, protoc searches the PATH for
                              plugins, but you may specify additional
                              executables not in the path using this flag.
                              Additionally, EXECUTABLE may be of the form
                              NAME=PATH, in which case the given plugin name
                              is mapped to the given executable even if
                              the executable's own name differs.

我一直在阅读 PROTOBUF_GENERATE_CPP 文档，但未找到答案！

Answer 1

模块findProtobuf.cmake仅为常见的protoc调用定义函数包装：PROTOBUF_GENERATE_CPP - 用于--cpp_out和PROTOBUF_GENERATE_PYTHON - 用于--py_out。但是你可以为所需的插件实现自己的函数包装器。以下代码基于PROTOBUF_GENERATE_CPP实施。

find_program(GRPC_CPP_PLUGIN grpc_cpp_plugin) # Get full path to plugin

function(PROTOBUF_GENERATE_GRPC_CPP SRCS HDRS)
  if(NOT ARGN)
    message(SEND_ERROR "Error: PROTOBUF_GENERATE_GRPC_CPP() called without any proto files")
    return()
  endif()

  if(PROTOBUF_GENERATE_CPP_APPEND_PATH) # This variable is common for all types of output.
    # Create an include path for each file specified
    foreach(FIL ${ARGN})
      get_filename_component(ABS_FIL ${FIL} ABSOLUTE)
      get_filename_component(ABS_PATH ${ABS_FIL} PATH)
      list(FIND _protobuf_include_path ${ABS_PATH} _contains_already)
      if(${_contains_already} EQUAL -1)
          list(APPEND _protobuf_include_path -I ${ABS_PATH})
      endif()
    endforeach()
  else()
    set(_protobuf_include_path -I ${CMAKE_CURRENT_SOURCE_DIR})
  endif()

  if(DEFINED PROTOBUF_IMPORT_DIRS)
    foreach(DIR ${Protobuf_IMPORT_DIRS})
      get_filename_component(ABS_PATH ${DIR} ABSOLUTE)
      list(FIND _protobuf_include_path ${ABS_PATH} _contains_already)
      if(${_contains_already} EQUAL -1)
          list(APPEND _protobuf_include_path -I ${ABS_PATH})
      endif()
    endforeach()
  endif()

  set(${SRCS})
  set(${HDRS})
  foreach(FIL ${ARGN})
    get_filename_component(ABS_FIL ${FIL} ABSOLUTE)
    get_filename_component(FIL_WE ${FIL} NAME_WE)

    list(APPEND ${SRCS} "${CMAKE_CURRENT_BINARY_DIR}/${FIL_WE}.grpc.pb.cc")
    list(APPEND ${HDRS} "${CMAKE_CURRENT_BINARY_DIR}/${FIL_WE}.grpc.pb.h")

    add_custom_command(
      OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/${FIL_WE}.grpc.pb.cc"
             "${CMAKE_CURRENT_BINARY_DIR}/${FIL_WE}.grpc.pb.h"
      COMMAND  ${Protobuf_PROTOC_EXECUTABLE}
      ARGS --grpc_out=${CMAKE_CURRENT_BINARY_DIR}
           --plugin=protoc-gen-grpc=${GRPC_CPP_PLUGIN}
           ${_protobuf_include_path} ${ABS_FIL}
      DEPENDS ${ABS_FIL} ${Protobuf_PROTOC_EXECUTABLE}
      COMMENT "Running gRPC C++ protocol buffer compiler on ${FIL}"
      VERBATIM)
  endforeach()

  set_source_files_properties(${${SRCS}} ${${HDRS}} PROPERTIES GENERATED TRUE)
  set(${SRCS} ${${SRCS}} PARENT_SCOPE)
  set(${HDRS} ${${HDRS}} PARENT_SCOPE)
endfunction()

用法与PROTOBUF_GENERATE_CPP相同：

file(GLOB ProtoFiles "${CMAKE_CURRENT_SOURCE_DIR}/*.proto")
PROTOBUF_GENERATE_GRPC_CPP(ProtoGRPCSources ProtoGRPCHeaders ${ProtoFiles})

Answer 2

从版本3.12开始，protobuf_generate支持PLUGIN参数

https://github.com/protocolbuffers/protobuf/blob/v3.12.0/cmake/protobuf-config.cmake.in#L46

因此您可以尝试一些方法： PROTOBUF_GENERATE_CPP(ProtoSources ProtoHeaders ${ProtoFiles} PLUGIN protoc-gen-grpc=${GRPC_CPP_PLUGIN_PATH})

Answer 3

对我来说，博文 https://www.falkoaxmann.de/dev/2020/11/08/grpc-plugin-cmake-support.html 导致成功，因为它提供了一个完整的例子（感谢 @powerpete）。

我把代码放在这里，所以它可以作为答案而不仅仅是作为评论：

project(my-service VERSION 1.0 LANGUAGES CXX C)

find_package(protobuf CONFIG REQUIRED)
find_package(gRPC CONFIG REQUIRED)
find_package(Threads)

set(PROTO_FILES
    MyService.proto
)

# protobuf source files go into the lib just like any other CPP source file
add_library(my-service ${PROTO_FILES})
target_link_libraries(my-service
    PUBLIC
        protobuf::libprotobuf
        gRPC::grpc
        gRPC::grpc++
)

target_include_directories(my-service
    PUBLIC
        ${CMAKE_CURRENT_BINARY_DIR}
)

get_target_property(grpc_cpp_plugin_location gRPC::grpc_cpp_plugin LOCATION)

# compile the message types
protobuf_generate(TARGET my-service LANGUAGE cpp)

# compile the GRPC services
protobuf_generate(
    TARGET
        my-service
    LANGUAGE
        grpc
    GENERATE_EXTENSIONS
        .grpc.pb.h
        .grpc.pb.cc
    PLUGIN
        "protoc-gen-grpc=${grpc_cpp_plugin_location}"
)

使用cmake创建protobuf / grpc cc文件

3 个答案: