gRPC C++ 的 Makefile 编写

gRPC 的库有点多，手工编写 Makefile 不简单，它有如下这么多的库和依赖库：

$ ls
cmake                          libabsl_log_severity.a          libabsl_throw_delegate.a  libgrpc.a                  libgrpc_plugin_support.a  libssl.a
libabsl_bad_optional_access.a  libabsl_raw_logging_internal.a  libaddress_sorting.a      libgrpc++.a                libgrpcpp_channelz.a      libupb.a
libabsl_base.a                 libabsl_spinlock_wait.a         libcares.a                libgrpc++_alts.a           libgrpc++_reflection.a    libz.a
libabsl_dynamic_annotations.a  libabsl_strings.a               libcrypto.a               libgrpc_cronet.a           libgrpc_unsecure.a        pkgconfig
libabsl_int128.a               libabsl_strings_internal.a      libgpr.a                  libgrpc++_error_details.a  libgrpc++_unsecure.a

其中，cmake和pkgconfig为目录，如果使用CMake编译则会简单些。以下为一个Makefile示例：

# Protobuf - 必须为 Protobuf3
PROTOBUF_HOME=/usr/local/protobuf
PROTOBUF_INCL=-I${PROTOBUF_HOME}/include
PROTOBUF_LIB=${PROTOBUF_HOME}/lib/libprotobuf.a ${PROTOBUF_HOME}/lib/libprotobuf-lite.a

# gRPC
GRPC_HOME=/usr/local/grpc
GRPC_INCL=-I${GRPC_HOME}/include
ABSL_LIB=${GRPC_HOME}/lib/libabsl_strings.a ${GRPC_HOME}/lib/libabsl_strings_internal.a ${GRPC_HOME}/lib/libabsl_throw_delegate.a ${GRPC_HOME}/lib/libabsl_base.a
GRPC_LIB=${ABSL_LIB} ${GRPC_HOME}/lib/libgpr.a ${GRPC_HOME}/lib/libgrpc++.a ${GRPC_HOME}/lib/libgrpc.a ${GRPC_HOME}/lib/libupb.a ${GRPC_HOME}/lib/libssl.a ${GRPC_HOME}/lib/libcrypto.a ${GRPC_HOME}/lib/libcares.a ${GRPC_HOME}/lib/libaddress_sorting.a

INCLS=${GRPC_INCL} ${PROTOBUF_INCL}
LIBS=-pthread -ldl -lrt -lz -Wl,--start-group ${GRPC_LIB} ${PROTOBUF_LIB} -Wl,--end-group

.PHONY: build
build:
	g++ -std=c++11 -Wno-deprecated-declarations -o test test.cpp ../grpc/common.pb.cc ../grpc/proxy.pb.cc ../grpc/proxy.grpc.pb.cc -I../grpc ${INCLS} $(LIBS)

.PHONY: clean
clean:
	rm -f test

上述的“-Wno-deprecated-declarations”是为消除下列编译警告：

/usr/local/grpc/include/grpcpp/impl/codegen/proto_utils.h:52:32: 警告：不建议使用‘int google::protobuf::MessageLite::ByteSize() const’(声明于 /usr/local/grpc/include/google/protobuf/message_lite.h:402)：Please use ByteSizeLong() instead [-Wdeprecated-declarations]

因为库实在有点多，为避免因为静态库顺序的坑，直接使用了“--start-group”和“--end-group”忽略顺序关系。建议使用CMake或automake编译，以省去处理依赖的麻烦。