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[PATCHv2] package/grpc: restrict host-grpc to the absolute minimum

Message ID 20210525182044.13785-1-patrickdepinguin@gmail.com
State New
Headers show
Series [PATCHv2] package/grpc: restrict host-grpc to the absolute minimum | expand

Commit Message

Thomas De Schampheleire May 25, 2021, 6:20 p.m. UTC
From: Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>

Currently, grpc depends on the full host-grpc, which in turn depends on host
versions of many other libraries. One of these, host-libabseil-cpp, also
requires a host gcc 4.9 or larger, a dependency which is not met on CentOS
7.
But in fact, the target grpc only needs the 'grpc_cpp_plugin' binary from
host-grpc. And that binary does not depend on host-libabseil-cpp or other
libraries, only on host-protobuf.

Given the above, simplify the grpc/host-grpc situation.
- Add a patch to the (host-)grpc CMakeLists.txt file to add an option to
  only build grpc_cpp_plugin.
- Update grpc.mk and Config.in to remove the unnecessary dependencies, and
  change the host-grpc configure options to make cmake happy.

The advantages of these changes are:
- making grpc available to older hosts with gcc < 4.8, like CentOS 7
- significantly reducing the build time of host-grpc and its dependencies

The patch was proposed upstream but not accepted with below rationale.
Perhaps input from others can help in persuading upstream in a future
attempt.

    'What you're doing sounds like quite a narrow use case. But we simply
    cannot provide a cmake option for every possible scenario in the world.
    Introducing a new cmake option isn't for free and requires careful
    design and maintenance.'

Nevertheless, given the benefits in terms of build time and dependency
reduction, it makes sense to apply this patch in spite of the disadvantage
of a local non-upstreamed patch.

Signed-off-by: Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>
---

v2: fix typo in Config.in comment (Baruch Siach)


 .../grpc/0004-host-grpc-only-cpp-plugin.patch | 223 ++++++++++++++++++
 package/grpc/Config.in                        |   6 +-
 package/grpc/grpc.mk                          |  27 ++-
 3 files changed, 244 insertions(+), 12 deletions(-)
 create mode 100644 package/grpc/0004-host-grpc-only-cpp-plugin.patch
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Patch

diff --git a/package/grpc/0004-host-grpc-only-cpp-plugin.patch b/package/grpc/0004-host-grpc-only-cpp-plugin.patch
new file mode 100644
index 0000000000..43fad7e3d6
--- /dev/null
+++ b/package/grpc/0004-host-grpc-only-cpp-plugin.patch
@@ -0,0 +1,223 @@ 
+From a1922eadfc87da3dd221ff631f94ddd4a8ee7049 Mon Sep 17 00:00:00 2001
+From: Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>
+Date: Tue, 25 May 2021 14:55:23 +0200
+Subject: [PATCH] Add option to restrict building of (host-)grpc to
+ grpc_cpp_plugin only.
+
+This avoids unnecessary dependencies on big packages like libabseil-cpp and
+others.
+
+Upstream-status: not accepted (see https://github.com/grpc/grpc/issues/25322)
+
+Signed-off-by: Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>
+---
+ CMakeLists.txt | 43 +++++++++++++++++++++++++++++++++++--------
+ 1 file changed, 35 insertions(+), 8 deletions(-)
+
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index e8934a3e03..c2df332cc6 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -48,12 +48,16 @@ option(gRPC_BUILD_TESTS "Build tests" OFF)
+ option(gRPC_BUILD_CODEGEN "Build codegen" ON)
+ option(gRPC_BUILD_CSHARP_EXT "Build C# extensions" ON)
+ option(gRPC_BACKWARDS_COMPATIBILITY_MODE "Build libraries that are binary compatible across a larger number of OS and libc versions" OFF)
++option(gRPC_BUILD_PLUGIN_SUPPORT_ONLY "Build plugin support only" OFF)
+ 
+ set(gRPC_INSTALL_default ON)
+ if(NOT CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
+   # Disable gRPC_INSTALL by default if building as a submodule
+   set(gRPC_INSTALL_default OFF)
+ endif()
++if(gRPC_BUILD_PLUGIN_SUPPORT_ONLY)
++  set(gRPC_INSTALL_default OFF)
++endif()
+ set(gRPC_INSTALL ${gRPC_INSTALL_default} CACHE BOOL
+     "Generate installation target")
+ 
+@@ -367,6 +371,8 @@ add_custom_target(plugins
+   DEPENDS ${_gRPC_PLUGIN_LIST}
+ )
+ 
++if (NOT gRPC_BUILD_PLUGIN_SUPPORT_ONLY)
++
+ add_custom_target(tools_c
+   DEPENDS
+   check_epollexclusive
+@@ -382,6 +388,8 @@ add_custom_target(tools_cxx
+ add_custom_target(tools
+   DEPENDS tools_c tools_cxx)
+ 
++endif() # gRPC_BUILD_PLUGIN_SUPPORT_ONLY
++
+ protobuf_generate_grpc_cpp(
+   src/proto/grpc/channelz/channelz.proto
+ )
+@@ -1000,6 +1008,7 @@ if(gRPC_BUILD_TESTS)
+     DEPENDS buildtests_c buildtests_cxx)
+ endif()
+ 
++if (NOT gRPC_BUILD_PLUGIN_SUPPORT_ONLY)
+ 
+ add_library(address_sorting
+   third_party/address_sorting/address_sorting.c
+@@ -1051,6 +1060,8 @@ if(gRPC_INSTALL)
+   )
+ endif()
+ 
++endif() # gRPC_BUILD_PLUGIN_SUPPORT_ONLY
++
+ if(gRPC_BUILD_TESTS)
+ 
+ add_library(end2end_nosec_tests
+@@ -1313,6 +1324,8 @@ target_link_libraries(end2end_tests
+ 
+ endif()
+ 
++if(NOT gRPC_BUILD_PLUGIN_SUPPORT_ONLY)
++
+ add_library(gpr
+   src/core/lib/gpr/alloc.cc
+   src/core/lib/gpr/atm.cc
+@@ -2106,6 +2119,8 @@ if(gRPC_INSTALL)
+   )
+ endif()
+ 
++endif() # gRPC_BUILD_PLUGIN_SUPPORT_ONLY
++
+ if(gRPC_BUILD_CSHARP_EXT)
+ 
+ add_library(grpc_csharp_ext SHARED
+@@ -2288,6 +2303,8 @@ endif()
+ 
+ endif()
+ 
++if(NOT gRPC_BUILD_PLUGIN_SUPPORT_ONLY)
++
+ add_library(grpc_unsecure
+   src/core/ext/filters/census/grpc_context.cc
+   src/core/ext/filters/client_channel/backend_metric.cc
+@@ -2650,6 +2667,8 @@ if(gRPC_INSTALL)
+   )
+ endif()
+ 
++endif() # gRPC_BUILD_PLUGIN_SUPPORT_ONLY
++
+ if(gRPC_BUILD_TESTS)
+ 
+ if(gRPC_BUILD_CODEGEN)
+@@ -2717,6 +2736,8 @@ endif()
+ 
+ endif()
+ 
++if(NOT gRPC_BUILD_PLUGIN_SUPPORT_ONLY)
++
+ add_library(grpc++
+   src/cpp/client/channel_cc.cc
+   src/cpp/client/client_callback.cc
+@@ -3134,6 +3155,7 @@ if(gRPC_INSTALL)
+   )
+ endif()
+ 
++endif() # gRPC_BUILD_PLUGIN_SUPPORT_ONLY
+ 
+ if(gRPC_BUILD_CODEGEN)
+ add_library(grpc++_reflection
+@@ -3374,6 +3396,8 @@ target_link_libraries(grpc++_test_util
+ 
+ endif()
+ 
++if(NOT gRPC_BUILD_PLUGIN_SUPPORT_ONLY)
++
+ add_library(grpc++_unsecure
+   src/cpp/client/channel_cc.cc
+   src/cpp/client/client_callback.cc
+@@ -3656,6 +3680,7 @@ if(gRPC_INSTALL)
+   )
+ endif()
+ 
++endif() # gRPC_BUILD_PLUGIN_SUPPORT_ONLY
+ 
+ add_library(grpc_plugin_support
+   src/compiler/cpp_generator.cc
+@@ -3715,7 +3740,7 @@ foreach(_hdr
+ endforeach()
+ 
+ 
+-if(gRPC_INSTALL)
++if(gRPC_INSTALL OR gRPC_BUILD_PLUGIN_SUPPORT_ONLY)
+   install(TARGETS grpc_plugin_support EXPORT gRPCTargets
+     RUNTIME DESTINATION ${gRPC_INSTALL_BINDIR}
+     LIBRARY DESTINATION ${gRPC_INSTALL_LIBDIR}
+@@ -3795,6 +3820,8 @@ endif()
+ 
+ endif()
+ 
++if(NOT gRPC_BUILD_PLUGIN_SUPPORT_ONLY)
++
+ add_library(upb
+   third_party/upb/upb/decode_fast.c
+   third_party/upb/upb/decode.c
+@@ -3852,8 +3879,6 @@ if(gRPC_INSTALL)
+   )
+ endif()
+ 
+-
+-
+ add_executable(check_epollexclusive
+   test/build/check_epollexclusive.c
+ )
+@@ -3906,8 +3931,6 @@ target_link_libraries(gen_hpack_tables
+   gpr
+ )
+ 
+-
+-
+ add_executable(gen_legal_metadata_characters
+   tools/codegen/core/gen_legal_metadata_characters.cc
+ )
+@@ -3958,6 +3981,8 @@ target_link_libraries(gen_percent_encoding_tables
+   ${_gRPC_ALLTARGETS_LIBRARIES}
+ )
+ 
++endif() # gRPC_BUILD_PLUGIN_SUPPORT_ONLY
++
+ 
+ if(gRPC_BUILD_TESTS)
+ 
+@@ -10722,7 +10747,7 @@ target_link_libraries(grpc_cli
+ 
+ 
+ endif()
+-if(gRPC_BUILD_CODEGEN AND gRPC_BUILD_GRPC_CPP_PLUGIN)
++if(gRPC_BUILD_GRPC_CPP_PLUGIN)
+ 
+ add_executable(grpc_cpp_plugin
+   src/compiler/cpp_plugin.cc
+@@ -10752,7 +10777,7 @@ target_link_libraries(grpc_cpp_plugin
+ 
+ 
+ 
+-if(gRPC_INSTALL)
++if(gRPC_INSTALL OR gRPC_BUILD_PLUGIN_SUPPORT_ONLY)
+   install(TARGETS grpc_cpp_plugin EXPORT gRPCTargets
+     RUNTIME DESTINATION ${gRPC_INSTALL_BINDIR}
+     LIBRARY DESTINATION ${gRPC_INSTALL_LIBDIR}
+@@ -15420,7 +15445,7 @@ endif()
+ 
+ 
+ 
+-
++if (NOT gRPC_BUILD_PLUGIN_SUPPORT_ONLY)
+ 
+ if(gRPC_INSTALL)
+   install(EXPORT gRPCTargets
+@@ -15517,3 +15542,5 @@ generate_pkgconfig(
+   "-lgrpc++_unsecure -labsl_statusor -labsl_status -labsl_raw_hash_set -labsl_hashtablez_sampler -labsl_synchronization -labsl_time -labsl_time_zone -labsl_civil_time -labsl_graphcycles_internal -labsl_symbolize -labsl_demangle_internal -labsl_malloc_internal -labsl_stacktrace -labsl_debugging_internal -labsl_exponential_biased -labsl_cord -labsl_str_format_internal -labsl_hash -labsl_bad_variant_access -labsl_bad_optional_access -labsl_strings -labsl_strings_internal -labsl_base -labsl_spinlock_wait -labsl_int128 -labsl_city -labsl_throw_delegate -labsl_raw_logging_internal -labsl_log_severity"
+   ""
+   "grpc++_unsecure.pc")
++
++endif() # gRPC_BUILD_PLUGIN_SUPPORT_ONLY
+-- 
+2.26.3
+
diff --git a/package/grpc/Config.in b/package/grpc/Config.in
index d1bf0d078d..ad3ddbcf19 100644
--- a/package/grpc/Config.in
+++ b/package/grpc/Config.in
@@ -4,7 +4,6 @@  config BR2_PACKAGE_GRPC
 	depends on BR2_TOOLCHAIN_HAS_THREADS # protobuf, re2
 	depends on BR2_PACKAGE_PROTOBUF_ARCH_SUPPORTS # protobuf
 	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_9 # protobuf, re2, libabseil-cpp
-	depends on BR2_HOST_GCC_AT_LEAST_4_9 # host-libabseil-cpp
 	depends on !BR2_STATIC_LIBS # protobuf, libabseil-cpp
 	depends on BR2_TOOLCHAIN_HAS_SYNC_4 || BR2_TOOLCHAIN_HAS_ATOMIC
 	depends on BR2_PACKAGE_LIBABSEIL_CPP_ARCH_SUPPORTS
@@ -20,10 +19,9 @@  config BR2_PACKAGE_GRPC
 
 	  http://github.com/grpc/grpc
 
-comment "grpc needs a toolchain w/ C++, threads, dynamic library, gcc >= 4.9, host gcc >= 4.9"
+comment "grpc needs a toolchain w/ C++, threads, dynamic library, gcc >= 4.9"
 	depends on BR2_PACKAGE_LIBABSEIL_CPP_ARCH_SUPPORTS
 	depends on BR2_TOOLCHAIN_HAS_SYNC_4 || BR2_TOOLCHAIN_HAS_ATOMIC
 	depends on !BR2_INSTALL_LIBSTDCPP || !BR2_TOOLCHAIN_HAS_THREADS \
-		|| BR2_STATIC_LIBS || !BR2_TOOLCHAIN_GCC_AT_LEAST_4_9 \
-		|| !BR2_HOST_GCC_AT_LEAST_4_9
+		|| BR2_STATIC_LIBS || !BR2_TOOLCHAIN_GCC_AT_LEAST_4_9
 	depends on BR2_PACKAGE_PROTOBUF_ARCH_SUPPORTS
diff --git a/package/grpc/grpc.mk b/package/grpc/grpc.mk
index ee8dc38e70..8718b0e956 100644
--- a/package/grpc/grpc.mk
+++ b/package/grpc/grpc.mk
@@ -14,8 +14,7 @@  GRPC_INSTALL_STAGING = YES
 
 # Need to use host grpc_cpp_plugin during cross compilation.
 GRPC_DEPENDENCIES = c-ares host-grpc libabseil-cpp openssl protobuf re2 zlib
-HOST_GRPC_DEPENDENCIES = host-c-ares host-libabseil-cpp host-openssl host-protobuf \
-	host-re2 host-zlib
+HOST_GRPC_DEPENDENCIES = host-protobuf
 
 # gRPC_CARES_PROVIDER=package won't work because it requires c-ares to have
 # installed a cmake config file, but buildroot uses c-ares' autotools build,
@@ -70,14 +69,26 @@  GRPC_CONF_OPTS += \
 	-DCMAKE_C_FLAGS="$(GRPC_CFLAGS)" \
 	-DCMAKE_CXX_FLAGS="$(GRPC_CXXFLAGS)"
 
+# For host-grpc, we only need the 'grpc_cpp_plugin' binary, which is needed for
+# target grpc compilation. To avoid unnecessary build steps and host
+# dependencies, supply enough options to pass the configure checks without
+# requiring other host packages, unless those needed by grpc_cpp_plugin.
 HOST_GRPC_CONF_OPTS = \
-	-DgRPC_ABSL_PROVIDER=package \
-	-D_gRPC_CARES_LIBRARIES=cares \
-	-DgRPC_CARES_PROVIDER=none \
 	-DgRPC_PROTOBUF_PROVIDER=package \
-	-DgRPC_RE2_PROVIDER=package \
-	-DgRPC_SSL_PROVIDER=package \
-	-DgRPC_ZLIB_PROVIDER=package
+	-DgRPC_ABSL_PROVIDER=none \
+	-DgRPC_CARES_PROVIDER=none \
+	-DgRPC_RE2_PROVIDER=none \
+	-DgRPC_SSL_PROVIDER=none \
+	-DgRPC_ZLIB_PROVIDER=none \
+	-DgRPC_BUILD_CODEGEN=OFF \
+	-DgRPC_BUILD_CSHARP_EXT=OFF \
+	-DgRPC_BUILD_PLUGIN_SUPPORT_ONLY=ON \
+	-DgRPC_BUILD_GRPC_CSHARP_PLUGIN=OFF \
+	-DgRPC_BUILD_GRPC_NODE_PLUGIN=OFF \
+	-DgRPC_BUILD_GRPC_OBJECTIVE_C_PLUGIN=OFF \
+	-DgRPC_BUILD_GRPC_PHP_PLUGIN=OFF \
+	-DgRPC_BUILD_GRPC_PYTHON_PLUGIN=OFF \
+	-DgRPC_BUILD_GRPC_RUBY_PLUGIN=OFF
 
 $(eval $(cmake-package))
 $(eval $(host-cmake-package))