MDEV-37463 Avoid libaio/liburing dependencies in mariadb-import

On Linux, mariadb-import may depend on liburing and libaio. To avoid
pulling in these dependencies when tpool is only used as a generic
thread pool (submit_task), introduce a minimalistic variant of the tpool
library, tpool_min.

This variant has no new library dependencies, and exists only on Linux.
Elsewhere, tpool_min is the same as tpool

Author: vaintroub

client/CMakeLists.txt

@@ -64,8 +64,7 @@ TARGET_LINK_LIBRARIES(import_util PRIVATE pcre2-posix pcre2-8)
 TARGET_INCLUDE_DIRECTORIES(import_util PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
 
 MYSQL_ADD_EXECUTABLE(mariadb-import mysqlimport.cc)
-TARGET_INCLUDE_DIRECTORIES(mariadb-import PRIVATE ${CMAKE_SOURCE_DIR}/tpool)
-TARGET_LINK_LIBRARIES(mariadb-import PRIVATE tpool ${CLIENT_LIB} import_util)
+TARGET_LINK_LIBRARIES(mariadb-import PRIVATE tpool_min ${CLIENT_LIB} import_util)
 
 
 MYSQL_ADD_EXECUTABLE(mariadb-upgrade mysql_upgrade.c COMPONENT Server)

tpool/CMakeLists.txt

@@ -1,17 +1,18 @@
-ADD_LIBRARY(tpool STATIC
+
+SET(SOURCES
   aio_simulated.cc
   tpool_structs.h
-  CMakeLists.txt
   tpool.h
   tpool_generic.cc
   task_group.cc
   task.cc
   wait_notification.cc
 )
 
-TARGET_INCLUDE_DIRECTORIES(tpool PUBLIC "${CMAKE_CURRENT_SOURCE_DIR}"
- PRIVATE ${PROJECT_SOURCE_DIR}/include)
+ADD_LIBRARY(tpool OBJECT ${SOURCES})
 
+TARGET_INCLUDE_DIRECTORIES(tpool PUBLIC "${CMAKE_CURRENT_SOURCE_DIR}"
+  ${PROJECT_SOURCE_DIR}/include)
 IF(WIN32)
   TARGET_SOURCES(tpool PRIVATE tpool_win.cc aio_win.cc)
 ELSEIF(CMAKE_SYSTEM_NAME STREQUAL "Linux")
@@ -31,6 +32,7 @@ ELSEIF(CMAKE_SYSTEM_NAME STREQUAL "Linux")
     TARGET_LINK_LIBRARIES(tpool PRIVATE ${URING_LIBRARIES})
     TARGET_INCLUDE_DIRECTORIES(tpool PUBLIC ${URING_INCLUDE_DIRS})
     TARGET_SOURCES(tpool PRIVATE aio_liburing.cc)
+    ADD_DEPENDENCIES(tpool GenError)
     SET(CMAKE_REQUIRED_INCLUDES_SAVE ${CMAKE_REQUIRED_INCLUDES})
     SET(CMAKE_REQUIRED_LIBRARIES_SAVE ${CMAKE_REQUIRED_LIBRARIES})
     SET(CMAKE_REQUIRED_INCLUDES ${URING_INCLUDE_DIRS})
@@ -50,8 +52,17 @@ ELSEIF(CMAKE_SYSTEM_NAME STREQUAL "Linux")
     TARGET_LINK_LIBRARIES(tpool PRIVATE ${LIBAIO_LIBRARIES})
     TARGET_SOURCES(tpool PRIVATE aio_libaio.cc)
   ENDIF()
+
+  IF(LIBAIO_FOUND OR URING_FOUND)
+    # Create a "light" version of the library that does not link
+    # to additional io libs, and is not compiled with
+    # -DHAVE_LIBAIO or -DHAVE_URING flags.
+    ADD_LIBRARY(tpool_min STATIC ${SOURCES} aio_linux.cc)
+    TARGET_INCLUDE_DIRECTORIES(tpool_min
+      PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}  ${PROJECT_SOURCE_DIR}/include)
+  ENDIF()
 ENDIF()
 
-IF(URING_FOUND)
-  ADD_DEPENDENCIES(tpool GenError)
+IF(NOT TARGET tpool_min)
+  ADD_LIBRARY(tpool_min ALIAS tpool)
 ENDIF()