make rocksdb cmake checks less verbose on repeat

* fix FindLZ4 to follow convention (LIBRARIES, not LIBRARY)
* remove redundant checks from rocksdb/CMakeLists.txt
* put all checks through the same macro that uniformly
  checks for a package, prints the message, adds definition

cmake/FindLZ4.cmake

 find_path(LZ4_INCLUDE_DIR NAMES lz4.h)
-find_library(LZ4_LIBRARY NAMES lz4)
+find_library(LZ4_LIBRARIES NAMES lz4)
 
 include(FindPackageHandleStandardArgs)
 FIND_PACKAGE_HANDLE_STANDARD_ARGS(
     LZ4 DEFAULT_MSG
-    LZ4_LIBRARY LZ4_INCLUDE_DIR)
+    LZ4_LIBRARIES LZ4_INCLUDE_DIR)
 
-mark_as_advanced(LZ4_INCLUDE_DIR LZ4_LIBRARY)
+mark_as_advanced(LZ4_INCLUDE_DIR LZ4_LIBRARIES)

cmake/FindZSTD.cmake

@@ -5,10 +5,6 @@
 # ZSTD_LIBRARIES - List of libraries when using zstd.
 # ZSTD_FOUND - True if zstd found.
 
-if (DEFINED ZSTD_LIBRARIES)
-  return()
-endif()
-
 find_path(ZSTD_INCLUDE_DIR
   NAMES zstd.h
   HINTS ${ZSTD_ROOT_DIR}/include)
@@ -18,7 +14,7 @@ find_library(ZSTD_LIBRARIES
   HINTS ${ZSTD_ROOT_DIR}/lib)
 
 include(FindPackageHandleStandardArgs)
-find_package_handle_standard_args(zstd DEFAULT_MSG ZSTD_LIBRARIES ZSTD_INCLUDE_DIR)
+find_package_handle_standard_args(ZSTD DEFAULT_MSG ZSTD_LIBRARIES ZSTD_INCLUDE_DIR)
 
 mark_as_advanced(
   ZSTD_LIBRARIES

storage/rocksdb/CMakeLists.txt

@@ -188,9 +188,6 @@ endif()
 
 
 TARGET_LINK_LIBRARIES(rocksdb rocksdb_aux_lib)
-  FIND_LIBRARY(LZ4_LIBRARY
-    NAMES liblz4${PIC_EXT}.a lz4
-    HINTS ${WITH_LZ4}/lib)
 
 IF(CMAKE_CXX_COMPILER_ID MATCHES "GNU" OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
 
@@ -273,13 +270,6 @@ IF(MSVC)
   ENDIF()
 ENDIF()
 
-# Enable ZSTD if available. Upstream rocksdb cmake will use WITH_ZSTD and set
-# defines within their code.
-FIND_PACKAGE(zstd)
-IF (ZSTD_FOUND)
-  SET(WITH_ZSTD ON)
-ENDIF()
-
 IF(GIT_EXECUTABLE AND EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/rocksdb/.git)
   EXECUTE_PROCESS(
     COMMAND ${GIT_EXECUTABLE} rev-parse HEAD

storage/rocksdb/build_rocksdb.cmake

@@ -35,52 +35,47 @@ endif()
 
 # Optional compression libraries.
 
-foreach(compression_lib LZ4 BZip2 ZSTD snappy)
-  FIND_PACKAGE(${compression_lib})
-
-  SET(WITH_ROCKSDB_${compression_lib} AUTO CACHE STRING
-  "Build RocksDB  with ${compression_lib} compression. Possible values are 'ON', 'OFF', 'AUTO' and default is 'AUTO'")
-
-  if(${WITH_ROCKSDB_${compression_lib}} STREQUAL "ON"  AND NOT ${${compression_lib}_FOUND})
-    MESSAGE(FATAL_ERROR
-      "${compression_lib} library was not found, but WITH_ROCKSDB_${compression_lib} option is ON.\
-      Either set WITH_ROCKSDB_${compression_lib} to OFF, or make sure ${compression_lib} is installed")
-  endif()
-endforeach()
-
-if(LZ4_FOUND AND (NOT WITH_ROCKSDB_LZ4 STREQUAL "OFF"))
-  add_definitions(-DLZ4)
-  include_directories(${LZ4_INCLUDE_DIR})
-  list(APPEND THIRDPARTY_LIBS ${LZ4_LIBRARY})
-endif()
-
-if(BZIP2_FOUND AND (NOT WITH_ROCKSDB_BZip2 STREQUAL "OFF"))
-  add_definitions(-DBZIP2)
-  include_directories(${BZIP2_INCLUDE_DIR})
-  list(APPEND THIRDPARTY_LIBS ${BZIP2_LIBRARIES})
-endif()
-
-if(SNAPPY_FOUND  AND (NOT WITH_ROCKSDB_snappy STREQUAL "OFF"))
-  add_definitions(-DSNAPPY)
-  include_directories(${snappy_INCLUDE_DIR})
-  list(APPEND THIRDPARTY_LIBS ${snappy_LIBRARIES})
-endif()
-
 include(CheckFunctionExists)
-if(ZSTD_FOUND AND (NOT WITH_ROCKSDB_ZSTD STREQUAL "OFF"))
-  SET(CMAKE_REQUIRED_LIBRARIES zstd)
-  CHECK_FUNCTION_EXISTS(ZDICT_trainFromBuffer ZSTD_VALID)
-  UNSET(CMAKE_REQUIRED_LIBRARIES)
-  if (WITH_ROCKSDB_ZSTD STREQUAL "ON" AND NOT ZSTD_VALID)
+macro(check_lib package var)
+  STRING(TOUPPER ${package} PACKAGE_NAME)
+  SET(WITH_ROCKSDB_${package} AUTO CACHE STRING
+        "Build RocksDB  with ${package} compression. Possible values are 'ON', 'OFF', 'AUTO' and default is 'AUTO'")
+
+  IF (NOT ${WITH_ROCKSDB_${package}} STREQUAL "OFF")
+    FIND_PACKAGE(${package} QUIET)
+    IF (${${PACKAGE_NAME}_FOUND})
+      IF(${ARGC} GREATER 2)
+        SET(CMAKE_REQUIRED_LIBRARIES ${${var}_LIBRARIES})
+        CHECK_FUNCTION_EXISTS(${ARGV2} ${var}_VALID)
+        UNSET(CMAKE_REQUIRED_LIBRARIES)
+      ELSE()
+        SET(${var}_VALID TRUE)
+      ENDIF()
+    ENDIF()
+  ENDIF()
+
+  IF(${${var}_VALID})
+    MESSAGE_ONCE(rocksdb_${var} "Found ${package}: ${${var}_LIBRARIES}")
+    add_definitions(-D${PACKAGE_NAME})
+    include_directories(${${var}_INCLUDE_DIR})
+    list(APPEND THIRDPARTY_LIBS ${${var}_LIBRARIES})
+  ELSEIF(${${PACKAGE_NAME}_FOUND})
+    MESSAGE_ONCE(rocksdb_${var} "Found unusable ${package}: ${${var}_LIBRARIES} [${ARGV2}]")
+  ELSE()
+    MESSAGE_ONCE(rocksdb_${var} "Could NOT find ${package}")
+  ENDIF()
+
+  IF (${WITH_ROCKSDB_${package}} STREQUAL "ON"  AND NOT ${${PACKAGE_NAME}_FOUND})
     MESSAGE(FATAL_ERROR
-      "WITH_ROCKSDB_ZSTD is ON and ZSTD library was found, but the version needs to be >= 1.1.3")
+      "${package} library was not found, but WITH_ROCKSDB_${package} option is ON.\
+      Either set WITH_ROCKSDB_${package} to OFF, or make sure ${package} is installed")
   endif()
-  if (ZSTD_VALID)
-    add_definitions(-DZSTD)
-    include_directories(${ZSTD_INCLUDE_DIR})
-    list(APPEND THIRDPARTY_LIBS ${ZSTD_LIBRARIES})
-  endif()
-endif()
+endmacro()
+
+check_lib(LZ4    LZ4)
+check_lib(BZip2  BZIP2)
+check_lib(snappy snappy) # rocksdb/cmake/modules/Findsnappy.cmake violates the convention
+check_lib(ZSTD   ZSTD ZDICT_trainFromBuffer)
 
 add_definitions(-DZLIB)
 list(APPEND THIRDPARTY_LIBS ${ZLIB_LIBRARY})