From dd838e513ca9559257ddf5efac588fc3625f3fdd Mon Sep 17 00:00:00 2001
From: quicksilver <zhifeng.zhang@zilliz.com>
Date: Thu, 8 Aug 2019 19:21:21 +0800
Subject: [PATCH] update cpp/cmake/BuildUtils.cmake

Former-commit-id: 0abe49b884bf39247e0e1f303c7f3f71b2511f5f
---
 cpp/cmake/BuildUtils.cmake | 49 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/cpp/cmake/BuildUtils.cmake b/cpp/cmake/BuildUtils.cmake
index 867a7ce9..9c8d7638 100644
--- a/cpp/cmake/BuildUtils.cmake
+++ b/cpp/cmake/BuildUtils.cmake
@@ -1,3 +1,52 @@
+# Define a function that check last file modification
+function(Check_Last_Modify cache_ignore_file_path working_dir last_modified_commit_id)
+    if(EXISTS "${working_dir}")
+        if(EXISTS "${cache_ignore_file_path}")
+            set(GIT_LOG_SKIP_NUM 0)
+            set(_MATCH_ALL ON CACHE BOOL "Match all")
+            set(_LOOP_STATUS ON CACHE BOOL "Whether out of loop")
+            file(STRINGS ${cache_ignore_file_path} CACHE_IGNORE_TXT)
+            while(_LOOP_STATUS)
+                foreach(_IGNORE_ENTRY ${CACHE_IGNORE_TXT})
+                    if(NOT _IGNORE_ENTRY MATCHES "^[^#]+")
+                        continue()
+                    endif()
+
+                    set(_MATCH_ALL OFF)
+                    execute_process(COMMAND git log --no-merges -1 --skip=${GIT_LOG_SKIP_NUM} --name-status --pretty= WORKING_DIRECTORY ${working_dir} OUTPUT_VARIABLE CHANGE_FILES)
+                    if(NOT CHANGE_FILES STREQUAL "")
+                        string(REPLACE "\n" ";" _CHANGE_FILES ${CHANGE_FILES})
+                        foreach(_FILE_ENTRY ${_CHANGE_FILES})
+                            string(REGEX MATCH "[^ \t]+$" _FILE_NAME ${_FILE_ENTRY})
+                            execute_process(COMMAND sh -c "echo ${_FILE_NAME} | grep ${_IGNORE_ENTRY}" RESULT_VARIABLE return_code)
+                            if (return_code EQUAL 0)
+                                execute_process(COMMAND git log --no-merges -1 --skip=${GIT_LOG_SKIP_NUM} --pretty=%H WORKING_DIRECTORY ${working_dir} OUTPUT_VARIABLE LAST_MODIFIED_COMMIT_ID)
+                                set (${last_modified_commit_id} ${LAST_MODIFIED_COMMIT_ID} PARENT_SCOPE)
+                                set(_LOOP_STATUS OFF)
+                            endif()
+                        endforeach()
+                    else()
+                        set(_LOOP_STATUS OFF)
+                    endif()
+                endforeach()
+
+                if(_MATCH_ALL)
+                    execute_process(COMMAND git log --no-merges -1 --skip=${GIT_LOG_SKIP_NUM} --pretty=%H WORKING_DIRECTORY ${working_dir} OUTPUT_VARIABLE LAST_MODIFIED_COMMIT_ID)
+                    set (${last_modified_commit_id} ${LAST_MODIFIED_COMMIT_ID} PARENT_SCOPE)
+                    set(_LOOP_STATUS OFF)
+                endif()
+
+                math(EXPR GIT_LOG_SKIP_NUM "${GIT_LOG_SKIP_NUM} + 1")
+            endwhile(_LOOP_STATUS)
+        else()
+            execute_process(COMMAND git log --no-merges -1 --skip=${GIT_LOG_SKIP_NUM} --pretty=%H WORKING_DIRECTORY ${working_dir} OUTPUT_VARIABLE LAST_MODIFIED_COMMIT_ID)
+            set (${last_modified_commit_id} ${LAST_MODIFIED_COMMIT_ID} PARENT_SCOPE)
+        endif()
+    else()
+        message(FATAL_ERROR "The directory ${working_dir} does not exist")
+    endif()
+endfunction()
+
 # Define a function that extracts a cached package
 function(ExternalProject_Use_Cache project_name package_file install_path)
     message(STATUS "Will use cached package file: ${package_file}")
-- 
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