Fix build for macos

CHANGELOG.md

@@ -26,6 +26,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Add check to directly use ANN Search when filters match all docs. (#2320)[https://github.com/opensearch-project/k-NN/pull/2320]
 - Use one formula to calculate cosine similarity (#2357)[https://github.com/opensearch-project/k-NN/pull/2357]
 - Add WithFieldName implementation to KNNQueryBuilder (#2398)[https://github.com/opensearch-project/k-NN/pull/2398]
+- Make the build work for M series MacOS without manual code changes and local JAVA_HOME config (#2397)[https://github.com/opensearch-project/k-NN/pull/2397]
 ### Bug Fixes
 * Fixing the bug when a segment has no vector field present for disk based vector search (#2282)[https://github.com/opensearch-project/k-NN/pull/2282]
 * Fixing the bug where search fails with "fields" parameter for an index with a knn_vector field (#2314)[https://github.com/opensearch-project/k-NN/pull/2314]

DEVELOPER_GUIDE.md

@@ -143,6 +143,21 @@ export OPENSEARCH_HOME=the directory of opensearch...
 export JAVA_LIBRARY_PATH=$JAVA_LIBRARY_PATH:$OPENSEARCH_HOME/plugins/opensearch-knn/lib
 ```
 
+CMAKE will use as JAVA_HOME environment whatever your gradle is currently using. For example:
+```bash
+Java home directory found by gradle: /opt/homebrew/Cellar/openjdk@21/21.0.5/libexec/openjdk.jdk/Contents/Home
+=======================================
+OpenSearch Build Hamster says Hello!
+  Gradle Version        : 8.4
+  OS Info               : Mac OS X 14.4 (aarch64)
+  JDK Version           : 21 (Homebrew JDK)
+  JAVA_HOME             : /opt/homebrew/Cellar/openjdk@21/21.0.5/libexec/openjdk.jdk/Contents/Home
+  Random Testing Seed   : 8AB32A4719AA345E
+  In FIPS 140 mode      : false
+=======================================
+```
+The JAVA_HOME used by gradle will be the default that the project will be using.
+
 #### Environment
 
 Currently, the plugin only supports Linux on x64 and arm platforms.

build.gradle

@@ -3,6 +3,8 @@
  *  SPDX-License-Identifier: Apache-2.0
  */
 
+
+import org.gradle.internal.jvm.Jvm
 import org.opensearch.gradle.test.RestIntegTestTask
 import org.opensearch.gradle.testclusters.OpenSearchCluster
 import org.apache.tools.ant.taskdefs.condition.Os
@@ -336,13 +338,19 @@ task cmakeJniLib(type:Exec) {
     args.add("-DAVX512_ENABLED=${avx512_enabled}")
     args.add("-DCOMMIT_LIB_PATCHES=${commit_lib_patches}")
     args.add("-DAPPLY_LIB_PATCHES=${apply_lib_patches}")
+    def javaHome = Jvm.current().getJavaHome()
+    logger.lifecycle("Java home directory used by gradle: $javaHome")
+    if (Os.isFamily(Os.FAMILY_MAC)) {
+        environment('JAVA_HOME',javaHome)
+    }
     if (Os.isFamily(Os.FAMILY_WINDOWS)) {
         dependsOn windowsPatches
         args.add("-G")
         args.add("Unix Makefiles")
         args.add("-DBLAS_LIBRARIES=$rootDir\\src\\main\\resources\\windowsDependencies\\libopenblas.dll")
         args.add("-DLAPACK_LIBRARIES=$rootDir\\src\\main\\resources\\windowsDependencies\\libopenblas.dll")
     }
+
     commandLine args
 }
 

jni/cmake/init-faiss.cmake

@@ -54,18 +54,37 @@ if(NOT DEFINED APPLY_LIB_PATCHES OR "${APPLY_LIB_PATCHES}" STREQUAL true)
     endforeach()
 endif()
 
-if (${CMAKE_SYSTEM_NAME} STREQUAL Darwin)
-    if(CMAKE_C_COMPILER_ID MATCHES "Clang\$")
-        set(OpenMP_C_FLAGS "-Xpreprocessor -fopenmp")
-        set(OpenMP_C_LIB_NAMES "omp")
-        set(OpenMP_omp_LIBRARY /usr/local/opt/libomp/lib/libomp.dylib)
-    endif()
+if (APPLE)
+    message(STATUS "darwin macos detected")
+    if(CMAKE_SYSTEM_PROCESSOR STREQUAL "arm64")
+        message(STATUS "detected Mac with ARM architecture")
+        if(CMAKE_C_COMPILER_ID MATCHES "Clang\$")
+            set(OpenMP_C_FLAGS "-Xpreprocessor -fopenmp")
+            set(OpenMP_C_LIB_NAMES "omp")
+            set(OpenMP_omp_LIBRARY /opt/homebrew/opt/libomp/lib/libomp.dylib)
+        endif()
+
+        if(CMAKE_CXX_COMPILER_ID MATCHES "Clang\$")
+            set(OpenMP_CXX_FLAGS "-Xpreprocessor -fopenmp -I/opt/homebrew/opt/libomp/include")
+            set(OpenMP_CXX_LIB_NAMES "omp")
+            set(OpenMP_omp_LIBRARY /opt/homebrew/opt/libomp/lib/libomp.dylib)
+        endif()
+    else()
+        message(STATUS "detected Mac with x86 architecture")
+        if(CMAKE_C_COMPILER_ID MATCHES "Clang\$")
+            set(OpenMP_C_FLAGS "-Xpreprocessor -fopenmp")
+            set(OpenMP_C_LIB_NAMES "omp")
+            set(OpenMP_omp_LIBRARY /usr/local/opt/libomp/lib/libomp.dylib)
+        endif()
 
-    if(CMAKE_CXX_COMPILER_ID MATCHES "Clang\$")
-        set(OpenMP_CXX_FLAGS "-Xpreprocessor -fopenmp -I/usr/local/opt/libomp/include")
-        set(OpenMP_CXX_LIB_NAMES "omp")
-        set(OpenMP_omp_LIBRARY /usr/local/opt/libomp/lib/libomp.dylib)
+        if(CMAKE_CXX_COMPILER_ID MATCHES "Clang\$")
+            set(OpenMP_CXX_FLAGS "-Xpreprocessor -fopenmp -I/usr/local/opt/libomp/include")
+            set(OpenMP_CXX_LIB_NAMES "omp")
+            set(OpenMP_omp_LIBRARY /usr/local/opt/libomp/lib/libomp.dylib)
+        endif()
     endif()
+
+
 endif()
 
 find_package(ZLIB REQUIRED)