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Merge pull request #28159 from asmorkalov:as/java_cleaners

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Introduce option to generate Java code with finalize() or Cleaners interface #28159
 
Closes https://github.com/opencv/opencv/issues/22260
Replaces https://github.com/opencv/opencv/pull/23467

The PR introduce configuration option to generate Java code with Cleaner interface for Java 9+ and old-fashion finalize() method for old Java and Android. Mat class and derivatives are manually written. The PR introduce 2 base classes for it depending on the generator configuration.

Pros:
1. No need to implement complex and error prone cleaner on library side.
2. No new CMake templates, easier to modify code in IDE.

Cons:
1. More generator branches and different code for modern desktop and Android.

TODO: 
- [x] Add Java version check to cmake
- [x] Use Cleaners for ANDROID API 33+

### Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [ ] The PR is proposed to the proper branch
- [ ] There is a reference to the original bug report and related work
- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [ ] The feature is well documented and sample code can be built with the project CMake
This commit is contained in:
Alexander Smorkalov
2025-12-16 14:21:34 +03:00
committed by GitHub
parent 7ca9d9ce03
commit c03734475f
10 changed files with 145 additions and 57 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
CMakeLists.txt
View File

@@ -834,12 +834,12 @@ if(BUILD_JAVA)
if(ANDROID)
include(cmake/android/OpenCVDetectAndroidSDK.cmake)
else()
include(cmake/OpenCVDetectApacheAnt.cmake)
if(ANT_EXECUTABLE AND NOT OPENCV_JAVA_IGNORE_ANT)
ocv_update(OPENCV_JAVA_SDK_BUILD_TYPE "ANT")
elseif(NOT ANDROID)
find_package(Java)
if(Java_FOUND)
find_package(Java QUIET)
if(Java_FOUND)
include(cmake/OpenCVDetectApacheAnt.cmake)
if(ANT_EXECUTABLE AND NOT OPENCV_JAVA_IGNORE_ANT)
ocv_update(OPENCV_JAVA_SDK_BUILD_TYPE "ANT")
else()
include(UseJava)
ocv_update(OPENCV_JAVA_SDK_BUILD_TYPE "JAVA")
endif()
@@ -1997,7 +1997,7 @@ if(BUILD_JAVA)
status(" Java:" Java_FOUND THEN "YES (ver ${Java_VERSION})" ELSE NO)
status(" JNI:" JNI_INCLUDE_DIRS THEN "${JNI_INCLUDE_DIRS}" ELSE NO)
endif()
status(" Java wrappers:" HAVE_opencv_java THEN "YES (${OPENCV_JAVA_SDK_BUILD_TYPE})" ELSE NO)
status(" Java wrappers:" HAVE_opencv_java THEN "YES (${OPENCV_JAVA_SDK_BUILD_TYPE})" ELSE NO)
status(" Java tests:" BUILD_TESTS AND (opencv_test_java_BINARY_DIR OR opencv_test_android_BINARY_DIR) THEN YES ELSE NO)
endif()

2
cmake/android/OpenCVDetectAndroidSDK.cmake
View File

@@ -220,8 +220,10 @@ else()
endif() # BUILD_ANDROID_PROJECTS
if(ANDROID_PROJECTS_BUILD_TYPE STREQUAL "ANT")
ocv_update(OPENCV_JAVA_SDK_BUILD_TYPE "ANT")
include(${CMAKE_CURRENT_LIST_DIR}/android_ant_projects.cmake)
elseif(ANDROID_PROJECTS_BUILD_TYPE STREQUAL "GRADLE")
ocv_update(OPENCV_JAVA_SDK_BUILD_TYPE "GRADLE")
include(${CMAKE_CURRENT_LIST_DIR}/android_gradle_projects.cmake)
elseif(BUILD_ANDROID_PROJECTS)
message(FATAL_ERROR "Internal error")

43
modules/core/misc/java/src/java/core+Mat.java
View File

@@ -4,14 +4,10 @@ import java.nio.ByteBuffer;
// C++: class Mat
//javadoc: Mat
public class Mat {
public final long nativeObj;
public class Mat extends CleanableMat {
public Mat(long addr) {
if (addr == 0)
throw new UnsupportedOperationException("Native object address is NULL");
nativeObj = addr;
super(addr);
}
//
@@ -20,7 +16,7 @@ public class Mat {
// javadoc: Mat::Mat()
public Mat() {
nativeObj = n_Mat();
super(n_Mat());
}
//
@@ -29,7 +25,7 @@ public class Mat {
// javadoc: Mat::Mat(rows, cols, type)
public Mat(int rows, int cols, int type) {
nativeObj = n_Mat(rows, cols, type);
super(n_Mat(rows, cols, type));
}
//
@@ -38,7 +34,7 @@ public class Mat {
// javadoc: Mat::Mat(rows, cols, type, data)
public Mat(int rows, int cols, int type, ByteBuffer data) {
nativeObj = n_Mat(rows, cols, type, data);
super(n_Mat(rows, cols, type, data));
}
//
@@ -47,7 +43,7 @@ public class Mat {
// javadoc: Mat::Mat(rows, cols, type, data, step)
public Mat(int rows, int cols, int type, ByteBuffer data, long step) {
nativeObj = n_Mat(rows, cols, type, data, step);
super(n_Mat(rows, cols, type, data, step));
}
//
@@ -56,7 +52,7 @@ public class Mat {
// javadoc: Mat::Mat(size, type)
public Mat(Size size, int type) {
nativeObj = n_Mat(size.width, size.height, type);
super(n_Mat(size.width, size.height, type));
}
//
@@ -65,7 +61,7 @@ public class Mat {
// javadoc: Mat::Mat(sizes, type)
public Mat(int[] sizes, int type) {
nativeObj = n_Mat(sizes.length, sizes, type);
super(n_Mat(sizes.length, sizes, type));
}
//
@@ -74,7 +70,7 @@ public class Mat {
// javadoc: Mat::Mat(rows, cols, type, s)
public Mat(int rows, int cols, int type, Scalar s) {
nativeObj = n_Mat(rows, cols, type, s.val[0], s.val[1], s.val[2], s.val[3]);
super(n_Mat(rows, cols, type, s.val[0], s.val[1], s.val[2], s.val[3]));
}
//
@@ -83,7 +79,7 @@ public class Mat {
// javadoc: Mat::Mat(size, type, s)
public Mat(Size size, int type, Scalar s) {
nativeObj = n_Mat(size.width, size.height, type, s.val[0], s.val[1], s.val[2], s.val[3]);
super(n_Mat(size.width, size.height, type, s.val[0], s.val[1], s.val[2], s.val[3]));
}
//
@@ -92,7 +88,7 @@ public class Mat {
// javadoc: Mat::Mat(sizes, type, s)
public Mat(int[] sizes, int type, Scalar s) {
nativeObj = n_Mat(sizes.length, sizes, type, s.val[0], s.val[1], s.val[2], s.val[3]);
super(n_Mat(sizes.length, sizes, type, s.val[0], s.val[1], s.val[2], s.val[3]));
}
//
@@ -101,12 +97,12 @@ public class Mat {
// javadoc: Mat::Mat(m, rowRange, colRange)
public Mat(Mat m, Range rowRange, Range colRange) {
nativeObj = n_Mat(m.nativeObj, rowRange.start, rowRange.end, colRange.start, colRange.end);
super(n_Mat(m.nativeObj, rowRange.start, rowRange.end, colRange.start, colRange.end));
}
// javadoc: Mat::Mat(m, rowRange)
public Mat(Mat m, Range rowRange) {
nativeObj = n_Mat(m.nativeObj, rowRange.start, rowRange.end);
super(n_Mat(m.nativeObj, rowRange.start, rowRange.end));
}
//
@@ -115,7 +111,7 @@ public class Mat {
// javadoc: Mat::Mat(m, ranges)
public Mat(Mat m, Range[] ranges) {
nativeObj = n_Mat(m.nativeObj, ranges);
super(n_Mat(m.nativeObj, ranges));
}
//
@@ -124,7 +120,7 @@ public class Mat {
// javadoc: Mat::Mat(m, roi)
public Mat(Mat m, Rect roi) {
nativeObj = n_Mat(m.nativeObj, roi.y, roi.y + roi.height, roi.x, roi.x + roi.width);
super(n_Mat(m.nativeObj, roi.y, roi.y + roi.height, roi.x, roi.x + roi.width));
}
//
@@ -754,12 +750,6 @@ public class Mat {
return new Mat(n_zeros(sizes.length, sizes, type));
}
@Override
protected void finalize() throws Throwable {
n_delete(nativeObj);
super.finalize();
}
// javadoc:Mat::toString()
@Override
public String toString() {
@@ -1834,9 +1824,6 @@ public class Mat {
// C++: static Mat Mat::zeros(int ndims, const int* sizes, int type)
private static native long n_zeros(int ndims, int[] sizes, int type);
// native support for java finalize()
private static native void n_delete(long nativeObj);
private static native int nPutD(long self, int row, int col, int count, double[] data);
private static native int nPutDIdx(long self, int[] idx, int count, double[] data);

21
modules/java/generator/CMakeLists.txt
View File

@@ -62,6 +62,24 @@ ocv_bindings_generator_populate_preprocessor_definitions(
opencv_preprocessor_defs
)
if(OPENCV_JAVA_CLEANING_API)
if(OPENCV_JAVA_CLEANING_API STREQUAL "finalize")
set(opencv_supported_cleaners "false")
elseif(OPENCV_JAVA_CLEANING_API STREQUAL "cleaner")
set(opencv_supported_cleaners "true")
else()
message(FATAL_ERROR "OPENCV_JAVA_CLEANING_API should be one of \"finalize\" or \"cleaner\"")
endif()
else()
if(ANDROID OR (Java_VERSION VERSION_LESS 9))
message(STATUS "Set Cleaners to False")
set(opencv_supported_cleaners "false")
else()
message(STATUS "Set Cleaners to True")
set(opencv_supported_cleaners "true")
endif()
endif(OPENCV_JAVA_CLEANING_API)
set(CONFIG_FILE "${CMAKE_CURRENT_BINARY_DIR}/gen_java.json")
set(__config_str
"{
@@ -74,7 +92,8 @@ ${opencv_preprocessor_defs}
},
\"files_remap\": [
${__remap_config}
]
],
\"support_cleaners\": ${opencv_supported_cleaners}
}
")
if(EXISTS "${CONFIG_FILE}")

29
modules/java/generator/gen_java.py
View File

@@ -23,6 +23,7 @@ SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
# list of modules + files remap
config = None
ROOT_DIR = None
USE_CLEANERS = True
FILES_REMAP = {}
def checkFileRemap(path):
path = os.path.realpath(path)
@@ -366,6 +367,7 @@ class ClassInfo(GeneralInfo):
module = m,
name = self.name,
jname = self.jname,
jcleaner = "long nativeObjCopy = nativeObj;\n org.opencv.core.Mat.cleaner.register(this, () -> delete(nativeObjCopy));" if USE_CLEANERS else "",
imports = "\n".join(self.getAllImports(M)),
docs = self.docstring,
annotation = "\n" + "\n".join(self.annotation) if self.annotation else "",
@@ -948,6 +950,7 @@ class JavaWrapperGenerator(object):
tail = ")"
else:
ret_val = "nativeObj = "
tail = ";\n long nativeObjCopy = nativeObj;\n org.opencv.core.Mat.cleaner.register(this, () -> delete(nativeObjCopy))" if USE_CLEANERS else ""
ret = ""
elif self.isWrapped(ret_type): # wrapped class
constructor = self.getClass(ret_type).jname + "("
@@ -1214,8 +1217,9 @@ JNIEXPORT $rtype JNICALL Java_org_opencv_${module}_${clazz}_$fname
ci.cpp_code.write("\n".join(fn["cpp_code"]))
if ci.name != self.Module or ci.base:
# finalize()
ci.j_code.write(
# finalize() for old Java
if not USE_CLEANERS:
ci.j_code.write(
"""
@Override
protected void finalize() throws Throwable {
@@ -1225,7 +1229,7 @@ JNIEXPORT $rtype JNICALL Java_org_opencv_${module}_${clazz}_$fname
ci.jn_code.write(
"""
// native support for java finalize()
// native support for java finalize() or cleaner
private static native void delete(long nativeObj);
""" )
@@ -1233,7 +1237,7 @@ JNIEXPORT $rtype JNICALL Java_org_opencv_${module}_${clazz}_$fname
ci.cpp_code.write(
"""
//
// native support for java finalize()
// native support for java finalize() or cleaner
// static void %(cls)s::delete( __int64 self )
//
JNIEXPORT void JNICALL Java_org_opencv_%(module)s_%(j_cls)s_delete(JNIEnv*, jclass, jlong);
@@ -1454,6 +1458,12 @@ if __name__ == "__main__":
FILES_REMAP = { os.path.realpath(os.path.join(ROOT_DIR, f['src'])): f['target'] for f in config['files_remap'] }
logging.info("\nRemapped configured files (%d):\n%s", len(FILES_REMAP), pformat(FILES_REMAP))
USE_CLEANERS = config['support_cleaners']
if (USE_CLEANERS):
logging.info("\nUse Java 9+ cleaners\n")
else:
logging.info("\nUse old style Java finalize()\n")
dstdir = "./gen"
jni_path = os.path.join(dstdir, 'cpp'); mkdir_p(jni_path)
java_base_path = os.path.join(dstdir, 'java'); mkdir_p(java_base_path)
@@ -1543,6 +1553,17 @@ if __name__ == "__main__":
preprocessor_definitions)
else:
logging.info("No generated code for module: %s", module)
# Copy Cleaner / finalize() related files
if USE_CLEANERS:
cleaner_src = os.path.join(SCRIPT_DIR, "src", "java9", "CleanableMat.java")
else:
cleaner_src = os.path.join(SCRIPT_DIR, "src", "java_classic", "CleanableMat.java")
cleaner_dst = os.path.join(java_base_path, "org", "opencv", "core", "CleanableMat.java")
print("cleaner_dst: ", cleaner_dst)
copyfile(cleaner_src, cleaner_dst)
generator.finalize(jni_path)
print('Generated files: %d (updated %d)' % (total_files, updated_files))

28
modules/java/generator/src/cpp/CleanableMat.cpp Normal file
View File

@@ -0,0 +1,28 @@
// This file is part of OpenCV project.
// It is subject to the license terms in the LICENSE file found in the top-level directory
// of this distribution and at http://opencv.org/license.html
#include "opencv2/core.hpp"
#define LOG_TAG "org.opencv.core.CleanableMat"
#include "common.h"
#include <iostream>
using namespace cv;
extern "C" {
//
// native support for java finalize() or cleaners
// static void CleanableMat::n_delete( __int64 self )
//
JNIEXPORT void JNICALL Java_org_opencv_core_CleanableMat_n_1delete
(JNIEnv*, jclass, jlong self);
JNIEXPORT void JNICALL Java_org_opencv_core_CleanableMat_n_1delete
(JNIEnv*, jclass, jlong self)
{
// LOGD("CleanableMat.n_delete() called\n");
delete (Mat*) self;
}
}

16
modules/java/generator/src/cpp/Mat.cpp
View File

@@ -2114,22 +2114,6 @@ JNIEXPORT jlong JNICALL Java_org_opencv_core_Mat_n_1zeros__I_3II
return 0;
}
//
// native support for java finalize()
// static void Mat::n_delete( __int64 self )
//
JNIEXPORT void JNICALL Java_org_opencv_core_Mat_n_1delete
(JNIEnv*, jclass, jlong self);
JNIEXPORT void JNICALL Java_org_opencv_core_Mat_n_1delete
(JNIEnv*, jclass, jlong self)
{
delete (Mat*) self;
}
} // extern "C"
namespace {

23
modules/java/generator/src/java9/CleanableMat.java Normal file
View File

@@ -0,0 +1,23 @@
package org.opencv.core;
import java.lang.ref.Cleaner;
public abstract class CleanableMat {
// A native memory cleaner for the OpenCV library
public static Cleaner cleaner = Cleaner.create();
protected CleanableMat(long obj) {
if (obj == 0)
throw new UnsupportedOperationException("Native object address is NULL");
nativeObj = obj;
// The n_delete action must not refer to the object being registered. So, do not use nativeObj directly.
long nativeObjCopy = nativeObj;
cleaner.register(this, () -> n_delete(nativeObjCopy));
}
private static native void n_delete(long nativeObj);
public final long nativeObj;
}

21
modules/java/generator/src/java_classic/CleanableMat.java Normal file
View File

@@ -0,0 +1,21 @@
package org.opencv.core;
public abstract class CleanableMat {
protected CleanableMat(long obj) {
if (obj == 0)
throw new UnsupportedOperationException("Native object address is NULL");
nativeObj = obj;
}
@Override
protected void finalize() throws Throwable {
n_delete(nativeObj);
super.finalize();
}
private static native void n_delete(long nativeObj);
public final long nativeObj;
}

5
modules/java/generator/templates/java_class.prolog
View File

@@ -9,7 +9,10 @@ $docs$annotation
public class $jname {
protected final long nativeObj;
protected $jname(long addr) { nativeObj = addr; }
protected $jname(long addr) {
nativeObj = addr;
$jcleaner
}
public long getNativeObjAddr() { return nativeObj; }