Add jpy.byte_buffer() function (#112)

* Add jpy.byte_buffer() function

* Fix memory leak when error occurs

* Fix potential memory leak with PyBuffer_release

* Update src/main/c/jpy_jbyte_buffer.c

Co-authored-by: Chip Kent <[email protected]>

* Auto perform buffer->ByteBuffer conv for args

* Refactor code in preparation for varargs support

* No support of varargs of Python buffer objects

* Tidy up a bit

* Fix a type-checking error in dealloc

* Remove auto-conversion

* Remove unused code and improve docstring

* Add and use JByteBuffer_Check for cstr/dstr

* Naming change

* Remove unnecessary decl

---------

Co-authored-by: Chip Kent <[email protected]>

src/main/c/jpy_conv.c

@@ -293,4 +293,3 @@ int JPy_AsJString(JNIEnv* jenv, PyObject* arg, jstring* stringRef)
 
     return 0;
 }
-

src/main/c/jpy_jbyte_buffer.c

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2023 JPY-CONSORTIUM Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "jpy_module.h"
+#include "jpy_diag.h"
+#include "jpy_jarray.h"
+#include "jpy_jbyte_buffer.h"
+
+/* 
+ * This file for now is just a place-holder for future JPy_JByteBufferObj specific functions.
+ */

src/main/c/jpy_jbyte_buffer.h

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2023 JPY-CONSORTIUM Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef JPY_JBYTE_BUFFER_H
+#define JPY_JBYTE_BUFFER_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "jpy_compat.h"
+
+/**
+ * The Java ByteBuffer representation in Python.
+ *
+ * IMPORTANT: JPy_JByteBufferObj must only differ from the JPy_JObj structure by the 'pyBuffer' member
+ * since we use the same basic type, name JPy_JType for it. DON'T ever change member positions!
+ * @see JPy_JObj
+ */
+typedef struct JPy_JByteBufferObj
+{
+    PyObject_HEAD
+    jobject objectRef;
+    Py_buffer *pyBuffer;
+}
+JPy_JByteBufferObj;
+
+#ifdef __cplusplus
+}  /* extern "C" */
+#endif
+#endif /* !JPY_JBYTE_BUFFER_H */

src/main/c/jpy_jobj.c

@@ -20,6 +20,7 @@
 #include "jpy_module.h"
 #include "jpy_diag.h"
 #include "jpy_jarray.h"
+#include "jpy_jbyte_buffer.h"
 #include "jpy_jtype.h"
 #include "jpy_jobj.h"
 #include "jpy_jmethod.h"
@@ -63,9 +64,15 @@ PyObject* JObj_FromType(JNIEnv* jenv, JPy_JType* type, jobject objectRef)
         array = (JPy_JArray*) obj;
         array->bufferExportCount = 0;
         array->buf = NULL;
+    } else if (JByteBuffer_Check(type)) {
+        JPy_JByteBufferObj *byteBuffer;
+
+        byteBuffer = (JPy_JByteBufferObj *) obj;
+        byteBuffer->pyBuffer = NULL;
     }
 
-    // we check the type translations dictionary for a callable for this java type name,
+
+// we check the type translations dictionary for a callable for this java type name,
     // and apply the returned callable to the wrapped object
     callable = PyDict_GetItemString(JPy_Type_Translations, type->javaName);
     if (callable != NULL) {
@@ -181,8 +188,14 @@ void JObj_dealloc(JPy_JObj* self)
         if (array->buf != NULL) {
             JArray_ReleaseJavaArrayElements(array, array->javaType);
         }
-
-    }    
+    } else if (JByteBuffer_Check(jtype)) {
+        JPy_JByteBufferObj *byteBuffer;
+        byteBuffer = (JPy_JByteBufferObj *) self;
+        if (byteBuffer->pyBuffer != NULL) {
+            PyBuffer_Release(byteBuffer->pyBuffer);
+            PyMem_Free(byteBuffer->pyBuffer);
+        }
+    }
 
     jenv = JPy_GetJNIEnv();
     if (jenv != NULL) {
@@ -727,7 +740,13 @@ int JType_InitSlots(JPy_JType* type)
     //Py_SET_TYPE(type, &JType_Type);
     //Py_SET_SIZE(type, sizeof (JPy_JType));
 
-    typeObj->tp_basicsize = isPrimitiveArray ? sizeof (JPy_JArray) : sizeof (JPy_JObj);
+    if (isPrimitiveArray) {
+        typeObj->tp_basicsize = sizeof(JPy_JArray);
+    } else if (JByteBuffer_Check(type)) {
+        typeObj->tp_basicsize = sizeof(JPy_JByteBufferObj);
+    } else {
+        typeObj->tp_basicsize = sizeof(JPy_JObj);
+    }
     typeObj->tp_itemsize = 0;
     typeObj->tp_base = type->superType != NULL ? JTYPE_AS_PYTYPE(type->superType) : &JType_Type;
     //typeObj->tp_base = (PyTypeObject*) type->superType;
@@ -822,3 +841,13 @@ int JType_Check(PyObject* arg)
     return PyType_Check(arg) && JPY_IS_JTYPE(arg);
 }
 
+int JByteBuffer_Check(JPy_JType* type) {
+    while (type != NULL) {
+        if (type == JPy_JByteBuffer || strcmp(type->javaName, "java.nio.ByteBuffer") == 0) {
+            JPy_DIAG_PRINT(JPy_DIAG_F_TYPE, "JByteBuffer_Check: java ByteBuffer or its sub-type (%s) found.\n", type->javaName);
+            return -1;
+        }
+        type = type->superType;
+    }
+    return 0;
+}

src/main/c/jpy_jobj.h

@@ -40,6 +40,8 @@ JPy_JObj;
 
 int JObj_Check(PyObject* arg);
 
+int JByteBuffer_Check(JPy_JType* type);
+
 PyObject* JObj_New(JNIEnv* jenv, jobject objectRef);
 PyObject* JObj_FromType(JNIEnv* jenv, JPy_JType* type, jobject objectRef);
 

src/main/c/jpy_jtype.c

@@ -23,6 +23,7 @@
 #include "jpy_jfield.h"
 #include "jpy_jmethod.h"
 #include "jpy_jobj.h"
+#include "jpy_jbyte_buffer.h"
 #include "jpy_conv.h"
 #include "jpy_compat.h"
 
@@ -1659,7 +1660,6 @@ int JType_ConvertPyArgToJPyObjectArg(JNIEnv* jenv, JPy_ParamDescriptor* paramDes
     return JType_CreateJavaPyObject(jenv, JPy_JPyObject, pyArg, &value->l);
 }
 
-
 int JType_MatchPyArgAsJPyObjectParam(JNIEnv* jenv, JPy_ParamDescriptor* paramDescriptor, PyObject* pyArg)
 {
     // We can always turn a python object into a PyObject

src/main/c/jpy_module.c

@@ -26,6 +26,7 @@
 #include "jpy_jobj.h"
 #include "jpy_conv.h"
 #include "jpy_compat.h"
+#include "jpy_jbyte_buffer.h"
 
 
 #include <stdlib.h>
@@ -38,6 +39,7 @@ PyObject* JPy_destroy_jvm(PyObject* self, PyObject* args);
 PyObject* JPy_get_type(PyObject* self, PyObject* args, PyObject* kwds);
 PyObject* JPy_cast(PyObject* self, PyObject* args);
 PyObject* JPy_array(PyObject* self, PyObject* args);
+PyObject* JPy_byte_buffer(PyObject* self, PyObject* args);
 
 
 static PyMethodDef JPy_Functions[] = {
@@ -63,6 +65,11 @@ static PyMethodDef JPy_Functions[] = {
                     "array(name, init) - Return a new Java array of given Java type (type name or type object) and initializer (array length or sequence). "
                     "Possible primitive types are 'boolean', 'byte', 'char', 'short', 'int', 'long', 'float', and 'double'."},
 
+    {"byte_buffer", JPy_byte_buffer, METH_VARARGS,
+            "byte_buffer(obj) - Return a new Java direct ByteBuffer sharing the same underlying, contiguous buffer of obj via its implemented Buffer Protocol. The resulting PYObject must live "
+            "longer than the Java object to ensure the underlying data remains valid. In most cases, this means that java functions called in this manner must not keep any references"
+            " to the ByteBuffer"},
+
     {NULL, NULL, 0, NULL} /*Sentinel*/
 };
 
@@ -126,7 +133,7 @@ JPy_JType* JPy_JPyObject = NULL;
 JPy_JType* JPy_JPyModule = NULL;
 JPy_JType* JPy_JThrowable = NULL;
 JPy_JType* JPy_JStackTraceElement = NULL;
-
+JPy_JType* JPy_JByteBuffer = NULL;
 
 // java.lang.Comparable
 jclass JPy_Comparable_JClass = NULL;
@@ -228,6 +235,8 @@ jclass JPy_Void_JClass = NULL;
 jclass JPy_String_JClass = NULL;
 jclass JPy_PyObject_JClass = NULL;
 jclass JPy_PyDictWrapper_JClass = NULL;
+jclass JPy_ByteBuffer_JClass = NULL;
+jmethodID JPy_ByteBuffer_AsReadOnlyBuffer_MID = NULL;
 
 jmethodID JPy_PyObject_GetPointer_MID = NULL;
 jmethodID JPy_PyObject_UnwrapProxy_SMID = NULL;
@@ -660,6 +669,83 @@ PyObject* JPy_array(PyObject* self, PyObject* args)
     JPy_FRAME(PyObject*, NULL, JPy_array_internal(jenv, self, args), 16)
 }
 
+PyObject* JType_CreateJavaByteBufferObj(JNIEnv* jenv, PyObject* pyObj)
+{
+    jobject byteBufferRef, tmpByteBufferRef;
+    Py_buffer *pyBuffer;
+    PyObject *newPyObj;
+    JPy_JByteBufferObj* byteBuffer;
+
+    pyBuffer = (Py_buffer *)PyMem_Malloc(sizeof(Py_buffer));
+    if (pyBuffer == NULL) {
+        PyErr_NoMemory();
+        return NULL;
+    }
+
+    if (PyObject_GetBuffer(pyObj, pyBuffer, PyBUF_SIMPLE | PyBUF_C_CONTIGUOUS) != 0) {
+        PyErr_SetString(PyExc_ValueError, "JType_CreateJavaByteBufferObj: the Python object failed to return a contiguous buffer.");
+        PyMem_Free(pyBuffer);
+        return NULL;
+    }
+
+    tmpByteBufferRef = (*jenv)->NewDirectByteBuffer(jenv, pyBuffer->buf, pyBuffer->len);
+    if (tmpByteBufferRef == NULL) {
+        PyBuffer_Release(pyBuffer);
+        PyMem_Free(pyBuffer);
+        PyErr_NoMemory();
+        return NULL;
+    }
+
+    byteBufferRef = (*jenv)->CallObjectMethod(jenv, tmpByteBufferRef, JPy_ByteBuffer_AsReadOnlyBuffer_MID);
+    if (byteBufferRef == NULL) {
+        PyBuffer_Release(pyBuffer);
+        PyMem_Free(pyBuffer);
+        JPy_DELETE_LOCAL_REF(tmpByteBufferRef);
+        PyErr_SetString(PyExc_RuntimeError, "jpy: internal error: failed to create a read-only direct ByteBuffer instance.");
+        return NULL;
+    }
+    JPy_DELETE_LOCAL_REF(tmpByteBufferRef);
+
+    newPyObj = JObj_New(jenv, byteBufferRef);
+    if (newPyObj == NULL) {
+        PyErr_SetString(PyExc_RuntimeError, "jpy: internal error: failed to create a byteBuffer instance.");
+        PyBuffer_Release(pyBuffer);
+        PyMem_Free(pyBuffer);
+        JPy_DELETE_LOCAL_REF(byteBufferRef);
+        return NULL;
+    }
+    JPy_DELETE_LOCAL_REF(byteBufferRef);
+
+    byteBuffer = (JPy_JByteBufferObj *) newPyObj;
+    byteBuffer->pyBuffer = pyBuffer;
+    return (PyObject *)byteBuffer;
+}
+
+PyObject* JPy_byte_buffer_internal(JNIEnv* jenv, PyObject* self, PyObject* args)
+{
+    jobject byteBufferRef;
+    PyObject* pyObj;
+    PyObject* newPyObj;
+    Py_buffer *pyBuffer;
+    JPy_JByteBufferObj* byteBuffer;
+
+    if (!PyArg_ParseTuple(args, "O:byte_buffer", &pyObj)) {
+        return NULL;
+    }
+
+    if (PyObject_CheckBuffer(pyObj) == 0) {
+        PyErr_SetString(PyExc_ValueError, "byte_buffer: argument 1 must be a Python object that supports the buffer protocol.");
+        return NULL;
+    }
+
+    return JType_CreateJavaByteBufferObj(jenv, pyObj);
+}
+
+PyObject* JPy_byte_buffer(PyObject* self, PyObject* args)
+{
+    JPy_FRAME(PyObject*, NULL, JPy_byte_buffer_internal(jenv, self, args), 16)
+}
+
 JPy_JType* JPy_GetNonObjectJType(JNIEnv* jenv, jclass classRef)
 {
     jclass primClassRef;
@@ -927,6 +1013,9 @@ int JPy_InitGlobalVars(JNIEnv* jenv)
     DEFINE_CLASS(JPy_String_JClass, "java/lang/String");
     DEFINE_CLASS(JPy_Throwable_JClass, "java/lang/Throwable");
     DEFINE_CLASS(JPy_StackTraceElement_JClass, "java/lang/StackTraceElement");
+    DEFINE_CLASS(JPy_ByteBuffer_JClass, "java/nio/ByteBuffer");
+    DEFINE_METHOD(JPy_ByteBuffer_AsReadOnlyBuffer_MID, JPy_ByteBuffer_JClass, "asReadOnlyBuffer", "()Ljava/nio/ByteBuffer;");
+
 
     // Non-Object types: Primitive types and void.
     DEFINE_NON_OBJECT_TYPE(JPy_JBoolean, JPy_Boolean_JClass);
@@ -953,6 +1042,8 @@ int JPy_InitGlobalVars(JNIEnv* jenv)
     DEFINE_OBJECT_TYPE(JPy_JDoubleObj, JPy_Double_JClass);
     // Other objects.
     DEFINE_OBJECT_TYPE(JPy_JString, JPy_String_JClass);
+    DEFINE_OBJECT_TYPE(JPy_JByteBuffer, JPy_ByteBuffer_JClass);
+
     DEFINE_OBJECT_TYPE(JPy_JThrowable, JPy_Throwable_JClass);
     DEFINE_OBJECT_TYPE(JPy_JStackTraceElement, JPy_StackTraceElement_JClass);
     DEFINE_METHOD(JPy_Throwable_getCause_MID, JPy_Throwable_JClass, "getCause", "()Ljava/lang/Throwable;");
@@ -994,6 +1085,7 @@ void JPy_ClearGlobalVars(JNIEnv* jenv)
         (*jenv)->DeleteGlobalRef(jenv, JPy_Number_JClass);
         (*jenv)->DeleteGlobalRef(jenv, JPy_Void_JClass);
         (*jenv)->DeleteGlobalRef(jenv, JPy_String_JClass);
+        (*jenv)->DeleteGlobalRef(jenv, JPy_ByteBuffer_JClass);
     }
 
     JPy_Comparable_JClass = NULL;
@@ -1014,6 +1106,7 @@ void JPy_ClearGlobalVars(JNIEnv* jenv)
     JPy_Number_JClass = NULL;
     JPy_Void_JClass = NULL;
     JPy_String_JClass = NULL;
+    JPy_ByteBuffer_JClass = NULL;
 
     JPy_Object_ToString_MID = NULL;
     JPy_Object_HashCode_MID = NULL;
@@ -1051,6 +1144,7 @@ void JPy_ClearGlobalVars(JNIEnv* jenv)
     JPy_Number_DoubleValue_MID = NULL;
     JPy_PyObject_GetPointer_MID = NULL;
     JPy_PyObject_UnwrapProxy_SMID = NULL;
+    JPy_ByteBuffer_AsReadOnlyBuffer_MID = NULL;
 
     JPy_XDECREF(JPy_JBoolean);
     JPy_XDECREF(JPy_JChar);
@@ -1061,6 +1155,8 @@ void JPy_ClearGlobalVars(JNIEnv* jenv)
     JPy_XDECREF(JPy_JFloat);
     JPy_XDECREF(JPy_JDouble);
     JPy_XDECREF(JPy_JVoid);
+    JPy_XDECREF(JPy_JString);
+    JPy_XDECREF(JPy_JByteBuffer);
     JPy_XDECREF(JPy_JBooleanObj);
     JPy_XDECREF(JPy_JCharacterObj);
     JPy_XDECREF(JPy_JByteObj);
@@ -1082,6 +1178,7 @@ void JPy_ClearGlobalVars(JNIEnv* jenv)
     JPy_JDouble = NULL;
     JPy_JVoid = NULL;
     JPy_JString = NULL;
+    JPy_JByteBuffer = NULL;
     JPy_JBooleanObj = NULL;
     JPy_JCharacterObj = NULL;
     JPy_JByteObj = NULL;

src/main/c/jpy_module.h

@@ -156,6 +156,7 @@ extern struct JPy_JType* JPy_JClass;
 extern struct JPy_JType* JPy_JString;
 extern struct JPy_JType* JPy_JPyObject;
 extern struct JPy_JType* JPy_JPyModule;
+extern struct JPy_JType* JPy_JByteBuffer;
 
 // java.lang.Comparable
 extern jclass JPy_Comparable_JClass;
@@ -250,6 +251,9 @@ extern jmethodID JPy_Number_DoubleValue_MID;
 extern jclass JPy_String_JClass;
 extern jclass JPy_Void_JClass;
 
+extern jclass JPy_ByteBuffer_JClass;
+extern jmethodID JPy_ByteBuffer_AsReadOnlyBuffer_MID;
+
 extern jclass JPy_PyObject_JClass;
 extern jmethodID JPy_PyObject_GetPointer_MID;
 extern jmethodID JPy_PyObject_UnwrapProxy_SMID;