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FFmpeg/libavcodec/ffjni.h
Matthieu Bouron 376d8fb2c5 lavc/ffjni: replace ff_jni_{attach,detach} with ff_jni_get_env
If a JNI environment is not already attached to the thread where the
MediaCodec calls are made the current implementation will attach /
detach an environment for each MediaCodec call wasting some CPU time.

ff_jni_get_env replaces ff_jni_{attach,detach} by permanently attaching
an environment (if it is not already the case) to the current thread.
The environment will be automatically detached at the thread destruction
using a pthread_key callback.

Saves around 5% of CPU time (out of 20%) while decoding a stream with
MediaCodec.
2016-07-27 15:43:39 +02:00

146 lines
4.8 KiB
C

/*
* JNI utility functions
*
* Copyright (c) 2015-2016 Matthieu Bouron <matthieu.bouron stupeflix.com>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef AVCODEC_FFJNI_H
#define AVCODEC_FFJNI_H
#include <jni.h>
/*
* Attach permanently a JNI environment to the current thread and retrieve it.
*
* If successfully attached, the JNI environment will automatically be detached
* at thread destruction.
*
* @param attached pointer to an integer that will be set to 1 if the
* environment has been attached to the current thread or 0 if it is
* already attached.
* @param log_ctx context used for logging, can be NULL
* @return the JNI environment on success, NULL otherwise
*/
JNIEnv *ff_jni_get_env(void *log_ctx);
/*
* Convert a jstring to its utf characters equivalent.
*
* @param env JNI environment
* @param string Java string to convert
* @param log_ctx context used for logging, can be NULL
* @return a pointer to an array of unicode characters on success, NULL
* otherwise
*/
char *ff_jni_jstring_to_utf_chars(JNIEnv *env, jstring string, void *log_ctx);
/*
* Convert utf chars to its jstring equivalent.
*
* @param env JNI environment
* @param utf_chars a pointer to an array of unicode characters
* @param log_ctx context used for logging, can be NULL
* @return a Java string object on success, NULL otherwise
*/
jstring ff_jni_utf_chars_to_jstring(JNIEnv *env, const char *utf_chars, void *log_ctx);
/*
* Extract the error summary from a jthrowable in the form of "className: errorMessage"
*
* @param env JNI environment
* @param exception exception to get the summary from
* @param error address pointing to the error, the value is updated if a
* summary can be extracted
* @param log_ctx context used for logging, can be NULL
* @return 0 on success, < 0 otherwise
*/
int ff_jni_exception_get_summary(JNIEnv *env, jthrowable exception, char **error, void *log_ctx);
/*
* Check if an exception has occurred,log it using av_log and clear it.
*
* @param env JNI environment
* @param log value used to enable logging if an exception has occurred,
* 0 disables logging, != 0 enables logging
* @param log_ctx context used for logging, can be NULL
*/
int ff_jni_exception_check(JNIEnv *env, int log, void *log_ctx);
/*
* Jni field type.
*/
enum FFJniFieldType {
FF_JNI_CLASS,
FF_JNI_FIELD,
FF_JNI_STATIC_FIELD,
FF_JNI_METHOD,
FF_JNI_STATIC_METHOD
};
/*
* Jni field describing a class, a field or a method to be retrieved using
* the ff_jni_init_jfields method.
*/
struct FFJniField {
const char *name;
const char *method;
const char *signature;
enum FFJniFieldType type;
int offset;
int mandatory;
};
/*
* Retrieve class references, field ids and method ids to an arbitrary structure.
*
* @param env JNI environment
* @param jfields a pointer to an arbitrary structure where the different
* fields are declared and where the FFJNIField mapping table offsets are
* pointing to
* @param jfields_mapping null terminated array of FFJNIFields describing
* the class/field/method to be retrieved
* @param global make the classes references global. It is the caller
* responsibility to properly release global references.
* @param log_ctx context used for logging, can be NULL
* @return 0 on success, < 0 otherwise
*/
int ff_jni_init_jfields(JNIEnv *env, void *jfields, const struct FFJniField *jfields_mapping, int global, void *log_ctx);
/*
* Delete class references, field ids and method ids of an arbitrary structure.
*
* @param env JNI environment
* @param jfields a pointer to an arbitrary structure where the different
* fields are declared and where the FFJNIField mapping table offsets are
* pointing to
* @param jfields_mapping null terminated array of FFJNIFields describing
* the class/field/method to be deleted
* @param global threat the classes references as global and delete them
* accordingly
* @param log_ctx context used for logging, can be NULL
* @return 0 on success, < 0 otherwise
*/
int ff_jni_reset_jfields(JNIEnv *env, void *jfields, const struct FFJniField *jfields_mapping, int global, void *log_ctx);
#endif /* AVCODEC_FFJNI_H */