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