Constness changes
[melted] / src / framework / mlt_pool.c
1 /**
2 * \file mlt_pool.c
3 * \brief memory pooling functionality
4 * \see mlt_pool_s
5 *
6 * Copyright (C) 2003-2009 Ushodaya Enterprises Limited
7 * \author Charles Yates <charles.yates@pandora.be>
8 *
9 * This library is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
13 *
14 * This library is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with this library; if not, write to the Free Software
21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22 */
23
24 #include "mlt_properties.h"
25 #include "mlt_deque.h"
26
27 #include <stdlib.h>
28 #include <string.h>
29 #include <pthread.h>
30
31 // Not nice - memalign is defined here apparently?
32 #ifdef linux
33 #include <malloc.h>
34 #endif
35
36 /** global singleton for tracking pools */
37
38 static mlt_properties pools = NULL;
39
40 /** \brief Pool (memory) class
41 */
42
43 typedef struct mlt_pool_s
44 {
45 pthread_mutex_t lock; ///< lock to prevent race conditions
46 mlt_deque stack; ///< a stack of addresses to memory blocks
47 int size; ///< the size of the memory block as a power of 2
48 int count; ///< the number of blocks in the pool
49 }
50 *mlt_pool;
51
52 /** \brief private to mlt_pool_s, for tracking items to release
53 */
54
55 typedef struct mlt_release_s
56 {
57 mlt_pool pool;
58 int references;
59 }
60 *mlt_release;
61
62 /** Create a pool.
63 *
64 * \private \memberof mlt_pool_s
65 * \param size the size of the memory blocks to hold as some power of two
66 * \return a new pool object
67 */
68
69 static mlt_pool pool_init( int size )
70 {
71 // Create the pool
72 mlt_pool this = calloc( 1, sizeof( struct mlt_pool_s ) );
73
74 // Initialise it
75 if ( this != NULL )
76 {
77 // Initialise the mutex
78 pthread_mutex_init( &this->lock, NULL );
79
80 // Create the stack
81 this->stack = mlt_deque_init( );
82
83 // Assign the size
84 this->size = size;
85 }
86
87 // Return it
88 return this;
89 }
90
91 /** Get an item from the pool.
92 *
93 * \private \memberof mlt_pool_s
94 * \param this a pool
95 * \return an opaque pointer
96 */
97
98 static void *pool_fetch( mlt_pool this )
99 {
100 // We will generate a release object
101 void *ptr = NULL;
102
103 // Sanity check
104 if ( this != NULL )
105 {
106 // Lock the pool
107 pthread_mutex_lock( &this->lock );
108
109 // Check if the stack is empty
110 if ( mlt_deque_count( this->stack ) != 0 )
111 {
112 // Pop the top of the stack
113 ptr = mlt_deque_pop_back( this->stack );
114
115 // Assign the reference
116 ( ( mlt_release )ptr )->references = 1;
117 }
118 else
119 {
120 // We need to generate a release item
121 #ifdef linux
122 mlt_release release = memalign( 16, this->size );
123 #else
124 mlt_release release = malloc( this->size );
125 #endif
126
127 // Initialise it
128 if ( release != NULL )
129 {
130 // Increment the number of items allocated to this pool
131 this->count ++;
132
133 // Assign the pool
134 release->pool = this;
135
136 // Assign the reference
137 release->references = 1;
138
139 // Determine the ptr
140 ptr = ( void * )release + sizeof( struct mlt_release_s );
141 }
142 }
143
144 // Unlock the pool
145 pthread_mutex_unlock( &this->lock );
146 }
147
148 // Return the generated release object
149 return ptr;
150 }
151
152 /** Return an item to the pool.
153 *
154 * \private \memberof mlt_pool_s
155 * \param ptr an opaque pointer
156 */
157
158 static void pool_return( void *ptr )
159 {
160 // Sanity checks
161 if ( ptr != NULL )
162 {
163 // Get the release pointer
164 mlt_release that = ptr - sizeof( struct mlt_release_s );
165
166 // Get the pool
167 mlt_pool this = that->pool;
168
169 if ( this != NULL )
170 {
171 // Lock the pool
172 pthread_mutex_lock( &this->lock );
173
174 // Push the that back back on to the stack
175 mlt_deque_push_back( this->stack, ptr );
176
177 // Unlock the pool
178 pthread_mutex_unlock( &this->lock );
179
180 // Ensure that we don't clean up
181 ptr = NULL;
182 }
183 }
184
185 // Tidy up - this will only occur if the returned item is incorrect
186 if ( ptr != NULL )
187 {
188 // Free the release itself
189 free( ptr - sizeof( struct mlt_release_s ) );
190 }
191 }
192
193 /** Destroy a pool.
194 *
195 * \private \memberof mlt_pool_s
196 * \param this a pool
197 */
198
199 static void pool_close( mlt_pool this )
200 {
201 if ( this != NULL )
202 {
203 // We need to free up all items in the pool
204 void *release = NULL;
205
206 // Iterate through the stack until depleted
207 while ( ( release = mlt_deque_pop_back( this->stack ) ) != NULL )
208 {
209 // We'll free this item now
210 free( release - sizeof( struct mlt_release_s ) );
211 }
212
213 // We can now close the stack
214 mlt_deque_close( this->stack );
215
216 // Destroy the mutex
217 pthread_mutex_destroy( &this->lock );
218
219 // Close the pool
220 free( this );
221 }
222 }
223
224 /** Initialise the global pool.
225 *
226 * \public \memberof mlt_pool_s
227 */
228
229 void mlt_pool_init( )
230 {
231 // Loop variable used to create the pools
232 int i = 0;
233
234 // Create the pools
235 pools = mlt_properties_new( );
236
237 // Create the pools
238 for ( i = 8; i < 31; i ++ )
239 {
240 // Each properties item needs a name
241 char name[ 32 ];
242
243 // Construct a pool
244 mlt_pool pool = pool_init( 1 << i );
245
246 // Generate a name
247 sprintf( name, "%d", i );
248
249 // Register with properties
250 mlt_properties_set_data( pools, name, pool, 0, ( mlt_destructor )pool_close, NULL );
251 }
252 }
253
254 /** Allocate size bytes from the pool.
255 *
256 * \public \memberof mlt_pool_s
257 * \param size the number of bytes
258 */
259
260 void *mlt_pool_alloc( int size )
261 {
262 // This will be used to obtain the pool to use
263 mlt_pool pool = NULL;
264
265 // Determines the index of the pool to use
266 int index = 8;
267
268 // Minimum size pooled is 256 bytes
269 size = size + sizeof( mlt_release );
270 while ( ( 1 << index ) < size )
271 index ++;
272
273 // Now get the pool at the index
274 pool = mlt_properties_get_data_at( pools, index - 8, NULL );
275
276 // Now get the real item
277 return pool_fetch( pool );
278 }
279
280 /** Allocate size bytes from the pool.
281 *
282 * \public \memberof mlt_pool_s
283 * \param ptr an opaque pointer - can be in the pool or a new block to allocate
284 * \param size the number of bytes
285 */
286
287 void *mlt_pool_realloc( void *ptr, int size )
288 {
289 // Result to return
290 void *result = NULL;
291
292 // Check if we actually have an address
293 if ( ptr != NULL )
294 {
295 // Get the release pointer
296 mlt_release that = ptr - sizeof( struct mlt_release_s );
297
298 // If the current pool this ptr belongs to is big enough
299 if ( size > that->pool->size - sizeof( struct mlt_release_s ) )
300 {
301 // Allocate
302 result = mlt_pool_alloc( size );
303
304 // Copy
305 memcpy( result, ptr, that->pool->size - sizeof( struct mlt_release_s ) );
306
307 // Release
308 mlt_pool_release( ptr );
309 }
310 else
311 {
312 // Nothing to do
313 result = ptr;
314 }
315 }
316 else
317 {
318 // Simply allocate
319 result = mlt_pool_alloc( size );
320 }
321
322 return result;
323 }
324
325 /** Purge unused items in the pool.
326 *
327 * A form of garbage collection.
328 * \public \memberof mlt_pool_s
329 */
330
331 void mlt_pool_purge( )
332 {
333 int i = 0;
334
335 // For each pool
336 for ( i = 0; i < mlt_properties_count( pools ); i ++ )
337 {
338 // Get the pool
339 mlt_pool this = mlt_properties_get_data_at( pools, i, NULL );
340
341 // Pointer to unused memory
342 void *release = NULL;
343
344 // Lock the pool
345 pthread_mutex_lock( &this->lock );
346
347 // We'll free all unused items now
348 while ( ( release = mlt_deque_pop_back( this->stack ) ) != NULL )
349 free( release - sizeof( struct mlt_release_s ) );
350
351 // Unlock the pool
352 pthread_mutex_unlock( &this->lock );
353 }
354 }
355
356 /** Release the allocated memory.
357 *
358 * \public \memberof mlt_pool_s
359 * \param release an opaque pointer of a block in the pool
360 */
361
362 void mlt_pool_release( void *release )
363 {
364 // Return to the pool
365 pool_return( release );
366 }
367
368 /** Close the pool.
369 *
370 * \public \memberof mlt_pool_s
371 */
372
373 void mlt_pool_close( )
374 {
375 #ifdef _MLT_POOL_CHECKS_
376 // Stats dump on close
377 int i = 0;
378 for ( i = 0; i < mlt_properties_count( pools ); i ++ )
379 {
380 mlt_pool pool = mlt_properties_get_data_at( pools, i, NULL );
381 if ( pool->count )
382 mlt_log( NULL, MLT_LOG_DEBUG, "%s: size %d allocated %d returned %d %c\n", __FUNCTION__,
383 pool->size, pool->count, mlt_deque_count( pool->stack ),
384 pool->count != mlt_deque_count( pool->stack ) ? '*' : ' ' );
385 }
386 #endif
387
388 // Close the properties
389 mlt_properties_close( pools );
390 }
391