1 /*****************************************************************************
2 * block.c: Data blocks management functions
3 *****************************************************************************
4 * Copyright (C) 2003-2004 VLC authors and VideoLAN
5 * Copyright (C) 2007-2009 RĂ©mi Denis-Courmont
7 * Authors: Laurent Aimar <fenrir@videolan.org>
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU Lesser General Public License as published by
11 * the Free Software Foundation; either version 2.1 of the License, or
12 * (at your option) any later version.
14 * This program 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
17 * GNU Lesser General Public License for more details.
19 * You should have received a copy of the GNU Lesser General Public License
20 * along with this program; if not, write to the Free Software Foundation,
21 * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
22 *****************************************************************************/
24 /*****************************************************************************
26 *****************************************************************************/
39 #include <vlc_common.h>
40 #include <vlc_block.h>
44 * @section Block handling functions.
48 static void BlockNoRelease( block_t *b )
50 fprintf( stderr, "block %p has no release callback! This is a bug!\n", b );
54 static void block_Check (block_t *block)
58 unsigned char *start = block->p_start;
59 unsigned char *end = block->p_start + block->i_size;
60 unsigned char *bufstart = block->p_buffer;
61 unsigned char *bufend = block->p_buffer + block->i_buffer;
63 assert (block->pf_release != BlockNoRelease);
64 assert (start <= end);
65 assert (bufstart <= bufend);
66 assert (bufstart >= start);
67 assert (bufend <= end);
69 block = block->p_next;
73 static void block_Invalidate (block_t *block)
77 block->pf_release = BlockNoRelease;
80 # define block_Check(b) ((void)(b))
81 # define block_Invalidate(b) ((void)(b))
84 void block_Init( block_t *restrict b, void *buf, size_t size )
86 /* Fill all fields to their default */
95 b->i_dts = VLC_TS_INVALID;
98 b->pf_release = BlockNoRelease;
102 static void block_generic_Release (block_t *block)
104 /* That is always true for blocks allocated with block_Alloc(). */
105 assert (block->p_start == (unsigned char *)(block + 1));
106 block_Invalidate (block);
110 static void BlockMetaCopy( block_t *restrict out, const block_t *in )
112 out->p_next = in->p_next;
113 out->i_nb_samples = in->i_nb_samples;
114 out->i_dts = in->i_dts;
115 out->i_pts = in->i_pts;
116 out->i_flags = in->i_flags;
117 out->i_length = in->i_length;
120 /* Memory alignment (must be a multiple of sizeof(void*) and a power of two) */
121 #define BLOCK_ALIGN 16
122 /* Initial reserved header and footer size (must be multiple of alignment) */
123 #define BLOCK_PADDING 32
124 /* Maximum size of reserved footer before we release with realloc() */
125 #define BLOCK_WASTE_SIZE 2048
127 block_t *block_Alloc (size_t size)
129 /* 2 * BLOCK_PADDING: pre + post padding */
130 const size_t alloc = sizeof (block_t) + BLOCK_ALIGN + (2 * BLOCK_PADDING)
132 if (unlikely(alloc <= size))
135 block_t *b = malloc (alloc);
136 if (unlikely(b == NULL))
139 block_Init (b, b + 1, alloc - sizeof (*b));
140 static_assert ((BLOCK_PADDING % BLOCK_ALIGN) == 0,
141 "BLOCK_PADDING must be a multiple of BLOCK_ALIGN");
142 b->p_buffer += BLOCK_PADDING + BLOCK_ALIGN - 1;
143 b->p_buffer = (void *)(((uintptr_t)b->p_buffer) & ~(BLOCK_ALIGN - 1));
145 b->pf_release = block_generic_Release;
149 block_t *block_Realloc( block_t *p_block, ssize_t i_prebody, size_t i_body )
151 size_t requested = i_prebody + i_body;
153 block_Check( p_block );
155 /* Corner case: empty block requested */
156 if( i_prebody <= 0 && i_body <= (size_t)(-i_prebody) )
158 block_Release( p_block );
162 assert( p_block->p_start <= p_block->p_buffer );
163 assert( p_block->p_start + p_block->i_size
164 >= p_block->p_buffer + p_block->i_buffer );
166 /* Corner case: the current payload is discarded completely */
167 if( i_prebody <= 0 && p_block->i_buffer <= (size_t)-i_prebody )
168 p_block->i_buffer = 0; /* discard current payload */
169 if( p_block->i_buffer == 0 )
171 if( requested <= p_block->i_size )
172 { /* Enough room: recycle buffer */
173 size_t extra = p_block->i_size - requested;
175 p_block->p_buffer = p_block->p_start + (extra / 2);
176 p_block->i_buffer = requested;
179 /* Not enough room: allocate a new buffer */
180 block_t *p_rea = block_Alloc( requested );
182 BlockMetaCopy( p_rea, p_block );
183 block_Release( p_block );
187 /* First, shrink payload */
189 /* Pull payload start */
192 assert( p_block->i_buffer >= (size_t)-i_prebody );
193 p_block->p_buffer -= i_prebody;
194 p_block->i_buffer += i_prebody;
199 /* Trim payload end */
200 if( p_block->i_buffer > i_body )
201 p_block->i_buffer = i_body;
203 uint8_t *p_start = p_block->p_start;
204 uint8_t *p_end = p_start + p_block->i_size;
206 /* Second, reallocate the buffer if we lack space. This is done now to
207 * minimize the payload size for memory copy. */
208 assert( i_prebody >= 0 );
209 if( (size_t)(p_block->p_buffer - p_start) < (size_t)i_prebody
210 || (size_t)(p_end - p_block->p_buffer) < i_body )
212 block_t *p_rea = block_Alloc( requested );
215 BlockMetaCopy( p_rea, p_block );
216 p_rea->p_buffer += i_prebody;
217 p_rea->i_buffer -= i_prebody;
218 memcpy( p_rea->p_buffer, p_block->p_buffer, p_block->i_buffer );
220 block_Release( p_block );
226 /* We have a very large reserved footer now? Release some of it.
227 * XXX it might not preserve the alignment of p_buffer */
228 if( p_end - (p_block->p_buffer + i_body) > BLOCK_WASTE_SIZE )
230 block_t *p_rea = block_Alloc( requested );
233 BlockMetaCopy( p_rea, p_block );
234 p_rea->p_buffer += i_prebody;
235 p_rea->i_buffer -= i_prebody;
236 memcpy( p_rea->p_buffer, p_block->p_buffer, p_block->i_buffer );
237 block_Release( p_block );
242 /* NOTE: p_start and p_end are corrupted from this point */
244 /* Third, expand payload */
246 /* Push payload start */
249 p_block->p_buffer -= i_prebody;
250 p_block->i_buffer += i_prebody;
255 /* Expand payload to requested size */
256 p_block->i_buffer = i_body;
262 static void block_heap_Release (block_t *block)
264 block_Invalidate (block);
265 free (block->p_start);
270 * Creates a block from a heap allocation.
271 * This is provided by LibVLC so that manually heap-allocated blocks can safely
272 * be deallocated even after the origin plugin has been unloaded from memory.
274 * When block_Release() is called, VLC will free() the specified pointer.
276 * @param ptr base address of the heap allocation (will be free()'d)
277 * @param length bytes length of the heap allocation
278 * @return NULL in case of error (ptr free()'d in that case), or a valid
281 block_t *block_heap_Alloc (void *addr, size_t length)
283 block_t *block = malloc (sizeof (*block));
290 block_Init (block, addr, length);
291 block->pf_release = block_heap_Release;
296 # include <sys/mman.h>
298 static void block_mmap_Release (block_t *block)
300 block_Invalidate (block);
301 munmap (block->p_start, block->i_size);
306 * Creates a block from a virtual address memory mapping (mmap).
307 * This is provided by LibVLC so that mmap blocks can safely be deallocated
308 * even after the allocating plugin has been unloaded from memory.
310 * @param addr base address of the mapping (as returned by mmap)
311 * @param length length (bytes) of the mapping (as passed to mmap)
312 * @return NULL if addr is MAP_FAILED, or an error occurred (in the later
313 * case, munmap(addr, length) is invoked before returning).
315 block_t *block_mmap_Alloc (void *addr, size_t length)
317 if (addr == MAP_FAILED)
320 block_t *block = malloc (sizeof (*block));
323 munmap (addr, length);
327 block_Init (block, addr, length);
328 block->pf_release = block_mmap_Release;
332 block_t *block_mmap_Alloc (void *addr, size_t length)
334 (void)addr; (void)length; return NULL;
343 ssize_t pread (int fd, void *buf, size_t count, off_t offset)
345 HANDLE handle = (HANDLE)(intptr_t)_get_osfhandle (fd);
346 if (handle == INVALID_HANDLE_VALUE)
349 OVERLAPPED olap; olap.Offset = offset; olap.OffsetHigh = (offset >> 32);
351 /* This braindead API will override the file pointer even if we specify
352 * an explicit read offset... So do not expect this to mix well with
353 * regular read() calls. */
354 if (ReadFile (handle, buf, count, &written, &olap))
361 * Loads a file into a block of memory through a file descriptor.
362 * If possible a private file mapping is created. Otherwise, the file is read
363 * normally. This function is a cancellation point.
365 * @note On 32-bits platforms,
366 * this function will not work for very large files,
367 * due to memory space constraints.
369 * @param fd file descriptor to load from
370 * @return a new block with the file content at p_buffer, and file length at
371 * i_buffer (release it with block_Release()), or NULL upon error (see errno).
373 block_t *block_File (int fd)
378 /* First, get the file size */
382 /* st_size is meaningful for regular files, shared memory and typed memory.
383 * It's also meaning for symlinks, but that's not possible with fstat().
384 * In other cases, it's undefined, and we should really not go further. */
386 # define S_TYPEISSHM( buf ) (0)
388 if (S_ISDIR (st.st_mode))
393 if (!S_ISREG (st.st_mode) && !S_TYPEISSHM (&st))
399 /* Prevent an integer overflow in mmap() and malloc() */
400 if (st.st_size >= SIZE_MAX)
405 length = (size_t)st.st_size;
412 addr = mmap (NULL, length, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
413 if (addr != MAP_FAILED)
414 return block_mmap_Alloc (addr, length);
418 /* If mmap() is not implemented by the OS _or_ the filesystem... */
419 block_t *block = block_Alloc (length);
422 block_cleanup_push (block);
424 for (size_t i = 0; i < length;)
426 ssize_t len = pread (fd, block->p_buffer + i, length - i, i);
429 block_Release (block);
440 * Loads a file into a block of memory from the file path.
441 * See also block_File().
443 block_t *block_FilePath (const char *path)
445 int fd = vlc_open (path, O_RDONLY);
449 block_t *block = block_File (fd);
455 * @section Thread-safe block queue functions
459 * Internal state for block queues
463 vlc_mutex_t lock; /* fifo data lock */
464 vlc_cond_t wait; /**< Wait for data */
465 vlc_cond_t wait_room; /**< Wait for queue depth to shrink */
474 block_fifo_t *block_FifoNew( void )
476 block_fifo_t *p_fifo = malloc( sizeof( block_fifo_t ) );
480 vlc_mutex_init( &p_fifo->lock );
481 vlc_cond_init( &p_fifo->wait );
482 vlc_cond_init( &p_fifo->wait_room );
483 p_fifo->p_first = NULL;
484 p_fifo->pp_last = &p_fifo->p_first;
485 p_fifo->i_depth = p_fifo->i_size = 0;
486 p_fifo->b_force_wake = false;
491 void block_FifoRelease( block_fifo_t *p_fifo )
493 block_FifoEmpty( p_fifo );
494 vlc_cond_destroy( &p_fifo->wait_room );
495 vlc_cond_destroy( &p_fifo->wait );
496 vlc_mutex_destroy( &p_fifo->lock );
500 void block_FifoEmpty( block_fifo_t *p_fifo )
504 vlc_mutex_lock( &p_fifo->lock );
505 block = p_fifo->p_first;
508 p_fifo->i_depth = p_fifo->i_size = 0;
509 p_fifo->p_first = NULL;
510 p_fifo->pp_last = &p_fifo->p_first;
512 vlc_cond_broadcast( &p_fifo->wait_room );
513 vlc_mutex_unlock( &p_fifo->lock );
515 while (block != NULL)
520 block_Release (block);
526 * Wait until the FIFO gets below a certain size (if needed).
528 * Note that if more than one thread writes to the FIFO, you cannot assume that
529 * the FIFO is actually below the requested size upon return (since another
530 * thread could have refilled it already). This is typically not an issue, as
531 * this function is meant for (relaxed) congestion control.
533 * This function may be a cancellation point and it is cancel-safe.
535 * @param fifo queue to wait on
536 * @param max_depth wait until the queue has no more than this many blocks
537 * (use SIZE_MAX to ignore this constraint)
538 * @param max_size wait until the queue has no more than this many bytes
539 * (use SIZE_MAX to ignore this constraint)
542 void block_FifoPace (block_fifo_t *fifo, size_t max_depth, size_t max_size)
546 vlc_mutex_lock (&fifo->lock);
547 while ((fifo->i_depth > max_depth) || (fifo->i_size > max_size))
549 mutex_cleanup_push (&fifo->lock);
550 vlc_cond_wait (&fifo->wait_room, &fifo->lock);
553 vlc_mutex_unlock (&fifo->lock);
557 * Immediately queue one block at the end of a FIFO.
559 * @param block head of a block list to queue (may be NULL)
560 * @return total number of bytes appended to the queue
562 size_t block_FifoPut( block_fifo_t *p_fifo, block_t *p_block )
564 size_t i_size = 0, i_depth = 0;
569 for (p_last = p_block; ; p_last = p_last->p_next)
571 i_size += p_last->i_buffer;
577 vlc_mutex_lock (&p_fifo->lock);
578 *p_fifo->pp_last = p_block;
579 p_fifo->pp_last = &p_last->p_next;
580 p_fifo->i_depth += i_depth;
581 p_fifo->i_size += i_size;
582 /* We queued at least one block: wake up one read-waiting thread */
583 vlc_cond_signal( &p_fifo->wait );
584 vlc_mutex_unlock( &p_fifo->lock );
589 void block_FifoWake( block_fifo_t *p_fifo )
591 vlc_mutex_lock( &p_fifo->lock );
592 if( p_fifo->p_first == NULL )
593 p_fifo->b_force_wake = true;
594 vlc_cond_broadcast( &p_fifo->wait );
595 vlc_mutex_unlock( &p_fifo->lock );
599 * Dequeue the first block from the FIFO. If necessary, wait until there is
600 * one block in the queue. This function is (always) cancellation point.
602 * @return a valid block, or NULL if block_FifoWake() was called.
604 block_t *block_FifoGet( block_fifo_t *p_fifo )
610 vlc_mutex_lock( &p_fifo->lock );
611 mutex_cleanup_push( &p_fifo->lock );
613 /* Remember vlc_cond_wait() may cause spurious wakeups
614 * (on both Win32 and POSIX) */
615 while( ( p_fifo->p_first == NULL ) && !p_fifo->b_force_wake )
616 vlc_cond_wait( &p_fifo->wait, &p_fifo->lock );
621 p_fifo->b_force_wake = false;
625 vlc_mutex_unlock( &p_fifo->lock );
629 p_fifo->p_first = b->p_next;
631 p_fifo->i_size -= b->i_buffer;
633 if( p_fifo->p_first == NULL )
635 p_fifo->pp_last = &p_fifo->p_first;
638 /* We don't know how many threads can queue new packets now. */
639 vlc_cond_broadcast( &p_fifo->wait_room );
640 vlc_mutex_unlock( &p_fifo->lock );
647 * Peeks the first block in the FIFO.
648 * If necessary, wait until there is one block.
649 * This function is (always) a cancellation point.
651 * @warning This function leaves the block in the FIFO.
652 * You need to protect against concurrent threads who could dequeue the block.
653 * Preferrably, there should be only one thread reading from the FIFO.
655 * @return a valid block.
657 block_t *block_FifoShow( block_fifo_t *p_fifo )
663 vlc_mutex_lock( &p_fifo->lock );
664 mutex_cleanup_push( &p_fifo->lock );
666 while( p_fifo->p_first == NULL )
667 vlc_cond_wait( &p_fifo->wait, &p_fifo->lock );
675 /* FIXME: not thread-safe */
676 size_t block_FifoSize( const block_fifo_t *p_fifo )
678 return p_fifo->i_size;
681 /* FIXME: not thread-safe */
682 size_t block_FifoCount( const block_fifo_t *p_fifo )
684 return p_fifo->i_depth;