xcb: Refresh.

Still an experimental backend, it's now a little too late to stabilise
for 1.10, but this should represent a major step forward in its feature
set and an attempt to catch up with all the bug fixes that have been
performed on xlib. Notably not tested yet (and expected to be broken)
are mixed-endian connections and low bitdepth servers (the dithering
support has not been copied over for instance). However, it seems robust
enough for daily use...

Of particular note in this update is that the xcb surface is now capable
of subverting the xlib surface through the ./configure --enable-xlib-xcb
option. This replaces the xlib surface with a proxy that forwards all
operations to an equivalent xcb surface whilst preserving the cairo-xlib
API that is required for compatibility with the existing applications,
for instance GTK+ and Mozilla. Also you can experiment with enabling a
DRM bypass, though you need to be extremely foolhardy to do so.

1 files changed, 576 insertions, 0 deletions

diff --git a/src/cairo-xcb-shm.c b/src/cairo-xcb-shm.c
new file mode 100644
index 000000000..7a47f338b
--- /dev/null
+++ b/src/cairo-xcb-shm.c
@@ -0,0 +1,576 @@
+/* Cairo - a vector graphics library with display and print output
+ *
+ * Copyright © 2007 Chris Wilson
+ * Copyright © 2009 Intel Corporation
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it either under the terms of the GNU Lesser General Public
+ * License version 2.1 as published by the Free Software Foundation
+ * (the "LGPL") or, at your option, under the terms of the Mozilla
+ * Public License Version 1.1 (the "MPL"). If you do not alter this
+ * notice, a recipient may use your version of this file under either
+ * the MPL or the LGPL.
+ *
+ * You should have received a copy of the LGPL along with this library
+ * in the file COPYING-LGPL-2.1; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ * You should have received a copy of the MPL along with this library
+ * in the file COPYING-MPL-1.1
+ *
+ * The contents of this file are subject to the Mozilla Public License
+ * Version 1.1 (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.mozilla.org/MPL/
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
+ * OF ANY KIND, either express or implied. See the LGPL or the MPL for
+ * the specific language governing rights and limitations.
+ *
+ * The Original Code is the cairo graphics library.
+ *
+ * The Initial Developer of the Original Code is Red Hat, Inc.
+ *
+ * Contributors(s):
+ *	Chris Wilson <chris@chris-wilson.co.uk>
+ */
+
+#include "cairoint.h"
+
+#include "cairo-xcb-private.h"
+
+#include <xcb/shm.h>
+#include <sys/ipc.h>
+#include <sys/shm.h>
+#include <errno.h>
+
+/* a simple buddy allocator for memory pools
+ * XXX fragmentation? use Doug Lea's malloc?
+ */
+
+typedef struct _cairo_xcb_shm_mem_block cairo_xcb_shm_mem_block_t;
+
+struct _cairo_xcb_shm_mem_block {
+    unsigned int bits;
+    cairo_list_t link;
+};
+
+struct _cairo_xcb_shm_mem_pool {
+    int shmid;
+    uint32_t shmseg;
+
+    char *base;
+    unsigned int nBlocks;
+    cairo_xcb_shm_mem_block_t *blocks;
+    cairo_list_t free[32];
+    unsigned char *map;
+
+    unsigned int min_bits;     /* Minimum block size is 1 << min_bits */
+    unsigned int num_sizes;
+
+    size_t free_bytes;
+    size_t max_bytes;
+    unsigned int max_free_bits;
+
+    cairo_list_t link;
+};
+
+#define BITTEST(p, n)  ((p)->map[(n) >> 3] &   (128 >> ((n) & 7)))
+#define BITSET(p, n)   ((p)->map[(n) >> 3] |=  (128 >> ((n) & 7)))
+#define BITCLEAR(p, n) ((p)->map[(n) >> 3] &= ~(128 >> ((n) & 7)))
+
+static void
+clear_bits (cairo_xcb_shm_mem_pool_t *pi, size_t first, size_t last)
+{
+    size_t i, n = last;
+    size_t first_full = (first + 7) & ~7;
+    size_t past_full = last & ~7;
+    size_t bytes;
+
+    if (n > first_full)
+	n = first_full;
+    for (i = first; i < n; i++)
+	  BITCLEAR (pi, i);
+
+    if (past_full > first_full) {
+	bytes = past_full - first_full;
+	bytes = bytes >> 3;
+	memset (pi->map + (first_full >> 3), 0, bytes);
+    }
+
+    if (past_full < n)
+	past_full = n;
+    for (i = past_full; i < last; i++)
+	BITCLEAR (pi, i);
+}
+
+static void
+free_bits (cairo_xcb_shm_mem_pool_t *pi,
+	   size_t start,
+	   unsigned int bits,
+	   cairo_bool_t clear)
+{
+    cairo_xcb_shm_mem_block_t *block;
+
+    if (clear)
+	clear_bits (pi, start, start + (1 << bits));
+
+    block = pi->blocks + start;
+    block->bits = bits;
+
+    cairo_list_add (&block->link, &pi->free[bits]);
+
+    pi->free_bytes += 1 << (bits + pi->min_bits);
+    if (bits > pi->max_free_bits)
+	pi->max_free_bits = bits;
+}
+
+/* Add a chunk to the free list */
+static void
+free_blocks (cairo_xcb_shm_mem_pool_t *pi,
+	     size_t first,
+	     size_t last,
+	     cairo_bool_t clear)
+{
+    size_t i;
+    size_t bits = 0;
+    size_t len = 1;
+
+    i = first;
+    while (i < last) {
+        /* To avoid cost quadratic in the number of different
+	 * blocks produced from this chunk of store, we have to
+	 * use the size of the previous block produced from this
+	 * chunk as the starting point to work out the size of the
+	 * next block we can produce. If you look at the binary
+	 * representation of the starting points of the blocks
+	 * produced, you can see that you first of all increase the
+	 * size of the blocks produced up to some maximum as the
+	 * address dealt with gets offsets added on which zap out
+	 * low order bits, then decrease as the low order bits of the
+	 * final block produced get added in. E.g. as you go from
+	 * 001 to 0111 you generate blocks
+	 * of size 001 at 001 taking you to 010
+	 * of size 010 at 010 taking you to 100
+	 * of size 010 at 100 taking you to 110
+	 * of size 001 at 110 taking you to 111
+	 * So the maximum total cost of the loops below this comment
+	 * is one trip from the lowest blocksize to the highest and
+	 * back again.
+	 */
+	while (bits < pi->num_sizes - 1) {
+	    size_t next_bits = bits + 1;
+	    size_t next_len = len << 1;
+
+	    if (i + next_bits > last) {
+		/* off end of chunk to be freed */
+	        break;
+	    }
+
+	    if (i & (next_len - 1)) /* block would not be on boundary */
+	        break;
+
+	    bits = next_bits;
+	    len = next_len;
+	}
+
+	do {
+	    if (i + len > last) /* off end of chunk to be freed */
+	        continue;
+
+	    if (i & (len - 1)) /* block would not be on boundary */
+	        continue;
+
+	    /* OK */
+	    break;
+
+	    bits--;
+	    len >>=1;
+	} while (len > 0);
+
+	if (len == 0)
+	    break;
+
+	free_bits (pi, i, bits, clear);
+	i += len;
+    }
+}
+
+static cairo_status_t
+_cairo_xcb_shm_mem_pool_init (cairo_xcb_shm_mem_pool_t *pi,
+			      size_t bytes,
+			      unsigned int min_bits,
+			      unsigned int num_sizes)
+{
+    size_t setBits;
+    int i;
+
+    assert ((((unsigned long) pi->base) & ((1 << min_bits) - 1)) == 0);
+    assert (num_sizes < ARRAY_LENGTH (pi->free));
+
+    pi->free_bytes = 0;
+    pi->max_bytes = bytes;
+    pi->max_free_bits = 0;
+
+    setBits = bytes >> min_bits;
+    pi->blocks = calloc (setBits, sizeof (cairo_xcb_shm_mem_block_t));
+    if (pi->blocks == NULL)
+	return _cairo_error (CAIRO_STATUS_NO_MEMORY);
+
+    pi->nBlocks = setBits;
+    pi->min_bits = min_bits;
+    pi->num_sizes = num_sizes;
+
+    for (i = 0; i < ARRAY_LENGTH (pi->free); i++)
+	cairo_list_init (&pi->free[i]);
+
+    pi->map = malloc ((setBits + 7) >> 3);
+    if (pi->map == NULL) {
+	free (pi->blocks);
+	return _cairo_error (CAIRO_STATUS_NO_MEMORY);
+    }
+
+    memset (pi->map, -1, (setBits + 7) >> 3);
+    clear_bits (pi, 0, setBits);
+
+    /* Now add all blocks to the free list */
+    free_blocks (pi, 0, setBits, 1);
+
+    return CAIRO_STATUS_SUCCESS;
+}
+
+static cairo_xcb_shm_mem_block_t *
+get_buddy (cairo_xcb_shm_mem_pool_t *pi,
+	   size_t offset,
+	   unsigned int bits)
+{
+    cairo_xcb_shm_mem_block_t *block;
+
+    assert (offset + (1 << bits) <= pi->nBlocks);
+
+    if (BITTEST (pi, offset + (1 << bits) - 1))
+	return NULL; /* buddy is allocated */
+
+    block = pi->blocks + offset;
+    if (block->bits != bits)
+	return NULL; /* buddy is partially allocated */
+
+    return block;
+}
+
+static void
+merge_buddies (cairo_xcb_shm_mem_pool_t *pi,
+	       cairo_xcb_shm_mem_block_t *block,
+	       unsigned int max_bits)
+{
+    size_t block_offset = block_offset = block - pi->blocks;
+    unsigned int bits = block->bits;
+
+    while (bits < max_bits - 1) {
+	/* while you can, merge two blocks and get a legal block size */
+	size_t buddy_offset = block_offset ^ (1 << bits);
+
+	block = get_buddy (pi, buddy_offset, bits);
+	if (block == NULL)
+	    break;
+
+	cairo_list_del (&block->link);
+
+	/* Merged block starts at buddy */
+	if (buddy_offset < block_offset)
+	    block_offset = buddy_offset;
+
+	bits++;
+    }
+
+    block = pi->blocks + block_offset;
+    block->bits = bits;
+    cairo_list_add (&block->link, &pi->free[bits]);
+
+    if (bits > pi->max_free_bits)
+	pi->max_free_bits = bits;
+}
+
+/* attempt to merge all available buddies up to a particular size */
+static unsigned int
+merge_bits (cairo_xcb_shm_mem_pool_t *pi,
+	    unsigned int max_bits)
+{
+    cairo_xcb_shm_mem_block_t *block, *buddy, *next;
+    unsigned int bits;
+
+    for (bits = 0; bits < max_bits - 1; bits++) {
+	cairo_list_foreach_entry_safe (block, next,
+				       cairo_xcb_shm_mem_block_t,
+				       &pi->free[bits],
+				       link)
+	{
+	    size_t buddy_offset = (block - pi->blocks) ^ (1 << bits);
+
+	    buddy = get_buddy (pi, buddy_offset, bits);
+	    if (buddy == NULL)
+		continue;
+
+	    if (buddy == next) {
+		next = cairo_container_of (buddy->link.next,
+					   cairo_xcb_shm_mem_block_t,
+					   link);
+	    }
+
+	    cairo_list_del (&block->link);
+	    merge_buddies (pi, block, max_bits);
+	}
+    }
+
+    return pi->max_free_bits;
+}
+
+/* find store for 1 << bits blocks */
+static void *
+buddy_malloc (cairo_xcb_shm_mem_pool_t *pi,
+	      unsigned int bits)
+{
+    unsigned int b;
+    size_t offset;
+    size_t past;
+    cairo_xcb_shm_mem_block_t *block;
+
+    if (bits > pi->max_free_bits && bits > merge_bits (pi, bits))
+	return NULL;
+
+    /* Find a list with blocks big enough on it */
+    block = NULL;
+    for (b = bits; b <= pi->max_free_bits; b++) {
+	if (! cairo_list_is_empty (&pi->free[b])) {
+	    block = cairo_list_first_entry (&pi->free[b],
+					    cairo_xcb_shm_mem_block_t,
+					    link);
+	    break;
+	}
+    }
+    assert (block != NULL);
+
+    cairo_list_del (&block->link);
+
+    while (cairo_list_is_empty (&pi->free[pi->max_free_bits])) {
+	if (--pi->max_free_bits == 0)
+	    break;
+    }
+
+    /* Mark end of allocated area */
+    offset = block - pi->blocks;
+    past = offset + (1 << bits);
+    BITSET (pi, past - 1);
+    block->bits = bits;
+
+    /* If we used a larger free block than we needed, free the rest */
+    pi->free_bytes -= 1 << (b + pi->min_bits);
+    free_blocks (pi, past, offset + (1 << b), 0);
+
+    return pi->base + ((block - pi->blocks) << pi->min_bits);
+}
+
+static void *
+_cairo_xcb_shm_mem_pool_malloc (cairo_xcb_shm_mem_pool_t *pi,
+				size_t bytes)
+{
+    unsigned int bits;
+    size_t size;
+
+    size = 1 << pi->min_bits;
+    for (bits = 0; size < bytes; bits++)
+	size <<= 1;
+    if (bits >= pi->num_sizes)
+	return NULL;
+
+    return buddy_malloc (pi, bits);
+}
+
+static void
+_cairo_xcb_shm_mem_pool_free (cairo_xcb_shm_mem_pool_t *pi,
+			      char *storage)
+{
+    size_t block_offset;
+    cairo_xcb_shm_mem_block_t *block;
+
+    block_offset = (storage - pi->base) >> pi->min_bits;
+    block = pi->blocks + block_offset;
+
+    BITCLEAR (pi, block_offset + ((1 << block->bits) - 1));
+    pi->free_bytes += 1 << (block->bits + pi->min_bits);
+
+    merge_buddies (pi, block, pi->num_sizes);
+}
+
+static void
+_cairo_xcb_shm_mem_pool_destroy (cairo_xcb_shm_mem_pool_t *pool)
+{
+    shmdt (pool->base);
+    cairo_list_del (&pool->link);
+
+    free (pool->map);
+    free (pool->blocks);
+    free (pool);
+}
+
+cairo_int_status_t
+_cairo_xcb_connection_allocate_shm_info (cairo_xcb_connection_t *connection,
+					 size_t size,
+					 cairo_xcb_shm_info_t **shm_info_out)
+{
+    cairo_xcb_shm_info_t *shm_info;
+    cairo_xcb_shm_mem_pool_t *pool, *next;
+    size_t bytes, maxbits = 16, minbits = 8;
+    void *mem = NULL;
+    cairo_status_t status;
+
+    assert (connection->flags & CAIRO_XCB_HAS_SHM);
+
+    CAIRO_MUTEX_LOCK (connection->shm_mutex);
+    cairo_list_foreach_entry_safe (pool, next, cairo_xcb_shm_mem_pool_t,
+				   &connection->shm_pools, link)
+    {
+	if (pool->free_bytes > size) {
+	    mem = _cairo_xcb_shm_mem_pool_malloc (pool, size);
+	    if (mem != NULL) {
+		/* keep the active pools towards the front */
+		cairo_list_move (&pool->link, &connection->shm_pools);
+		goto allocate_shm_info;
+	    }
+	}
+	/* scan for old, unused pools */
+	if (pool->free_bytes == pool->max_bytes) {
+	    _cairo_xcb_connection_shm_detach (connection,
+					      pool->shmseg);
+	    _cairo_xcb_shm_mem_pool_destroy (pool);
+	}
+    }
+
+    pool = malloc (sizeof (cairo_xcb_shm_mem_pool_t));
+    if (unlikely (pool == NULL)) {
+	CAIRO_MUTEX_UNLOCK (connection->shm_mutex);
+	return _cairo_error (CAIRO_STATUS_NO_MEMORY);
+    }
+
+    bytes = 1 << maxbits;
+    while (bytes <= size)
+	bytes <<= 1, maxbits++;
+    bytes <<= 3;
+
+    do {
+	pool->shmid = shmget (IPC_PRIVATE, bytes, IPC_CREAT | 0600);
+	if (pool->shmid != -1)
+	    break;
+
+	if (errno == EINVAL && bytes > size) {
+	    bytes >>= 1;
+	    continue;
+	}
+    } while (FALSE);
+    if (pool->shmid == -1) {
+	int err = errno;
+	if (! (err == EINVAL || err == ENOMEM))
+	    connection->flags &= ~CAIRO_XCB_HAS_SHM;
+	free (pool);
+	CAIRO_MUTEX_UNLOCK (connection->shm_mutex);
+	return CAIRO_INT_STATUS_UNSUPPORTED;
+    }
+
+    pool->base = shmat (pool->shmid, NULL, 0);
+    if (unlikely (pool->base == (char *) -1)) {
+	shmctl (pool->shmid, IPC_RMID, NULL);
+	free (pool);
+	CAIRO_MUTEX_UNLOCK (connection->shm_mutex);
+	return _cairo_error (CAIRO_STATUS_NO_MEMORY);
+    }
+
+    status = _cairo_xcb_shm_mem_pool_init (pool,
+					   bytes,
+					   minbits,
+					   maxbits - minbits + 1);
+    if (unlikely (status)) {
+	shmdt (pool->base);
+	free (pool);
+	CAIRO_MUTEX_UNLOCK (connection->shm_mutex);
+	return status;
+    }
+
+    pool->shmseg = _cairo_xcb_connection_shm_attach (connection, pool->shmid, FALSE);
+    shmctl (pool->shmid, IPC_RMID, NULL);
+
+    cairo_list_add (&pool->link, &connection->shm_pools);
+    mem = _cairo_xcb_shm_mem_pool_malloc (pool, size);
+
+  allocate_shm_info:
+    shm_info = _cairo_freepool_alloc (&connection->shm_info_freelist);
+    if (unlikely (shm_info == NULL)) {
+	_cairo_xcb_shm_mem_pool_free (pool, mem);
+	CAIRO_MUTEX_UNLOCK (connection->shm_mutex);
+	return _cairo_error (CAIRO_STATUS_NO_MEMORY);
+    }
+
+    shm_info->connection = connection;
+    shm_info->pool = pool;
+    shm_info->shm = pool->shmseg;
+    shm_info->offset = (char *) mem - (char *) pool->base;
+    shm_info->mem = mem;
+
+    /* scan for old, unused pools */
+    cairo_list_foreach_entry_safe (pool, next, cairo_xcb_shm_mem_pool_t,
+				   &connection->shm_pools, link)
+    {
+	if (pool->free_bytes == pool->max_bytes) {
+	    _cairo_xcb_connection_shm_detach (connection,
+					      pool->shmseg);
+	    _cairo_xcb_shm_mem_pool_destroy (pool);
+	}
+    }
+    CAIRO_MUTEX_UNLOCK (connection->shm_mutex);
+
+    *shm_info_out = shm_info;
+    return CAIRO_STATUS_SUCCESS;
+}
+
+void
+_cairo_xcb_shm_info_destroy (cairo_xcb_shm_info_t *shm_info)
+{
+    cairo_xcb_connection_t *connection = shm_info->connection;
+
+    CAIRO_MUTEX_LOCK (connection->shm_mutex);
+
+    _cairo_xcb_shm_mem_pool_free (shm_info->pool, shm_info->mem);
+    _cairo_freepool_free (&connection->shm_info_freelist, shm_info);
+
+    /* scan for old, unused pools - hold at least one in reserve */
+    if (! cairo_list_is_singular (&connection->shm_pools) &&
+	_cairo_xcb_connection_take_socket (connection) == CAIRO_STATUS_SUCCESS)
+    {
+	cairo_xcb_shm_mem_pool_t *pool, *next;
+	cairo_list_t head;
+
+	cairo_list_init (&head);
+	cairo_list_move (connection->shm_pools.next, &head);
+
+	cairo_list_foreach_entry_safe (pool, next, cairo_xcb_shm_mem_pool_t,
+				       &connection->shm_pools, link)
+	{
+	    if (pool->free_bytes == pool->max_bytes) {
+		_cairo_xcb_connection_shm_detach (connection, pool->shmseg);
+		_cairo_xcb_shm_mem_pool_destroy (pool);
+	    }
+	}
+
+	cairo_list_move (head.next, &connection->shm_pools);
+    }
+
+    CAIRO_MUTEX_UNLOCK (connection->shm_mutex);
+}
+
+void
+_cairo_xcb_connection_shm_mem_pools_fini (cairo_xcb_connection_t *connection)
+{
+    while (! cairo_list_is_empty (&connection->shm_pools)) {
+	_cairo_xcb_shm_mem_pool_destroy (cairo_list_first_entry (&connection->shm_pools,
+								 cairo_xcb_shm_mem_pool_t,
+								 link));
+    }
+}