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[cairo] Keep a small stash of cairo contexts

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A cairo context is meant to be extremely cheap to create such that it can
be used in transient expose events. Thus these are allocated reasonably
frequently and show up malloc profiles.
This commit is contained in:
Chris Wilson 2009-06-07 17:01:57 +01:00
parent f08fe5b550
commit 7d8a0a1cdd
1 changed files with 49 additions and 2 deletions
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51
src/cairo.c
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@ -117,6 +117,53 @@ _cairo_set_error (cairo_t *cr, cairo_status_t status)
status = _cairo_error (status);
}
#if HAS_ATOMIC_OPS
/* We keep a small stash of contexts to reduce malloc pressure */
#define CAIRO_STASH_SIZE 4
static struct {
cairo_t pool[CAIRO_STASH_SIZE];
int occupied;
} _context_stash;
static cairo_t *
_context_get (void)
{
int avail, old, new;
do {
old = _context_stash.occupied;
avail = ffs (~old) - 1;
if (avail >= CAIRO_STASH_SIZE)
return malloc (sizeof (cairo_t));
new = old | (1 << avail);
} while (_cairo_atomic_int_cmpxchg (&_context_stash.occupied, old, new) != old);
return &_context_stash.pool[avail];
}
static void
_context_put (cairo_t *cr)
{
int old, new, avail;
if (cr < &_context_stash.pool[0] ||
cr >= &_context_stash.pool[CAIRO_STASH_SIZE])
{
return free (cr);
}
avail = ~(1 << (cr - &_context_stash.pool[0]));
do {
old = _context_stash.occupied;
new = old & avail;
} while (_cairo_atomic_int_cmpxchg (&_context_stash.occupied, old, new) != old);
}
#else
#define _context_get() malloc (sizeof (cairo_t))
#define _context_put(cr) free (cr)
#endif
/**
* cairo_create:
* @target: target surface for the context
@ -150,7 +197,7 @@ cairo_create (cairo_surface_t *target)
if (target && target->status == CAIRO_STATUS_NO_MEMORY)
return (cairo_t *) &_cairo_nil;
cr = malloc (sizeof (cairo_t));
cr = _context_get ();
if (unlikely (cr == NULL)) {
status = _cairo_error (CAIRO_STATUS_NO_MEMORY);
return (cairo_t *) &_cairo_nil;
@ -248,7 +295,7 @@ cairo_destroy (cairo_t *cr)
_cairo_user_data_array_fini (&cr->user_data);
free (cr);
_context_put (cr);
}
slim_hidden_def (cairo_destroy);