168 lines
4.2 KiB
C
168 lines
4.2 KiB
C
/*
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MMapings - manage ranges of mmaped areas on a file descriptor
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Copyright (C) Lumiera.org
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2008, Christian Thaeter <ct@pipapo.org>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of
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the License, or (at your option) any later version.
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This program 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
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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* *****************************************************/
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/** @file mmapings.c
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** Implementation of organisational data of memory mapped file regions
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** @todo development in this area is stalled since 2010
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*/
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#include "include/logging.h"
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#include "lib/mutex.h"
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#include "lib/safeclib.h"
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#include "vault/mmapings.h"
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#include "vault/mmapcache.h"
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LumieraMMapings
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lumiera_mmapings_init (LumieraMMapings self, LumieraFile file, size_t chunksize, size_t bias)
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{
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TRACE (mmapings_dbg);
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REQUIRE (!file->descriptor->mmapings);
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llist_init (&self->mmaps);
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self->descriptor = file->descriptor;
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TODO("align chunksize on 2's exponent or error out?");
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self->chunksize = chunksize;
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self->bias = bias;
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lumiera_mutex_init (&self->lock, "mmapings", &NOBUG_FLAG(mutex_dbg), NOBUG_CONTEXT);
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return self;
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}
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LumieraMMapings
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lumiera_mmapings_destroy (LumieraMMapings self)
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{
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TRACE (mmapings_dbg);
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if (!self)
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return NULL;
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LLIST_WHILE_TAIL (&self->mmaps, node)
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{
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LumieraMMap map = LLIST_TO_STRUCTP (node, lumiera_mmap, searchnode);
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REQUIRE (map->refcnt == 0, "map still in use: %p", map);
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lumiera_mmap_delete (map);
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}
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lumiera_mutex_destroy (&self->lock, &NOBUG_FLAG(mutex_dbg), NOBUG_CONTEXT);
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return self;
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}
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LumieraMMapings
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lumiera_mmapings_new (LumieraFile file, size_t chunksize, size_t bias)
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{
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TRACE (mmapings_dbg);
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LumieraMMapings self = lumiera_malloc (sizeof (*self));
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return lumiera_mmapings_init (self, file, chunksize, bias);
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}
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void
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lumiera_mmapings_delete (LumieraMMapings self)
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{
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TRACE (mmapings_dbg);
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free (lumiera_mmapings_destroy (self));
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}
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LumieraMMap
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lumiera_mmapings_mmap_acquire (LumieraMMapings self, LumieraFile file, off_t start, size_t size)
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{
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TRACE (mmapings_dbg);
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LumieraMMap ret = NULL;
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if (self)
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LUMIERA_MUTEX_SECTION (mutex_sync, &self->lock)
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{
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/* find first matching mmap, crude way */
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LLIST_FOREACH (&self->mmaps, node)
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{
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////////////TODO improve the algorithm used here: choose mmaps by size, move mfu to head etc...
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LumieraMMap mmap = LLIST_TO_STRUCTP (node, lumiera_mmap, searchnode);
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if (mmap->size >= size && mmap->start <= start && mmap->start+mmap->size >= start+size)
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{
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ret = mmap;
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break;
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}
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}
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/* found? */
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if (ret)
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{
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if (!ret->refcnt)
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/* in cache, needs to be checked out */
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lumiera_mmapcache_checkout (ret);
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++ret->refcnt;
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}
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else
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{
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/* create new mmap */
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TRACE (mmapings_dbg, "mmap not found, creating");
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ret = lumiera_mmap_new (file, start, size);
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llist_insert_head (&self->mmaps, &ret->searchnode);
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TODO ("sort search list?");
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}
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PLANNED ("use refmap for finer grained refcounting");
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ENSURE (llist_is_empty(&ret->cachenode));
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}
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return ret;
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}
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void
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lumiera_mmapings_release_mmap (LumieraMMapings self, LumieraMMap map)
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{
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TRACE (mmapings_dbg);
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if (self)
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LUMIERA_MUTEX_SECTION (mutex_sync, &self->lock)
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{
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if (!--map->refcnt)
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{
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TRACE (mmapcache_dbg, "checkin");
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lumiera_mmapcache_checkin (map);
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}
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}
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}
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/*
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// Local Variables:
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// mode: C
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// c-file-style: "gnu"
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// indent-tabs-mode: nil
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// End:
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*/
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