137 lines
4 KiB
C
137 lines
4 KiB
C
/*
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filehandlecache - filehandle management and caching
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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 the
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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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#include "lib/safeclib.h"
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#include "backend/file.h"
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#include "backend/filehandlecache.h"
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NOBUG_DEFINE_FLAG_PARENT (filehandlecache, file_all);
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/* errors */
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LUMIERA_ERROR_DEFINE (FILEHANDLECACHE_NOHANDLE, "No filehandle available");
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LumieraFilehandlecache lumiera_fhcache = NULL;
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void
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lumiera_filehandlecache_new (int max_entries)
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{
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REQUIRE (!lumiera_fhcache, "Filehandlecache already initialized");
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NOBUG_INIT_FLAG (filehandlecache);
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lumiera_fhcache = lumiera_malloc (sizeof (lumiera_filehandlecache));
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lumiera_mrucache_init (&lumiera_fhcache->cache, lumiera_filehandle_destroy_node);
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lumiera_fhcache->available = max_entries;
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lumiera_fhcache->checked_out = 0;
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lumiera_mutex_init (&lumiera_fhcache->lock, "filehandlecache", &NOBUG_FLAG (filehandlecache));
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}
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void
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lumiera_filehandlecache_delete (void)
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{
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if (lumiera_fhcache)
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{
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REQUIRE (!lumiera_fhcache->checked_out, "Filehandles in use at shutdown");
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lumiera_mrucache_destroy (&lumiera_fhcache->cache);
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lumiera_mutex_destroy (&lumiera_fhcache->lock, &NOBUG_FLAG (filehandlecache));
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lumiera_free (lumiera_fhcache);
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lumiera_fhcache = NULL;
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}
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}
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LumieraFilehandle
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lumiera_filehandlecache_handle_acquire (LumieraFilehandlecache self, LumieraFiledescriptor desc)
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{
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TRACE (filehandlecache);
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LumieraFilehandle ret = NULL;
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LUMIERA_MUTEX_SECTION (filehandlecache, &self->lock)
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{
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if (self->available <= 0 && self->cache.cached)
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{
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/* pop a filehandle from cache */
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ret = lumiera_mrucache_pop (&self->cache);
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if (self->available < 0)
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/* try to free overallocated filehandles */
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self->available -= self->available + lumiera_mrucache_age (&self->cache, -self->available);
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}
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else
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{
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/* allocate new filehandle if we are below the limit or no cached handles are available (overallocating) */
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ret = lumiera_filehandle_new ();
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if (!ret)
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LUMIERA_ERROR_SET (filehandlecache, FILEHANDLECACHE_NOHANDLE);
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else
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--self->available;
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}
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ret->use_cnt = 1;
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ret->descriptor = desc;
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desc->handle = ret;
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++self->checked_out;
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}
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return ret;
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}
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LumieraFilehandle
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lumiera_filehandlecache_checkout (LumieraFilehandlecache self, LumieraFilehandle handle)
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{
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REQUIRE (self);
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REQUIRE (handle);
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/* This function is called with the associated descriptor locked, nothing can modify 'handle' */
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if (!handle->use_cnt)
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{
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/* lock cache and checkout */
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LUMIERA_MUTEX_SECTION (filehandlecache, &self->lock)
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{
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lumiera_mrucache_checkout (&self->cache, &handle->cachenode);
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}
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}
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++handle->use_cnt;
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++self->checked_out;
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return handle;
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}
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void
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lumiera_filehandlecache_checkin (LumieraFilehandlecache self, LumieraFilehandle handle)
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{
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REQUIRE (self);
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REQUIRE (handle);
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REQUIRE (handle->use_cnt);
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/* This function is called with the associated descriptor locked, nothing can modify 'self' */
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if (!--handle->use_cnt)
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{
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/* lock cache and checin */
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LUMIERA_MUTEX_SECTION (filehandlecache, &self->lock)
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{
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--self->checked_out;
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lumiera_mrucache_checkin (&self->cache, &handle->cachenode);
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}
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}
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}
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