pkgconf/libpkgconf/cache.c

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/*
* cache.c
* package object cache
*
* Copyright (c) 2013 pkgconf authors (see AUTHORS).
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* This software is provided 'as is' and without any warranty, express or
* implied. In no event shall the authors be liable for any damages arising
* from the use of this software.
*/
#include <libpkgconf/stdinc.h>
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#include <libpkgconf/libpkgconf.h>
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#include <assert.h>
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/*
* !doc
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*
* libpkgconf `cache` module
* =========================
*
* The libpkgconf `cache` module manages a package/module object cache, allowing it to
* avoid loading duplicate copies of a package/module.
*
* A cache is tied to a specific pkgconf client object, so package objects should not
* be shared across threads.
*/
static int
cache_member_cmp(const void *a, const void *b)
{
const char *key = a;
const pkgconf_pkg_t *pkg = *(void **) b;
return strcmp(key, pkg->id);
}
static int
cache_member_sort_cmp(const void *a, const void *b)
{
const pkgconf_pkg_t *pkgA = *(void **) a;
const pkgconf_pkg_t *pkgB = *(void **) b;
if (pkgA == NULL)
return 1;
if (pkgB == NULL)
return -1;
return strcmp(pkgA->id, pkgB->id);
}
static void
cache_dump(const pkgconf_client_t *client)
{
size_t i;
PKGCONF_TRACE(client, "dumping package cache contents");
for (i = 0; i < client->cache_count; i++)
{
const pkgconf_pkg_t *pkg = client->cache_table[i];
PKGCONF_TRACE(client, "%zu: %p(%s)",
i, pkg, pkg == NULL ? "NULL" : pkg->id);
}
}
/*
* !doc
*
* .. c:function:: pkgconf_pkg_t *pkgconf_cache_lookup(const pkgconf_client_t *client, const char *id)
*
* Looks up a package in the cache given an `id` atom,
* such as ``gtk+-3.0`` and returns the already loaded version
* if present.
*
* :param pkgconf_client_t* client: The client object to access.
* :param char* id: The package atom to look up in the client object's cache.
* :return: A package object if present, else ``NULL``.
* :rtype: pkgconf_pkg_t *
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*/
pkgconf_pkg_t *
pkgconf_cache_lookup(pkgconf_client_t *client, const char *id)
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{
if (client->cache_table == NULL)
return NULL;
pkgconf_pkg_t **pkg;
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pkg = bsearch(id, client->cache_table,
client->cache_count, sizeof (void *),
cache_member_cmp);
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if (pkg != NULL)
{
PKGCONF_TRACE(client, "found: %s @%p", id, *pkg);
return pkgconf_pkg_ref(client, *pkg);
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}
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PKGCONF_TRACE(client, "miss: %s", id);
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return NULL;
}
/*
* !doc
*
* .. c:function:: void pkgconf_cache_add(pkgconf_client_t *client, pkgconf_pkg_t *pkg)
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*
* Adds an entry for the package to the package cache.
* The cache entry must be removed if the package is freed.
*
* :param pkgconf_client_t* client: The client object to modify.
* :param pkgconf_pkg_t* pkg: The package object to add to the client object's cache.
* :return: nothing
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*/
void
pkgconf_cache_add(pkgconf_client_t *client, pkgconf_pkg_t *pkg)
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{
if (pkg == NULL)
return;
pkgconf_pkg_ref(client, pkg);
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PKGCONF_TRACE(client, "added @%p to cache", pkg);
/* mark package as cached */
pkg->flags |= PKGCONF_PKG_PROPF_CACHED;
++client->cache_count;
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client->cache_table = pkgconf_reallocarray(client->cache_table,
client->cache_count, sizeof (void *));
client->cache_table[client->cache_count - 1] = pkg;
qsort(client->cache_table, client->cache_count,
sizeof(void *), cache_member_sort_cmp);
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}
/*
* !doc
*
* .. c:function:: void pkgconf_cache_remove(pkgconf_client_t *client, pkgconf_pkg_t *pkg)
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*
* Deletes a package from the client object's package cache.
*
* :param pkgconf_client_t* client: The client object to modify.
* :param pkgconf_pkg_t* pkg: The package object to remove from the client object's cache.
* :return: nothing
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*/
void
pkgconf_cache_remove(pkgconf_client_t *client, pkgconf_pkg_t *pkg)
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{
if (client->cache_table == NULL)
return;
if (pkg == NULL)
return;
if (!(pkg->flags & PKGCONF_PKG_PROPF_CACHED))
return;
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PKGCONF_TRACE(client, "removed @%p from cache", pkg);
pkgconf_pkg_t **slot;
slot = bsearch(pkg->id, client->cache_table,
client->cache_count, sizeof (void *),
cache_member_cmp);
if (slot == NULL)
return;
(*slot)->flags &= ~PKGCONF_PKG_PROPF_CACHED;
pkgconf_pkg_unref(client, *slot);
*slot = NULL;
qsort(client->cache_table, client->cache_count,
sizeof(void *), cache_member_sort_cmp);
if (client->cache_table[client->cache_count - 1] != NULL)
{
PKGCONF_TRACE(client, "end of cache table refers to %p, not NULL",
client->cache_table[client->cache_count - 1]);
cache_dump(client);
abort();
}
client->cache_count--;
if (client->cache_count > 0)
{
client->cache_table = pkgconf_reallocarray(client->cache_table,
client->cache_count, sizeof(void *));
}
else
{
free(client->cache_table);
client->cache_table = NULL;
}
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}
/*
* !doc
*
* .. c:function:: void pkgconf_cache_free(pkgconf_client_t *client)
*
* Releases all resources related to a client object's package cache.
* This function should only be called to clear a client object's package cache,
* as it may release any package in the cache.
*
* :param pkgconf_client_t* client: The client object to modify.
*/
void
pkgconf_cache_free(pkgconf_client_t *client)
{
if (client->cache_table == NULL)
return;
while (client->cache_count > 0)
pkgconf_cache_remove(client, client->cache_table[0]);
free(client->cache_table);
client->cache_table = NULL;
client->cache_count = 0;
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PKGCONF_TRACE(client, "cleared package cache");
}