1 files changed, 231 insertions, 0 deletions
diff --git a/libpkgconf/cache.c b/libpkgconf/cache.c
new file mode 100644
index 000000000000..883c8df7127e
--- /dev/null
+++ b/libpkgconf/cache.c
@@ -0,0 +1,231 @@
+/*
+ * 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>
+#include <libpkgconf/libpkgconf.h>
+
+#include <assert.h>
+
+/*
+ * !doc
+ *
+ * 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, SIZE_FMT_SPECIFIER": %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 *
+ */
+pkgconf_pkg_t *
+pkgconf_cache_lookup(pkgconf_client_t *client, const char *id)
+{
+	if (client->cache_table == NULL)
+		return NULL;
+
+	pkgconf_pkg_t **pkg;
+
+	pkg = bsearch(id, client->cache_table,
+		client->cache_count, sizeof (void *),
+		cache_member_cmp);
+
+	if (pkg != NULL)
+	{
+		PKGCONF_TRACE(client, "found: %s @%p", id, *pkg);
+		return pkgconf_pkg_ref(client, *pkg);
+	}
+
+	PKGCONF_TRACE(client, "miss: %s", id);
+	return NULL;
+}
+
+/*
+ * !doc
+ *
+ * .. c:function:: void pkgconf_cache_add(pkgconf_client_t *client, pkgconf_pkg_t *pkg)
+ *
+ *    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
+ */
+void
+pkgconf_cache_add(pkgconf_client_t *client, pkgconf_pkg_t *pkg)
+{
+	if (pkg == NULL)
+		return;
+
+	pkgconf_pkg_ref(client, pkg);
+
+	PKGCONF_TRACE(client, "added @%p to cache", pkg);
+
+	/* mark package as cached */
+	pkg->flags |= PKGCONF_PKG_PROPF_CACHED;
+
+	++client->cache_count;
+	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);
+}
+
+/*
+ * !doc
+ *
+ * .. c:function:: void pkgconf_cache_remove(pkgconf_client_t *client, pkgconf_pkg_t *pkg)
+ *
+ *    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
+ */
+void
+pkgconf_cache_remove(pkgconf_client_t *client, pkgconf_pkg_t *pkg)
+{
+	if (client->cache_table == NULL)
+		return;
+
+	if (pkg == NULL)
+		return;
+
+	if (!(pkg->flags & PKGCONF_PKG_PROPF_CACHED))
+		return;
+
+	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;
+	}
+}
+
+/*
+ * !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;
+
+	PKGCONF_TRACE(client, "cleared package cache");
+}