[open-ils-commits] r16439 - trunk/Open-ILS/src/sql/Pg (miker)

[svn at svn.open-ils.org]

Author: miker
Date: 2010-05-16 16:19:09 -0400 (Sun, 16 May 2010)
New Revision: 16439

Added:
   trunk/Open-ILS/src/sql/Pg/pgmemcache-perm_cache.sql
Log:
Optional pgmemcache-based caching of permission checks.  Significantly speeds permission testing for common checks against heavy-use users, such as circulation-related permissions.

Added: trunk/Open-ILS/src/sql/Pg/pgmemcache-perm_cache.sql
===================================================================
--- trunk/Open-ILS/src/sql/Pg/pgmemcache-perm_cache.sql	                        (rev 0)
+++ trunk/Open-ILS/src/sql/Pg/pgmemcache-perm_cache.sql	2010-05-16 20:19:09 UTC (rev 16439)
@@ -0,0 +1,126 @@
+BEGIN;
+
+/*
+ * Use pgmemcache and memcached to increase the speed of permission tests
+ * ----------------------------------------------------------------------
+ *
+ * This set of fuctions allows the use of memcached as a caching mechanism for
+ * permission checks.  It is transparent an optional.  If memcache is not set
+ * up, either by not running or the lack of the pgmemcache postgres addon,
+ * then the default, existing behaviour is preserved and live database queries
+ * are used to test all permissions.
+ *
+ *
+ * On postgres 8.2 and before, pgmemcache 1.1 is required.  For this older
+ * version of pgmemcache, configuration of memcached servers is performed by
+ * stored procs.  Therefore, the installer of this Evergreen addition must
+ * edit the stored proc called permission.old_mc_servers() to initialize the
+ * appropriate set of memcached servers.  For simple, single-database
+ * installations, the default of 'localhost' is most likely the desired
+ * setting.
+ *
+ *
+ * On postgres 8.3 and later, pgmemcache 2.x is required.  In this new
+ * pgmemecache the server configuration is controlled from within the
+ * postgresql.conf file via user-defined variables read by the pgmemcache
+ * intialization routines.  Please see the README for pgmemcache at
+ *
+ *    http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pgmemcache/pgmemcache/README.pgmemcache?rev=1.21&content-type=text/plain
+ *
+ * or in the release tarball that was installed for details on configuration.
+ *
+ *
+ * TODO: Make the cache timout configurable via a global setting for EG 2.0
+ *
+ */
+
+CREATE OR REPLACE FUNCTION permission.old_mc_servers() RETURNS BOOL AS $f$
+BEGIN
+    PERFORM memcache_server_add('localhost', '11211');
+END;
+$f$ LANGUAGE PLPGSQL;
+
+CREATE OR REPLACE FUNCTION permission.mc_init() RETURNS BOOL AS $f$
+DECLARE
+    old_memcache BOOL;
+BEGIN
+    old_memcache = FALSE;
+    IF REGEXP_REPLACE(VERSION(),E'^.+?(\\d+\\.\\d+).*?$',E'\\1')::FLOAT < 8.3 THEN
+        old_memcache = TRUE;
+        IF memcache_init() THEN
+            PERFORM permission.old_mc_servers();
+        END IF;
+        -- RAISE NOTICE 'Old postgres, must be old pgmemcache';
+    ELSE
+        BEGIN
+            old_memcache = TRUE; 
+            IF memcache_init() THEN
+                PERFORM permission.old_mc_servers();
+            END IF;
+            -- RAISE NOTICE 'New postgres, but old pgmemcache';
+        EXCEPTION WHEN OTHERS THEN
+            old_memcache = FALSE;
+        END;
+    END IF;
+
+    IF NOT old_memcache THEN
+        PERFORM current_setting('pgmemcache.default_servers');
+        -- RAISE NOTICE 'New postgres, new pgmemcache';
+    END IF;
+
+    -- no exception, we're good
+    RETURN TRUE;
+EXCEPTION WHEN OTHERS THEN
+    RETURN FALSE;
+END;
+$f$ LANGUAGE PLPGSQL;
+
+CREATE OR REPLACE FUNCTION permission.set_cached_perm( iusr INT, tperm TEXT, iorg INT, bool_value BOOL, timeout INTERVAL ) RETURNS BOOL AS $f$
+BEGIN
+    IF permission.mc_init() THEN
+        -- RAISE NOTICE 'Setting perm cache';
+        IF bool_value THEN
+            EXECUTE $$SELECT memcache_set('oils_permcache_$$ || iusr || tperm || iorg || $$', 't',$$ || quote_literal(timeout) || $$::INTERVAL);$$;
+        ELSE
+            EXECUTE $$SELECT memcache_set('oils_permcache_$$ || iusr || tperm || iorg || $$', 'f',$$ || quote_literal(timeout) || $$::INTERVAL);$$;
+        END IF;
+    END IF;
+
+    RETURN bool_value;
+EXCEPTION WHEN OTHERS THEN
+    RETURN bool_value;
+END;
+$f$ LANGUAGE PLPGSQL STABLE;
+
+CREATE OR REPLACE FUNCTION permission.set_cached_perm( iusr INT, tperm TEXT, iorg INT, bool_value BOOL ) RETURNS BOOL AS $f$
+    SELECT permission.set_cached_perm( $1, $2, $3, $4, '10 minutes'::INTERVAL);
+$f$ LANGUAGE SQL;
+
+CREATE OR REPLACE FUNCTION permission.check_cached_perm( iusr INT, tperm TEXT, iorg INT ) RETURNS BOOL AS $f$
+DECLARE
+    cached_value  RECORD;
+    bool_value    BOOL;
+BEGIN
+    IF permission.mc_init() THEN
+        -- RAISE NOTICE 'Getting perm from cache';
+        EXECUTE $$SELECT memcache_get('oils_permcache_$$ || iusr || tperm || iorg || $$') AS x;$$ INTO cached_value;
+        bool_value := cached_value.x = 't';
+    END IF;
+
+    RETURN bool_value;
+EXCEPTION WHEN OTHERS THEN
+    RETURN NULL;
+END;
+$f$ LANGUAGE PLPGSQL STABLE;
+
+CREATE OR REPLACE FUNCTION permission.usr_has_perm ( INT, TEXT, INT ) RETURNS BOOL AS $f$
+    SELECT  CASE
+            WHEN permission.check_cached_perm( $1, $2, $3 ) IS NOT NULL THEN permission.check_cached_perm( $1, $2, $3 )
+            WHEN permission.set_cached_perm($1, $2, $3, permission.usr_has_home_perm( $1, $2, $3 )) THEN TRUE
+            WHEN permission.set_cached_perm($1, $2, $3, permission.usr_has_work_perm( $1, $2, $3 )) THEN TRUE
+            ELSE FALSE
+        END;
+$f$ LANGUAGE SQL;
+
+COMMIT;
+