Source Code for Module base.includes.cache

  1  #!/usr/bin/env python 
  2  # $Id: cache.inc,v 1.20 2008/07/02 20:42:25 dries Exp $ 
  3   
  4  """ 
  5    Cache functions 
  6   
  7    @package includes 
  8    @see <a href='http://drupy.net'>Drupy Homepage</a> 
  9    @see <a href='http://drupal.org'>Drupal Homepage</a> 
 10    @note Drupy is a port of the Drupal project. 
 11    @note This file was ported from Drupal's includes/cache.inc 
 12    @author Brendon Crawford 
 13    @copyright 2008 Brendon Crawford 
 14    @contact message144 at users dot sourceforge dot net 
 15    @created 2008-01-10 
 16    @version 0.1 
 17    @note License: 
 18   
 19      This program is free software; you can redistribute it and/or 
 20      modify it under the terms of the GNU General Public License 
 21      as published by the Free Software Foundation; either version 2 
 22      of the License, or (at your option) any later version. 
 23   
 24      This program is distributed in the hope that it will be useful, 
 25      but WITHOUT ANY WARRANTY; without even the implied warranty of 
 26      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 27      GNU General Public License for more details. 
 28   
 29      You should have received a copy of the GNU General Public License 
 30      along with this program; if not, write to: 
 31       
 32      The Free Software Foundation, Inc., 
 33      51 Franklin Street, Fifth Floor, 
 34      Boston, MA  02110-1301, 
 35      USA 
 36  """ 
 37   
 38  __version__ = "$Revision: 1 $" 
 39   
 40  from lib.drupy import DrupyPHP as php 
 41  import bootstrap as lib_bootstrap 
 42  import database as lib_database 
 43   
 44 -def get(cid, table = 'cache'): 
 45    """ 
 46     Return data from the persistent cache. Data may be stored as  
 47     either plain text or as serialized data. 
 48     cache_get will automatically return unserialized objects and arrays. 
 49     
 50     @param cid 
 51       The cache ID of the data to retrieve. 
 52     @param table 
 53       The table table to store the data in. 
 54       Valid core values are 'cache_filter', 
 55       'cache_menu', 'cache_page', or 'cache' for the default cache. 
 56     @return The cache or FALSE on failure. 
 57    """ 
 58    # Garbage collection necessary when enforcing a minimum cache lifetime 
 59    cache_flush = lib_bootstrap.variable_get('cache_flush', 0); 
 60    if (cache_flush and (cache_flush + \ 
 61        variable_get('cache_lifetime', 0) <= php.time_())): 
 62      # Reset the variable immediately to prevent a meltdown in heavy 
 63      # load situations. 
 64      variable_set('cache_flush', 0); 
 65      # Time to php.flush old cache data 
 66      lib_database.query(\ 
 67        "DELETE FROM {" + table + "} WHERE expire != %d AND expire <= %d", \ 
 68        CACHE_PERMANENT, cache_flush); 
 69    cache = lib_database.fetch_object(lib_database.query(\ 
 70      "SELECT data, created, headers, expire, serialized " + \ 
 71      "FROM {" + table + "} WHERE cid = '%s'", cid)); 
 72    if (php.isset(cache, 'data')): 
 73      # If the data is permanent or we're not enforcing a minimum cache lifetime 
 74      # always return the cached data. 
 75      if (cache.expire == CACHE_PERMANENT or not \ 
 76          variable_get('cache_lifetime', 0)): 
 77        cache.data = db_decode_blob(cache.data); 
 78        if (cache.serialized): 
 79          cache.data = php.unserialize(cache.data); 
 80      # If enforcing a minimum cache lifetime, validate that the data is 
 81      # currently valid for this user before we return it by making sure the 
 82      # cache entry was created before the timestamp in the current session's 
 83      # cache timer. The cache variable is loaded into the user object by 
 84      # sess_read() in session.inc. 
 85      else: 
 86        if (lib_appglobals.user.cache > cache.created): 
 87          # This cache data is too old and thus not valid for us, ignore it. 
 88          return False; 
 89        else: 
 90          cache.data = db_decode_blob(cache.data); 
 91          if (cache.serialized): 
 92            cache.data = php.unserialize(cache.data); 
 93      return cache; 
 94    return False; 
 95   
 96   
 97   
 98 -def set(cid, data, table = 'cache', expire = None, headers = None): 
 99    """ 
100     Store data in the persistent cache. 
101     
102     The persistent cache is split up into four database 
103     tables. Contributed plugins can add additional tables. 
104     
105     'cache_page': This table stores generated pages for anonymous 
106     users. This is the only table affected by the page cache setting on 
107     the administrator panel. 
108     
109     'cache_menu': Stores the cachable part of the users' menus. 
110     
111     'cache_filter': Stores filtered pieces of content. This table is 
112     periodically cleared of stale entries by cron. 
113     
114     'cache': Generic cache storage table. 
115     
116     The reasons for having several tables are as follows: 
117     
118     - smaller tables allow for faster selects and inserts 
119     - we try to put fast changing cache items and rather static 
120       ones into different tables. The effect is that only the fast 
121       changing tables will need a lot of writes to disk. The more 
122       static tables will also be better cachable with MySQL's query cache 
123     
124     @param cid 
125       The cache ID of the data to store. 
126     @param data 
127       The data to store in the cache. Complex data types will be 
128       automatically serialized before insertion. 
129       Strings will be stored as plain text and not serialized. 
130     @param table 
131       The table table to store the data in. Valid core values are 'cache_filter', 
132       'cache_menu', 'cache_page', or 'cache'. 
133     @param expire 
134       One of the following values: 
135       - CACHE_PERMANENT: Indicates that the item should never be removed unless 
136         explicitly told to using cache_clear_all() with a cache ID. 
137       - CACHE_TEMPORARY: Indicates that the item should be removed at the next 
138         general cache wipe. 
139       - A Unix timestamp: Indicates that the item should be kept at least until 
140         the given time, after which it behaves like CACHE_TEMPORARY. 
141     @param headers 
142       A string containing HTTP php.header information for cached pages. 
143    """ 
144    if expire is None: 
145      expire = lib_bootstrap.CACHE_PERMANENT 
146    serialized = 0; 
147    if (not php.is_string(data)): 
148      data = php.serialize(data); 
149      serialized = 1; 
150    created = php.time_(); 
151    lib_database.query( 
152      "UPDATE {" + table + "} SET data = %b, created = %d, expire = %d, " + \ 
153      "headers = '%s', serialized = %d WHERE cid = '%s'", \ 
154      data, created, expire, headers, serialized, cid); 
155    #if (not db_affected_rows()): 
156      #db_query("INSERT INTO {" + table + "} (cid, data, created, 
157      #expire, headers, serialized) VALUES ('%s', %b, %d, %d, '%s', %d)", 
158      #cid, data, created, expire, headers, serialized); 
159   
160   
161   
162   
163 -def clear_all(cid = None, table = None, wildcard = False): 
164    """ 
165     Expire data from the cache. If called without arguments, expirable 
166     entries will be cleared from the cache_page and cache_block tables. 
167     
168     @param cid 
169       If set, the cache ID to delete. Otherwise, all cache entries that can 
170       expire are deleted. 
171     
172     @param table 
173       If set, the table table to delete from. Mandatory 
174       argument if cid is set. 
175     
176     @param wildcard 
177       If set to TRUE, the cid is treated as a substring 
178       to match rather than a complete ID. The match is a right hand 
179       match. If '*' is given as cid, the table table will be emptied. 
180    """ 
181    thisTime = php.time_(); 
182    if (cid == None and table == None): 
183      # Clear the block cache first, so stale data will 
184      # not end up in the page cache. 
185      clear_all(None, 'cache_block'); 
186      clear_all(None, 'cache_page'); 
187      return; 
188    if (cid == None): 
189      if (variable_get('cache_lifetime', 0)): 
190        # We store the time in the current user's user.cache variable which 
191        # will be saved into the sessions table by sess_write(). We then 
192        # simulate that the cache was flushed for this user by not returning 
193        # cached data that was cached before the timestamp. 
194        lib_appglobals.user.cache = thisTime; 
195        cache_flush = variable_get('cache_flush', 0); 
196        if (cache_flush == 0): 
197          # This is the first request to clear the cache, start a timer. 
198          variable_set('cache_flush', thisTime); 
199        elif (thisTime > (cache_flush + variable_get('cache_lifetime', 0))): 
200          # Clear the cache for everyone, cache_flush_delay seconds have 
201          # passed since the first request to clear the cache. 
202          db_query(\ 
203            "DELETE FROM {" + table + "} WHERE expire != %d AND expire < %d", \ 
204            CACHE_PERMANENT, thisTime); 
205          variable_set('cache_flush', 0); 
206      else: 
207        # No minimum cache lifetime, php.flush all temporary cache entries now. 
208        db_query(\ 
209          "DELETE FROM {" + table + "} WHERE expire != %d AND expire < %d", \ 
210          CACHE_PERMANENT, thisTime); 
211    else: 
212      if (wildcard): 
213        if (cid == '*'): 
214          db_query("DELETE FROM {" + table + "}"); 
215        else: 
216          db_query("DELETE FROM {" + table + "} WHERE cid LIKE '%s%%'", cid); 
217      else: 
218        db_query("DELETE FROM {" + table + "} WHERE cid = '%s'", cid); 
219