1 files changed, 121 insertions, 0 deletions
diff --git a/includes/cache.inc b/includes/cache.inc
new file mode 100644
index 000000000..e7982835a
--- /dev/null
+++ b/includes/cache.inc
@@ -0,0 +1,121 @@
+<?php
+
+/**
+ * Return data from the persistent cache.
+ *
+ * @param $key
+ *   The cache ID of the data to retrieve.
+ */
+function cache_get($key) {
+  global $user;
+
+  // Garbage collection necessary when enforcing a minimum cache lifetime
+  $cache_flush = variable_get('cache_flush', 0);
+  if ($cache_flush && ($cache_flush + variable_get('cache_lifetime', 0) <= time())) {
+    // Time to flush old cache data
+    db_query("DELETE FROM {cache} WHERE expire != %d AND expire <= %d", CACHE_PERMANENT, $cache_flush);
+    variable_set('cache_flush', 0);
+  }
+
+  $cache = db_fetch_object(db_query("SELECT data, created, headers, expire FROM {cache} WHERE cid = '%s'", $key));
+  if (isset($cache->data)) {
+    // If the data is permanent or we're not enforcing a minimum cache lifetime
+    // always return the cached data.
+    if ($cache->expire == CACHE_PERMANENT || !variable_get('cache_lifetime', 0)) {
+      $cache->data = db_decode_blob($cache->data);
+    }
+    // If enforcing a minimum cache lifetime, validate that the data is
+    // currently valid for this user before we return it by making sure the
+    // cache entry was created before the timestamp in the current session's
+    // cache timer. The cache variable is loaded into the $user object by
+    // sess_read() in session.inc.
+    else {
+      if ($user->cache > $cache->created) {
+        // This cache data is too old and thus not valid for us, ignore it.
+        return 0;
+      }
+      else {
+        $cache->data = db_decode_blob($cache->data);
+      }
+    }
+    return $cache;
+  }
+  return 0;
+}
+
+/**
+ * Store data in the persistent cache.
+ *
+ * @param $cid
+ *   The cache ID of the data to store.
+ * @param $data
+ *   The data to store in the cache. Complex data types must be serialized first.
+ * @param $expire
+ *   One of the following values:
+ *   - CACHE_PERMANENT: Indicates that the item should never be removed unless
+ *     explicitly told to using cache_clear_all() with a cache ID.
+ *   - CACHE_TEMPORARY: Indicates that the item should be removed at the next
+ *     general cache wipe.
+ *   - A Unix timestamp: Indicates that the item should be kept at least until
+ *     the given time, after which it behaves like CACHE_TEMPORARY.
+ * @param $headers
+ *   A string containing HTTP header information for cached pages.
+ */
+function cache_set($cid, $data, $expire = CACHE_PERMANENT, $headers = NULL) {
+  db_lock_table('cache');
+  db_query("UPDATE {cache} SET data = %b, created = %d, expire = %d, headers = '%s' WHERE cid = '%s'", $data, time(), $expire, $headers, $cid);
+  if (!db_affected_rows()) {
+    @db_query("INSERT INTO {cache} (cid, data, created, expire, headers) VALUES ('%s', %b, %d, %d, '%s')", $cid, $data, time(), $expire, $headers);
+  }
+  db_unlock_tables();
+}
+
+/**
+ * Expire data from the cache.
+ *
+ * @param $cid
+ *   If set, the cache ID to delete. Otherwise, all cache entries that can
+ *   expire are deleted.
+ *
+ * @param $wildcard
+ *   If set to true, the $cid is treated as a substring to match rather than a
+ *   complete ID.
+ */
+function cache_clear_all($cid = NULL, $wildcard = false) {
+  global $user;
+
+  if (empty($cid)) {
+    if (variable_get('cache_lifetime', 0)) {
+      // We store the time in the current user's $user->cache variable which
+      // will be saved into the sessions table by sess_write(). We then
+      // simulate that the cache was flushed for this user by not returning
+      // cached data that was cached before the timestamp.
+      $user->cache = time();
+
+      $cache_flush = variable_get('cache_flush', 0);
+      if ($cache_flush == 0) {
+        // This is the first request to clear the cache, start a timer.
+        variable_set('cache_flush', time());
+      }
+      else if (time() > ($cache_flush + variable_get('cache_lifetime', 0))) {
+        // Clear the cache for everyone, cache_flush_delay seconds have
+        // passed since the first request to clear the cache.
+        db_query("DELETE FROM {cache} WHERE expire != %d AND expire < %d", CACHE_PERMANENT, time());
+        variable_set('cache_flush', 0);
+      }
+    }
+    else {
+      // No minimum cache lifetime, flush all temporary cache entries now.
+      db_query("DELETE FROM {cache} WHERE expire != %d AND expire < %d", CACHE_PERMANENT, time());
+    }
+  }
+  else {
+    if ($wildcard) {
+      db_query("DELETE FROM {cache} WHERE cid LIKE '%%%s%%'", $cid);
+    }
+    else {
+      db_query("DELETE FROM {cache} WHERE cid = '%s'", $cid);
+    }
+  }
+}
+