#171646 by JirkaRybka: store version usage information for every source string, optimize caching and prune the initially unused strings

3 files changed, 23 insertions, 4 deletions

diff --git a/modules/locale/locale.install b/modules/locale/locale.install
index b532fecfa..f283dca1c 100644
--- a/modules/locale/locale.install
+++ b/modules/locale/locale.install
@@ -106,6 +106,15 @@ function locale_update_6004() {
 }
 
 /**
+ * Prune strings with no translations (will be automatically re-registered if still in use)
+ */
+function locale_update_6005() {
+  $ret = array();
+  $ret[] = update_sql("DELETE s FROM {locales_source} s LEFT JOIN {locales_target} t ON s.lid = t.lid WHERE t.lid IS NULL");
+  return $ret;
+}
+
+/**
  * @} End of "defgroup updates-5.x-to-6.x"
  */
 
diff --git a/modules/locale/locale.module b/modules/locale/locale.module
index a9eb60014..28ff60ff2 100644
--- a/modules/locale/locale.module
+++ b/modules/locale/locale.module
@@ -335,15 +335,23 @@ function locale($string = NULL, $langcode = NULL) {
   if (!isset($locale_t[$langcode][$string])) {
 
     // We do not have this translation cached, so get it from the DB.
-    $translation = db_fetch_object(db_query("SELECT s.lid, t.translation FROM {locales_source} s LEFT JOIN {locales_target} t ON s.lid = t.lid AND t.language = '%s' WHERE s.source = '%s' AND s.textgroup = 'default'", $langcode, $string));
+    $translation = db_fetch_object(db_query("SELECT s.lid, t.translation, s.version FROM {locales_source} s LEFT JOIN {locales_target} t ON s.lid = t.lid AND t.language = '%s' WHERE s.source = '%s' AND s.textgroup = 'default'", $langcode, $string));
     if ($translation) {
       // We have the source string at least.
       // Cache translation string or TRUE if no translation exists.
       $locale_t[$langcode][$string] = (empty($translation->translation) ? TRUE : $translation->translation);
+
+      if ($translation->version != VERSION) {
+        // This is the first use of this string under current Drupal version. Save version
+        // and clear cache, to include the string into caching next time. Saved version is
+        // also a string-history information for later pruning of the tables.
+        db_query("UPDATE {locales_source} SET version = '%s' WHERE lid = %d LIMIT 1", VERSION, $translation->lid);
+        cache_clear_all('locale:'. $langcode, 'cache');
+      }
     }
     else {
       // We don't have the source string, cache this as untranslated.
-      db_query("INSERT INTO {locales_source} (location, source, textgroup) VALUES ('%s', '%s', 'default')", request_uri(), $string);
+      db_query("INSERT INTO {locales_source} (location, source, textgroup, version) VALUES ('%s', '%s', 'default', '%s')", request_uri(), $string, VERSION);
       $locale_t[$langcode][$string] = TRUE;
       // Clear locale cache so this string can be added in a later request.
       cache_clear_all('locale:'. $langcode, 'cache');
@@ -356,7 +364,7 @@ function locale($string = NULL, $langcode = NULL) {
 /**
  * Refreshes database stored cache of translations.
  *
- * We only store short strings to improve performance and consume less memory.
+ * We only store short strings used in current version, to improve performance and consume less memory.
  */
 function locale_refresh_cache() {
   $languages = language_list('enabled');
@@ -364,7 +372,7 @@ function locale_refresh_cache() {
   unset($languages['en']);
 
   foreach ($languages as $language) {
-    $result = db_query("SELECT s.source, t.translation, t.language FROM {locales_source} s LEFT JOIN {locales_target} t ON s.lid = t.lid AND t.language = '%s' WHERE s.textgroup = 'default' AND LENGTH(s.source) < 75", $language->language);
+    $result = db_query("SELECT s.source, t.translation, t.language FROM {locales_source} s LEFT JOIN {locales_target} t ON s.lid = t.lid AND t.language = '%s' WHERE s.textgroup = 'default' AND s.version = '%s' AND LENGTH(s.source) < 75", $language->language, VERSION);
     $t = array();
     while ($data = db_fetch_object($result)) {
       $t[$data->source] = (empty($data->translation) ? TRUE : $data->translation);
diff --git a/modules/locale/locale.schema b/modules/locale/locale.schema
index f511a020f..be31341e9 100644
--- a/modules/locale/locale.schema
+++ b/modules/locale/locale.schema
@@ -40,6 +40,8 @@ function locale_schema() {
       'textgroup' => array('type' => 'varchar', 'length' => 255, 'not null' => TRUE, 'default' => 'default'),
       // The original string in English.
       'source'    => array('type' => 'text', 'mysql_type' => 'blob', 'not null' => TRUE),
+      // Drupal core version, which last used the string.
+      'version'   => array('type' => 'varchar', 'length' => 20, 'not null' => TRUE, 'default' => 'none'),
     ),
     'primary key' => array('lid'),
     'indexes' => array