#5655 Fix freeze on purging cef cache

Author: akleshchev

indra/newview/llappviewer.cpp

@@ -4564,13 +4564,45 @@ void LLAppViewer::purgeCefStaleCaches()
     LL_PROFILE_ZONE_SCOPED;
     // TODO: we really shouldn't use a hard coded name for the cache folder here...
     const std::string browser_parent_cache = gDirUtilp->getExpandedFilename(LL_PATH_CACHE, "cef_cache");
-    if (LLFile::isdir(browser_parent_cache))
+    if (!LLFile::isdir(browser_parent_cache))
     {
-        // This is a sledgehammer approach - nukes the cef_cache dir entirely
-        // which is then recreated the first time a CEF instance creates an
-        // individual cache folder. If we ever decide to retain some folders
-        // e.g. Search UI cache - then we will need a more granular approach.
-        gDirUtilp->deleteDirAndContents(browser_parent_cache);
+        return;
+    }
+    // We are using a fixed name to not leave stale fodlers
+    // around in case something goes wrong on startup.
+    const std::string holder_cache_name = browser_parent_cache + "_rename";
+
+    // Rename the directory first to be able to clean it at our leasure.
+    if (LLFile::rename(browser_parent_cache, holder_cache_name) != 0)
+    {
+        LL_WARNS() << "Failed to rename CEF cache folder from " << browser_parent_cache
+            << " to " << holder_cache_name << LL_ENDL;
+        // Shouldn't happen, perhaps viewer crashed on startup?
+        // Clean holder cache and retry.
+        gDirUtilp->deleteDirAndContents(holder_cache_name);
+
+        if (LLFile::rename(browser_parent_cache, holder_cache_name) != 0)
+        {
+            LL_WARNS() << "Failed to rename CEF cache folder from " << browser_parent_cache
+                << " to " << holder_cache_name << " on retry" << LL_ENDL;
+            // Shouldn't happen, but if it does, just delete the cache and move on.
+            gDirUtilp->deleteDirAndContents(browser_parent_cache);
+            return;
+        }
+    } // renamed
+
+    if (auto queue = LL::WorkQueue::getInstance("General"))
+    {
+        queue->post([holder_cache_name]()
+        {
+            LL_PROFILE_ZONE_NAMED("cef_cache_cleanup");
+            gDirUtilp->deleteDirAndContents(holder_cache_name);
+        });
+    }
+    else
+    {
+        LL_WARNS() << "Failed to get General work queue, deleting CEF cache synchronously" << LL_ENDL;
+        gDirUtilp->deleteDirAndContents(holder_cache_name);
     }
 }