Bug 549632 - Remove storage cache, which is mostly un/incorrectly used [r=mconnor]

Remove incorrectly used cache from some engines and clean up references from SyncEngine.

services/sync/modules/engines.js

@@ -407,13 +407,6 @@ SyncEngine.prototype = {
     if (Svc.Prefs.get("client.type") == "mobile")
       fetchNum = 50;
 
-    // enable cache, and keep only the first few items.  Otherwise (when
-    // we have more outgoing items than can fit in the cache), we will
-    // keep rotating items in and out, perpetually getting cache misses
-    this._store.cache.enabled = true;
-    this._store.cache.fifo = false; // filo
-    this._store.cache.clear();
-
     let newitems = new Collection(this.engineURL, this._recordObj);
     newitems.newer = this.lastSync;
     newitems.full = true;
@@ -502,9 +495,6 @@ SyncEngine.prototype = {
 
     this._log.info(["Records:", count.applied, "applied,", count.reconciled,
       "reconciled,", this.toFetch.length, "left to fetch"].join(" "));
-
-    // try to free some memory
-    this._store.cache.clear();
   },
 
   /**
@@ -554,8 +544,6 @@ SyncEngine.prototype = {
       this._store.changeItemID(dupeId, item.id);
       this._deleteId(dupeId);
     }
-
-    this._store.cache.clear(); // because parentid refs will be wrong
   },
 
   // Reconciliation has three steps:
@@ -632,9 +620,6 @@ SyncEngine.prototype = {
         up.clearRecords();
       });
 
-      // don't cache the outgoing items, we won't need them later
-      this._store.cache.enabled = false;
-
       for (let id in this._tracker.changedIDs) {
         try {
           let out = this._createRecord(id);
@@ -658,8 +643,6 @@ SyncEngine.prototype = {
       // Final upload
       if (count % MAX_UPLOAD_RECORDS > 0)
         doUpload(count >= MAX_UPLOAD_RECORDS ? "last batch" : "all");
-
-      this._store.cache.enabled = true;
     }
     this._tracker.clearChangedIDs();
   },

services/sync/modules/engines/bookmarks.js

@@ -638,9 +638,8 @@ BookmarksStore.prototype = {
   },
 
   changeItemID: function BStore_changeItemID(oldID, newID) {
-    // Remember the GUID change for incoming records and avoid invalid refs
+    // Remember the GUID change for incoming records
     this.aliases[oldID] = newID;
-    this.cache.clear();
 
     // Update any existing annotation references
     this._findAnnoItems(PARENT_ANNO, oldID).forEach(function(itemId) {
@@ -706,16 +705,11 @@ BookmarksStore.prototype = {
 
   // Create a record starting from the weave id (places guid)
   createRecord: function BStore_createRecord(guid, cryptoMetaURL) {
-    let record = this.cache.get(guid);
-    if (record)
-      return record;
-
     let placeId = idForGUID(guid);
     if (placeId <= 0) { // deleted item
       record = new PlacesItem();
       record.id = guid;
       record.deleted = true;
-      this.cache.put(guid, record);
       return record;
     }
 
@@ -799,7 +793,6 @@ BookmarksStore.prototype = {
     record.encryption = cryptoMetaURL;
     record.sortindex = this._calculateIndex(record);
 
-    this.cache.put(guid, record);
     return record;
   },
 

services/sync/modules/engines/history.js

@@ -262,7 +262,7 @@ HistoryStore.prototype = {
     }
     else
       record.deleted = true;
-    this.cache.put(guid, record);
+
     return record;
   },
 

services/sync/modules/stores.js

@@ -59,12 +59,6 @@ function Store(name) {
   this._log.level = Log4Moz.Level[level];
 }
 Store.prototype = {
-  get cache() {
-    let cache = new Cache();
-    this.__defineGetter__("cache", function() cache);
-    return cache;
-  },
-
   applyIncoming: function Store_applyIncoming(record) {
     if (record.deleted)
       this.remove(record);
@@ -108,76 +102,3 @@ Store.prototype = {
     throw "override wipe in a subclass";
   }
 };
-
-function Cache() {
-  this.count = 0;
-  this.maxItems = 100;
-  this.fifo = true;
-  this.enabled = true;
-  this._head = this._tail = null;
-  this._items = {};
-}
-Cache.prototype = {
-  remove: function Cache_remove(item) {
-    if (this.count <= 0 || this.count == 1) {
-      this.clear();
-      return;
-    }
-
-    item.next.prev = item.prev;
-    item.prev.next = item.next;
-
-    if (item == this._head)
-      this._head = item.next;
-    if (item == this._tail)
-      this._tail = item.prev;
-
-    item.next = null;
-    item.prev = null;
-
-    delete this._items[item.id];
-    this.count--;
-  },
-  pop: function Cache_pop() {
-    if (this.fifo)
-      this.remove(this._tail);
-    else
-      this.remove(this._head);
-  },
-  put: function Cache_put(id, item) {
-    if (!this.enabled)
-      return;
-
-    let wrapper = {id: id, item: item};
-
-    if (this._head === null) {
-      wrapper.next = wrapper;
-      wrapper.prev = wrapper;
-      this._head = wrapper;
-      this._tail = wrapper;
-    } else {
-      wrapper.next = this._tail;
-      wrapper.prev = this._head;
-      this._head.prev = wrapper;
-      this._tail.next = wrapper;
-      this._tail = wrapper;
-    }
-
-    this._items[wrapper.id] = wrapper;
-    this.count++;
-
-    if (this.count >= this.maxItems)
-      this.pop();
-  },
-  get: function Cache_get(id) {
-    if (id in this._items)
-      return this._items[id].item;
-    return undefined;
-  },
-  clear: function Cache_clear() {
-    this.count = 0;
-    this._head = null;
-    this._tail = null;
-    this._items = {};
-  }
-};