Optimitic write back cache storage.

This cache doesn't have any conflict detection and can lead to data lose.

src/jio.storage/cachestorage.js

+/*jslint nomen: true, maxlen: 200*/
+/*global RSVP, console*/
+(function (jIO) {
+  "use strict";
+
+  /**
+   * The jIO CacheStorage extension
+   *
+   * @class CacheStorage
+   * @constructor
+   */
+
+  // XXX Delete entry when put post delete
+  function enqueueDefer(storage, callback) {
+    var deferred = storage._current_deferred;
+
+    // Unblock queue
+    if (deferred !== undefined) {
+      deferred.resolve("Another event added");
+    }
+
+    // Add next callback
+    try {
+      storage._service_queue.push(callback);
+    } catch (error) {
+      throw new Error("Cache storage already crashed... " +
+                      storage._service_queue.rejectedReason.toString());
+    }
+
+    // Block the queue
+    deferred = RSVP.defer();
+    storage._current_deferred = deferred;
+    storage._service_queue.push(function () {
+      return deferred.promise;
+    });
+
+  }
+
+
+
+  function CacheStorage(spec) {
+    this._cache_storage = jIO.createJIO(spec.cache_storage);
+    this._sub_storage = jIO.createJIO(spec.sub_storage);
+
+    this._service_queue = new RSVP.Queue();
+    enqueueDefer(this, function () {return; });
+
+  }
+
+  CacheStorage.prototype.get = function () {
+    var context = this,
+      argument_list = arguments;
+    return this._cache_storage.get.apply(this._cache_storage, arguments)
+      .push(undefined, function (error) {
+        if ((error instanceof jIO.util.jIOError) && (error.status_code === 404)) {
+          return context._sub_storage.get.apply(context._sub_storage, argument_list)
+            .push(function (document) {
+
+              var clone = JSON.parse(JSON.stringify(document));
+              // XXX Deep clone
+              clone._id = argument_list[0]._id;
+
+              enqueueDefer(context, function () {
+                return context._cache_storage.put(clone);
+              });
+
+              return document;
+            });
+        }
+        throw error;
+      });
+  };
+
+  CacheStorage.prototype.post = function (param) {
+    var context = this;
+    return this._cache_storage.post.apply(this._cache_storage, arguments)
+      .push(function (id) {
+        // XXX Deep clone
+        param._id = id;
+        enqueueDefer(context, function () {
+          return context._sub_storage.put(param)
+            .push(undefined, function (error) {
+              console.warn(error);
+              console.warn(param);
+              throw error;
+            });
+        });
+        return id;
+      });
+  };
+  CacheStorage.prototype.put = function () {
+    var context = this,
+      argument_list = arguments;
+    return this._cache_storage.put.apply(this._cache_storage, arguments)
+      .push(function (result) {
+        enqueueDefer(context, function () {
+          return context._sub_storage.put.apply(context._sub_storage, argument_list);
+        });
+        return result;
+      });
+  };
+  CacheStorage.prototype.remove = function () {
+    var context = this,
+      argument_list = arguments;
+    return this._cache_storage.remove.apply(this._cache_storage, arguments)
+      .push(function (result) {
+        enqueueDefer(context, function () {
+          return context._sub_storage.remove.apply(context._sub_storage, argument_list);
+        });
+        return result;
+      });
+  };
+  CacheStorage.prototype.getAttachment = function () {
+    var context = this,
+      argument_list = arguments;
+    return this._cache_storage.getAttachment.apply(this._cache_storage, arguments)
+      .push(undefined, function (error) {
+        if ((error instanceof jIO.util.jIOError) && (error.status_code === 404)) {
+          return context._sub_storage.getAttachment.apply(context._sub_storage, argument_list)
+            .push(function (blob) {
+
+              enqueueDefer(context, function () {
+                return context._cache_storage.putAttachment(argument_list[0], blob);
+              });
+
+              return blob;
+            });
+        }
+        throw error;
+      });
+  };
+  CacheStorage.prototype.putAttachment = function () {
+    var context = this,
+      argument_list = arguments;
+    return this._cache_storage.putAttachment.apply(this._cache_storage, arguments)
+      .push(function (result) {
+        enqueueDefer(context, function () {
+          return context._sub_storage.putAttachment.apply(context._sub_storage, argument_list);
+        });
+        return result;
+      });
+  };
+  CacheStorage.prototype.removeAttachment = function () {
+    var context = this,
+      argument_list = arguments;
+    return this._cache_storage.removeAttachment.apply(this._cache_storage, arguments)
+      .push(function (result) {
+        enqueueDefer(context, function () {
+          return context._sub_storage.removeAttachment.apply(context._sub_storage, argument_list);
+        });
+        return result;
+      });
+  };
+  CacheStorage.prototype.hasCapacity = function () {
+    return this._sub_storage.hasCapacity.apply(this._sub_storage, arguments);
+  };
+  CacheStorage.prototype.buildQuery = function () {
+    return this._sub_storage.buildQuery.apply(this._sub_storage, arguments);
+  };
+
+  jIO.addStorage('cache', CacheStorage);
+
+}(jIO));