Modified: olingo/site/trunk/content/doc/javascript/apidoc/cache.js.html URL: http://svn.apache.org/viewvc/olingo/site/trunk/content/doc/javascript/apidoc/cache.js.html?rev=1672271&r1=1672270&r2=1672271&view=diff ============================================================================== --- olingo/site/trunk/content/doc/javascript/apidoc/cache.js.html (original) +++ olingo/site/trunk/content/doc/javascript/apidoc/cache.js.html Thu Apr 9 09:03:39 2015 @@ -25,1456 +25,1452 @@ <section> <article> - <pre class="prettyprint source"><code>/* - * Licensed to the Apache Software Foundation (ASF) under one - * or more contributor license agreements. See the NOTICE file - * distributed with this work for additional information - * regarding copyright ownership. The ASF licenses this file - * to you under the Apache License, Version 2.0 (the - * "License"); you may not use this file except in compliance - * with the License. You may obtain a copy of the License at - * - * http://www.apache.org/licenses/LICENSE-2.0 - * - * Unless required by applicable law or agreed to in writing, - * software distributed under the License is distributed on an - * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY - * KIND, either express or implied. See the License for the - * specific language governing permissions and limitations - * under the License. - */ - - /** @module cache */ - -var odatajs = require('./odatajs.js'); -var utils = odatajs.utils; -var deferred = odatajs.deferred; -var storeReq = odatajs.store; -var cacheSource = require('./cache/source'); - - -var assigned = utils.assigned; -var delay = utils.delay; -var extend = utils.extend; -var djsassert = utils.djsassert; -var isArray = utils.isArray; -var normalizeURI = utils.normalizeURI; -var parseInt10 = utils.parseInt10; -var undefinedDefault = utils.undefinedDefault; - -var createDeferred = deferred.createDeferred; -var DjsDeferred = deferred.DjsDeferred; - - -var getJsonValueArraryLength = utils.getJsonValueArraryLength; -var sliceJsonValueArray = utils.sliceJsonValueArray; -var concatJsonValueArray = utils.concatJsonValueArray; - - - -/** Appends a page's data to the operation data. - * @param {Object} operation - Operation with (i)ndex, (c)ount and (d)ata. - * @param {Object} page - Page with (i)ndex, (c)ount and (d)ata. - */ -function appendPage(operation, page) { - - var intersection = intersectRanges(operation, page); - var start = 0; - var end = 0; - if (intersection) { - start = intersection.i - page.i; - end = start + (operation.c - getJsonValueArraryLength(operation.d)); - } - - operation.d = concatJsonValueArray(operation.d, sliceJsonValueArray(page.d, start, end)); -} - -/** Returns the {(i)ndex, (c)ount} range for the intersection of x and y. - * @param {Object} x - Range with (i)ndex and (c)ount members. - * @param {Object} y - Range with (i)ndex and (c)ount members. - * @returns {Object} The intersection (i)ndex and (c)ount; undefined if there is no intersection. - */ -function intersectRanges(x, y) { - - var xLast = x.i + x.c; - var yLast = y.i + y.c; - var resultIndex = (x.i > y.i) ? x.i : y.i; - var resultLast = (xLast < yLast) ? xLast : yLast; - var result; - if (resultLast >= resultIndex) { - result = { i: resultIndex, c: resultLast - resultIndex }; - } - - return result; -} - -/** Checks whether val is a defined number with value zero or greater. - * @param {Number} val - Value to check. - * @param {String} name - Parameter name to use in exception. - * @throws Throws an exception if the check fails - */ -function checkZeroGreater(val, name) { - - if (val === undefined || typeof val !== "number") { - throw { message: "'" + name + "' must be a number." }; - } - - if (isNaN(val) || val < 0 || !isFinite(val)) { - throw { message: "'" + name + "' must be greater than or equal to zero." }; - } -} - -/** Checks whether val is undefined or a number with value greater than zero. - * @param {Number} val - Value to check. - * @param {String} name - Parameter name to use in exception. - * @throws Throws an exception if the check fails - */ -function checkUndefinedGreaterThanZero(val, name) { - - if (val !== undefined) { - if (typeof val !== "number") { - throw { message: "'" + name + "' must be a number." }; - } - - if (isNaN(val) || val <= 0 || !isFinite(val)) { - throw { message: "'" + name + "' must be greater than zero." }; - } - } -} - -/** Checks whether val is undefined or a number - * @param {Number} val - Value to check. - * @param {String} name - Parameter name to use in exception. - * @throws Throws an exception if the check fails - */ -function checkUndefinedOrNumber(val, name) { - if (val !== undefined && (typeof val !== "number" || isNaN(val) || !isFinite(val))) { - throw { message: "'" + name + "' must be a number." }; - } -} - -/** Performs a linear search on the specified array and removes the first instance of 'item'. - * @param {Array} arr - Array to search. - * @param {*} item - Item being sought. - * @returns {Boolean} true if the item was removed otherwise false - */ -function removeFromArray(arr, item) { - - var i, len; - for (i = 0, len = arr.length; i < len; i++) { - if (arr[i] === item) { - arr.splice(i, 1); - return true; - } - } - - return false; -} - -/** Estimates the size of an object in bytes. - * Object trees are traversed recursively - * @param {Object} object - Object to determine the size of. - * @returns {Integer} Estimated size of the object in bytes. - */ -function estimateSize(object) { - var size = 0; - var type = typeof object; - - if (type === "object" && object) { - for (var name in object) { - size += name.length * 2 + estimateSize(object[name]); - } - } else if (type === "string") { - size = object.length * 2; - } else { - size = 8; - } - return size; -} - -/** Snaps low and high indices into page sizes and returns a range. - * @param {Number} lowIndex - Low index to snap to a lower value. - * @param {Number} highIndex - High index to snap to a higher value. - * @param {Number} pageSize - Page size to snap to. - * @returns {Object} A range with (i)ndex and (c)ount of elements. - */ -function snapToPageBoundaries(lowIndex, highIndex, pageSize) { - lowIndex = Math.floor(lowIndex / pageSize) * pageSize; - highIndex = Math.ceil((highIndex + 1) / pageSize) * pageSize; - return { i: lowIndex, c: highIndex - lowIndex }; -} - -// The DataCache is implemented using state machines. The following constants are used to properly -// identify and label the states that these machines transition to. -var CACHE_STATE_DESTROY = "destroy"; -var CACHE_STATE_IDLE = "idle"; -var CACHE_STATE_INIT = "init"; -var CACHE_STATE_READ = "read"; -var CACHE_STATE_PREFETCH = "prefetch"; -var CACHE_STATE_WRITE = "write"; - -// DataCacheOperation state machine states. -// Transitions on operations also depend on the cache current of the cache. -var OPERATION_STATE_CANCEL = "cancel"; -var OPERATION_STATE_END = "end"; -var OPERATION_STATE_ERROR = "error"; -var OPERATION_STATE_START = "start"; -var OPERATION_STATE_WAIT = "wait"; - -// Destroy state machine states -var DESTROY_STATE_CLEAR = "clear"; - -// Read / Prefetch state machine states -var READ_STATE_DONE = "done"; -var READ_STATE_LOCAL = "local"; -var READ_STATE_SAVE = "save"; -var READ_STATE_SOURCE = "source"; - -/** Creates a new operation object. - * @class DataCacheOperation - * @param {Function} stateMachine - State machine that describes the specific behavior of the operation. - * @param {DjsDeferred} promise - Promise for requested values. - * @param {Boolean} isCancelable - Whether this operation can be canceled or not. - * @param {Number} index - Index of first item requested. - * @param {Number} count - Count of items requested. - * @param {Array} data - Array with the items requested by the operation. - * @param {Number} pending - Total number of pending prefetch records. - * @returns {DataCacheOperation} A new data cache operation instance. - */ -function DataCacheOperation(stateMachine, promise, isCancelable, index, count, data, pending) { - - /// <field name="p" type="DjsDeferred">Promise for requested values.</field> - /// <field name="i" type="Number">Index of first item requested.</field> - /// <field name="c" type="Number">Count of items requested.</field> - /// <field name="d" type="Array">Array with the items requested by the operation.</field> - /// <field name="s" type="Array">Current state of the operation.</field> - /// <field name="canceled" type="Boolean">Whether the operation has been canceled.</field> - /// <field name="pending" type="Number">Total number of pending prefetch records.</field> - /// <field name="oncomplete" type="Function">Callback executed when the operation reaches the end state.</field> - - var stateData; - var cacheState; - var that = this; - - that.p = promise; - that.i = index; - that.c = count; - that.d = data; - that.s = OPERATION_STATE_START; - - that.canceled = false; - that.pending = pending; - that.oncomplete = null; - - /** Transitions this operation to the cancel state and sets the canceled flag to true. - * The function is a no-op if the operation is non-cancelable.</summary> - * @method DataCacheOperation#cancel - */ - that.cancel = function cancel() { - - if (!isCancelable) { - return; - } - - var state = that.s; - if (state !== OPERATION_STATE_ERROR && state !== OPERATION_STATE_END && state !== OPERATION_STATE_CANCEL) { - that.canceled = true; - transition(OPERATION_STATE_CANCEL, stateData); - } - }; - - /** Transitions this operation to the end state. - * @method DataCacheOperation#complete - */ - that.complete = function () { - - djsassert(that.s !== OPERATION_STATE_END, "DataCacheOperation.complete() - operation is in the end state", that); - transition(OPERATION_STATE_END, stateData); - }; - - /** Transitions this operation to the error state. - * @method DataCacheOperation#error - */ - that.error = function (err) { - if (!that.canceled) { - djsassert(that.s !== OPERATION_STATE_END, "DataCacheOperation.error() - operation is in the end state", that); - djsassert(that.s !== OPERATION_STATE_ERROR, "DataCacheOperation.error() - operation is in the error state", that); - transition(OPERATION_STATE_ERROR, err); - } - }; - - /** Executes the operation's current state in the context of a new cache state. - * @method DataCacheOperation#run - * @param {Object} state - New cache state. - */ - that.run = function (state) { - - cacheState = state; - that.transition(that.s, stateData); - }; - - /** Transitions this operation to the wait state. - * @method DataCacheOperation#wait - */ - that.wait = function (data) { - - djsassert(that.s !== OPERATION_STATE_END, "DataCacheOperation.wait() - operation is in the end state", that); - transition(OPERATION_STATE_WAIT, data); - }; - - /** State machine that describes all operations common behavior. - * @method DataCacheOperation#operationStateMachine - * @param {Object} opTargetState - Operation state to transition to. - * @param {Object} cacheState - Current cache state. - * @param {Object} [data] - Additional data passed to the state. - */ - var operationStateMachine = function (opTargetState, cacheState, data) { - - switch (opTargetState) { - case OPERATION_STATE_START: - // Initial state of the operation. The operation will remain in this state until the cache has been fully initialized. - if (cacheState !== CACHE_STATE_INIT) { - stateMachine(that, opTargetState, cacheState, data); - } - break; - - case OPERATION_STATE_WAIT: - // Wait state indicating that the operation is active but waiting for an asynchronous operation to complete. - stateMachine(that, opTargetState, cacheState, data); - break; - - case OPERATION_STATE_CANCEL: - // Cancel state. - stateMachine(that, opTargetState, cacheState, data); - that.fireCanceled(); - transition(OPERATION_STATE_END); - break; - - case OPERATION_STATE_ERROR: - // Error state. Data is expected to be an object detailing the error condition. - stateMachine(that, opTargetState, cacheState, data); - that.canceled = true; - that.fireRejected(data); - transition(OPERATION_STATE_END); - break; - - case OPERATION_STATE_END: - // Final state of the operation. - if (that.oncomplete) { - that.oncomplete(that); - } - if (!that.canceled) { - that.fireResolved(); - } - stateMachine(that, opTargetState, cacheState, data); - break; - - default: - // Any other state is passed down to the state machine describing the operation's specific behavior. - // DATAJS INTERNAL START - if (true) { - // Check that the state machine actually handled the sate. - var handled = stateMachine(that, opTargetState, cacheState, data); - djsassert(handled, "Bad operation state: " + opTargetState + " cacheState: " + cacheState, this); - } else { - // DATAJS INTERNAL END - stateMachine(that, opTargetState, cacheState, data); - // DATAJS INTERNAL START - } - // DATAJS INTERNAL END - break; - } - }; - - - - /** Transitions this operation to a new state. - * @method DataCacheOperation#transition - * @param {Object} state - State to transition the operation to. - * @param {Object} [data] - - */ - var transition = function (state, data) { - that.s = state; - stateData = data; - operationStateMachine(state, cacheState, data); - }; - - that.transition = transition; - - return that; -} - -/** Fires a resolved notification as necessary. - * @method DataCacheOperation#fireResolved - */ -DataCacheOperation.prototype.fireResolved = function () { - - // Fire the resolve just once. - var p = this.p; - if (p) { - this.p = null; - p.resolve(this.d); - } -}; - -/** Fires a rejected notification as necessary. - * @method DataCacheOperation#fireRejected - */ -DataCacheOperation.prototype.fireRejected = function (reason) { - - // Fire the rejection just once. - var p = this.p; - if (p) { - this.p = null; - p.reject(reason); - } -}; - -/** Fires a canceled notification as necessary. - * @method DataCacheOperation#fireCanceled - */ -DataCacheOperation.prototype.fireCanceled = function () { - - this.fireRejected({ canceled: true, message: "Operation canceled" }); -}; - - -/** Creates a data cache for a collection that is efficiently loaded on-demand. - * @class DataCache - * @param options - Options for the data cache, including name, source, pageSize, - * prefetchSize, cacheSize, storage mechanism, and initial prefetch and local-data handler. - * @returns {DataCache} A new data cache instance. - */ -function DataCache(options) { - - var state = CACHE_STATE_INIT; - var stats = { counts: 0, netReads: 0, prefetches: 0, cacheReads: 0 }; - - var clearOperations = []; - var readOperations = []; - var prefetchOperations = []; - - var actualCacheSize = 0; // Actual cache size in bytes. - var allDataLocal = false; // Whether all data is local. - var cacheSize = undefinedDefault(options.cacheSize, 1048576); // Requested cache size in bytes, default 1 MB. - var collectionCount = 0; // Number of elements in the server collection. - var highestSavedPage = 0; // Highest index of all the saved pages. - var highestSavedPageSize = 0; // Item count of the saved page with the highest index. - var overflowed = cacheSize === 0; // If the cache has overflowed (actualCacheSize > cacheSize or cacheSize == 0); - var pageSize = undefinedDefault(options.pageSize, 50); // Number of elements to store per page. - var prefetchSize = undefinedDefault(options.prefetchSize, pageSize); // Number of elements to prefetch from the source when the cache is idling. - var version = "1.0"; - var cacheFailure; - - var pendingOperations = 0; - - var source = options.source; - if (typeof source === "string") { - // Create a new cache source. - source = new cacheSource.ODataCacheSource(options); - } - source.options = options; - - // Create a cache local store. - var store = storeReq.createStore(options.name, options.mechanism); - - var that = this; - - that.onidle = options.idle; - that.stats = stats; - - /** Counts the number of items in the collection. - * @method DataCache#count - * @returns {Object} A promise with the number of items. - */ - that.count = function () { - - if (cacheFailure) { - throw cacheFailure; - } - - var deferred = createDeferred(); - var canceled = false; - - if (allDataLocal) { - delay(function () { - deferred.resolve(collectionCount); - }); - - return deferred.promise(); - } - - // TODO: Consider returning the local data count instead once allDataLocal flag is set to true. - var request = source.count(function (count) { - request = null; - stats.counts++; - deferred.resolve(count); - }, function (err) { - request = null; - deferred.reject(extend(err, { canceled: canceled })); - }); - - return extend(deferred.promise(), { - - /** Aborts the count operation (used within promise callback) - * @method DataCache#cancelCount - */ - cancel: function () { - - if (request) { - canceled = true; - request.abort(); - request = null; - } - } - }); - }; - - /** Cancels all running operations and clears all local data associated with this cache. - * New read requests made while a clear operation is in progress will not be canceled. - * Instead they will be queued for execution once the operation is completed. - * @method DataCache#clear - * @returns {Object} A promise that has no value and can't be canceled. - */ - that.clear = function () { - - if (cacheFailure) { - throw cacheFailure; - } - - if (clearOperations.length === 0) { - var deferred = createDeferred(); - var op = new DataCacheOperation(destroyStateMachine, deferred, false); - queueAndStart(op, clearOperations); - return deferred.promise(); - } - return clearOperations[0].p; - }; - - /** Filters the cache data based a predicate. - * Specifying a negative count value will yield all the items in the cache that satisfy the predicate. - * @method DataCache#filterForward - * @param {Number} index - The index of the item to start filtering forward from. - * @param {Number} count - Maximum number of items to include in the result. - * @param {Function} predicate - Callback function returning a boolean that determines whether an item should be included in the result or not. - * @returns {DjsDeferred} A promise for an array of results. - */ - that.filterForward = function (index, count, predicate) { - return filter(index, count, predicate, false); - }; - - /** Filters the cache data based a predicate. - * Specifying a negative count value will yield all the items in the cache that satisfy the predicate. - * @method DataCache#filterBack - * @param {Number} index - The index of the item to start filtering backward from. - * @param {Number} count - Maximum number of items to include in the result. - * @param {Function} predicate - Callback function returning a boolean that determines whether an item should be included in the result or not. - * @returns {DjsDeferred} A promise for an array of results. - */ - that.filterBack = function (index, count, predicate) { - return filter(index, count, predicate, true); - }; - - /** Reads a range of adjacent records. - * New read requests made while a clear operation is in progress will not be canceled. - * Instead they will be queued for execution once the operation is completed. - * @method DataCache#readRange - * @param {Number} index - Zero-based index of record range to read. - * @param {Number} count - Number of records in the range. - * @returns {DjsDeferred} A promise for an array of records; less records may be returned if the - * end of the collection is found. - */ - that.readRange = function (index, count) { - - checkZeroGreater(index, "index"); - checkZeroGreater(count, "count"); - - if (cacheFailure) { - throw cacheFailure; - } - - var deferred = createDeferred(); - - // Merging read operations would be a nice optimization here. - var op = new DataCacheOperation(readStateMachine, deferred, true, index, count, {}, 0); - queueAndStart(op, readOperations); - - return extend(deferred.promise(), { - cancel: function () { - /** Aborts the readRange operation (used within promise callback) - * @method DataCache#cancelReadRange - */ - op.cancel(); - } - }); - }; - - /** Creates an Observable object that enumerates all the cache contents. - * @method DataCache#toObservable - * @returns A new Observable object that enumerates all the cache contents. - */ - that.ToObservable = that.toObservable = function () { - if ( !utils.inBrowser()) { - throw { message: "Only in broser supported" }; - } - - if (!window.Rx || !window.Rx.Observable) { - throw { message: "Rx library not available - include rx.js" }; - } - - if (cacheFailure) { - throw cacheFailure; - } - - return new window.Rx.Observable(function (obs) { - var disposed = false; - var index = 0; - - var errorCallback = function (error) { - if (!disposed) { - obs.onError(error); - } - }; - - var successCallback = function (data) { - if (!disposed) { - var i, len; - for (i = 0, len = data.value.length; i < len; i++) { - // The wrapper automatically checks for Dispose - // on the observer, so we don't need to check it here. - obs.onNext(data.value[i]); - } - - if (data.value.length < pageSize) { - obs.onCompleted(); - } else { - index += pageSize; - that.readRange(index, pageSize).then(successCallback, errorCallback); - } - } - }; - - that.readRange(index, pageSize).then(successCallback, errorCallback); - - return { Dispose: function () { - obs.dispose(); // otherwise the check isStopped obs.onNext(data.value[i]); - disposed = true; - } }; - }); - }; - - /** Creates a function that handles a callback by setting the cache into failure mode. - * @method DataCache~cacheFailureCallback - * @param {String} message - Message text. - * @returns {Function} Function to use as error callback. - * This function will specifically handle problems with critical store resources - * during cache initialization. - */ - var cacheFailureCallback = function (message) { - - - return function (error) { - cacheFailure = { message: message, error: error }; - - // Destroy any pending clear or read operations. - // At this point there should be no prefetch operations. - // Count operations will go through but are benign because they - // won't interact with the store. - djsassert(prefetchOperations.length === 0, "prefetchOperations.length === 0"); - var i, len; - for (i = 0, len = readOperations.length; i < len; i++) { - readOperations[i].fireRejected(cacheFailure); - } - for (i = 0, len = clearOperations.length; i < len; i++) { - clearOperations[i].fireRejected(cacheFailure); - } - - // Null out the operation arrays. - readOperations = clearOperations = null; - }; - }; - - /** Updates the cache's state and signals all pending operations of the change. - * @method DataCache~changeState - * @param {Object} newState - New cache state. - * This method is a no-op if the cache's current state and the new state are the same.</remarks> - */ - var changeState = function (newState) { - - if (newState !== state) { - state = newState; - var operations = clearOperations.concat(readOperations, prefetchOperations); - var i, len; - for (i = 0, len = operations.length; i < len; i++) { - operations[i].run(state); - } - } - }; - - /** Removes all the data stored in the cache. - * @method DataCache~clearStore - * @returns {DjsDeferred} A promise with no value. - */ - var clearStore = function () { - djsassert(state === CACHE_STATE_DESTROY || state === CACHE_STATE_INIT, "DataCache.clearStore() - cache is not on the destroy or initialize state, current sate = " + state); - - var deferred = new DjsDeferred(); - store.clear(function () { - - // Reset the cache settings. - actualCacheSize = 0; - allDataLocal = false; - collectionCount = 0; - highestSavedPage = 0; - highestSavedPageSize = 0; - overflowed = cacheSize === 0; - - // version is not reset, in case there is other state in eg V1.1 that is still around. - - // Reset the cache stats. - stats = { counts: 0, netReads: 0, prefetches: 0, cacheReads: 0 }; - that.stats = stats; - - store.close(); - deferred.resolve(); - }, function (err) { - deferred.reject(err); - }); - return deferred; - }; - - /** Removes an operation from the caches queues and changes the cache state to idle. - * @method DataCache~dequeueOperation - * @param {DataCacheOperation} operation - Operation to dequeue. - * This method is used as a handler for the operation's oncomplete event.</remarks> - */ - var dequeueOperation = function (operation) { - - var removed = removeFromArray(clearOperations, operation); - if (!removed) { - removed = removeFromArray(readOperations, operation); - if (!removed) { - removeFromArray(prefetchOperations, operation); - } - } - - pendingOperations--; - changeState(CACHE_STATE_IDLE); - }; - - /** Requests data from the cache source. - * @method DataCache~fetchPage - * @param {Number} start - Zero-based index of items to request. - * @returns {DjsDeferred} A promise for a page object with (i)ndex, (c)ount, (d)ata. - */ - var fetchPage = function (start) { - - djsassert(state !== CACHE_STATE_DESTROY, "DataCache.fetchPage() - cache is on the destroy state"); - djsassert(state !== CACHE_STATE_IDLE, "DataCache.fetchPage() - cache is on the idle state"); - - var deferred = new DjsDeferred(); - var canceled = false; - - var request = source.read(start, pageSize, function (data) { - var length = getJsonValueArraryLength(data); - var page = { i: start, c: length, d: data }; - deferred.resolve(page); - }, function (err) { - deferred.reject(err); - }); - - return extend(deferred, { - cancel: function () { - if (request) { - request.abort(); - canceled = true; - request = null; - } - } - }); - }; - - /** Filters the cache data based a predicate. - * @method DataCache~filter - * @param {Number} index - The index of the item to start filtering from. - * @param {Number} count - Maximum number of items to include in the result. - * @param {Function} predicate - Callback function returning a boolean that determines whether an item should be included in the result or not. - * @param {Boolean} backwards - True if the filtering should move backward from the specified index, falsey otherwise. - * Specifying a negative count value will yield all the items in the cache that satisfy the predicate. - * @returns {DjsDeferred} A promise for an array of results. - */ - var filter = function (index, count, predicate, backwards) { - - index = parseInt10(index); - count = parseInt10(count); - - if (isNaN(index)) { - throw { message: "'index' must be a valid number.", index: index }; - } - if (isNaN(count)) { - throw { message: "'count' must be a valid number.", count: count }; - } - - if (cacheFailure) { - throw cacheFailure; - } - - index = Math.max(index, 0); - - var deferred = createDeferred(); - var returnData = {}; - returnData.value = []; - var canceled = false; - var pendingReadRange = null; - - var readMore = function (readIndex, readCount) { - if (!canceled) { - if (count > 0 && returnData.value.length >= count) { - deferred.resolve(returnData); - } else { - pendingReadRange = that.readRange(readIndex, readCount).then(function (data) { - if (data["@odata.context"] && !returnData["@odata.context"]) { - returnData["@odata.context"] = data["@odata.context"]; - } - - for (var i = 0, length = data.value.length; i < length && (count < 0 || returnData.value.length < count); i++) { - var dataIndex = backwards ? length - i - 1 : i; - var item = data.value[dataIndex]; - if (predicate(item)) { - var element = { - index: readIndex + dataIndex, - item: item - }; - - backwards ? returnData.value.unshift(element) : returnData.value.push(element); - } - } - - // Have we reached the end of the collection? - if ((!backwards && data.value.length < readCount) || (backwards && readIndex <= 0)) { - deferred.resolve(returnData); - } else { - var nextIndex = backwards ? Math.max(readIndex - pageSize, 0) : readIndex + readCount; - readMore(nextIndex, pageSize); - } - }, function (err) { - deferred.reject(err); - }); - } - } - }; - - // Initially, we read from the given starting index to the next/previous page boundary - var initialPage = snapToPageBoundaries(index, index, pageSize); - var initialIndex = backwards ? initialPage.i : index; - var initialCount = backwards ? index - initialPage.i + 1 : initialPage.i + initialPage.c - index; - readMore(initialIndex, initialCount); - - return extend(deferred.promise(), { - /** Aborts the filter operation (used within promise callback) - * @method DataCache#cancelFilter - */ - cancel: function () { - - if (pendingReadRange) { - pendingReadRange.cancel(); - } - canceled = true; - } - }); - }; - - /** Fires an onidle event if any functions are assigned. - * @method DataCache~fireOnIdle - */ - var fireOnIdle = function () { - - if (that.onidle && pendingOperations === 0) { - that.onidle(); - } - }; - - /** Creates and starts a new prefetch operation. - * @method DataCache~prefetch - * @param {Number} start - Zero-based index of the items to prefetch. - * This method is a no-op if any of the following conditions is true: - * 1.- prefetchSize is 0 - * 2.- All data has been read and stored locally in the cache. - * 3.- There is already an all data prefetch operation queued. - * 4.- The cache has run out of available space (overflowed). - */ - var prefetch = function (start) { - - - if (allDataLocal || prefetchSize === 0 || overflowed) { - return; - } - - djsassert(state === CACHE_STATE_READ, "DataCache.prefetch() - cache is not on the read state, current state: " + state); - - if (prefetchOperations.length === 0 || (prefetchOperations[0] && prefetchOperations[0].c !== -1)) { - // Merging prefetch operations would be a nice optimization here. - var op = new DataCacheOperation(prefetchStateMachine, null, true, start, prefetchSize, null, prefetchSize); - queueAndStart(op, prefetchOperations); - } - }; - - /** Queues an operation and runs it. - * @param {DataCacheOperation} op - Operation to queue. - * @param {Array} queue - Array that will store the operation. - */ - var queueAndStart = function (op, queue) { - - op.oncomplete = dequeueOperation; - queue.push(op); - pendingOperations++; - op.run(state); - }; - - /** Requests a page from the cache local store. - * @method DataCache~readPage - * @param {Number} key - Zero-based index of the reuqested page. - * @returns {DjsDeferred} A promise for a found flag and page object with (i)ndex, (c)ount, (d)ata, and (t)icks. - */ - var readPage = function (key) { - - djsassert(state !== CACHE_STATE_DESTROY, "DataCache.readPage() - cache is on the destroy state"); - - var canceled = false; - var deferred = extend(new DjsDeferred(), { - /** Aborts the readPage operation. (used within promise callback) - * @method DataCache#cancelReadPage - */ - cancel: function () { - canceled = true; - } - }); - - var error = storeFailureCallback(deferred, "Read page from store failure"); - - store.contains(key, function (contained) { - if (canceled) { - return; - } - if (contained) { - store.read(key, function (_, data) { - if (!canceled) { - deferred.resolve(data !== undefined, data); - } - }, error); - return; - } - deferred.resolve(false); - }, error); - return deferred; - }; - - /** Saves a page to the cache local store. - * @method DataCache~savePage - * @param {Number} key - Zero-based index of the requested page. - * @param {Object} page - Object with (i)ndex, (c)ount, (d)ata, and (t)icks. - * @returns {DjsDeferred} A promise with no value. - */ - var savePage = function (key, page) { - - djsassert(state !== CACHE_STATE_DESTROY, "DataCache.savePage() - cache is on the destroy state"); - djsassert(state !== CACHE_STATE_IDLE, "DataCache.savePage() - cache is on the idle state"); - - var canceled = false; - - var deferred = extend(new DjsDeferred(), { - /** Aborts the savePage operation. (used within promise callback) - * @method DataCache#cancelReadPage - */ - cancel: function () { - canceled = true; - } - }); - - var error = storeFailureCallback(deferred, "Save page to store failure"); - - var resolve = function () { - deferred.resolve(true); - }; - - if (page.c > 0) { - var pageBytes = estimateSize(page); - overflowed = cacheSize >= 0 && cacheSize < actualCacheSize + pageBytes; - - if (!overflowed) { - store.addOrUpdate(key, page, function () { - updateSettings(page, pageBytes); - saveSettings(resolve, error); - }, error); - } else { - resolve(); - } - } else { - updateSettings(page, 0); - saveSettings(resolve, error); - } - return deferred; - }; - - /** Saves the cache's current settings to the local store. - * @method DataCache~saveSettings - * @param {Function} success - Success callback. - * @param {Function} error - Errror callback. - */ - var saveSettings = function (success, error) { - - var settings = { - actualCacheSize: actualCacheSize, - allDataLocal: allDataLocal, - cacheSize: cacheSize, - collectionCount: collectionCount, - highestSavedPage: highestSavedPage, - highestSavedPageSize: highestSavedPageSize, - pageSize: pageSize, - sourceId: source.identifier, - version: version - }; - - store.addOrUpdate("__settings", settings, success, error); - }; - - /** Creates a function that handles a store error. - * @method DataCache~storeFailureCallback - * @param {DjsDeferred} deferred - Deferred object to resolve. - * @param {String} message - Message text. - * @returns {Function} Function to use as error callback. - - * This function will specifically handle problems when interacting with the store. - */ - var storeFailureCallback = function (deferred/*, message*/) { - - - return function (/*error*/) { - // var console = windo1w.console; - // if (console && console.log) { - // console.log(message); - // console.dir(error); - // } - deferred.resolve(false); - }; - }; - - /** Updates the cache's settings based on a page object. - * @method DataCache~updateSettings - * @param {Object} page - Object with (i)ndex, (c)ount, (d)ata. - * @param {Number} pageBytes - Size of the page in bytes. - */ - var updateSettings = function (page, pageBytes) { - - var pageCount = page.c; - var pageIndex = page.i; - - // Detect the collection size. - if (pageCount === 0) { - if (highestSavedPage === pageIndex - pageSize) { - collectionCount = highestSavedPage + highestSavedPageSize; - } - } else { - highestSavedPage = Math.max(highestSavedPage, pageIndex); - if (highestSavedPage === pageIndex) { - highestSavedPageSize = pageCount; - } - actualCacheSize += pageBytes; - if (pageCount < pageSize && !collectionCount) { - collectionCount = pageIndex + pageCount; - } - } - - // Detect the end of the collection. - if (!allDataLocal && collectionCount === highestSavedPage + highestSavedPageSize) { - allDataLocal = true; - } - }; - - /** State machine describing the behavior for cancelling a read or prefetch operation. - * @method DataCache~cancelStateMachine - * @param {DataCacheOperation} operation - Operation being run. - * @param {Object} opTargetState - Operation state to transition to. - * @param {Object} cacheState - Current cache state. - * @param {Object} [data] - - * This state machine contains behavior common to read and prefetch operations. - */ - var cancelStateMachine = function (operation, opTargetState, cacheState, data) { - - - var canceled = operation.canceled && opTargetState !== OPERATION_STATE_END; - if (canceled) { - if (opTargetState === OPERATION_STATE_CANCEL) { - // Cancel state. - // Data is expected to be any pending request made to the cache. - if (data && data.cancel) { - data.cancel(); - } - } - } - return canceled; - }; - - /** State machine describing the behavior of a clear operation. - * @method DataCache~destroyStateMachine - * @param {DataCacheOperation} operation - Operation being run. - * @param {Object} opTargetState - Operation state to transition to. - * @param {Object} cacheState - Current cache state. - - * Clear operations have the highest priority and can't be interrupted by other operations; however, - * they will preempt any other operation currently executing. - */ - var destroyStateMachine = function (operation, opTargetState, cacheState) { - - - var transition = operation.transition; - - // Signal the cache that a clear operation is running. - if (cacheState !== CACHE_STATE_DESTROY) { - changeState(CACHE_STATE_DESTROY); - return true; - } - - switch (opTargetState) { - case OPERATION_STATE_START: - // Initial state of the operation. - transition(DESTROY_STATE_CLEAR); - break; - - case OPERATION_STATE_END: - // State that signals the operation is done. - fireOnIdle(); - break; - - case DESTROY_STATE_CLEAR: - // State that clears all the local data of the cache. - clearStore().then(function () { - // Terminate the operation once the local store has been cleared. - operation.complete(); - }); - // Wait until the clear request completes. - operation.wait(); - break; - - default: - return false; - } - return true; - }; - - /** State machine describing the behavior of a prefetch operation. - * @method DataCache~prefetchStateMachine - * @param {DataCacheOperation} operation - Operation being run. - * @param {Object} opTargetState - Operation state to transition to. - * @param {Object} cacheState - Current cache state. - * @param {Object} [data] - - - * Prefetch operations have the lowest priority and will be interrupted by operations of - * other kinds. A preempted prefetch operation will resume its execution only when the state - * of the cache returns to idle. - * - * If a clear operation starts executing then all the prefetch operations are canceled, - * even if they haven't started executing yet. - */ - var prefetchStateMachine = function (operation, opTargetState, cacheState, data) { - - - // Handle cancelation - if (!cancelStateMachine(operation, opTargetState, cacheState, data)) { - - var transition = operation.transition; - - // Handle preemption - if (cacheState !== CACHE_STATE_PREFETCH) { - if (cacheState === CACHE_STATE_DESTROY) { - if (opTargetState !== OPERATION_STATE_CANCEL) { - operation.cancel(); - } - } else if (cacheState === CACHE_STATE_IDLE) { - // Signal the cache that a prefetch operation is running. - changeState(CACHE_STATE_PREFETCH); - } - return true; - } - - switch (opTargetState) { - case OPERATION_STATE_START: - // Initial state of the operation. - if (prefetchOperations[0] === operation) { - transition(READ_STATE_LOCAL, operation.i); - } - break; - - case READ_STATE_DONE: - // State that determines if the operation can be resolved or has to - // continue processing. - // Data is expected to be the read page. - var pending = operation.pending; - - if (pending > 0) { - pending -= Math.min(pending, data.c); - } - - // Are we done, or has all the data been stored? - if (allDataLocal || pending === 0 || data.c < pageSize || overflowed) { - operation.complete(); - } else { - // Continue processing the operation. - operation.pending = pending; - transition(READ_STATE_LOCAL, data.i + pageSize); - } - break; - - default: - return readSaveStateMachine(operation, opTargetState, cacheState, data, true); - } - } - return true; - }; - - /** State machine describing the behavior of a read operation. - * @method DataCache~readStateMachine - * @param {DataCacheOperation} operation - Operation being run. - * @param {Object} opTargetState - Operation state to transition to. - * @param {Object} cacheState - Current cache state. - * @param {Object} [data] - - - * Read operations have a higher priority than prefetch operations, but lower than - * clear operations. They will preempt any prefetch operation currently running - * but will be interrupted by a clear operation. - * - * If a clear operation starts executing then all the currently running - * read operations are canceled. Read operations that haven't started yet will - * wait in the start state until the destory operation finishes. - */ - var readStateMachine = function (operation, opTargetState, cacheState, data) { - - - // Handle cancelation - if (!cancelStateMachine(operation, opTargetState, cacheState, data)) { - - var transition = operation.transition; - - // Handle preemption - if (cacheState !== CACHE_STATE_READ && opTargetState !== OPERATION_STATE_START) { - if (cacheState === CACHE_STATE_DESTROY) { - if (opTargetState !== OPERATION_STATE_START) { - operation.cancel(); - } - } else if (cacheState !== CACHE_STATE_WRITE) { - // Signal the cache that a read operation is running. - djsassert(state == CACHE_STATE_IDLE || state === CACHE_STATE_PREFETCH, "DataCache.readStateMachine() - cache is not on the read or idle state."); - changeState(CACHE_STATE_READ); - } - - return true; - } - - switch (opTargetState) { - case OPERATION_STATE_START: - // Initial state of the operation. - // Wait until the cache is idle or prefetching. - if (cacheState === CACHE_STATE_IDLE || cacheState === CACHE_STATE_PREFETCH) { - // Signal the cache that a read operation is running. - changeState(CACHE_STATE_READ); - if (operation.c >= 0) { - // Snap the requested range to a page boundary. - var range = snapToPageBoundaries(operation.i, operation.c, pageSize); - transition(READ_STATE_LOCAL, range.i); - } else { - transition(READ_STATE_DONE, operation); - } - } - break; - - case READ_STATE_DONE: - // State that determines if the operation can be resolved or has to - // continue processing. - // Data is expected to be the read page. - appendPage(operation, data); - var len = getJsonValueArraryLength(operation.d); - // Are we done? - if (operation.c === len || data.c < pageSize) { - // Update the stats, request for a prefetch operation. - stats.cacheReads++; - prefetch(data.i + data.c); - // Terminate the operation. - operation.complete(); - } else { - // Continue processing the operation. - transition(READ_STATE_LOCAL, data.i + pageSize); - } - break; - - default: - return readSaveStateMachine(operation, opTargetState, cacheState, data, false); - } - } - - return true; - }; - - /** State machine describing the behavior for reading and saving data into the cache. - * @method DataCache~readSaveStateMachine - * @param {DataCacheOperation} operation - Operation being run. - * @param {Object} opTargetState - Operation state to transition to. - * @param {Object} cacheState - Current cache state. - * @param {Object} [data] - - * @param {Boolean} isPrefetch - Flag indicating whether a read (false) or prefetch (true) operation is running. - * This state machine contains behavior common to read and prefetch operations. - */ - var readSaveStateMachine = function (operation, opTargetState, cacheState, data, isPrefetch) { - - var error = operation.error; - var transition = operation.transition; - var wait = operation.wait; - var request; - - switch (opTargetState) { - case OPERATION_STATE_END: - // State that signals the operation is done. - fireOnIdle(); - break; - - case READ_STATE_LOCAL: - // State that requests for a page from the local store. - // Data is expected to be the index of the page to request. - request = readPage(data).then(function (found, page) { - // Signal the cache that a read operation is running. - if (!operation.canceled) { - if (found) { - // The page is in the local store, check if the operation can be resolved. - transition(READ_STATE_DONE, page); - } else { - // The page is not in the local store, request it from the source. - transition(READ_STATE_SOURCE, data); - } - } - }); - break; - - case READ_STATE_SOURCE: - // State that requests for a page from the cache source. - // Data is expected to be the index of the page to request. - request = fetchPage(data).then(function (page) { - // Signal the cache that a read operation is running. - if (!operation.canceled) { - // Update the stats and save the page to the local store. - if (isPrefetch) { - stats.prefetches++; - } else { - stats.netReads++; - } - transition(READ_STATE_SAVE, page); - } - }, error); - break; - - case READ_STATE_SAVE: - // State that saves a page to the local store. - // Data is expected to be the page to save. - // Write access to the store is exclusive. - if (cacheState !== CACHE_STATE_WRITE) { - changeState(CACHE_STATE_WRITE); - request = savePage(data.i, data).then(function (saved) { - if (!operation.canceled) { - if (!saved && isPrefetch) { - operation.pending = 0; - } - // Check if the operation can be resolved. - transition(READ_STATE_DONE, data); - } - changeState(CACHE_STATE_IDLE); - }); - } - break; - - default: - // Unknown state that can't be handled by this state machine. - return false; - } - - if (request) { - // The operation might have been canceled between stack frames do to the async calls. - if (operation.canceled) { - request.cancel(); - } else if (operation.s === opTargetState) { - // Wait for the request to complete. - wait(request); - } - } - - return true; - }; - - // Initialize the cache. - store.read("__settings", function (_, settings) { - if (assigned(settings)) { - var settingsVersion = settings.version; - if (!settingsVersion || settingsVersion.indexOf("1.") !== 0) { - cacheFailureCallback("Unsupported cache store version " + settingsVersion)(); - return; - } - - if (pageSize !== settings.pageSize || source.identifier !== settings.sourceId) { - // The shape or the source of the data was changed so invalidate the store. - clearStore().then(function () { - // Signal the cache is fully initialized. - changeState(CACHE_STATE_IDLE); - }, cacheFailureCallback("Unable to clear store during initialization")); - } else { - // Restore the saved settings. - actualCacheSize = settings.actualCacheSize; - allDataLocal = settings.allDataLocal; - cacheSize = settings.cacheSize; - collectionCount = settings.collectionCount; - highestSavedPage = settings.highestSavedPage; - highestSavedPageSize = settings.highestSavedPageSize; - version = settingsVersion; - - // Signal the cache is fully initialized. - changeState(CACHE_STATE_IDLE); - } - } else { - // This is a brand new cache. - saveSettings(function () { - // Signal the cache is fully initialized. - changeState(CACHE_STATE_IDLE); - }, cacheFailureCallback("Unable to write settings during initialization.")); - } - }, cacheFailureCallback("Unable to read settings from store.")); - - return that; -} - -/** Creates a data cache for a collection that is efficiently loaded on-demand. - * @param options - * Options for the data cache, including name, source, pageSize, TODO check doku - * prefetchSize, cacheSize, storage mechanism, and initial prefetch and local-data handler. - * @returns {DataCache} A new data cache instance. - */ -function createDataCache (options) { - checkUndefinedGreaterThanZero(options.pageSize, "pageSize"); - checkUndefinedOrNumber(options.cacheSize, "cacheSize"); - checkUndefinedOrNumber(options.prefetchSize, "prefetchSize"); - - if (!assigned(options.name)) { - throw { message: "Undefined or null name", options: options }; - } - - if (!assigned(options.source)) { - throw { message: "Undefined source", options: options }; - } - - return new DataCache(options); -} - - -/** estimateSize (see {@link estimateSize}) */ -exports.estimateSize = estimateSize; - -/** createDataCache */ -exports.createDataCache = createDataCache;</code></pre> + <pre class="prettyprint source"><code>/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + */ +'use strict'; + + /** @module cache */ + +//var odatajs = require('./odatajs/utils.js'); +var utils = require('./utils.js'); +var deferred = require('./deferred.js'); +var storeReq = require('./store.js'); +var cacheSource = require('./cache/source.js'); + + +var assigned = utils.assigned; +var delay = utils.delay; +var extend = utils.extend; +var djsassert = utils.djsassert; +var isArray = utils.isArray; +var normalizeURI = utils.normalizeURI; +var parseInt10 = utils.parseInt10; +var undefinedDefault = utils.undefinedDefault; + +var createDeferred = deferred.createDeferred; +var DjsDeferred = deferred.DjsDeferred; + + +var getJsonValueArraryLength = utils.getJsonValueArraryLength; +var sliceJsonValueArray = utils.sliceJsonValueArray; +var concatJsonValueArray = utils.concatJsonValueArray; + + + +/** Appends a page's data to the operation data. + * @param {Object} operation - Operation with (i)ndex, (c)ount and (d)ata. + * @param {Object} page - Page with (i)ndex, (c)ount and (d)ata. + */ +function appendPage(operation, page) { + + var intersection = intersectRanges(operation, page); + var start = 0; + var end = 0; + if (intersection) { + start = intersection.i - page.i; + end = start + (operation.c - getJsonValueArraryLength(operation.d)); + } + + operation.d = concatJsonValueArray(operation.d, sliceJsonValueArray(page.d, start, end)); +} + +/** Returns the {(i)ndex, (c)ount} range for the intersection of x and y. + * @param {Object} x - Range with (i)ndex and (c)ount members. + * @param {Object} y - Range with (i)ndex and (c)ount members. + * @returns {Object} The intersection (i)ndex and (c)ount; undefined if there is no intersection. + */ +function intersectRanges(x, y) { + + var xLast = x.i + x.c; + var yLast = y.i + y.c; + var resultIndex = (x.i > y.i) ? x.i : y.i; + var resultLast = (xLast < yLast) ? xLast : yLast; + var result; + if (resultLast >= resultIndex) { + result = { i: resultIndex, c: resultLast - resultIndex }; + } + + return result; +} + +/** Checks whether val is a defined number with value zero or greater. + * @param {Number} val - Value to check. + * @param {String} name - Parameter name to use in exception. + * @throws Throws an exception if the check fails + */ +function checkZeroGreater(val, name) { + + if (val === undefined || typeof val !== "number") { + throw { message: "'" + name + "' must be a number." }; + } + + if (isNaN(val) || val < 0 || !isFinite(val)) { + throw { message: "'" + name + "' must be greater than or equal to zero." }; + } +} + +/** Checks whether val is undefined or a number with value greater than zero. + * @param {Number} val - Value to check. + * @param {String} name - Parameter name to use in exception. + * @throws Throws an exception if the check fails + */ +function checkUndefinedGreaterThanZero(val, name) { + + if (val !== undefined) { + if (typeof val !== "number") { + throw { message: "'" + name + "' must be a number." }; + } + + if (isNaN(val) || val <= 0 || !isFinite(val)) { + throw { message: "'" + name + "' must be greater than zero." }; + } + } +} + +/** Checks whether val is undefined or a number + * @param {Number} val - Value to check. + * @param {String} name - Parameter name to use in exception. + * @throws Throws an exception if the check fails + */ +function checkUndefinedOrNumber(val, name) { + if (val !== undefined && (typeof val !== "number" || isNaN(val) || !isFinite(val))) { + throw { message: "'" + name + "' must be a number." }; + } +} + +/** Performs a linear search on the specified array and removes the first instance of 'item'. + * @param {Array} arr - Array to search. + * @param {*} item - Item being sought. + * @returns {Boolean} true if the item was removed otherwise false + */ +function removeFromArray(arr, item) { + + var i, len; + for (i = 0, len = arr.length; i < len; i++) { + if (arr[i] === item) { + arr.splice(i, 1); + return true; + } + } + + return false; +} + +/** Estimates the size of an object in bytes. + * Object trees are traversed recursively + * @param {Object} object - Object to determine the size of. + * @returns {Number} Estimated size of the object in bytes. + */ +function estimateSize(object) { + var size = 0; + var type = typeof object; + + if (type === "object" && object) { + for (var name in object) { + size += name.length * 2 + estimateSize(object[name]); + } + } else if (type === "string") { + size = object.length * 2; + } else { + size = 8; + } + return size; +} + +/** Snaps low and high indices into page sizes and returns a range. + * @param {Number} lowIndex - Low index to snap to a lower value. + * @param {Number} highIndex - High index to snap to a higher value. + * @param {Number} pageSize - Page size to snap to. + * @returns {Object} A range with (i)ndex and (c)ount of elements. + */ +function snapToPageBoundaries(lowIndex, highIndex, pageSize) { + lowIndex = Math.floor(lowIndex / pageSize) * pageSize; + highIndex = Math.ceil((highIndex + 1) / pageSize) * pageSize; + return { i: lowIndex, c: highIndex - lowIndex }; +} + +// The DataCache is implemented using state machines. The following constants are used to properly +// identify and label the states that these machines transition to. +var CACHE_STATE_DESTROY = "destroy"; +var CACHE_STATE_IDLE = "idle"; +var CACHE_STATE_INIT = "init"; +var CACHE_STATE_READ = "read"; +var CACHE_STATE_PREFETCH = "prefetch"; +var CACHE_STATE_WRITE = "write"; + +// DataCacheOperation state machine states. +// Transitions on operations also depend on the cache current of the cache. +var OPERATION_STATE_CANCEL = "cancel"; +var OPERATION_STATE_END = "end"; +var OPERATION_STATE_ERROR = "error"; +var OPERATION_STATE_START = "start"; +var OPERATION_STATE_WAIT = "wait"; + +// Destroy state machine states +var DESTROY_STATE_CLEAR = "clear"; + +// Read / Prefetch state machine states +var READ_STATE_DONE = "done"; +var READ_STATE_LOCAL = "local"; +var READ_STATE_SAVE = "save"; +var READ_STATE_SOURCE = "source"; + +/** Creates a new operation object. + * @class DataCacheOperation + * @param {Function} stateMachine - State machine that describes the specific behavior of the operation. + * @param {DjsDeferred} promise - Promise for requested values. + * @param {Boolean} isCancelable - Whether this operation can be canceled or not. + * @param {Number} index - Index of first item requested. + * @param {Number} count - Count of items requested. + * @param {Array} data - Array with the items requested by the operation. + * @param {Number} pending - Total number of pending prefetch records. + * @returns {DataCacheOperation} A new data cache operation instance. + */ +function DataCacheOperation(stateMachine, promise, isCancelable, index, count, data, pending) { + + var stateData; + var cacheState; + var that = this; + + that.p = promise; + that.i = index; + that.c = count; + that.d = data; + that.s = OPERATION_STATE_START; + + that.canceled = false; + that.pending = pending; + that.oncomplete = null; + + /** Transitions this operation to the cancel state and sets the canceled flag to true. + * The function is a no-op if the operation is non-cancelable. + * @method DataCacheOperation#cancel + */ + that.cancel = function cancel() { + + if (!isCancelable) { + return; + } + + var state = that.s; + if (state !== OPERATION_STATE_ERROR && state !== OPERATION_STATE_END && state !== OPERATION_STATE_CANCEL) { + that.canceled = true; + that.transition(OPERATION_STATE_CANCEL, stateData); + } + }; + + /** Transitions this operation to the end state. + * @method DataCacheOperation#complete + */ + that.complete = function () { + + djsassert(that.s !== OPERATION_STATE_END, "DataCacheOperation.complete() - operation is in the end state", that); + that.transition(OPERATION_STATE_END, stateData); + }; + + /** Transitions this operation to the error state. + * @method DataCacheOperation#error + */ + that.error = function (err) { + if (!that.canceled) { + djsassert(that.s !== OPERATION_STATE_END, "DataCacheOperation.error() - operation is in the end state", that); + djsassert(that.s !== OPERATION_STATE_ERROR, "DataCacheOperation.error() - operation is in the error state", that); + that.transition(OPERATION_STATE_ERROR, err); + } + }; + + /** Executes the operation's current state in the context of a new cache state. + * @method DataCacheOperation#run + * @param {Object} state - New cache state. + */ + that.run = function (state) { + + cacheState = state; + that.transition(that.s, stateData); + }; + + /** Transitions this operation to the wait state. + * @method DataCacheOperation#wait + */ + that.wait = function (data) { + + djsassert(that.s !== OPERATION_STATE_END, "DataCacheOperation.wait() - operation is in the end state", that); + that.transition(OPERATION_STATE_WAIT, data); + }; + + /** State machine that describes all operations common behavior. + * @method DataCacheOperation#operationStateMachine + * @param {Object} opTargetState - Operation state to transition to. + * @param {Object} cacheState - Current cache state. + * @param {Object} [data] - Additional data passed to the state. + */ + var operationStateMachine = function (opTargetState, cacheState, data) { + + switch (opTargetState) { + case OPERATION_STATE_START: + // Initial state of the operation. The operation will remain in this state until the cache has been fully initialized. + if (cacheState !== CACHE_STATE_INIT) { + stateMachine(that, opTargetState, cacheState, data); + } + break; + + case OPERATION_STATE_WAIT: + // Wait state indicating that the operation is active but waiting for an asynchronous operation to complete. + stateMachine(that, opTargetState, cacheState, data); + break; + + case OPERATION_STATE_CANCEL: + // Cancel state. + stateMachine(that, opTargetState, cacheState, data); + that.fireCanceled(); + that.transition(OPERATION_STATE_END); + break; + + case OPERATION_STATE_ERROR: + // Error state. Data is expected to be an object detailing the error condition. + stateMachine(that, opTargetState, cacheState, data); + that.canceled = true; + that.fireRejected(data); + that.transition(OPERATION_STATE_END); + break; + + case OPERATION_STATE_END: + // Final state of the operation. + if (that.oncomplete) { + that.oncomplete(that); + } + if (!that.canceled) { + that.fireResolved(); + } + stateMachine(that, opTargetState, cacheState, data); + break; + + default: + // Any other state is passed down to the state machine describing the operation's specific behavior. + + if (true) { + // Check that the state machine actually handled the sate. + var handled = stateMachine(that, opTargetState, cacheState, data); + djsassert(handled, "Bad operation state: " + opTargetState + " cacheState: " + cacheState, this); + } else { + + stateMachine(that, opTargetState, cacheState, data); + + } + + break; + } + }; + + + + /** Transitions this operation to a new state. + * @method DataCacheOperation#transition + * @param {Object} state - State to transition the operation to. + * @param {Object} [data] - + */ + that.transition = function (state, data) { + that.s = state; + stateData = data; + operationStateMachine(state, cacheState, data); + }; + + return that; +} + +/** Fires a resolved notification as necessary. + * @method DataCacheOperation#fireResolved + */ +DataCacheOperation.prototype.fireResolved = function () { + + // Fire the resolve just once. + var p = this.p; + if (p) { + this.p = null; + p.resolve(this.d); + } +}; + +/** Fires a rejected notification as necessary. + * @method DataCacheOperation#fireRejected + */ +DataCacheOperation.prototype.fireRejected = function (reason) { + + // Fire the rejection just once. + var p = this.p; + if (p) { + this.p = null; + p.reject(reason); + } +}; + +/** Fires a canceled notification as necessary. + * @method DataCacheOperation#fireCanceled + */ +DataCacheOperation.prototype.fireCanceled = function () { + + this.fireRejected({ canceled: true, message: "Operation canceled" }); +}; + + +/** Creates a data cache for a collection that is efficiently loaded on-demand. + * @class DataCache + * @param options - Options for the data cache, including name, source, pageSize, + * prefetchSize, cacheSize, storage mechanism, and initial prefetch and local-data handler. + * @returns {DataCache} A new data cache instance. + */ +function DataCache(options) { + + var state = CACHE_STATE_INIT; + var stats = { counts: 0, netReads: 0, prefetches: 0, cacheReads: 0 }; + + var clearOperations = []; + var readOperations = []; + var prefetchOperations = []; + + var actualCacheSize = 0; // Actual cache size in bytes. + var allDataLocal = false; // Whether all data is local. + var cacheSize = undefinedDefault(options.cacheSize, 1048576); // Requested cache size in bytes, default 1 MB. + var collectionCount = 0; // Number of elements in the server collection. + var highestSavedPage = 0; // Highest index of all the saved pages. + var highestSavedPageSize = 0; // Item count of the saved page with the highest index. + var overflowed = cacheSize === 0; // If the cache has overflowed (actualCacheSize > cacheSize or cacheSize == 0); + var pageSize = undefinedDefault(options.pageSize, 50); // Number of elements to store per page. + var prefetchSize = undefinedDefault(options.prefetchSize, pageSize); // Number of elements to prefetch from the source when the cache is idling. + var version = "1.0"; + var cacheFailure; + + var pendingOperations = 0; + + var source = options.source; + if (typeof source === "string") { + // Create a new cache source. + source = new cacheSource.ODataCacheSource(options); + } + source.options = options; + + // Create a cache local store. + var store = storeReq.createStore(options.name, options.mechanism); + + var that = this; + + that.onidle = options.idle; + that.stats = stats; + + /** Counts the number of items in the collection. + * @method DataCache#count + * @returns {Object} A promise with the number of items. + */ + that.count = function () { + + if (cacheFailure) { + throw cacheFailure; + } + + var deferred = createDeferred(); + var canceled = false; + + if (allDataLocal) { + delay(function () { + deferred.resolve(collectionCount); + }); + + return deferred.promise(); + } + + // TODO: Consider returning the local data count instead once allDataLocal flag is set to true. + var request = source.count(function (count) { + request = null; + stats.counts++; + deferred.resolve(count); + }, function (err) { + request = null; + deferred.reject(extend(err, { canceled: canceled })); + }); + + return extend(deferred.promise(), { + + /** Aborts the count operation (used within promise callback) + * @method DataCache#cancelCount + */ + cancel: function () { + + if (request) { + canceled = true; + request.abort(); + request = null; + } + } + }); + }; + + /** Cancels all running operations and clears all local data associated with this cache. + * New read requests made while a clear operation is in progress will not be canceled. + * Instead they will be queued for execution once the operation is completed. + * @method DataCache#clear + * @returns {Object} A promise that has no value and can't be canceled. + */ + that.clear = function () { + + if (cacheFailure) { + throw cacheFailure; + } + + if (clearOperations.length === 0) { + var deferred = createDeferred(); + var op = new DataCacheOperation(destroyStateMachine, deferred, false); + queueAndStart(op, clearOperations); + return deferred.promise(); + } + return clearOperations[0].p; + }; + + /** Filters the cache data based a predicate. + * Specifying a negative count value will yield all the items in the cache that satisfy the predicate. + * @method DataCache#filterForward + * @param {Number} index - The index of the item to start filtering forward from. + * @param {Number} count - Maximum number of items to include in the result. + * @param {Function} predicate - Callback function returning a boolean that determines whether an item should be included in the result or not. + * @returns {DjsDeferred} A promise for an array of results. + */ + that.filterForward = function (index, count, predicate) { + return filter(index, count, predicate, false); + }; + + /** Filters the cache data based a predicate. + * Specifying a negative count value will yield all the items in the cache that satisfy the predicate. + * @method DataCache#filterBack + * @param {Number} index - The index of the item to start filtering backward from. + * @param {Number} count - Maximum number of items to include in the result. + * @param {Function} predicate - Callback function returning a boolean that determines whether an item should be included in the result or not. + * @returns {DjsDeferred} A promise for an array of results. + */ + that.filterBack = function (index, count, predicate) { + return filter(index, count, predicate, true); + }; + + /** Reads a range of adjacent records. + * New read requests made while a clear operation is in progress will not be canceled. + * Instead they will be queued for execution once the operation is completed. + * @method DataCache#readRange + * @param {Number} index - Zero-based index of record range to read. + * @param {Number} count - Number of records in the range. + * @returns {DjsDeferred} A promise for an array of records; less records may be returned if the + * end of the collection is found. + */ + that.readRange = function (index, count) { + + checkZeroGreater(index, "index"); + checkZeroGreater(count, "count"); + + if (cacheFailure) { + throw cacheFailure; + } + + var deferred = createDeferred(); + + // Merging read operations would be a nice optimization here. + var op = new DataCacheOperation(readStateMachine, deferred, true, index, count, {}, 0); + queueAndStart(op, readOperations); + + return extend(deferred.promise(), { + cancel: function () { + /** Aborts the readRange operation (used within promise callback) + * @method DataCache#cancelReadRange + */ + op.cancel(); + } + }); + }; + + /** Creates an Observable object that enumerates all the cache contents. + * @method DataCache#toObservable + * @returns A new Observable object that enumerates all the cache contents. + */ + that.ToObservable = that.toObservable = function () { + if ( !utils.inBrowser()) { + throw { message: "Only in broser supported" }; + } + + if (!window.Rx || !window.Rx.Observable) { + throw { message: "Rx library not available - include rx.js" }; + } + + if (cacheFailure) { + throw cacheFailure; + } + + //return window.Rx.Observable.create(function (obs) { + return new window.Rx.Observable(function (obs) { + var disposed = false; + var index = 0; + + var errorCallback = function (error) { + if (!disposed) { + obs.onError(error); + } + }; + + var successCallback = function (data) { + if (!disposed) { + var i, len; + for (i = 0, len = data.value.length; i < len; i++) { + // The wrapper automatically checks for Dispose + // on the observer, so we don't need to check it here. + //obs.next(data.value[i]); + obs.onNext(data.value[i]); + } + + if (data.value.length < pageSize) { + //obs.completed(); + obs.onCompleted(); + } else { + index += pageSize; + that.readRange(index, pageSize).then(successCallback, errorCallback); + } + } + }; + + that.readRange(index, pageSize).then(successCallback, errorCallback); + + return { Dispose: function () { + obs.dispose(); // otherwise the check isStopped obs.onNext(data.value[i]); + disposed = true; + } }; + }); + }; + + /** Creates a function that handles a callback by setting the cache into failure mode. + * @method DataCache~cacheFailureCallback + * @param {String} message - Message text. + * @returns {Function} Function to use as error callback. + * This function will specifically handle problems with critical store resources + * during cache initialization. + */ + var cacheFailureCallback = function (message) { + + + return function (error) { + cacheFailure = { message: message, error: error }; + + // Destroy any pending clear or read operations. + // At this point there should be no prefetch operations. + // Count operations will go through but are benign because they + // won't interact with the store. + djsassert(prefetchOperations.length === 0, "prefetchOperations.length === 0"); + var i, len; + for (i = 0, len = readOperations.length; i < len; i++) { + readOperations[i].fireRejected(cacheFailure); + } + for (i = 0, len = clearOperations.length; i < len; i++) { + clearOperations[i].fireRejected(cacheFailure); + } + + // Null out the operation arrays. + readOperations = clearOperations = null; + }; + }; + + /** Updates the cache's state and signals all pending operations of the change. + * @method DataCache~changeState + * @param {Object} newState - New cache state. + * This method is a no-op if the cache's current state and the new state are the same. + */ + var changeState = function (newState) { + + if (newState !== state) { + state = newState; + var operations = clearOperations.concat(readOperations, prefetchOperations); + var i, len; + for (i = 0, len = operations.length; i < len; i++) { + operations[i].run(state); + } + } + }; + + /** Removes all the data stored in the cache. + * @method DataCache~clearStore + * @returns {DjsDeferred} A promise with no value. + */ + var clearStore = function () { + djsassert(state === CACHE_STATE_DESTROY || state === CACHE_STATE_INIT, "DataCache.clearStore() - cache is not on the destroy or initialize state, current sate = " + state); + + var deferred = new DjsDeferred(); + store.clear(function () { + + // Reset the cache settings. + actualCacheSize = 0; + allDataLocal = false; + collectionCount = 0; + highestSavedPage = 0; + highestSavedPageSize = 0; + overflowed = cacheSize === 0; + + // version is not reset, in case there is other state in eg V1.1 that is still around. + + // Reset the cache stats. + stats = { counts: 0, netReads: 0, prefetches: 0, cacheReads: 0 }; + that.stats = stats; + + store.close(); + deferred.resolve(); + }, function (err) { + deferred.reject(err); + }); + return deferred; + }; + + /** Removes an operation from the caches queues and changes the cache state to idle. + * @method DataCache~dequeueOperation + * @param {DataCacheOperation} operation - Operation to dequeue. + * This method is used as a handler for the operation's oncomplete event. + */ + var dequeueOperation = function (operation) { + + var removed = removeFromArray(clearOperations, operation); + if (!removed) { + removed = removeFromArray(readOperations, operation); + if (!removed) { + removeFromArray(prefetchOperations, operation); + } + } + + pendingOperations--; + changeState(CACHE_STATE_IDLE); + }; + + /** Requests data from the cache source. + * @method DataCache~fetchPage + * @param {Number} start - Zero-based index of items to request. + * @returns {DjsDeferred} A promise for a page object with (i)ndex, (c)ount, (d)ata. + */ + var fetchPage = function (start) { + + djsassert(state !== CACHE_STATE_DESTROY, "DataCache.fetchPage() - cache is on the destroy state"); + djsassert(state !== CACHE_STATE_IDLE, "DataCache.fetchPage() - cache is on the idle state"); + + var deferred = new DjsDeferred(); + var canceled = false; + + var request = source.read(start, pageSize, function (data) { + var length = getJsonValueArraryLength(data); + var page = { i: start, c: length, d: data }; + deferred.resolve(page); + }, function (err) { + deferred.reject(err); + }); + + return extend(deferred, { + cancel: function () { + if (request) { + request.abort(); + canceled = true; + request = null; + } + } + }); + }; + + /** Filters the cache data based a predicate. + * @method DataCache~filter + * @param {Number} index - The index of the item to start filtering from. + * @param {Number} count - Maximum number of items to include in the result. + * @param {Function} predicate - Callback function returning a boolean that determines whether an item should be included in the result or not. + * @param {Boolean} backwards - True if the filtering should move backward from the specified index, falsey otherwise. + * Specifying a negative count value will yield all the items in the cache that satisfy the predicate. + * @returns {DjsDeferred} A promise for an array of results. + */ + var filter = function (index, count, predicate, backwards) { + + index = parseInt10(index); + count = parseInt10(count); + + if (isNaN(index)) { + throw { message: "'index' must be a valid number.", index: index }; + } + if (isNaN(count)) { + throw { message: "'count' must be a valid number.", count: count }; + } + + if (cacheFailure) { + throw cacheFailure; + } + + index = Math.max(index, 0); + + var deferred = createDeferred(); + var returnData = {}; + returnData.value = []; + var canceled = false; + var pendingReadRange = null; + + var readMore = function (readIndex, readCount) { + if (!canceled) { + if (count > 0 && returnData.value.length >= count) { + deferred.resolve(returnData); + } else { + pendingReadRange = that.readRange(readIndex, readCount).then(function (data) { + if (data["@odata.context"] && !returnData["@odata.context"]) { + returnData["@odata.context"] = data["@odata.context"]; + } + + for (var i = 0, length = data.value.length; i < length && (count < 0 || returnData.value.length < count); i++) { + var dataIndex = backwards ? length - i - 1 : i; + var item = data.value[dataIndex]; + if (predicate(item)) { + var element = { + index: readIndex + dataIndex, + item: item + }; + + backwards ? returnData.value.unshift(element) : returnData.value.push(element); + } + } + + // Have we reached the end of the collection?
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