michael@0: /* -*- Mode: js2; js2-basic-offset: 2; indent-tabs-mode: nil; -*- */
michael@0: /* vim: set ft=javascript ts=2 et sw=2 tw=80: */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: 'use strict'
michael@0: 
michael@0: this.EXPORTED_SYMBOLS = ['DataStoreCursor'];
michael@0: 
michael@0: function debug(s) {
michael@0:   //dump('DEBUG DataStoreCursor: ' + s + '\n');
michael@0: }
michael@0: 
michael@0: const {classes: Cc, interfaces: Ci, utils: Cu, results: Cr} = Components;
michael@0: 
michael@0: const STATE_INIT = 0;
michael@0: const STATE_REVISION_INIT = 1;
michael@0: const STATE_REVISION_CHECK = 2;
michael@0: const STATE_SEND_ALL = 3;
michael@0: const STATE_REVISION_SEND = 4;
michael@0: const STATE_DONE = 5;
michael@0: 
michael@0: const REVISION_ADDED = 'added';
michael@0: const REVISION_UPDATED = 'updated';
michael@0: const REVISION_REMOVED = 'removed';
michael@0: const REVISION_VOID = 'void';
michael@0: const REVISION_SKIP = 'skip'
michael@0: 
michael@0: Cu.import('resource://gre/modules/XPCOMUtils.jsm');
michael@0: 
michael@0: /**
michael@0:  * legend:
michael@0:  * - RID = revision ID
michael@0:  * - R = revision object (with the internalRevisionId that is a number)
michael@0:  * - X = current object ID.
michael@0:  * - L = the list of revisions that we have to send
michael@0:  *
michael@0:  * State: init: do you have RID ?
michael@0:  *   YES: state->initRevision; loop
michael@0:  *   NO: get R; X=0; state->sendAll; send a 'clear'
michael@0:  *
michael@0:  * State: initRevision. Get R from RID. Done?
michael@0:  *   YES: state->revisionCheck; loop
michael@0:  *   NO: RID = null; state->init; loop
michael@0:  *
michael@0:  * State: revisionCheck: get all the revisions between R and NOW. Done?
michael@0:  *   YES and R == NOW: state->done; loop
michael@0:  *   YES and R != NOW: Store this revisions in L; state->revisionSend; loop
michael@0:  *   NO: R = NOW; X=0; state->sendAll; send a 'clear'
michael@0:  *
michael@0:  * State: sendAll: is R still the last revision?
michael@0:  *   YES get the first object with id > X. Done?
michael@0:  *     YES: X = object.id; send 'add'
michael@0:  *     NO: state->revisionCheck; loop
michael@0:  *   NO: R = NOW; X=0; send a 'clear'
michael@0:  *
michael@0:  * State: revisionSend: do you have something from L to send?
michael@0:  *   YES and L[0] == 'removed': R=L[0]; send 'remove' with ID
michael@0:  *   YES and L[0] == 'added': R=L[0]; get the object; found?
michael@0:  *     NO: loop
michael@0:  *     YES: send 'add' with ID and object
michael@0:  *   YES and L[0] == 'updated': R=L[0]; get the object; found?
michael@0:  *     NO: loop
michael@0:  *     YES and object.R > R: continue
michael@0:  *     YES and object.R <= R: send 'update' with ID and object
michael@0:  *   YES L[0] == 'void': R=L[0]; state->init; loop
michael@0:  *   NO: state->revisionCheck; loop
michael@0:  *
michael@0:  * State: done: send a 'done' with R
michael@0:  */
michael@0: 
michael@0: /* Helper functions */
michael@0: function createDOMError(aWindow, aEvent) {
michael@0:   return new aWindow.DOMError(aEvent.target.error.name);
michael@0: }
michael@0: 
michael@0: /* DataStoreCursor object */
michael@0: this.DataStoreCursor = function(aWindow, aDataStore, aRevisionId) {
michael@0:   debug("DataStoreCursor created");
michael@0:   this.init(aWindow, aDataStore, aRevisionId);
michael@0: }
michael@0: 
michael@0: this.DataStoreCursor.prototype = {
michael@0:   classDescription: 'DataStoreCursor XPCOM Component',
michael@0:   classID: Components.ID('{b6d14349-1eab-46b8-8513-584a7328a26b}'),
michael@0:   contractID: '@mozilla.org/dom/datastore-cursor-impl;1',
michael@0:   QueryInterface: XPCOMUtils.generateQI([Components.interfaces.nsISupports]),
michael@0: 
michael@0:   _window: null,
michael@0:   _dataStore: null,
michael@0:   _revisionId: null,
michael@0:   _revision: null,
michael@0:   _revisionsList: null,
michael@0:   _objectId: 0,
michael@0: 
michael@0:   _state: STATE_INIT,
michael@0: 
michael@0:   init: function(aWindow, aDataStore, aRevisionId) {
michael@0:     debug('DataStoreCursor init');
michael@0: 
michael@0:     this._window = aWindow;
michael@0:     this._dataStore = aDataStore;
michael@0:     this._revisionId = aRevisionId;
michael@0:   },
michael@0: 
michael@0:   // This is the implementation of the state machine.
michael@0:   // Read the comments at the top of this file in order to follow what it does.
michael@0:   stateMachine: function(aStore, aRevisionStore, aResolve, aReject) {
michael@0:     debug('StateMachine: ' + this._state);
michael@0: 
michael@0:     switch (this._state) {
michael@0:       case STATE_INIT:
michael@0:         this.stateMachineInit(aStore, aRevisionStore, aResolve, aReject);
michael@0:         break;
michael@0: 
michael@0:       case STATE_REVISION_INIT:
michael@0:         this.stateMachineRevisionInit(aStore, aRevisionStore, aResolve, aReject);
michael@0:         break;
michael@0: 
michael@0:       case STATE_REVISION_CHECK:
michael@0:         this.stateMachineRevisionCheck(aStore, aRevisionStore, aResolve, aReject);
michael@0:         break;
michael@0: 
michael@0:       case STATE_SEND_ALL:
michael@0:         this.stateMachineSendAll(aStore, aRevisionStore, aResolve, aReject);
michael@0:         break;
michael@0: 
michael@0:       case STATE_REVISION_SEND:
michael@0:         this.stateMachineRevisionSend(aStore, aRevisionStore, aResolve, aReject);
michael@0:         break;
michael@0: 
michael@0:       case STATE_DONE:
michael@0:         this.stateMachineDone(aStore, aRevisionStore, aResolve, aReject);
michael@0:         break;
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   stateMachineInit: function(aStore, aRevisionStore, aResolve, aReject) {
michael@0:     debug('StateMachineInit');
michael@0: 
michael@0:     if (this._revisionId) {
michael@0:       this._state = STATE_REVISION_INIT;
michael@0:       this.stateMachine(aStore, aRevisionStore, aResolve, aReject);
michael@0:       return;
michael@0:     }
michael@0: 
michael@0:     let self = this;
michael@0:     let request = aRevisionStore.openCursor(null, 'prev');
michael@0:     request.onsuccess = function(aEvent) {
michael@0:       self._revision = aEvent.target.result.value;
michael@0:       self._objectId = 0;
michael@0:       self._state = STATE_SEND_ALL;
michael@0:       aResolve(Cu.cloneInto({ operation: 'clear' }, self._window));
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   stateMachineRevisionInit: function(aStore, aRevisionStore, aResolve, aReject) {
michael@0:     debug('StateMachineRevisionInit');
michael@0: 
michael@0:     let self = this;
michael@0:     let request = this._dataStore._db.getInternalRevisionId(
michael@0:       self._revisionId,
michael@0:       aRevisionStore,
michael@0:       function(aInternalRevisionId) {
michael@0:         // This revision doesn't exist.
michael@0:         if (aInternalRevisionId == undefined) {
michael@0:           self._revisionId = null;
michael@0:           self._objectId = 0;
michael@0:           self._state = STATE_INIT;
michael@0:           self.stateMachine(aStore, aRevisionStore, aResolve, aReject);
michael@0:           return;
michael@0:         }
michael@0: 
michael@0:         self._revision = { revisionId: self._revisionId,
michael@0:                            internalRevisionId: aInternalRevisionId };
michael@0:         self._state = STATE_REVISION_CHECK;
michael@0:         self.stateMachine(aStore, aRevisionStore, aResolve, aReject);
michael@0:       }
michael@0:     );
michael@0:   },
michael@0: 
michael@0:   stateMachineRevisionCheck: function(aStore, aRevisionStore, aResolve, aReject) {
michael@0:     debug('StateMachineRevisionCheck');
michael@0: 
michael@0:     let changes = {
michael@0:       addedIds: {},
michael@0:       updatedIds: {},
michael@0:       removedIds: {}
michael@0:     };
michael@0: 
michael@0:     let self = this;
michael@0:     let request = aRevisionStore.mozGetAll(
michael@0:       self._window.IDBKeyRange.lowerBound(this._revision.internalRevisionId, true));
michael@0:     request.onsuccess = function(aEvent) {
michael@0: 
michael@0:       // Optimize the operations.
michael@0:       for (let i = 0; i < aEvent.target.result.length; ++i) {
michael@0:         let data = aEvent.target.result[i];
michael@0: 
michael@0:         switch (data.operation) {
michael@0:           case REVISION_ADDED:
michael@0:             changes.addedIds[data.objectId] = data.internalRevisionId;
michael@0:             break;
michael@0: 
michael@0:           case REVISION_UPDATED:
michael@0:             // We don't consider an update if this object has been added
michael@0:             // or if it has been already modified by a previous
michael@0:             // operation.
michael@0:             if (!(data.objectId in changes.addedIds) &&
michael@0:                 !(data.objectId in changes.updatedIds)) {
michael@0:               changes.updatedIds[data.objectId] = data.internalRevisionId;
michael@0:             }
michael@0:             break;
michael@0: 
michael@0:           case REVISION_REMOVED:
michael@0:             let id = data.objectId;
michael@0: 
michael@0:             // If the object has been added in this range of revisions
michael@0:             // we can ignore it and remove it from the list.
michael@0:             if (id in changes.addedIds) {
michael@0:               delete changes.addedIds[id];
michael@0:             } else {
michael@0:               changes.removedIds[id] = data.internalRevisionId;
michael@0:             }
michael@0: 
michael@0:             if (id in changes.updatedIds) {
michael@0:               delete changes.updatedIds[id];
michael@0:             }
michael@0:             break;
michael@0: 
michael@0:           case REVISION_VOID:
michael@0:             if (i != 0) {
michael@0:               dump('Internal error: Revision "' + REVISION_VOID + '" should not be found!!!\n');
michael@0:               return;
michael@0:             }
michael@0: 
michael@0:             self._revisionId = null;
michael@0:             self._objectId = 0;
michael@0:             self._state = STATE_INIT;
michael@0:             self.stateMachine(aStore, aRevisionStore, aResolve, aReject);
michael@0:             return;
michael@0:         }
michael@0:       }
michael@0: 
michael@0:       // From changes to a map of internalRevisionId.
michael@0:       let revisions = {};
michael@0:       function addRevisions(obj) {
michael@0:         for (let key in obj) {
michael@0:           revisions[obj[key]] = true;
michael@0:         }
michael@0:       }
michael@0: 
michael@0:       addRevisions(changes.addedIds);
michael@0:       addRevisions(changes.updatedIds);
michael@0:       addRevisions(changes.removedIds);
michael@0: 
michael@0:       // Create the list of revisions.
michael@0:       let list = [];
michael@0:       for (let i = 0; i < aEvent.target.result.length; ++i) {
michael@0:         let data = aEvent.target.result[i];
michael@0: 
michael@0:         // If this revision doesn't contain useful data, we still need to keep
michael@0:         // it in the list because we need to update the internal revision ID.
michael@0:         if (!(data.internalRevisionId in revisions)) {
michael@0:           data.operation = REVISION_SKIP;
michael@0:         }
michael@0: 
michael@0:         list.push(data);
michael@0:       }
michael@0: 
michael@0:       if (list.length == 0) {
michael@0:         self._state = STATE_DONE;
michael@0:         self.stateMachine(aStore, aRevisionStore, aResolve, aReject);
michael@0:         return;
michael@0:       }
michael@0: 
michael@0:       // Some revision has to be sent.
michael@0:       self._revisionsList = list;
michael@0:       self._state = STATE_REVISION_SEND;
michael@0:       self.stateMachine(aStore, aRevisionStore, aResolve, aReject);
michael@0:     };
michael@0:   },
michael@0: 
michael@0:   stateMachineSendAll: function(aStore, aRevisionStore, aResolve, aReject) {
michael@0:     debug('StateMachineSendAll');
michael@0: 
michael@0:     let self = this;
michael@0:     let request = aRevisionStore.openCursor(null, 'prev');
michael@0:     request.onsuccess = function(aEvent) {
michael@0:       if (self._revision.revisionId != aEvent.target.result.value.revisionId) {
michael@0:         self._revision = aEvent.target.result.value;
michael@0:         self._objectId = 0;
michael@0:         aResolve(Cu.cloneInto({ operation: 'clear' }, self._window));
michael@0:         return;
michael@0:       }
michael@0: 
michael@0:       let request = aStore.openCursor(self._window.IDBKeyRange.lowerBound(self._objectId, true));
michael@0:       request.onsuccess = function(aEvent) {
michael@0:         let cursor = aEvent.target.result;
michael@0:         if (!cursor) {
michael@0:           self._state = STATE_REVISION_CHECK;
michael@0:           self.stateMachine(aStore, aRevisionStore, aResolve, aReject);
michael@0:           return;
michael@0:         }
michael@0: 
michael@0:         self._objectId = cursor.key;
michael@0:         aResolve(Cu.cloneInto({ operation: 'add', id: self._objectId,
michael@0:                                 data: cursor.value }, self._window));
michael@0:       };
michael@0:     };
michael@0:   },
michael@0: 
michael@0:   stateMachineRevisionSend: function(aStore, aRevisionStore, aResolve, aReject) {
michael@0:     debug('StateMachineRevisionSend');
michael@0: 
michael@0:     if (!this._revisionsList.length) {
michael@0:       this._state = STATE_REVISION_CHECK;
michael@0:       this.stateMachine(aStore, aRevisionStore, aResolve, aReject);
michael@0:       return;
michael@0:     }
michael@0: 
michael@0:     this._revision = this._revisionsList.shift();
michael@0: 
michael@0:     switch (this._revision.operation) {
michael@0:       case REVISION_REMOVED:
michael@0:         aResolve(Cu.cloneInto({ operation: 'remove', id: this._revision.objectId },
michael@0:                               this._window));
michael@0:         break;
michael@0: 
michael@0:       case REVISION_ADDED: {
michael@0:         let request = aStore.get(this._revision.objectId);
michael@0:         let self = this;
michael@0:         request.onsuccess = function(aEvent) {
michael@0:           if (aEvent.target.result == undefined) {
michael@0:             self.stateMachine(aStore, aRevisionStore, aResolve, aReject);
michael@0:             return;
michael@0:           }
michael@0: 
michael@0:           aResolve(Cu.cloneInto({ operation: 'add', id: self._revision.objectId,
michael@0:                                   data: aEvent.target.result }, self._window));
michael@0:         }
michael@0:         break;
michael@0:       }
michael@0: 
michael@0:       case REVISION_UPDATED: {
michael@0:         let request = aStore.get(this._revision.objectId);
michael@0:         let self = this;
michael@0:         request.onsuccess = function(aEvent) {
michael@0:           if (aEvent.target.result == undefined) {
michael@0:             self.stateMachine(aStore, aRevisionStore, aResolve, aReject);
michael@0:             return;
michael@0:           }
michael@0: 
michael@0:           if (aEvent.target.result.revisionId >  self._revision.internalRevisionId) {
michael@0:             self.stateMachine(aStore, aRevisionStore, aResolve, aReject);
michael@0:             return;
michael@0:           }
michael@0: 
michael@0:           aResolve(Cu.cloneInto({ operation: 'update', id: self._revision.objectId,
michael@0:                                   data: aEvent.target.result }, self._window));
michael@0:         }
michael@0:         break;
michael@0:       }
michael@0: 
michael@0:       case REVISION_VOID:
michael@0:         // Internal error!
michael@0:         dump('Internal error: Revision "' + REVISION_VOID + '" should not be found!!!\n');
michael@0:         break;
michael@0: 
michael@0:       case REVISION_SKIP:
michael@0:         // This revision contains data that has already been sent by another one.
michael@0:         this.stateMachine(aStore, aRevisionStore, aResolve, aReject);
michael@0:         break;
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   stateMachineDone: function(aStore, aRevisionStore, aResolve, aReject) {
michael@0:     this.close();
michael@0:     aResolve(Cu.cloneInto({ revisionId: this._revision.revisionId,
michael@0:                             operation: 'done' }, this._window));
michael@0:   },
michael@0: 
michael@0:   // public interface
michael@0: 
michael@0:   get store() {
michael@0:     return this._dataStore.exposedObject;
michael@0:   },
michael@0: 
michael@0:   next: function() {
michael@0:     debug('Next');
michael@0: 
michael@0:     let self = this;
michael@0:     return new this._window.Promise(function(aResolve, aReject) {
michael@0:       self._dataStore._db.cursorTxn(
michael@0:         function(aTxn, aStore, aRevisionStore) {
michael@0:           self.stateMachine(aStore, aRevisionStore, aResolve, aReject);
michael@0:         },
michael@0:         function(aEvent) {
michael@0:           aReject(createDOMError(self._window, aEvent));
michael@0:         }
michael@0:       );
michael@0:     });
michael@0:   },
michael@0: 
michael@0:   close: function() {
michael@0:     this._dataStore.syncTerminated(this);
michael@0:   }
michael@0: };