ydn.db
Version:
Javascript database library for IndexedDB, WebDatabase (WebSQL) and WebStorage (localStorage) storage mechanisms supporting version migration, advanced query and transaction workflow.
250 lines (220 loc) • 7.36 kB
JavaScript
// Copyright 2012 YDN Authors. All Rights Reserved.
//
// Licensed 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.
/**
* @fileoverview Effective key conjunction cursor.
*
* @author kyawtun@yathit.com (Kyaw Tun)
*/
goog.provide('ydn.db.query.SKeyCursor');
goog.require('ydn.db.query.ConjunctionCursor');
/**
* Effective key conjunction cursor.
* @param {Array.<ydn.db.core.req.ICursor>} cursors cursors.
* @param {ydn.db.query.SKeyCursor=} opt_prev_cursor previous cursor, to resume cursor
* location.
* @param {IDBKey=} opt_key start position.
* @param {IDBKey=} opt_primary_key start position.
* @constructor
* @extends {ydn.db.query.ConjunctionCursor}
* @struct
*/
ydn.db.query.SKeyCursor = function(cursors, opt_prev_cursor, opt_key,
opt_primary_key) {
goog.base(this, cursors, opt_prev_cursor, opt_key, opt_primary_key);
};
goog.inherits(ydn.db.query.SKeyCursor, ydn.db.query.ConjunctionCursor);
/**
*
* @define {boolean} debug flag.
*/
ydn.db.query.SKeyCursor.DEBUG = false;
/**
* @protected
* @type {goog.debug.Logger} logger.
*/
ydn.db.query.SKeyCursor.prototype.logger =
goog.log.getLogger('ydn.db.query.SKeyCursor');
/**
* Open cursors for joining secondary keys.
* Base cursor is index cursor, meaning that its effective key is secondary key.
* Other cursors may not may not be index cursor. In any case, we will join
* primary key instead.
* The algorithm is zigzag merge join, except different index key retrieval.
* @private
*/
ydn.db.query.SKeyCursor.prototype.openSecondaryKeyMerge_ = function() {
var total = this.cursors_.length;
var result_count = 0;
var keys = [];
var primary_keys = [];
var me = this;
var listenCursor = function(i_cursor) {
/**
* @type {ydn.db.core.req.ICursor}
*/
var cursor = me.cursors_[i_cursor];
/**
* On success handler.
* @param {IDBKey=} opt_key effective key.
* @param {IDBKey=} opt_p_key primary key.
* @param {*=} opt_value reference value.
* @this {ydn.db.core.req.ICursor}
*/
cursor.onSuccess = function(opt_key, opt_p_key, opt_value) {
result_count++;
if (ydn.db.query.SKeyCursor.DEBUG) {
window.console.log(me + ' receiving result "' + opt_key + '" from ' +
i_cursor + '/' + total + ' ' + cursor);
}
//console.log([result_count, opt_key, opt_p_key]);
if (!goog.isDefAndNotNull(opt_key)) {
goog.log.finest(me.logger, 'cursor ' + cursor + ' finished.');
me.done_ = true;
}
me.keys_[i_cursor] = opt_key;
me.primary_keys_[i_cursor] = opt_p_key;
me.values_[i_cursor] = opt_value;
if (!cursor.isIndexCursor()) {
primary_keys[i_cursor] = opt_key;
} else {
primary_keys[i_cursor] = opt_p_key;
}
if (result_count == total) {
// all cursor results are ready
if (me.done_) {
me.count_++;
goog.log.finest(me.logger, me + ' DONE.');
me.onNext();
me.finalize_();
} else {
// to get successful step, all primary key must be same.
var max_key = primary_keys.reduce(function(p, c) {
if (goog.isNull(p)) {
return c;
} else {
return ydn.db.cmp(c, p) == 1 ? c : p;
}
}, null);
if (ydn.db.cmp(max_key, primary_keys[0]) == 0) {
// all keys are equal, hence we get matching key result.
var key_str = goog.isDefAndNotNull(me.primary_keys_[0]) ?
me.keys_[0] + ', ' + me.primary_keys_[0] : me.keys_[0];
goog.log.finest(me.logger, me + ' new cursor position {' + key_str + '}');
me.onNext(me.keys_[0]);
} else {
// request behind cursor to max key position.
for (var i = 0; i < total; i++) {
if (ydn.db.cmp(primary_keys[i], max_key) == -1) {
var cur = me.cursors_[i];
if (!cur.isIndexCursor()) {
cur.continueEffectiveKey(max_key);
} else {
cur.continuePrimaryKey(max_key);
}
}
}
}
}
result_count = 0;
goog.array.clear(primary_keys);
}
};
/**
* On error handler.
* @param {!Error} e error.
* @this {ydn.db.core.req.ICursor}
*/
cursor.onError = function(e) {
me.onFail(e);
me.finalize_();
me.done_ = true;
result_count = 0;
};
// if there is previous position, the cursor must advance over previous
// position.
var pk_str = goog.isDefAndNotNull(me.primary_keys_[i_cursor]) ?
', ' + me.primary_keys_[i_cursor] : '';
pk_str = goog.isDefAndNotNull(me.keys_[i_cursor]) ? ' resume from {' +
me.keys_[i_cursor] + pk_str + '}' : '';
goog.log.finest(me.logger, cursor + pk_str + ' opening');
cursor.openCursor(me.keys_[i_cursor], me.primary_keys_[i_cursor]);
};
for (var i = 0; i < total; i++) {
listenCursor(i);
}
};
/**
* Move cursor position to the primary key while remaining on same index key.
* @param {IDBKey} key primary key position to continue.
*/
ydn.db.query.SKeyCursor.prototype.continuePrimaryKey = function(key) {
// console.log(this + ' continuePrimaryKey ' + key)
this.cursors_[0].continuePrimaryKey(key);
};
/**
* Move cursor position to the effective key.
* @param {IDBKey=} opt_key effective key position to continue.
*/
ydn.db.query.SKeyCursor.prototype.continueEffectiveKey = function(opt_key) {
this.cursors_[0].continueEffectiveKey(opt_key);
};
/**
* Move cursor position to the effective key.
* @param {number} n number of steps.
*/
ydn.db.query.SKeyCursor.prototype.advance = function(n) {
for (var i = 0; i < this.cursors_.length; i++) {
this.cursors_[i].advance(n);
}
};
/**
* @param {!Object} obj record value.
* @param {number=} opt_idx cursor index.
* @return {!goog.async.Deferred} value.
*/
ydn.db.query.SKeyCursor.prototype.update = function(obj, opt_idx) {
var index = opt_idx || 0;
return this.cursors_[index].update(obj);
};
/**
* @param {number=} opt_idx cursor index.
* @return {!goog.async.Deferred} value.
*/
ydn.db.query.SKeyCursor.prototype.clear = function(opt_idx) {
var index = opt_idx || 0;
return this.cursors_[index].clear();
};
/**
*
* @return {boolean} true if cursor gone.
*/
ydn.db.query.SKeyCursor.prototype.hasDone = function() {
return this.done_;
};
/**
*
* @return {boolean} true if iteration is existed.
*/
ydn.db.query.SKeyCursor.prototype.isExited = function() {
return this.exited_;
};
/**
* Exit cursor
*/
ydn.db.query.SKeyCursor.prototype.exit = function() {
this.exited_ = true;
goog.log.finest(this.logger, this + ': exit');
this.finalize_();
this.dispose_();
};