!function(UNICACHE){
"use strict";
var PROTO = 'prototype',
DB_NAME = 'unicache_websql_db', DB_STORE_NAME = 'unicache_', DB_VER = '1.0', MAX_SIZE = 2 * 1024 * 1024 /* 2MB */,
_ = UNICACHE._;
var WebSqlCache = UNICACHE.WebSqlCache = function() {
this.queue = [];
};
function tryExecuteSql(t, sqlStatement, args, cb)
{
t.executeSql(sqlStatement, args, function(t, res) {
if ('function' === typeof cb) cb(null, res);
}, function(t, err) {
if ('function' === typeof cb) cb(err, null);
});
}
function set(db, prefix, key, value, expires, cb)
{
db.transaction(function(t) {
// insert or update, based if key exists already
tryExecuteSql(t, 'SELECT * FROM "'+DB_STORE_NAME + prefix+'" WHERE key=? LIMIT 1', [key], function(err, res) {
if (err)
{
if ('function' === typeof cb) cb(err, null);
return;
}
if (!res || !res.rows.length)
{
tryExecuteSql(t, 'INSERT INTO "'+DB_STORE_NAME + prefix+'" (key,value,expires) VALUES(?,?,?)', [key,value,+expires], function(err, res) {
if ('function' === typeof cb) cb(err, res);
});
}
else
{
tryExecuteSql(t, 'UPDATE "'+DB_STORE_NAME + prefix+'" SET value=?,expires=? WHERE key=?', [value,+expires,key], function(err, res) {
if ('function' === typeof cb) cb(err, res);
});
}
});
}, function(err) {
if ('function' === typeof cb) cb(err, null);
});
}
function get(db, prefix, key, expires, cb)
{
db.transaction(function(t) {
if (null == expires)
{
tryExecuteSql(t, 'SELECT * FROM "'+DB_STORE_NAME + prefix+'" WHERE key = ?', [key], function(err, res) {
if ('function' === typeof cb)
cb(err, res && res.rows.length ? {value:res.rows.item(0).value, expires:res.rows.item(0).expires} : null);
});
}
else
{
tryExecuteSql(t, 'SELECT * FROM "'+DB_STORE_NAME + prefix+'" WHERE key = ? AND expires >= ?', [key,+expires], function(err, res) {
if ('function' === typeof cb)
cb(err, res && res.rows.length ? {value:res.rows.item(0).value, expires:res.rows.item(0).expires} : null);
});
}
}, function(err) {
if ('function' === typeof cb) cb(err, null);
});
}
function del(db, prefix, key, cb)
{
db.transaction(function(t) {
// insert or update, based if key exists already
tryExecuteSql(t, 'DELETE FROM "'+DB_STORE_NAME + prefix+'" WHERE key=?', [key], function(err, res) {
if ('function' === typeof cb) cb(err, res);
});
}, function(err) {
if ('function' === typeof cb) cb(err, null);
});
}
function clear(db, prefix, cb)
{
db.transaction(function(t) {
// insert or update, based if key exists already
tryExecuteSql(t, 'DELETE FROM "'+DB_STORE_NAME + prefix+'"', [], function(err, res) {
if ('function' === typeof cb) cb(err, res);
});
}, function(err) {
if ('function' === typeof cb) cb(err, null);
});
}
function gc(db, prefix, maxlifetime, currenttime, cb)
{
if (null == currenttime) currenttime = _.time();
db.transaction(function(t) {
// insert or update, based if key exists already
tryExecuteSql(t, 'DELETE FROM "'+DB_STORE_NAME + prefix+'" WHERE expires < ?', [currenttime-maxlifetime], function(err, res) {
if ('function' === typeof cb) cb(err, res);
});
}, function(err) {
if ('function' === typeof cb) cb(err, null);
});
}
// extend UNICACHE.Cache class
WebSqlCache[PROTO] = Object.create(UNICACHE.Cache[PROTO]);
WebSqlCache.isSupported = function() {
return 'function' === typeof openDatabase;
};
WebSqlCache[PROTO].db = null;
WebSqlCache[PROTO].err = null;
WebSqlCache[PROTO].queue = null;
WebSqlCache[PROTO].open = function(cb) {
var self = this;
if (null == self.db)
{
if ('function' === typeof cb)
self.queue.push(cb);
try{
self.db = openDatabase(DB_NAME, DB_VER, 'UNICACHE Cache Database', MAX_SIZE);
} catch(e) {
self.err = e;
self.db = false;
}
if (self.db)
{
self.db.transaction(function(t) {
// create db table related to passed cache prefix
// NOTE: cannot change prefix in the middle of operations
// need to instantiate new instance of WebSqlCache with new prefix
// this is done to avoid having to run create table on every sql query, in case prefix has changed
tryExecuteSql(t, 'CREATE TABLE IF NOT EXISTS "'+DB_STORE_NAME + self.prefix+'" (id INTEGER PRIMARY KEY, key unique, value, expires INTEGER)', [], function(err, res) {
if (err) self.err = err;
var queue = self.queue;
self.queue = null;
queue.map(function(cb) {cb(self.err, self.db);});
});
}, function(err) {
self.err = err;
var queue = self.queue;
self.queue = null;
queue.map(function(cb) {cb(self.err, self.db);});
});
}
else
{
var queue = self.queue;
self.queue = null;
queue.map(function(cb) {cb(self.err, self.db);});
}
}
else if (self.queue)
{
if ('function' === typeof cb)
self.queue.push(cb);
}
else
{
if ('function' === typeof cb)
cb(self.err, self.db);
}
return this;
};
WebSqlCache[PROTO].close = function() {
var self = this;
if (self.db)
{
self.db = null;
}
return this;
};
WebSqlCache[PROTO].drop = function(prefix, cb) {
var self = this;
if (self.db)
{
if (null == prefix) prefix = self.prefix;
self.open(function(err, db) {
if (err)
{
if ('function' === typeof cb) cb(err, null);
return;
}
db.transaction(function(t) {
tryExecuteSql(t, 'DROP TABLE IF EXISTS "'+DB_STORE_NAME + prefix+'"', [], function(err, res) {
if ('function' === typeof cb) cb(err, res);
});
},function(err) {
if ('function' === typeof cb) cb(err, null);
});
});
}
};
WebSqlCache[PROTO].dispose = function() {
this.close();
this.db = null;
this.err = null;
this.queue = null;
return UNICACHE.Cache[PROTO].dispose.call(this);
};
WebSqlCache[PROTO].put = function(key, value, ttl, cb) {
var self = this;
self.open(function(err, db) {
if (err)
{
if ('function' === typeof cb) cb(err, null);
return;
}
ttl = +ttl;
set(db, self.prefix, key, _.serialize(value), _.time() + ttl, cb);
});
};
WebSqlCache[PROTO].get = function(key, cb) {
var self = this;
self.open(function(err, db) {
if (err)
{
if ('function' === typeof cb) cb(err, null);
return;
}
var currenttime = _.time();
get(db, self.prefix, key, currenttime, function(err, res) {
if (err)
{
if ('function' === typeof cb) cb(err, null);
return;
}
if (res && (res.expires < currenttime))
{
del(db, self.prefix, key);
}
if ('function' === typeof cb)
{
if (!res || (res.expires < currenttime))
{
cb(null, false);
}
else
{
cb(null, _.unserialize(res.value));
}
}
});
});
};
WebSqlCache[PROTO].remove = function(key, cb) {
var self = this;
self.open(function(err, db) {
if (err)
{
if ('function' === typeof cb) cb(err, null);
return;
}
del(db, self.prefix, key, cb);
});
};
WebSqlCache[PROTO].clear = function(cb) {
var self = this;
self.open(function(err, db) {
if (err)
{
if ('function' === typeof cb) cb(err, null);
return;
}
clear(db, self.prefix, cb);
});
};
WebSqlCache[PROTO].gc = function(maxlifetime, cb) {
var self = this;
self.open(function(err, db) {
if (err)
{
if ('function' === typeof cb) cb(err, null);
return;
}
maxlifetime = +maxlifetime;
var currenttime = _.time();
gc(db, self.prefix, maxlifetime, currenttime, cb);
});
};
return WebSqlCache;
}(UNICACHE);
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