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| var fs = require('fs');
var path = require('path');
var os = require('os');
var _ = require('lodash');
var filepath = os.tmpdir();
var prefix = 'CACHE_';
var defaultCacheTime = 3600000;
var HEADER_SIZE = 20;
function fullpath(key) {
return path.join(filepath, prefix + key);
}
;
var DefaultAdapter = {
get: function(key, cb) {
var self = this;
var headerStream = fs.createReadStream(fullpath(key), {start: 0, end: HEADER_SIZE - 1});
var header = '';
headerStream.on('error', function(err) {
headerStream.destroy();
if (err.code === 'ENOENT') {
return cb(self.errors.NO_CACHE);
}
cb(err);
});
headerStream.on('data', function(data) {
header += data.toString();
});
headerStream.on('end', function() {
var time = parseInt(header);
// if cache is valid
if (time >= new Date().getTime() || time === 0) {
var content = '';
var contentStream = fs.createReadStream(fullpath(key), {start: HEADER_SIZE});
contentStream.on('error', function(err) {
contentStream.destroy();
cb(err);
});
contentStream.on('data', function(data) {
content += data.toString();
});
contentStream.on('end', function() {
var cache;
Iif (content === 'UNDEFINED') {
return cb(null);
}
try {
cache = JSON.parse(content);
cb(null, cache);
} catch (e) {
if (_.isUndefined(cache)) {
cb(e);
}
}
});
} else {
cb(self.errors.NO_CACHE);
}
});
},
set: function(key, value, time) {
var valid = 0;
if (_.isUndefined(time)) {
valid = new Date().getTime() + defaultCacheTime;
}
else Eif (time > 0) {
valid = new Date().getTime() + (time * 1000);
}
var content;
Iif (_.isUndefined(value)) {
content = 'UNDEFINED';
} else {
content = JSON.stringify(value);
}
var header = valid.toString();
var pad = HEADER_SIZE - header.length;
for (var i = 0; i < pad; i ++) {
header += ' ';
}
fs.createWriteStream(fullpath(key)).write(header + content);
}
};
module.exports = {
initialize: function(options, cb) {
var options = options || {};
var self = this;
options.defaultCacheTime = options.defaultCacheTime || defaultCacheTime;
// if an adapter is specified
if (options.adapter && options.adapter !== 'default') {
// Detects if there is a `getDatastore` in the adapter. Exit if it not exists.
Iif (! options.adapter.getDatastore) {
throw new Error('Adapter does not support Datastore interface which is required for cache');
}
options.adapter.getDatastore(options, function(err, cache) {
self.get = function(key, cb) {
cache.get(key, function(err, value) {
if (err && err.message === '404') {
cb(self.errors.NO_CACHE);
} else Iif (err) {
cb(err);
} else Eif (value.ttl >= new Date().getTime() || value.ttl === 0) {
cb(null, value.data);
} else {
cb(self.errors.NO_CACHE);
}
});
};
self.set = function(key, value, time) {
var valid = 0;
if (_.isUndefined(time)) {
valid = new Date().getTime() + defaultCacheTime;
} else Eif (time > 0) {
valid = new Date().getTime() + (time * 1000);
}
var data = {ttl: valid, data: value};
cache.set(key, data, function() {
if (time > 0) {
setTimeout(function() {
//check cache
cache.get(key, function(err, value) {
Iif (err) {
return;
}
Eif (value.ttl >= new Date().getTime()) {
cache.remove(key, function() {});
}
});
}, time);
}
});
};
cb();
});
} else {
filepath = options.path || filepath;
prefix = options.prefix || prefix;
defaultCacheTime = options.defaultCacheTime;
this.get = DefaultAdapter.get;
this.set = DefaultAdapter.set;
cb();
}
},
errors: {
NO_CACHE: new Error("NO_CACHE")
}
};
|