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index.js
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index.js
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'use strict';
const fs = require('graceful-fs');
const path = require('path');
const mkdirp = require('mkdirp');
function FSCache(config) {
config = config || {};
this.cacheRoot = path.resolve(config.cacheRoot || './cache');
this.pathifyFn = config.pathify || this.relativePathify.bind(this);
this.verbose = config.verbose || false;
// cache module required config values
this.type = config.type || 'file-system';
this.defaultExpiration = config.defaultExpiration || 900;
this.checkOnPreviousEmpty = config.checkOnPreviousEmpty || true;
// TODO: implement readOnly checks?
this.readOnly = config.readOnly || false;
}
// === cache-service API (public) ===
FSCache.prototype.get = function get(key, callback) {
log(this, 'get() called', { key: key });
var name = fullPathify(this, key);
getFile(this, key, name, false, (err, obj) => {
if (err) {
// callback(err);
// errors treated as a miss...
callback(null, null);
return;
}
callback(null, obj && obj.data);
});
};
FSCache.prototype.mget = function mget(keys, callback) {
var self = this;
log(self, 'mget() called', { keys: keys });
var result = {};
var errors = [];
var done = 0;
for (const key of keys) {
self.get(key, (err, obj) => {
if (err) {
error(self, 'mget() error on key', { key: key, err: err })
errors.push({ key: key, err: err });
} else {
result[key] = obj;
}
done++;
if (done === keys.length) {
callback(null, result);
}
});
}
};
FSCache.prototype.set = function set(key, value, expiration, refresh, callback) {
var self = this;
log(self, 'set() called', { key: key, value: value, arguments: arguments });
if (arguments.length === 3 && typeof expiration === 'function') {
callback = expiration;
expiration = self.defaultExpiration;
} else if (arguments.length === 4) {
callback = refresh;
if (typeof expiration === 'function') {
refresh = expiration;
expiration = self.defaultExpiration;
}
}
callback = callback || noop;
var filePath = fullPathify(self, key);
// UTC expiration in milliseconds, zero means "never expires".
var expires = expiration > 0 ? Date.now() + (expiration * 1000) : 0;
var cacheData = {
key: key,
expires: expires,
data: value,
};
var data = JSON.stringify(cacheData);
mkdirp(path.dirname(filePath), (err, made) => {
if (err) {
callback(err);
return;
}
log(self, 'set() made directory', { made: made });
fs.writeFile(filePath, data, err => {
if (err) {
error(self, 'set() error', { key: key, err: err });
}
callback(err);
});
});
};
FSCache.prototype.mset = function mset(obj, expiration, callback) {
var self = this;
log(self, 'mset() called', { obj: obj });
if (arguments.length === 2 && typeof expiration === 'function') {
callback = expiration;
expiration = self.defaultExpiration;
}
callback = callback || noop;
var keys = obj.keys();
var errors = [];
var done = 0;
for (const key of keys) {
// TODO: see if obj[key] has a cacheValue property?
self.set(key, obj[key], expiration, err => {
if (err) {
error(self, 'mget() error on key', { key: key, err: err })
errors.push({ key: key, err: err });
}
done++;
if (done === keys.length) {
callback(null);
}
});
}
};
FSCache.prototype.del = function del(keys, callback) {
var self = this;
log(self, 'del() called', { keys: keys });
callback = callback || noop;
if (typeof keys === 'string') {
keys = [keys];
}
var succeeded = 0;
var done = 0;
for (const key of keys) {
delKey(self, key, err => {
if (err) {
error(self, 'del() err on key', { key: key, err: err });
} else {
succeeded++;
}
done++;
if (done === keys.length) {
// TODO: pass back partial errors?
callback(null, succeeded);
}
});
}
};
FSCache.prototype.flush = function flush(callback) {
error(this, 'flush() called... NYI!');
callback = callback || noop;
callback('NYI!');
};
FSCache.prototype.db = 'none'; // bogus truthy value, just in case
// mgetall and relativePathify aren't a part of the cache-service API, but are
// exposed as supported helpers.
FSCache.prototype.mgetall = function mgetall(callback) {
var self = this;
log(self, 'mgetall() called');
getTreeOrFile(self, self.cacheRoot, false, {}, (err, data) => {
log(self, 'mgetall() got', { data: data, err: err });
callback(err, data);
});
};
FSCache.prototype.relativePathify = function relativePathify(key) {
var parts = [];
var remaining = key;
while (remaining.length > 2) {
parts.push(remaining.substr(0, 2));
remaining = remaining.substr(2);
}
parts.push(key + '.json');
return path.join.apply(path, parts);
};
// === internal helpers (private, 'this' value explicity pased as 'self') ===
// TODO: handle missing/ENOENT slightly differently (not an error?) in some
// cases?
function getFile(self, key, name, expected, callback) {
log(self, 'getFile() called', { key: key, name: name });
fs.readFile(name, (err, data) => {
if (err) {
// only log an error if it's expected (or not ENOENT)
if (expected || err.code !== 'ENOENT') {
error(self, 'getFile() read error', { key: key, name: name, err: err });
callback(err);
return;
}
callback(null, null);
return;
}
try {
var obj = JSON.parse(data.toString());
if (!!key && obj.key !== key) {
error(self, 'getFile() key does not match!', { key: key, name: name, dataKey: obj.key });
throw new Error('key mismatch');
}
if (fullPathify(self, obj.key) !== name) {
error(self, 'getFile() key does not match path!', { name: name, innerKey: obj.key});
throw new Error('key/path mismatch');
}
if (obj.expires > 0 && obj.expires <= Date.now()) {
log(self, 'getFile() data has expired!', { key: key, name: name });
throw new Error('data has expired');
}
callback(null, obj);
} catch (err) {
error(self, 'getFile() JSON error', { key: key, name: name, err: err });
// Delete the file so that we don't worry about it anymore.
// Note that we call back with the original failure, not unlink's
// (if any).
fs.unlink(name, unlinkErr => {
if (unlinkErr) {
error(self, 'getFile() unlink error (eaten!)', { key: key, name: name, err: err });
}
callback(err);
});
}
});
}
function getTreeOrFile(self, curPath, expected, results, callback) {
log(self, 'getTreeOrFile() called', { curPath: curPath })
fs.readdir(curPath, (err, files) => {
if (err) {
// if file, try to load it directly!... and return the key/value in
// an object
if (err.code !== 'ENOENT') {
log(self, 'getTreeOrFile() readdir error', { curPath: curPath, err: err });
// REVIEW: do we bail for non-ENOENT failures?
}
getFile(self, null, curPath, expected, (err, obj) => {
if (err) {
// if (expected) {
// error(self, 'getTreeOrFile() file error', { curPath: curPath, err: err });
// }
// callback(err);
// This code path is only ever hit from .mgetall(), and the
// "right" behavior is to ignore any unloadable files.
callback(null, results);
return;
}
// Should we put in explicitly missing keys, or omit them?
// right now, we requre the key to be embedded in the data,
// so we *can't* set it if there's no data. (The `.mget()`
// docs don't describe what a partial return looks like.)
if (obj) {
results[obj.key] = obj.data;
}
callback(null, results);
});
return;
}
// successful means we need to recurse on each item...
log(self, 'getTreeOrFile() got', { files: files, err: err });
if (files.length === 0) {
callback(null, results);
return
}
var done = 0;
for (const file of files) {
getTreeOrFile(self, path.join(curPath, file), true, results, (err, data) => {
if (err) {
// error(self, 'getTreeOrFile() dir error', { curPath: curPath, file: file, err: err });
callback(err);
return;
}
done++;
if (done === files.length) {
callback(null, data);
}
});
}
});
}
function delKey(self, key, callback) {
log(self, 'delKey() called', { key: key });
var name = fullPathify(self, key);
fs.unlink(name, callback);
}
function fullPathify(self, key) {
return path.join(self.cacheRoot, self.pathifyFn(key));
}
function log(self, message, data) {
_log(self, false, message, data);
};
function error(self, message, data) {
_log(self, true, message, data);
};
function _log(self, isError, message, data) {
if (isError || self.verbose) {
console.log(self.type + ': ' + message, data);
}
};
function noop() {}
exports = module.exports = FSCache;