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// Copyright (c) 2018, Compiler Explorer Authors
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
const crypto = require('crypto'),
logger = require('../logger').logger;
const HashVersion = 'Compiler Explorer Cache Version 1';
class BaseCache {
constructor(name) {
this.name = name;
this.gets = 0;
this.hits = 0;
this.puts = 0;
}
stats() {
return {hits: this.hits, puts: this.puts, gets: this.gets};
}
statString() {
const pc = this.gets ? (100 * this.hits) / this.gets : 0;
const misses = this.gets - this.hits;
return `${this.puts} puts; ${this.gets} gets, ${this.hits} hits, ${misses} misses (${pc.toFixed(2)}%)`;
}
report() {
logger.info(`${this.name}: cache stats: ${this.statString()}`);
}
static hash(object) {
// See https://stackoverflow.com/questions/899574/which-is-best-to-use-typeof-or-instanceof/6625960#6625960
const asString = (typeof(object) === 'string') ? object : JSON.stringify(object);
return crypto.createHmac('sha256', HashVersion)
.update(asString)
.digest('hex');
}
get(key) {
this.gets++;
return this.getInternal(key)
.then(result => {
if (result.hit) {
this.hits++;
}
return result;
});
}
put(key, value, creator) {
if (!(value instanceof Buffer))
value = new Buffer(value);
this.puts++;
return this.putInternal(key, value, creator);
}
// eslint-disable-next-line no-unused-vars
getInternal(key) {
return Promise.reject("should be implemented in subclass");
}
// eslint-disable-next-line no-unused-vars
putInternal(key, value, creator) {
return Promise.reject("should be implemented in subclass");
}
}
module.exports = BaseCache;