genieacs/lib/cache.js

/**
 * Copyright 2013-2018  Zaid Abdulla
 *
 * This file is part of GenieACS.
 *
 * GenieACS is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * GenieACS is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with GenieACS.  If not, see <http://www.gnu.org/licenses/>.
 */
"use strict";

const config = require("./config");

const MAX_CACHE_TTL = config.get("MAX_CACHE_TTL");

let redisClient;
let mongoDb;
let mongoCollection;
let mongoTimeOffset = 0;

function connect(callback) {
  const REDIS_HOST = config.get("REDIS_HOST");

  if (REDIS_HOST) {
    const redis = require("redis");
    const REDIS_PORT = config.get("REDIS_PORT");
    const REDIS_DB = config.get("REDIS_DB");
    redisClient = redis.createClient(REDIS_PORT, REDIS_HOST);
    redisClient.select(REDIS_DB, err => {
      exports.get = redisGet;
      exports.set = redisSet;
      exports.del = redisDel;
      exports.pop = redisPop;
      exports.lock = redisLock;
      callback(err);
    });
  } else {
    const mongodb = require("mongodb");
    const MONGODB_CONNECTION_URL = config.get("MONGODB_CONNECTION_URL");

    mongodb.MongoClient.connect(
      MONGODB_CONNECTION_URL,
      (err, db) => {
        if (err) return callback(err);

        mongoDb = db;
        mongoCollection = db.collection("cache");
        mongoCollection.ensureIndex({ expire: 1 }, { expireAfterSeconds: 0 });

        const now = Date.now();
        mongoDb.command({ hostInfo: 1 }, (err, res) => {
          if (err) return callback(err);
          mongoTimeOffset = res.system.currentTime.getTime() - now;
          exports.get = mongoGet;
          exports.set = mongoSet;
          exports.del = mongoDel;
          exports.pop = mongoPop;
          exports.lock = mongoLock;
          callback();
        });
      }
    );
  }
}

function disconnect() {
  if (redisClient) redisClient.quit();

  if (mongoDb) mongoDb.close();
}

function redisGet(key, callback) {
  if (Array.isArray(key)) redisClient.mget(key, callback);
  else redisClient.get(key, callback);
}

function redisDel(key, callback) {
  redisClient.del(key, callback);
}

function redisSet(key, value, ttl, callback) {
  if (!callback && typeof v === "function") {
    callback = ttl;
    ttl = null;
  }

  if (!ttl) ttl = MAX_CACHE_TTL;

  redisClient.setex(key, ttl, value, callback);
}

function redisPop(key, callback) {
  const POP_SCRIPT =
    'local v=redis.call("get",KEYS[1]);redis.call("del",KEYS[1]);return v;';
  redisClient.eval(POP_SCRIPT, 1, key, callback);
}

function redisLock(lockName, ttl, callback) {
  const UNLOCK_SCRIPT =
    'if redis.call("get", KEYS[1]) == ARGV[1] then return redis.call("del", KEYS[1]) else return 0 end';
  const EXTEND_SCRIPT =
    'if redis.call("get", KEYS[1]) == ARGV[1] then return redis.call("pexpire", KEYS[1], ARGV[2]) else return 0 end';
  const token = Math.random()
    .toString(36)
    .slice(2);

  function unlockOrExtend(extendTtl) {
    if (!extendTtl) {
      redisClient.eval(UNLOCK_SCRIPT, 1, lockName, token, (err, res) => {
        if (err || !res) throw err || new Error("Lock expired");
      });
    } else {
      redisClient.eval(
        EXTEND_SCRIPT,
        1,
        lockName,
        token,
        extendTtl,
        (err, res) => {
          if (err || !res) throw err || new Error("Lock expired");
        }
      );
    }
  }

  redisClient.set(lockName, token, "NX", "EX", ttl, (err, res) => {
    if (err || res) return callback(err, unlockOrExtend);

    setTimeout(() => {
      redisLock(lockName, ttl, callback);
    }, 200);
  });
}

function mongoGet(key, callback) {
  let expire = new Date(Date.now() - mongoTimeOffset);
  if (Array.isArray(key)) {
    mongoCollection.find({ _id: { $in: key } }).toArray((err, res) => {
      if (err) return callback(err);

      let indices = {};
      key.forEach((v, i) => {
        indices[v] = i;
      });

      let values = [];
      res.forEach(r => {
        if (r["expire"] > expire) values[indices[r["_id"]]] = r["value"];
      });
      callback(null, values);
    });
  } else {
    mongoCollection.findOne({ _id: { $in: [key] } }, (err, res) => {
      if (err || !res) return callback(err);

      if (res["expire"] > expire) return callback(null, res["value"]);

      callback();
    });
  }
}

function mongoDel(key, callback) {
  if (Array.isArray(key))
    mongoCollection.remove({ _id: { $in: key } }, callback);
  else mongoCollection.remove({ _id: key }, callback);
}

function mongoSet(key, value, ttl, callback) {
  if (!callback && typeof v === "function") {
    callback = ttl;
    ttl = null;
  }

  if (!ttl) ttl = MAX_CACHE_TTL;

  let expire = new Date(Date.now() - mongoTimeOffset + ttl * 1000);
  mongoCollection.save({ _id: key, value: value, expire: expire }, callback);
}

function mongoPop(key, callback) {
  mongoCollection.findAndModify(
    { _id: key },
    null,
    null,
    { remove: true },
    (err, res) => {
      if (err || !res["value"]) return callback(err);

      if (res["value"]["expire"] > new Date(Date.now() - mongoTimeOffset))
        return callback(null, res["value"]["value"]);

      callback();
    }
  );
}

function mongoLock(lockName, ttl, callback) {
  const token = Math.random()
    .toString(36)
    .slice(2);

  function unlockOrExtend(extendTtl) {
    if (!extendTtl) {
      mongoCollection.remove({ _id: lockName, value: token }, (err, res) => {
        if (err || res["result"]["n"] !== 1)
          throw err || new Error("Lock expired");
      });
    } else {
      let expire = new Date(Date.now() - mongoTimeOffset + extendTtl * 1000);
      mongoCollection.update(
        { _id: lockName, value: token },
        { expire: expire },
        (err, res) => {
          if (err || res["result"]["n"] !== 1)
            throw err | new Error("Lock expired");
        }
      );
    }
  }

  let expireTest = new Date(Date.now() - mongoTimeOffset);
  let expireSet = new Date(Date.now() - mongoTimeOffset + ttl * 1000);

  mongoCollection.update(
    { _id: lockName, expire: { $lte: expireTest } },
    { $set: { value: token, expire: expireSet } },
    { upsert: true },
    err => {
      if (err && err.code === 11000) {
        return setTimeout(() => {
          mongoLock(lockName, ttl, callback);
        }, 200);
      }

      return callback(err, unlockOrExtend);
    }
  );
}

exports.connect = connect;
exports.disconnect = disconnect;