lib/cache.js
var logging = require("./logging");
var node_redis = require("redis");
var config = require("../config");
var redis = null;
// sets up redis connection
// flushes redis when using ephemeral storage (e.g. Heroku)
function connect_redis() {
logging.log("connecting to redis...");
redis = node_redis.createClient(config.redis);
redis.on("ready", function() {
logging.log("Redis connection established.");
if (config.caching.ephemeral) {
logging.log("Storage is ephemeral, flushing redis");
redis.flushall();
}
});
redis.on("error", function(err) {
logging.error(err);
});
redis.on("end", function() {
logging.warn("Redis connection lost!");
});
}
var exp = {};
// returns the redis instance
exp.get_redis = function() {
return redis;
};
// set model type to value of *slim*
exp.set_slim = function(rid, userId, slim, callback) {
logging.debug(rid, "setting slim for", userId, "to " + slim);
// store userId in lower case if not null
userId = userId && userId.toLowerCase();
redis.hmset(userId, ["a", Number(slim)], callback);
};
// sets the timestamp for +userId+
// if +temp+ is true, the timestamp is set so that the record will be outdated after 60 seconds
// these 60 seconds match the duration of Mojang's rate limit ban
// callback: error
exp.update_timestamp = function(rid, userId, temp, callback) {
logging.debug(rid, "updating cache timestamp (" + temp + ")");
var sub = temp ? config.caching.local - 60 : 0;
var time = Date.now() - sub;
// store userId in lower case if not null
userId = userId && userId.toLowerCase();
redis.hmset(userId, "t", time, function(err) {
callback(err);
});
};
// create the key +userId+, store +skin_hash+, +cape_hash+, +slim+ and current time
// if +skin_hash+ or +cape_hash+ are undefined, they aren't stored
// this is useful to store cape and skin at separate times, without overwriting the other
// +slim+ can be true (alex) or false (steve)
// +callback+ contans error
exp.save_hash = function(rid, userId, skin_hash, cape_hash, slim, callback) {
logging.debug(rid, "caching skin:" + skin_hash + " cape:" + cape_hash + " slim:" + slim);
// store shorter null value instead of "null" string
skin_hash = skin_hash === null ? "" : skin_hash;
cape_hash = cape_hash === null ? "" : cape_hash;
// store userId in lower case if not null
userId = userId && userId.toLowerCase();
var args = [];
if (cape_hash !== undefined) {
args.push("c", cape_hash);
}
if (skin_hash !== undefined) {
args.push("s", skin_hash);
}
if (slim !== undefined) {
args.push("a", Number(!!slim));
}
args.push("t", Date.now());
redis.hmset(userId, args, function(err) {
callback(err);
});
};
// removes the hash for +userId+ from the cache
exp.remove_hash = function(rid, userId) {
logging.debug(rid, "deleting hash from cache");
redis.del(userId.toLowerCase(), "h", "t");
};
// get a details object for +userId+
// {skin: "0123456789abcdef", cape: "gs1gds1g5d1g5ds1", time: 1414881524512}
// callback: error, details
// details is null when userId not cached
exp.get_details = function(userId, callback) {
// get userId in lower case if not null
userId = userId && userId.toLowerCase();
redis.hgetall(userId, function(err, data) {
var details = null;
if (data) {
details = {
skin: data.s === "" ? null : data.s,
cape: data.c === "" ? null : data.c,
slim: data.a === "1",
time: Number(data.t)
};
}
callback(err, details);
});
};
connect_redis();
module.exports = exp;