Auto-increment counters for REDIS
npm install redis-counterThis is a trivial redis auto-increment counter implementation.
npm install redis-counter
``javascript
// Initialization via redis URLs of the form: redis://user:password@host:port/
var counters = require('redis-counter').createCounters({redisUrl: 'redis://user:password@host:port/database'});
// Specifying collection name instead of defaulting to counters collection.
// The collection name is the hash name to store the counters under
var counters = require('redis-counter').createCounters({
redisUrl: '...',
collectionName: 'yoyo'
});
`
`javascript
counters('requests').increment(); // increments by one, throws away the result
counters('requests').increment(5); // increments by 5 throws away the result
counters('requests').increment(5, function (err, currentCount) {
// currentCount is the updated count.
});
// increment by one and get the new value
counters('requests').increment(function (err, currentCount) {
// currentCount is the updated count.
});
counters('requests').decrement(); // same options with decrement
counters('requests').get(function (err, val) {
// fetch the current value
});
counters('requests').set(52); // update the value.
// if you only want to generate unique ids (for URL shortening for example),
// a much faster method is getNextUniqueId. It only hits the database every 100
// calls. Ofcourse, this has the side effect that the sequence is not strictly
// monotonically increasing in order and there could be gaps when there are crashes
// but uniqueness is guaranteed and the ordering will be almost monotonic. This is
// suitable for a lot of cases where you just want a small unique ID.
function getShortUrl(longUrl, done) {
counters('requests').getNextUniqueId(function (err, uniqueId) {
if (err) return done(err);
var shortUrl = '/' + uniqueId.toString(36);
db.shortUrls.insert(
{shortUrl: '/' + uniqueId.toString(36), longUrl: longUrl},
function (err) { return done(err, !err && shortUrl); }
);
});
});
``