Redis Bitmap

Utility library for working with redis bit operations. Provides ability for chaining 
multiple bit operations together through redis and makes dealing with buffered 
responses easier.

Usage

var BitMap = require('redis-bitmap')
  , redis = require('redis')
  , db = redis.createClient(6379, '127.0.0.1', {detect_buffers: true})
  , bmap = new BitMap(db)

Buffering redis

NOTE: In order to use redis bitops correctly, the redis instance must have the return_buffers option set.

Example

Population count:

bmap.setbit('foo', 0, 1)
bmap.setbit('foo', 3, 1)
bmap.population('foo', function(err, count) {
  count === 2
})

Loading keys with this lib will return a BitArray instance to provide a little extra functionality when dealing with bits, the main purpose is to convert the buffered response redis returns into something usable.

bmap.get('foo', function(err, bitarray) {
  var bits = bitarray.toJSON()       // [1,0,0,1,0,0,0,0]
  var binary = bitarray.toString()   // '00001001'
  var count = bitarray.cardinality() // 2
})

Lets try it with some of the other commands, the redis.print command will end up calling toString() on each BitArray instance returned.

bmap.setbit('meow', 0, 1, redis.print) // 1
bmap.setbit('meow', 2, 1, redis.print) // 1
bmap.setbit('meow', 4, 1, redis.print) // 1
 
bmap.setbit('bark', 1, 1, redis.print) // 1
bmap.setbit('bark', 2, 1, redis.print) // 1
bmap.setbit('bark', 7, 1, redis.print) // 1
 
bmap.get('meow', redis.print)          // 00010101
bmap.get('bark', redis.print)          // 10000110
bmap.xor('meow', 'bark', redis.print)  // 10010011
bmap.or('meow', 'bark', redis.print)   // 10010111
bmap.and('meow', 'bark', redis.print)  // 00000100
bmap.not('meow', redis.print)          // 11101010
bmap.not('bark', redis.print)          // 01111001

Methods

instance.setbit(key, offset, value, [callback])

Pass-through to the redis SETBIT command.

• key - redis key
• offset - bit offset
• value - bit value (1 / 0)
• callback - standard callback (optional)

Alias: [set]

bmap.setbit('test', 2, 1, function(err, previous) {
  previous === 0 // true
})

instance.get(key, [key2], […], callback)

• key - redis key(s)
• callback - standard callback, called with BitArray instances

bmap.get('test', function(err, bitmap) {
  bitmap.toJSON() // [0,0,1,0,0,0,0,0]
})

instance.bitop(op, destination, key, [key2], […], [callback])

Pass-through to the redis BITOP command, used by all bitop command shortcuts, (xor, or, and). If a callback is not supplied, an Aggregate instance is returned that can be used for chaining commands. See below.

• operation - redis bitwise operation (xor, or, and)
• destination - destination key for results
• key - redis key(s)
• callback - standard callback (optional)

bmap.setbit('foo', 0, 1)
bmap.setbit('foo', 7, 1)
bmap.bitop('xor', 'foo:xor', function(err, len) {
  len === 1 // Length of destination
})

instance.tmpBitop(redisCmd, bitop, key, [key2], […], [callback])

Perform a bitop command and store the results in a temporary key supplied to the BitMap constructor, default "bitmap:tmp", which will be retrieved afterwards and then deleted. A command is supplied to designate if a GET should be used to get the bits, or a BITCOUNT for population / cardinality.

• operation - redis bitwise operation (xor, or, and)
• command - redis command to use once operation complete (get, bitcount)
• key - redis key(s)
• callback - standard callback (optional)

bmap.tmpBitop('get', 'or', 'foo', 'test', function(err, bitmap) {
  bitmap.toJSON() // [1,0,1,0,0,0,0,1]
})

instance.xor(key, [key2], […], [callback])

• key - redis key(s)
• callback - standard callback (optional)

Alias: [difference]

instance.or(key, [key2], […], [callback])

• key - redis key(s)
• callback - standard callback (optional)

Alias: [union]

instance.and(key, [key2], […], [callback])

• key - redis key(s)
• callback - standard callback (optional)

Alias: [intersect]

instance.not(key, [callback])

• key - redis key
• callback - standard callback (optional)

Alias: [reverse]

instance.bitcount(key, [key2], […], [callback])

• key - redis key(s)
• callback - standard callback (optional)

Alias: [count, population, cardinality]

instance.aggregate([destination])

Create an Aggregate instance for chaining commands together, uses the destination key to store all bitop results.

• destination - destination key for results (optional, default "bitmap:tmp")

Aggregation

If you want to perform a series of commands or perform bit operations on the results of previous commands, you can use the aggregate command to start a redis multi block.

bmap
  .aggregate('tmp')           // Set the destination key
  .setbit('meow', 0, 1)       // Set a bit
  .setbit('bark', 1, 1)       // Set a bit
  .setbit('bark', 2, 1)       // Set a bit
  .or('meow', 'bark')         // Perform a union of `one` and `two` into `tmp`
  .setbit('three', 1, 1)      // Set new bits
  .setbit('three', 2, 1)      // Set another
  .xor('three')               // Find the difference of the previous union with `three`
  .clean()                    // Remove `tmp` key after execution
  .exec(function(err, bits) { // Execute the current command queue  
    bits instance of BitArray // true
    bits.toJSON()             // [1,0,0,0,0,0,0,0]
    bits.cardinality()        // 1
    bits.toString             // '00000001'
  })

Install

With npm

npm install redis-bitmap

License

(The MIT License)

Copyright (c) 2013-2014 Beau Sorensen mail@beausorensen.com

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.