add getbit/setbit (non-counting) redis filter backend

Gemfile.lock

@@ -2,14 +2,14 @@ PATH
   remote: .
   specs:
     bloomfilter (1.3.1)
-      redis
+      redis (>= 2.1.1)
 
 GEM
   remote: http://rubygems.org/
   specs:
     diff-lcs (1.1.2)
     rake (0.8.7)
-    redis (2.0.5)
+    redis (2.1.1)
     rspec (2.3.0)
       rspec-core (~> 2.3.0)
       rspec-expectations (~> 2.3.0)
@@ -25,5 +25,5 @@ PLATFORMS
 DEPENDENCIES
   bloomfilter!
   rake
-  redis
+  redis (>= 2.1.1)
   rspec

bloomfilter.gemspec

@@ -13,7 +13,7 @@ Gem::Specification.new do |s|
   s.description = s.summary
   s.rubyforge_project = "bloomfilter"
 
-  s.add_dependency "redis"
+  s.add_dependency "redis", ">= 2.1.1"
   s.add_development_dependency "rspec"
   s.add_development_dependency "rake"
 

lib/bloomfilter.rb

@@ -5,4 +5,5 @@
 require 'bloomfilter/filter'
 require 'bloomfilter/native'
 require 'bloomfilter/counting_redis'
-require 'bloomfilter/version'
+require 'bloomfilter/redis'
+require 'bloomfilter/version'

lib/bloomfilter/redis.rb

@@ -0,0 +1,63 @@
+module BloomFilter
+  class Redis < Filter
+
+    def initialize(opts = {})
+      @opts = {
+        :size    => 100,
+        :hashes  => 4,
+        :seed    => Time.now.to_i,
+        :bucket  => 3,
+        :ttl => false,
+        :server => {}
+      }.merge opts
+      @db = ::Redis.new(@opts[:server])
+    end
+
+    def insert(key, ttl=nil)
+      indexes_for(key) { |idx| @db.setbit 'redis', idx, 1 }
+    end
+    alias :[]= :insert
+
+    def include?(*keys)
+      keys.each do |key|
+        indexes_for(key) do |idx|
+          return false if @db.getbit('redis', idx).zero?
+        end
+      end
+
+      true
+    end
+    alias :key? :include?
+
+    def delete(key)
+      indexes_for(key) do |idx|
+        @db.setbit 'redis', idx, 0
+      end
+    end
+
+    def clear
+      @db.set 'redis', 0
+    end
+
+    def num_set
+      @db.strlen 'redis'
+    end
+    alias :size :num_set
+
+    def stats
+      printf "Number of filter buckets (m): %d\n" % @opts[:size]
+      printf "Number of filter hashes (k) : %d\n" % @opts[:hashes]
+    end
+
+    private
+
+      # compute index offsets for provided key
+      def indexes_for(key)
+        indexes = []
+        @opts[:hashes].times do |i|
+          yield Zlib.crc32("#{key}:#{i+@opts[:seed]}") % @opts[:size]
+        end
+      end
+
+  end
+end

spec/redis_spec.rb

@@ -0,0 +1,45 @@
+require 'helper'
+
+describe BloomFilter::Redis do
+  include BloomFilter
+
+  context "use Redis bitstring for storage" do
+    let(:bf) { Redis.new }
+
+    it "should store data in Redis" do
+      bf.insert(:abcd)
+      bf.insert('test')
+      bf.include?('test').should be_true
+      bf.key?('test').should be_true
+
+      bf.include?('test', 'test2').should be_false
+      bf.include?('test', 'abcd').should be_true
+    end
+
+    it "should delete keys from Redis" do
+      bf.insert('test')
+      bf.include?('test').should be_true
+
+      bf.delete('test')
+      bf.include?('test').should be_false
+    end
+
+    it "should clear Redis filter" do
+      bf.insert('test')
+      bf.include?('test').should be_true
+
+      bf.clear
+      bf.include?('test').should be_false
+    end
+
+    it "should output current stats" do
+      bf.clear
+      bf.insert('test')
+      lambda { bf.stats }.should_not raise_error
+    end
+
+    it "should connect to remote redis server" do
+      lambda { Redis.new }.should_not raise_error
+    end
+  end
+end