add support for siphash

clandestined.gemspec

@@ -1,6 +1,6 @@
 Gem::Specification.new do |s|
   s.name = 'clandestined'
-  s.version = '1.0.0'
+  s.version = '1.0.1'
   s.licenses = ['MIT']
   s.date = Time.now.strftime('%Y-%m-%d')
   s.summary = 'rendezvous hashing implementation based on murmur3 hash'
@@ -13,6 +13,8 @@ Gem::Specification.new do |s|
   s.require_paths = ['lib', 'ext']
   s.extensions = ['ext/murmur3_native/extconf.rb']
 
+  %w{digest-siphash}.each { |gem| s.add_dependency gem }
+
   if RUBY_VERSION < "1.9"
     s.add_development_dependency 'rake', '0.8.7'
     s.add_development_dependency 'rake-compiler', '0.8.3'

lib/clandestined/rendezvous_hash.rb

@@ -1,4 +1,6 @@
 require 'murmur3'
+require 'string'
+require 'digest/siphash'
 
 module Clandestined
   class RendezvousHash
@@ -9,11 +11,23 @@ class RendezvousHash
     attr_reader :seed
     attr_reader :hash_function
 
-    def initialize(nodes=nil, seed=0)
+    def initialize(nodes=nil, seed=0, hash_type=:murmur)
       @nodes = nodes || []
       @seed = seed
 
-      @hash_function = lambda { |key| murmur3_32(key, seed) }
+      case hash_type
+      when :murmur
+        @hash_function = lambda { |key| murmur3_32(key, seed) }
+      when :siphash
+        if seed == 0
+          # siphash requires 128bit char
+          seed = "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
+        end
+
+        @hash_function = lambda { |key|
+          Digest::SipHash.digest(key, seed).reverse.hexencode.to_i(16)
+        }
+      end
     end
 
     def add_node(node)

lib/string.rb

@@ -0,0 +1,9 @@
+class String
+  def hexencode
+    self.unpack('H*').first
+  end
+
+  def hexdecode
+    [self].pack('H*')
+  end
+end

test/test_rendezvous_hash.rb

@@ -7,7 +7,7 @@
 include Clandestined
 
 
-class RendezvousHashTestCase < Test::Unit::TestCase
+class RendezvousHashMurMurTestCase < Test::Unit::TestCase
 
   def test_init_no_options
     rendezvous = RendezvousHash.new()
@@ -86,6 +86,85 @@ def test_find_node_after_addition
 
 end
 
+class RendezvousHashSipHashTestCase < Test::Unit::TestCase
+
+  def test_init_no_options
+    rendezvous = RendezvousHash.new(nil, 0, :siphash)
+    assert_equal(0, rendezvous.nodes.length)
+    assert_equal(12268983219697955183, rendezvous.hash_function.call('6666'))
+  end
+
+  def test_init
+    nodes = ['0', '1', '2']
+    rendezvous = RendezvousHash.new(nodes, 0, :siphash)
+    assert_equal(3, rendezvous.nodes.length)
+    assert_equal(12268983219697955183, rendezvous.hash_function.call('6666'))
+  end
+
+  def test_seed
+    rendezvous = RendezvousHash.new(nil, "8ed18c1098ec29a2", :siphash)
+    assert_equal("8ed18c1098ec29a2", rendezvous.seed)
+    assert_equal(9634808532907877200, rendezvous.hash_function.call('6666'))
+  end
+
+  def test_add_node
+    rendezvous = RendezvousHash.new(nil, 0, :siphash)
+    rendezvous.add_node('1')
+    assert_equal(1, rendezvous.nodes.length)
+    rendezvous.add_node('1')
+    assert_equal(1, rendezvous.nodes.length)
+    rendezvous.add_node('2')
+    assert_equal(2, rendezvous.nodes.length)
+    rendezvous.add_node('1')
+    assert_equal(2, rendezvous.nodes.length)
+  end
+
+  def test_remove_node
+    nodes = ['0', '1', '2']
+    rendezvous = RendezvousHash.new(nodes, 0, :siphash)
+    rendezvous.remove_node('2')
+    assert_equal(2, rendezvous.nodes.length)
+    assert_raises(ArgumentError) { rendezvous.remove_node(2, rendezvous.nodes.length) }
+    assert_equal(2, rendezvous.nodes.length)
+    rendezvous.remove_node('1')
+    assert_equal(1, rendezvous.nodes.length)
+    rendezvous.remove_node('0')
+    assert_equal(0, rendezvous.nodes.length)
+  end
+
+  def test_find_node
+    nodes = ['0', '1', '2']
+    rendezvous = RendezvousHash.new(nodes, 0, :siphash)
+    assert_equal('1', rendezvous.find_node('ok'))
+    assert_equal('0', rendezvous.find_node('mykey'))
+    assert_equal('0', rendezvous.find_node('wat'))
+  end
+
+  def test_find_node_after_removal
+    nodes = ['0', '1', '2']
+    rendezvous = RendezvousHash.new(nodes, 0, :siphash)
+    rendezvous.remove_node('1')
+    assert_equal('2', rendezvous.find_node('ok'))
+    assert_equal('0', rendezvous.find_node('mykey'))
+    assert_equal('0', rendezvous.find_node('wat'))
+  end
+
+  def test_find_node_after_addition
+    nodes = ['0', '1', '2']
+    rendezvous = RendezvousHash.new(nodes, 0, :siphash)
+    assert_equal('1', rendezvous.find_node('ok'))
+    assert_equal('0', rendezvous.find_node('mykey'))
+    assert_equal('0', rendezvous.find_node('wat'))
+    assert_equal('2', rendezvous.find_node('lol'))
+    rendezvous.add_node('3')
+    assert_equal('1', rendezvous.find_node('ok'))
+    assert_equal('3', rendezvous.find_node('mykey'))
+    assert_equal('3', rendezvous.find_node('wat'))
+    assert_equal('2', rendezvous.find_node('lol'))
+  end
+
+end
+
 class RendezvousHashIntegrationTestCase < Test::Unit::TestCase
 
   def test_grow