fixed simple_skiplist dump/load methods

lib/strokedb/data_structures/simple_skiplist.rb

@@ -12,36 +12,30 @@ class SimpleSkiplist
 
     attr_accessor :maxlevel, :probability
 
-    def initialize(raw_list = nil, options = {})
+    def initialize(options = {})
       options = options.stringify_keys
       @maxlevel    = options['maxlevel']    || DEFAULT_MAXLEVEL
       @probability = options['probability'] || DEFAULT_PROBABILITY
       @head, @tail = new_anchors(@maxlevel)
-      if raw_list
-        @head, @tail = unserialize_list!(raw_list)
-      end
       @mutex       = Mutex.new
     end
 
     def inspect
       "#<#{self.class}:0x#{object_id.to_s(16)} items: #{to_a.inspect}, maxlevel: #{@maxlevel}, probability: #{@probability}>"
     end
-
-    # Marshal API
-    def marshal_dump
-      raw_list = serialize_list(@head)
-      {
-        :options => {
-          :maxlevel    => @maxlevel,
-          :probability => @probability
-          },
-        :raw_list => raw_list
-      }
-    end
-
-    def marshal_load(dumped)
-      initialize(dumped[:raw_list], dumped[:options])
-      self
+
+    def dump
+      Marshal.dump({
+        :maxlevel    => @maxlevel,
+        :probability => @probability,
+        :arr         => to_a
+      })
+    end
+
+    def self.load(dumped)
+      hash = Marshal.load(dumped)
+      arr = hash.delete(:arr)
+      from_a(arr, hash)
     end
 
     # Tests whether skiplist is empty.
@@ -214,6 +208,7 @@ def find_nearest_node(key) #:nodoc:
       #   }
       # end
     end
+
     declare_optimized_methods(:C) do
     end
 
@@ -318,7 +313,7 @@ def self.from_hash(hash, options = {})
     # Constructs a skiplist from an array of key-value tuples (arrays).
     #
     def self.from_a(ary, options = {})
-      sl = new(nil, options)
+      sl = new(options)
       ary.each do |kv|
         sl.insert(kv[0], kv[1])
       end
@@ -335,52 +330,7 @@ def to_a
     end
 
   private
-
-    def serialize_list(head)
-      head           = anchor.dup
-      head[0]        = [ nil  ] * node_level(head)
-      raw_list       = [ head ]
-      prev_by_levels = [ head ] * node_level(head)
-      x = node_next(head, 0)
-      i = 1
-      while x
-        l = node_level(x)
-        nx = node_next(x, 0)
-        x  = x.dup                  # make modification-safe copy of node
-        forwards = x[0]
-        while l > 0                 # for each node level update forwards
-          l -= 1
-          prev_by_levels[l][l] = i  # set raw_list's index as a forward ref
-          forwards[l] = nil         # nullify forward pointer (point to tail)
-          prev_by_levels[l] = x     # set in a previous stack
-        end
-        raw_list << x               # store serialized node in an array
-        x = nx                      # step to next node
-        i += 1                      # increment index in a raw_list array
-      end
-      raw_list
-    end
 
-    # Returns head & tail of an imported skiplist. 
-    # Caution: raw_list is modified (thus the bang). 
-    # Pass dup-ed value if you need.
-    #
-    # TODO: add double-linking!
-    #
-    def unserialize_list!(raw_list)
-      x = raw_list[0]
-      while x != nil
-        forwards = x[0]
-        forwards.each_with_index do |rawindex, i|
-          forwards[i] = rawindex ? raw_list[rawindex] : nil
-        end
-        # go next node
-        x = forwards[0]
-      end
-      # return anchors (head, tail)
-      [raw_list[0], new_anchor]  # <- FIXME: normal tail anchor needed
-    end
-
     # C-style API for node operations    
     def anchor(reverse = false)
       reverse ? @tail : @head

lib/strokedb/volumes/skiplist_volume.rb

@@ -85,10 +85,10 @@ def error(*args); end
       end
 
       if File.exists?(@list_path)
-        @list = Marshal.load(File.read(@list_path))
+        @list = SimpleSkiplist.load(File.read(@list_path))
       else
         info "List file (#{@list_path}) not found, creating a brand new skiplist."
-        @list = SimpleSkiplist.new(nil, @params)
+        @list = SimpleSkiplist.new(@params)
       end
 
       if File.exists?(@log_path)
@@ -146,7 +146,7 @@ def closed?
     end
 
     def dump!
-      dumped_list = Marshal.dump(@list)
+      dumped_list = @list.dump
       f = File.open(@list_tmppath, 'w')
       f.sync = true
       f.write(dumped_list)

spec/lib/strokedb/data_structures/simple_skiplist_spec.rb

@@ -3,10 +3,11 @@
 
 describe "Skiplist serialization", :shared => true do
   it "should correctly load what it dumped" do
-    dump1 = @list.marshal_dump
-    newlist = @list.class.allocate
-    dump2 = newlist.marshal_load(dump1).marshal_dump
+    dump1 = @list.dump
+    newlist = @list.class.load(dump1)
+    dump2 = newlist.dump
     dump1.should == dump2
+    newlist.to_a.should == @list.to_a
   end
 
   it "should correctly load to_a results" do
@@ -24,25 +25,13 @@
     before(:each) do
       @maxlevel    = 8
       @probability = 0.5
-      @list = SimpleSkiplist.new(nil, :maxlevel => @maxlevel, :probability => @probability)
+      @list = SimpleSkiplist.new(:maxlevel => @maxlevel, :probability => @probability)
     end
 
   	it "should be empty" do
   		@list.should be_empty
   	end
 
-  	it "should be serialized with marshal_dump" do
-  	  @list.marshal_dump.should == {
-  	    :options => {
-  	      :probability => @probability,
-  	      :maxlevel => @maxlevel
-  	    },
-  	    :raw_list => [
-  	      [[nil]*@maxlevel, nil, nil, [nil]*@maxlevel]
-  	    ]
-  	  }
-    end
-
   	it "should find nil in a empty skiplist" do
   	  @list.find("xx").should == nil
   	  @list.find("").should == nil
@@ -57,7 +46,7 @@
     before(:each) do
       @maxlevel    = 8
       @probability = 0.5
-      @list = SimpleSkiplist.new(nil, :maxlevel => @maxlevel, :probability => @probability)
+      @list = SimpleSkiplist.new(:maxlevel => @maxlevel, :probability => @probability)
     end
 
     it "should insert empty key in place of default head" do
@@ -113,7 +102,7 @@
     before(:each) do
       @maxlevel    = 8
       @probability = 0.5
-      @list = SimpleSkiplist.new(nil, :maxlevel => @maxlevel, :probability => @probability)
+      @list = SimpleSkiplist.new(:maxlevel => @maxlevel, :probability => @probability)
       1000.times do 
         k = rand(2**64).to_s
         v = k
@@ -148,7 +137,7 @@
     before(:each) do
       @maxlevel    = 8
       @probability = 0.5
-      @list = SimpleSkiplist.new(nil, :maxlevel => @maxlevel, :probability => @probability)
+      @list = SimpleSkiplist.new(:maxlevel => @maxlevel, :probability => @probability)
     end
     it "should return nil for empty skiplist" do
       @list.first_key.should == nil
@@ -166,7 +155,7 @@
     before(:each) do
       @maxlevel    = 8
       @probability = 0.5
-      @list = SimpleSkiplist.new(nil, :maxlevel => @maxlevel, :probability => @probability)
+      @list = SimpleSkiplist.new(:maxlevel => @maxlevel, :probability => @probability)
     end
     it "should find nil in empty skiplist" do
       @list.find_nearest("a").should == nil

spec/lib/strokedb/volumes/skiplist_volume_spec.rb

@@ -72,8 +72,6 @@
       }.should raise_error(SkiplistVolume::MessageTooBig)
     end
 
-
-
     def init_volume
       @path = TEMP_STORAGES + '/skiplist_volume_files/volume'
       FileUtils.rm_rf(TEMP_STORAGES + '/skiplist_volume_files')