Refactoring the code, adding more tests

spec/crystal-scatter_spec.cr

@@ -20,10 +20,12 @@ describe Crystal::Scatter do
         
         (1..1000).each do |numb|
             slices = mr.get_slices_for(numb.to_s) 
+            slices_history = mr.get_slices_for(numb.to_s,2) 
             set = Set(String).new
             slices.each do |sl|
                 set<<sl.url
             end
+            slices_history.slices.size.should eq(2)
             set.size.should eq(3)
         end
     end

src/crystal-scatter/metaring.cr

@@ -1,4 +1,5 @@
 require "./ring.cr"
+require "json"
 require "mutex"
 require "openssl"
 
@@ -12,6 +13,18 @@ module Crystal::Scatter
         end
     end
 
+    class SliceInfo
+        JSON.mapping(
+            slices: Array(Array(Slice)),
+            last: Int32,
+            shards: UInt32
+        )
+
+        def initialize(@slices, @last, @shards)
+            
+        end
+    end
+
     class MetaRing
         getter rings : Array(Ring)
         getter ring_graph : RingGraph
@@ -44,12 +57,31 @@ module Crystal::Scatter
             return tag
         end
 
+        private def hash_and_split(data)
+            h = hash_impl data
+            space=UInt64::MAX/@shards
+            targets = Array(UInt64).new
+            (1..@shards).each do
+                targets << h
+                h+=space
+            end
+            return targets
+        end
+
         private def get_slice_from_hash(ring : Ring, h : UInt64)
             value = ring.find do |slice|
                 h>=slice.s_begin && slice.s_end>=h
             end
             return value.not_nil!
         end
+        
+        private def unfold_ring(ring : Ring, targets : Array(UInt64))
+            slices = Array(Slice).new
+            targets.each do |h|
+                slices << get_slice_from_hash(ring, h)
+            end
+            return slices
+        end
 
         def add(element : Daemon)
             @lock.synchronize do
@@ -78,44 +110,25 @@ module Crystal::Scatter
                 ring? = @rings.last
             end
             ring = ring?.not_nil!
-            h = hash_impl data
-            space=UInt64::MAX/@shards
-            targets = Array(UInt64).new
-            (1..@shards).each do
-                targets << h
-                h+=space
-            end
-            slices = Array(Slice).new
-            targets.each do |h|
-                slices << get_slice_from_hash(ring, h)
-            end
+            targets = hash_and_split(data)
+            slices = unfold_ring(ring,targets)
             return slices
         end
 
-        def get_slices_for(data : String, n_last o">= 1 : Int32)
+        def get_slices_for(data : String, n_last : UInt32)
             n_rings = Array(Ring).new
+            sllast = 0
             @lock.synchronize do
+                sllast = @rings.size - 1
                 t = @rings.size-n_last
-                n_rings = @rings.skip( t > 0 ? t : 1 ) 
+                n_rings = @rings.skip( t >= 0 ? t : 1 )
             end
-            h = hash_impl data
-            space=UInt64::MAX/@shards
-            targets = Array(UInt64).new
-            (1..@shards).each do
-                targets << h
-                h+=space
-            end
-
+            targets = hash_and_split(data)
             ret = Array(Array(Slice)).new
             n_rings.each do |ring|
-                slices = Array(Slice).new
-                targets.each do |h|
-                    slices << get_slice_from_hash(ring, h)
-                end
-                ret << slices
+                ret << unfold_ring(ring,targets)
             end
-            return ret
+            return SliceInfo.new ret, sllast, @shards
         end
     end
-
 end