More consistent API.

spec/test.cr

@@ -4,6 +4,9 @@ require "file_utils"
 require "../src/dodb.cr"
 require "./test-data.cr"
 
+def fork_process(&)
+	Process.new Crystal::System::Process.fork { yield }
+end
 
 class DODB::SpecDataBase < DODB::DataBase(Ship)
 	def initialize(storage_ext = "", remove_previous_data = true)
@@ -223,7 +226,7 @@ describe "DODB::DataBase" do
 				}.should be_true
 			end
 
-			db_ships_by_class.get("does-not-exist").should eq [] of Ship
+			db_ships_by_class.get?("does-not-exist").should eq nil
 		end
 
 		it "removes select elements from partitions" do
@@ -409,7 +412,7 @@ describe "DODB::DataBase" do
 			processes = [] of Process
 
 			fork_count.times do |fork_id|
-				processes << Process.fork do
+				processes << fork_process do
 					entries_per_fork.times do |entry_id|
 						db << Ship.new("entry-#{fork_id}-#{entry_id}", "???")
 					end
@@ -430,7 +433,7 @@ describe "DODB::DataBase" do
 			# First pass, creating data.
 			processes = [] of Process
 			fork_count.times do |fork_id|
-				processes << Process.fork do
+				processes << fork_process do
 					entries_per_fork.times do |entry_id|
 						db << Ship.new("entry-#{fork_id}-#{entry_id}", "???")
 					end
@@ -441,7 +444,7 @@ describe "DODB::DataBase" do
 			# Second pass, updating data.
 			processes = [] of Process
 			fork_count.times do |fork_id|
-				processes << Process.fork do
+				processes << fork_process do
 					entries_per_fork.times do |entry_id|
 						db_entries_by_name.update Ship.new("entry-#{fork_id}-#{entry_id}", "???", tags: ["updated"])
 					end
@@ -471,7 +474,7 @@ describe "DODB::DataBase" do
 
 			processes = [] of Process
 			fork_count.times do |fork_id|
-				processes << Process.fork do
+				processes << fork_process do
 					entries_per_fork.times do |entry_id|
 						db_entries_by_name.safe_get "test" do |entry|
 							entry.klass = (entry.klass.to_i + 1).to_s

src/dodb/partition.cr

@@ -43,11 +43,10 @@ class DODB::Partition(V) < DODB::Indexer(V)
 	end
 
 	def get(partition) : Array(V)
-		r_value = Array(V).new
-
 		partition_directory = indexing_directory partition
+		raise MissingEntry.new(@name, partition) unless Dir.exists? partition_directory
 
-		return r_value unless Dir.exists? partition_directory
+		r_value = Array(V).new
 
 		Dir.each_child partition_directory do |child|
 			r_value << @storage[get_key child]

src/dodb/tags.cr

@@ -42,11 +42,10 @@ class DODB::Tags(V) < DODB::Indexer(V)
 	end
 
 	def get_with_indice(tag : String) : Array(Tuple(V, Int32))
-		r_value = Array(Tuple(V, Int32)).new
-
 		tag_directory = indexing_directory tag
+		raise MissingEntry.new(@name, tag) unless Dir.exists? tag_directory
 
-		return r_value unless Dir.exists? tag_directory
+		r_value = Array(Tuple(V, Int32)).new
 
 		Dir.each_child tag_directory do |child|
 			key = get_key child
@@ -56,10 +55,18 @@ class DODB::Tags(V) < DODB::Indexer(V)
 		r_value
 	end
 
+	# `get_with_indices` gets values with all the tags.
+
 	def get_with_indices(keys : Array(String)) : Array(Tuple(V, Int32))
 		r_value = Array(Tuple(V, Int32)).new
+		return r_value if keys.size < 1
+
+		first_key = keys.pop
+		r_value = get_with_indice(first_key) rescue return [] of Tuple(V, Int32)
+
 		keys.each do |tag|
-			r_value.concat get_with_indice tag
+			values = get_with_indice(tag) rescue return [] of Tuple(V, Int32)
+			r_value &= values
 		end
 		r_value
 	end