Avoid filesystem limits using a trie

lib/gemstash/storage.rb

@@ -1,4 +1,5 @@
 require "gemstash"
+require "digest"
 require "pathname"
 require "fileutils"
 require "yaml"
@@ -36,11 +37,20 @@ def path_valid?(path)
 
   #:nodoc:
   class Resource
-    attr_accessor :name
+    attr_accessor :name, :folder
     def initialize(folder, name)
       @base_path = folder
       @name = name
-      @folder = File.join(@base_path, @name)
+      # Avoid odd characters in paths, in case of issues with the file system
+      safe_name = @name.gsub(/[^a-zA-Z0-9_]/, "_")
+      # Use a trie structure to avoid file system limits causing too many files in 1 folder
+      # Downcase to avoid issues with case insensitive file systems
+      trie_parents = safe_name[0...3].downcase.split("")
+      # The digest is included in case the name differs only by case
+      # Some file systems are case insensitive, so such collisions will be a problem
+      digest = Digest::MD5.hexdigest(@name)
+      child_folder = "#{safe_name}-#{digest}"
+      @folder = File.join(@base_path, *trie_parents, child_folder)
     end
 
     def exist?

spec/gemstash/storage_spec.rb

@@ -73,5 +73,36 @@
         expect(resource.content).to eq(content)
       end
     end
+
+    context "with resource name that is unique by case only" do
+      let(:first_resource_id) { "SomeResource" }
+      let(:second_resource_id) { "someresource" }
+
+      it "stores the content separately" do
+        storage.resource(first_resource_id).save("first content")
+        storage.resource(second_resource_id).save("second content")
+        expect(storage.resource(first_resource_id).load.content).to eq("first content")
+        expect(storage.resource(second_resource_id).load.content).to eq("second content")
+      end
+
+      it "uses different downcased paths to avoid issues with case insensitive file systems" do
+        first_resource = storage.resource(first_resource_id)
+        second_resource = storage.resource(second_resource_id)
+        expect(first_resource.folder.downcase).to_not eq(second_resource.folder.downcase)
+      end
+    end
+
+    context "with resource name that includes odd characters" do
+      let(:resource_id) { ".=$&resource" }
+
+      it "stores and retrieves the data" do
+        storage.resource(resource_id).save("odd name content")
+        expect(storage.resource(resource_id).load.content).to eq("odd name content")
+      end
+
+      it "doesn't include the odd characters in the path" do
+        expect(storage.resource(resource_id).folder).to_not match(/[.=$&]/)
+      end
+    end
   end
 end