Define ExamineContext, apply it when scanning

src/library/library.cr

@@ -142,20 +142,28 @@ class Library
 
     storage = Storage.new auto_close: false
 
+    examine_context : ExamineContext = {
+      file_count: 0,
+      cached_contents_signature: {} of String => String,
+      deleted_title_ids: [] of String,
+      deleted_entry_ids: [] of String
+    }
+
     @title_ids.select! do |title_id|
       title = @title_hash[title_id]
-      existence = title.examine
+      existence = title.examine examine_context
       @title_hash.delete title_id unless existence
       existence
     end
     remained_title_dirs = @title_ids.map { |id| title_hash[id].dir }
 
+    cache = examine_context["cached_contents_signature"]
     (Dir.entries @dir)
       .select { |fn| !fn.starts_with? "." }
       .map { |fn| File.join @dir, fn }
       .select { |path| !(remained_title_dirs.includes? path) }
       .select { |path| File.directory? path }
-      .map { |path| Title.new path, "" }
+      .map { |path| Title.new path, "", cache }
       .select { |title| !(title.entries.empty? && title.titles.empty?) }
       .sort! { |a, b| a.title <=> b.title }
       .each do |title|

src/library/title.cr

@@ -19,7 +19,7 @@ class Title
   @[YAML::Field(ignore: true)]
   @cached_cover_url : String?
 
-  def initialize(@dir : String, @parent_id)
+  def initialize(@dir : String, @parent_id, cache : Hash(String, String)?)
     storage = Storage.default
     @signature = Dir.signature dir
     id = storage.get_title_id dir, signature
@@ -32,7 +32,7 @@ class Title
       })
     end
     @id = id
-    @contents_signature = Dir.contents_signature dir
+    @contents_signature = Dir.contents_signature dir, cache
     @title = File.basename dir
     @encoded_title = URI.encode @title
     @title_ids = [] of String
@@ -70,9 +70,14 @@ class Title
     end
   end
 
-  def examine(cache = {} of String => String) : Bool
+  def self.new(dir : String, parent_id)
+    new dir, parent_id, nil
+  end
+
+  def examine(context : ExamineContext) : Bool
     return false unless Dir.exists? @dir # No title, Remove this
-    contents_signature = Dir.contents_signature @dir, cache
+    contents_signature = Dir.contents_signature @dir,
+      context["cached_contents_signature"]
     # Not changed. Reuse this
     return true if @contents_signature == contents_signature
 
@@ -95,7 +100,7 @@ class Title
     previous_titles_size = @title_ids.size
     @title_ids.select! do |title_id|
       title = Library.default.get_title! title_id
-      existence = title.examine cache
+      existence = title.examine context
       Library.default.title_hash.delete title_id unless existence
       existence
     end
@@ -115,7 +120,7 @@ class Title
       path = File.join dir, fn
       if File.directory? path
         next if remained_title_dirs.includes? path
-        title = Title.new path, @id
+        title = Title.new path, @id, context["cached_contents_signature"]
         next if title.entries.size == 0 && title.titles.size == 0
         Library.default.title_hash[title.id] = title
         @title_ids << title.id

src/library/types.cr

@@ -133,3 +133,10 @@ class TitleInfo
     LRUCache.set generate_cache_entry key, self.to_json
   end
 end
+
+alias ExamineContext = NamedTuple(
+  file_count: Int32,
+  cached_contents_signature: Hash(String, String),
+  deleted_title_ids: Array(String),
+  deleted_entry_ids: Array(String)
+)

src/util/signature.cr

@@ -55,7 +55,7 @@ class Dir
   #   - When a file added, moved, removed, renamed (including which in nested
   #       directories)
   def self.contents_signature(dirname, cache = {} of String => String) : String
-    return cache[dirname] if cache[dirname]?
+    return cache[dirname] if !cache.nil? && cache[dirname]?
     signatures = [] of String
     self.open dirname do |dir|
       dir.entries.sort.each do |fn|
@@ -71,7 +71,7 @@ class Dir
       end
     end
     hash = Digest::SHA1.hexdigest(signatures.join)
-    cache[dirname] = hash
+    cache[dirname] = hash unless cache.nil?
     hash
   end
 end