Implement library caching TitleInfo

* Cache sum of entry progress
* Cache cover_url
* Cache display_name
* Cache sort_opt

src/library/cache.cr

@@ -0,0 +1,159 @@
+require "digest"
+
+class InfoCache
+  alias ProgressCache = Tuple(String, Int32)
+
+  def self.clear
+    clear_cover_url
+    clear_progress_cache
+    clear_sort_opt
+  end
+
+  def self.clean
+    clean_cover_url
+    clean_progress_cache
+    clean_sort_opt
+  end
+
+  # item id => cover_url
+  @@cached_cover_url = {} of String => String
+  @@cached_cover_url_previous = {} of String => String # item id => cover_url
+
+  def self.set_cover_url(id : String, cover_url : String)
+    @@cached_cover_url[id] = cover_url
+  end
+
+  def self.get_cover_url(id : String)
+    @@cached_cover_url[id]?
+  end
+
+  def self.invalidate_cover_url(id : String)
+    @@cached_cover_url.delete id
+  end
+
+  def self.move_cover_url(id : String)
+    if @@cached_cover_url_previous[id]?
+      @@cached_cover_url[id] = @@cached_cover_url_previous[id]
+    end
+  end
+
+  private def self.clear_cover_url
+    @@cached_cover_url_previous = @@cached_cover_url
+    @@cached_cover_url = {} of String => String
+  end
+
+  private def self.clean_cover_url
+    @@cached_cover_url_previous = {} of String => String
+  end
+
+  # book.id:username => {signature, sum}
+  @@progress_cache = {} of String => ProgressCache
+  # book.id => username => {signature, sum}
+  @@progress_cache_previous = {} of String => Hash(String, ProgressCache)
+
+  def self.set_progress_cache(book_id : String, username : String,
+                              entries : Array(Entry), sum : Int32)
+    progress_cache_id = "#{book_id}:#{username}"
+    progress_cache_sig = Digest::SHA1.hexdigest (entries.map &.id).to_s
+    @@progress_cache[progress_cache_id] = {progress_cache_sig, sum}
+    Logger.debug "Progress Cached #{progress_cache_id}"
+  end
+
+  def self.get_progress_cache(book_id : String, username : String,
+                              entries : Array(Entry))
+    progress_cache_id = "#{book_id}:#{username}"
+    progress_cache_sig = Digest::SHA1.hexdigest (entries.map &.id).to_s
+    cached = @@progress_cache[progress_cache_id]?
+    if cached && cached[0] == progress_cache_sig
+      Logger.debug "Progress Cache Hit! #{progress_cache_id}"
+      return cached[1]
+    end
+  end
+
+  def self.invalidate_progress_cache(book_id : String, username : String)
+    progress_cache_id = "#{book_id}:#{username}"
+    if @@progress_cache[progress_cache_id]?
+      @@progress_cache.delete progress_cache_id
+      Logger.debug "Progress Invalidate Cache #{progress_cache_id}"
+    end
+  end
+
+  def self.move_progress_cache(book_id : String)
+    if @@progress_cache_previous[book_id]?
+      @@progress_cache_previous[book_id].each do |username, cached|
+        id = "#{book_id}:#{username}"
+        unless @@progress_cache[id]?
+          # It would be invalidated when entries changed
+          @@progress_cache[id] = cached
+        end
+      end
+    end
+  end
+
+  private def self.clear_progress_cache
+    @@progress_cache_previous = {} of String => Hash(String, ProgressCache)
+    @@progress_cache.each do |id, cached|
+      splitted = id.split(':', 2)
+      book_id = splitted[0]
+      username = splitted[1]
+      unless @@progress_cache_previous[book_id]?
+        @@progress_cache_previous[book_id] = {} of String => ProgressCache
+      end
+
+      @@progress_cache_previous[book_id][username] = cached
+    end
+    @@progress_cache = {} of String => ProgressCache
+  end
+
+  private def self.clean_progress_cache
+    @@progress_cache_previous = {} of String => Hash(String, ProgressCache)
+  end
+
+  # book.dir:username => SortOptions
+  @@cached_sort_opt = {} of String => SortOptions
+  @@cached_sort_opt_previous = {} of String => Hash(String, SortOptions)
+
+  def self.set_sort_opt(dir : String, username : String, sort_opt : SortOptions)
+    id = "#{dir}:#{username}"
+    @@cached_sort_opt[id] = sort_opt
+  end
+
+  def self.get_sort_opt(dir : String, username : String)
+    id = "#{dir}:#{username}"
+    @@cached_sort_opt[id]?
+  end
+
+  def self.invalidate_sort_opt(dir : String, username : String)
+    id = "#{dir}:#{username}"
+    @@cached_sort_opt.delete id
+  end
+
+  def self.move_sort_opt(dir : String)
+    if @@cached_sort_opt_previous[dir]?
+      @@cached_sort_opt_previous[dir].each do |username, cached|
+        id = "#{dir}:#{username}"
+        unless @@cached_sort_opt[id]?
+          @@cached_sort_opt[id] = cached
+        end
+      end
+    end
+  end
+
+  private def self.clear_sort_opt
+    @@cached_sort_opt_previous = {} of String => Hash(String, SortOptions)
+    @@cached_sort_opt.each do |id, cached|
+      splitted = id.split(':', 2)
+      book_dir = splitted[0]
+      username = splitted[1]
+      unless @@cached_sort_opt_previous[book_dir]?
+        @@cached_sort_opt_previous[book_dir] = {} of String => SortOptions
+      end
+      @@cached_sort_opt_previous[book_dir][username] = cached
+    end
+    @@cached_sort_opt = {} of String => SortOptions
+  end
+
+  private def self.clean_sort_opt
+    @@cached_sort_opt_previous = {} of String => Hash(String, SortOptions)
+  end
+end