BookInfoManager: Actually close the document after extraction

DocumentRegistry just decreases a ref, it doesn't close anything.

Plug the same Document leak in a few other places, and document this.

frontend/apps/filemanager/filemanagerbookinfo.lua

@@ -126,7 +126,7 @@ function BookInfo:show(file, book_props)
                 book_props = document:getProps()
                 book_props.pages = pages
             end
-            DocumentRegistry:closeDocument(file)
+            document:close()
         end
     end
 
@@ -219,7 +219,7 @@ function BookInfo:show(file, book_props)
                     fullscreen = true,
                 }
             end
-            DocumentRegistry:closeDocument(file)
+            document:close()
         end
         if not widget then
             widget = InfoMessage:new{

frontend/document/document.lua

@@ -91,6 +91,7 @@ function Document:unlock(password)
 end
 
 -- this might be overridden by a document implementation
+-- (in which case, do make sure it calls this one, too, to avoid refcounting mismatches in DocumentRegistry!)
 function Document:close()
     local DocumentRegistry = require("document/documentregistry")
     if self.is_open then

frontend/document/documentregistry.lua

@@ -191,6 +191,7 @@ function DocumentRegistry:mimeToExt(mimetype)
     return self.mimetype_ext[mimetype]
 end
 
+--- Returns a new Document instance on success
 function DocumentRegistry:openDocument(file, provider)
     -- force a GC, so that any previous document used memory can be reused
     -- immediately by this new document without having to wait for the
@@ -219,6 +220,8 @@ function DocumentRegistry:openDocument(file, provider)
     end
 end
 
+--- Does *NOT* finalize a Document instance, call its :close() instead if that's what you're looking for!
+--- (i.e., nothing but Document:close should call this!)
 function DocumentRegistry:closeDocument(file)
     if self.registry[file] then
         self.registry[file].refs = self.registry[file].refs - 1

plugins/coverbrowser.koplugin/bookinfomanager.lua

@@ -544,7 +544,7 @@ function BookInfoManager:extractBookInfo(filepath, cover_specs)
                 end
             end
         end
-        DocumentRegistry:closeDocument(filepath)
+        document:close()
     else
         loaded = false
     end

plugins/coverbrowser.koplugin/covermenu.lua

@@ -335,7 +335,7 @@ function CoverMenu:updateItems(select_number)
                                     })
                                 end
                                 UIManager:close(self.file_dialog)
-                                DocumentRegistry:closeDocument(file)
+                                document:close()
                             end
                         end,
                     },
@@ -468,7 +468,7 @@ function CoverMenu:onHistoryMenuHold(item)
                         })
                     end
                     UIManager:close(self.histfile_dialog)
-                    DocumentRegistry:closeDocument(file)
+                    document:close()
                 end
             end,
         },
@@ -590,7 +590,7 @@ function CoverMenu:onCollectionsMenuHold(item)
                         })
                     end
                     UIManager:close(self.collfile_dialog)
-                    DocumentRegistry:closeDocument(file)
+                    document:close()
                 end
             end,
         },