Added facility to register commands that do not need editor update

Summary: An editor update is a costly operation, possibly taking up to 10ms. There are situations where your Lexical command's handler does not need to be inside an update block. A big example is logging. This diff allows command handlers to opt out of the auto-update-wrapper functionality. When applied to logging plugins, this can produce a drastic speedup.

Reviewed By: Fetz

Differential Revision: D53517219

fbshipit-source-id: ff525cf6010e37d3ed9fdcdc5f1e758a06d0243e

Lexical/Core/Constants.swift

@@ -151,7 +151,11 @@ struct Listeners {
   var errors: [UUID: ErrorListener] = [:]
 }
 
-public typealias Commands = [CommandType: [CommandPriority: [UUID: CommandListener]]]
+public struct CommandListenerWithMetadata {
+  let listener: CommandListener
+  let shouldWrapInUpdateBlock: Bool
+}
+public typealias Commands = [CommandType: [CommandPriority: [UUID: CommandListenerWithMetadata]]]
 
 // enum is used in setting theme
 public enum TextTransform: String {

Lexical/Core/Editor.swift

@@ -266,7 +266,7 @@ public class Editor: NSObject {
   ///   - listener: The code to run when the command is dispatched.
   ///   - priority: The priority for your handler. Higher priority handlers run before lower priority handlers.
   /// - Returns: A closure to remove the command handler.
-  public func registerCommand(type: CommandType, listener: @escaping CommandListener, priority: CommandPriority = CommandPriority.Editor) -> RemovalHandler {
+  public func registerCommand(type: CommandType, listener: @escaping CommandListener, priority: CommandPriority = CommandPriority.Editor, shouldWrapInUpdateBlock: Bool = true) -> RemovalHandler {
     let uuid = UUID()
 
     if self.commands[type] == nil {
@@ -282,7 +282,9 @@ public class Editor: NSObject {
       )
     }
 
-    self.commands[type]?[priority]?[uuid] = listener
+    let wrapper = CommandListenerWithMetadata(listener: listener, shouldWrapInUpdateBlock: shouldWrapInUpdateBlock)
+
+    self.commands[type]?[priority]?[uuid] = wrapper
 
     return { [weak self] in
       guard let self else { return }

Lexical/Core/Updates.swift

@@ -78,7 +78,8 @@ public func triggerCommandListeners(activeEditor: Editor, type: CommandType, pay
       }
 
       // TODO: handle throws
-      for listener in listeners {
+      for wrapper in listeners {
+        let listener = wrapper.listener
         if listener(payload) {
           handled = true
           return
@@ -87,8 +88,17 @@ public func triggerCommandListeners(activeEditor: Editor, type: CommandType, pay
     }
   }
 
+  var shouldWrapInUpdateBlock = false
+  for p in (listenersInPriorityOrder ?? [:]).values {
+    for metadata in p.values {
+      if metadata.shouldWrapInUpdateBlock {
+        shouldWrapInUpdateBlock = true
+      }
+    }
+  }
+
   do {
-    if !activeEditor.isUpdating {
+    if shouldWrapInUpdateBlock && !activeEditor.isUpdating {
       try activeEditor.update(closure)
     } else {
       try closure()