Rewrite MacOS directory watcher. (#2268)

Author: davidmorgan

pkgs/watcher/CHANGELOG.md

@@ -37,8 +37,9 @@
   issues: tracking failure following subdirectory move, incorrect events when
   there are changes in a recently-moved subdirectory, incorrect events due to
   various situations involving subdirectory moves.
-- Bug fix: with `DirectoryWatcher` on MacOS, fix events for changes in new
-  directories: don't emit duplicate ADD, don't emit MODIFY without ADD.
+- Bug fix: new `DirectoryWatcher` implementation on MacOS that fixes various
+  issues including duplicate events for changes in new directories, incorrect
+  events when close together directory renames have overlapping names.
 - Bug fix: with `FileWatcher` on MacOS, a modify event was sometimes reported if
   the file was created immediately before the watcher was created. Now, if the
   file exists when the watcher is created then this modify event is not sent.

pkgs/watcher/lib/src/directory_watcher.dart

@@ -7,7 +7,7 @@ import 'dart:io';
 import '../watcher.dart';
 import 'custom_watcher_factory.dart';
 import 'directory_watcher/linux.dart';
-import 'directory_watcher/mac_os.dart';
+import 'directory_watcher/macos.dart';
 import 'directory_watcher/windows_resubscribable_watcher.dart';
 
 /// Watches the contents of a directory and emits [WatchEvent]s when something
@@ -54,7 +54,7 @@ abstract class DirectoryWatcher implements Watcher {
       );
       if (customWatcher != null) return customWatcher;
       if (Platform.isLinux) return LinuxDirectoryWatcher(directory);
-      if (Platform.isMacOS) return MacOSDirectoryWatcher(directory);
+      if (Platform.isMacOS) return MacosDirectoryWatcher(directory);
       if (Platform.isWindows) {
         return WindowsDirectoryWatcher(directory,
             runInIsolate: runInIsolateOnWindows);

pkgs/watcher/lib/src/directory_watcher/linux/native_watch.dart

@@ -6,8 +6,8 @@ import 'dart:async';
 import 'dart:io';
 
 import '../../event.dart';
+import '../../unix_paths.dart';
 import '../../utils.dart';
-import 'paths.dart';
 
 /// Watches a directory with the native Linux watcher.
 ///
@@ -104,8 +104,7 @@ class NativeWatch {
         // watched directory was deleted. But, it might be an incorrect event
         // that is the deletion event for the old location in a move. So, check
         // if the directory is actually now missing.
-        if (watchedDirectory.statSync().type ==
-            FileSystemEntityType.directory) {
+        if (watchedDirectory.typeSync() == FileSystemEntityType.directory) {
           // The directory is still present, indicating either a watch failure
           // or that the directoy has been replaced with a new one. Either way,
           // restart watching.

pkgs/watcher/lib/src/directory_watcher/linux/watch_tree.dart

@@ -5,10 +5,10 @@
 import 'dart:io';
 
 import '../../event.dart';
+import '../../unix_paths.dart';
 import '../../utils.dart';
 import '../../watch_event.dart';
 import 'native_watch.dart';
-import 'paths.dart';
 
 /// Linux directory watcher.
 ///
@@ -148,9 +148,9 @@ class WatchTree {
   /// needs to be watched again.
   void _poll(RelativePath path) {
     logForTesting?.call('Watch,$watchedDirectory,_poll,$path');
-    final stat = watchedDirectory.append(path).statSync();
-    if (stat.type == FileSystemEntityType.file ||
-        stat.type == FileSystemEntityType.link) {
+    final type = watchedDirectory.append(path).typeSync();
+    if (type == FileSystemEntityType.file ||
+        type == FileSystemEntityType.link) {
       logForTesting?.call('Watch,$watchedDirectory,poll,$path,file');
       if (_directories.containsKey(path)) {
         _emitDeleteDirectory(path);
@@ -160,7 +160,7 @@ class WatchTree {
       } else {
         _addFile(path);
       }
-    } else if (stat.type == FileSystemEntityType.directory) {
+    } else if (type == FileSystemEntityType.directory) {
       logForTesting?.call('Watch,$watchedDirectory,poll,$path,directory');
       if (_files.contains(path)) {
         _emitDeleteFile(path);

pkgs/watcher/lib/src/directory_watcher/linux/watch_tree_root.dart

@@ -4,9 +4,9 @@
 
 import 'dart:async';
 
+import '../../unix_paths.dart';
 import '../../utils.dart';
 import '../../watch_event.dart';
-import 'paths.dart';
 import 'watch_tree.dart';
 
 /// Linux directory watcher using a [WatchTree].