Add a finite retry for creating contexts.

Fixes #61931.

The exception we see when there are no file watchers available is a file path not found exception. This is not specific enough for us to exit on the exception, hence the finite retries.

Change-Id: I8ba5081e1e916d3a1272821367806dc7d8391ec4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/462780
Commit-Queue: Keerti Parthasarathy <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>

Author: keertip

pkg/analysis_server/lib/src/context_manager.dart

@@ -169,6 +169,9 @@ abstract class ContextManagerCallbacks {
 /// Class that maintains a mapping from included/excluded paths to a set of
 /// folders that should correspond to analysis contexts.
 class ContextManagerImpl implements ContextManager {
+  /// The max number of tries to add watchers while building contexts.
+  static const int _maxWatcherRetries = 5;
+
   /// The [OverlayResourceProvider] used to check for the existence of overlays
   /// and to convert paths into [Resource].
   final OverlayResourceProvider resourceProvider;
@@ -213,6 +216,9 @@ class ContextManagerImpl implements ContextManager {
   @override
   List<String> includedPaths = <String>[];
 
+  /// The number of trials to create watchers for the files in the context.
+  int _watcherRetries = 0;
+
   /// The instrumentation service used to report instrumentation data.
   final InstrumentationService _instrumentationService;
 
@@ -702,10 +708,15 @@ class ContextManagerImpl implements ContextManager {
                 // Errors in the watcher such as "Directory watcher closed
                 // unexpectedly" on Windows when the buffer overflows also
                 // require that we restarted to be consistent.
-                needsBuild = true;
+                if (_watcherRetries < _maxWatcherRetries) {
+                  needsBuild = true;
+                  _watcherRetries++;
+                } else {
+                  needsBuild = false;
+                }
                 _instrumentationService.logError(
                   'Temporary watcher error; restarting context build.\n'
-                  '$error\n$stackTrace',
+                  'watcherRetries:$_watcherRetries, needsBuild: $needsBuild, $error\n$stackTrace',
                 );
               },
             ),
@@ -906,8 +917,15 @@ class ContextManagerImpl implements ContextManager {
     _instrumentationService.logError(
       'Watcher error; refreshing contexts.\n$error\n$stackTrace',
     );
-    // TODO(mfairhurst): Optimize this, or perhaps be less complete.
-    refresh();
+    // Retry a finite number of times.
+    if (_watcherRetries < _maxWatcherRetries) {
+      _watcherRetries++;
+      refresh();
+    } else {
+      _instrumentationService.logError(
+        'Error: Unable to create contexts, exiting ...',
+      );
+    }
   }
 
   /// Checks whether the current roots were built using the same paths as