Support refresh of individual analysis roots (issue 22254)

pkg/analysis_server/lib/src/analysis_server.dart

Index: pkg/analysis_server/lib/src/analysis_server.dart
diff --git a/pkg/analysis_server/lib/src/analysis_server.dart b/pkg/analysis_server/lib/src/analysis_server.dart
index bad954c6c7ac1dccaaf732881d9474235c815967..1630a63a7f519348b07d49a3628e8fee326ffd3e 100644
--- a/pkg/analysis_server/lib/src/analysis_server.dart
+++ b/pkg/analysis_server/lib/src/analysis_server.dart
@@ -733,14 +733,21 @@ class AnalysisServer {
   }
 
   /**
-   * Trigger reanalysis of all files from disk.
+   * Trigger reanalysis of all files in the given list of analysis [roots], or
+   * everything if the analysis roots is `null`.
    */
-  void reanalyze() {
+  void reanalyze(List<Resource> roots) {
     // Clear any operations that are pending.
-    operationQueue.clear();
+    if (roots == null) {
+      operationQueue.clear();
+    } else {
+      for (AnalysisContext context in _getContexts(roots)) {
+        operationQueue.contextRemoved(context);
+      }
+    }
     // Instruct the contextDirectoryManager to rebuild all contexts from
     // scratch.
-    contextDirectoryManager.refresh();
+    contextDirectoryManager.refresh(roots);
   }
 
   /**
@@ -1096,6 +1103,20 @@ class AnalysisServer {
   }
 
   /**
+   * Return a set of contexts containing all of the resources in the given list
+   * of [resources].
+   */
+  Set<AnalysisContext> _getContexts(List<Resource> resources) {
+    Set<AnalysisContext> contexts = new HashSet<AnalysisContext>();
+    resources.forEach((Resource resource) {
+      if (resource is Folder) {
+        contexts.addAll(contextDirectoryManager.contextsInAnalysisRoot(resource));
+      }
+    });
+    return contexts;
+  }
+
+  /**
    * Returns the [CompilationUnit] of the Dart file with the given [source] that
    * should be used to resend notifications for already resolved unit.
    * Returns `null` if the file is not a part of any context, library has not