Merge pull request #18160 from benlangmuir/edit-test-race

[sourcekit] Fix a race between AST processing and reopening a document

Author: benlangmuir

tools/SourceKit/lib/SwiftLang/SwiftEditor.cpp

@@ -1673,8 +1673,13 @@ ImmutableTextSnapshotRef SwiftEditorDocument::replaceText(
 }
 
 void SwiftEditorDocument::updateSemaInfo() {
-  if (Impl.SemanticInfo) {
-    Impl.SemanticInfo->processLatestSnapshotAsync(Impl.EditableBuffer);
+  Impl.AccessMtx.lock();
+  auto EditableBuffer = Impl.EditableBuffer;
+  auto SemanticInfo = Impl.SemanticInfo;
+  Impl.AccessMtx.unlock(); // Not a recursive mutex, so unlock before processing
+
+  if (SemanticInfo) {
+    SemanticInfo->processLatestSnapshotAsync(EditableBuffer);
   }
 }
 
@@ -1978,6 +1983,7 @@ void SwiftEditorDocument::expandPlaceholder(unsigned Offset, unsigned Length,
 }
 
 ImmutableTextSnapshotRef SwiftEditorDocument::getLatestSnapshot() const {
+  llvm::sys::ScopedLock L(Impl.AccessMtx);
   return Impl.EditableBuffer->getSnapshot();
 }
 

unittests/SourceKit/SwiftLang/EditingTest.cpp

@@ -253,7 +253,7 @@ void EditTest::doubleOpenWithDelay(useconds_t delay, bool closeDoc) {
   // be queried, since the semantic info from the first open is unreachable.
   for (int i = 0; i < 2; ++i) {
     bool expired = waitForDocUpdate(/*reset=*/true);
-    ASSERT_FALSE(expired) << "no second notification";
+    ASSERT_FALSE(expired) << "no " << (i ? "second " : "") << "notification";
     replaceText(DocName, 0, 0, StringRef(), Consumer);
     if (!Consumer.Diags.empty())
       break;
@@ -262,6 +262,8 @@ void EditTest::doubleOpenWithDelay(useconds_t delay, bool closeDoc) {
 
   ASSERT_EQ(1u, Consumer.Diags.size());
   EXPECT_STREQ("use of unresolved identifier 'unknown_name'", Consumer.Diags[0].Description.c_str());
+
+  close(DocName);
 }
 
 // This test is failing occassionally in CI: rdar://42483323