[lib] Avoid empty stack-traces in Stream methods
This change leans on VMs ability to provide a awaiter stack traces (if
the code is written using async syntax sugar or properly annotated with
@pragma('vm:awaiter-link').
Currently doing
await Stream.fromIterable([]).first;
would result in an empty stack trace. However after this change
we actually get a meaningful stack trace when running on the VM.
Fixes https://github.com/dart-lang/sdk/issues/51025
TEST=vm/dart/awaiter_stacks/stream_methods
CoreLibraryReviewExempt: No functional or API changes. Just better error messages on exceptional code paths.
Change-Id: Ifc3e446c00121cc97f2f870c3e3f5bf56a6a6964
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/453940
Reviewed-by: Lasse Nielsen <lrn@google.com>
Commit-Queue: Slava Egorov <vegorov@google.com>
diff --git a/runtime/tests/vm/dart/awaiter_stacks/stream_methods_test.dart b/runtime/tests/vm/dart/awaiter_stacks/stream_methods_test.dart
index c74ba0f..7334411 100644
--- a/runtime/tests/vm/dart/awaiter_stacks/stream_methods_test.dart
+++ b/runtime/tests/vm/dart/awaiter_stacks/stream_methods_test.dart
@@ -12,6 +12,7 @@
// stack traces when unwinding through various built-in [Stream] methods.
import 'dart:async';
+import 'package:expect/expect.dart';
import 'harness.dart' as harness;
Future<void> baz() async {
@@ -34,8 +35,21 @@
await baz();
}
-Future<void> runTest(Future<void> Function(Stream<String> stream) body) async {
- await body(foo());
+Stream<String> Function() stream(Iterable<String> elements) {
+ return () => Stream.fromIterable(elements);
+}
+
+Future<void> runTest(
+ Future<void> Function(Stream<String> stream) body, {
+ Stream<String> Function() source = foo,
+ bool expectedToThrow = false,
+}) async {
+ try {
+ await body(source());
+ } catch (e, st) {
+ Expect.isTrue(expectedToThrow, 'Not expecting exception');
+ await harness.checkExpectedStack(st);
+ }
}
Future<void> main() async {
@@ -59,10 +73,56 @@
await runTest((s) => s.first);
await runTest((s) => s.last);
await runTest((s) => s.single);
+ await runTest((s) => s.singleWhere((element) => true));
await runTest((s) => s.firstWhere((element) => true));
await runTest((s) => s.lastWhere((element) => true));
await runTest((s) => s.elementAt(0));
+ // Check that error caused by empty stream also produces good stack traces.
+ await runTest(
+ (s) => s.reduce((a, b) => ''),
+ source: stream([]),
+ expectedToThrow: true,
+ );
+ await runTest((s) => s.first, source: stream([]), expectedToThrow: true);
+ await runTest((s) => s.last, source: stream([]), expectedToThrow: true);
+ await runTest((s) => s.single, source: stream([]), expectedToThrow: true);
+ await runTest(
+ (s) => s.single,
+ source: stream(['1', '2']),
+ expectedToThrow: true,
+ );
+ await runTest(
+ (s) => s.single,
+ source: stream(['1', '2']),
+ expectedToThrow: true,
+ );
+ await runTest(
+ (s) => s.singleWhere((_) => true),
+ source: stream([]),
+ expectedToThrow: true,
+ );
+ await runTest(
+ (s) => s.singleWhere((_) => true),
+ source: stream(['1', '2']),
+ expectedToThrow: true,
+ );
+ await runTest(
+ (s) => s.firstWhere((element) => true),
+ source: stream([]),
+ expectedToThrow: true,
+ );
+ await runTest(
+ (s) => s.lastWhere((element) => true),
+ source: stream([]),
+ expectedToThrow: true,
+ );
+ await runTest(
+ (s) => s.elementAt(0),
+ source: stream([]),
+ expectedToThrow: true,
+ );
+
harness.updateExpectations();
}
@@ -1226,6 +1286,93 @@
"""
#0 foo (%test%)
<asynchronous suspension>
+#1 Stream.singleWhere.<anonymous closure> (stream.dart)
+<asynchronous suspension>
+#2 runTest (%test%)
+<asynchronous suspension>
+#3 main (%test%)
+<asynchronous suspension>""",
+ """
+#0 baz (%test%)
+#1 foo (%test%)
+<asynchronous suspension>
+#2 Stream.singleWhere.<anonymous closure> (stream.dart)
+<asynchronous suspension>
+#3 runTest (%test%)
+<asynchronous suspension>
+#4 main (%test%)
+<asynchronous suspension>""",
+ """
+#0 baz (%test%)
+<asynchronous suspension>
+#1 foo (%test%)
+<asynchronous suspension>
+#2 Stream.singleWhere.<anonymous closure> (stream.dart)
+<asynchronous suspension>
+#3 runTest (%test%)
+<asynchronous suspension>
+#4 main (%test%)
+<asynchronous suspension>""",
+ """
+#0 bar (%test%)
+<asynchronous suspension>
+#1 foo (%test%)
+<asynchronous suspension>
+#2 Stream.singleWhere.<anonymous closure> (stream.dart)
+<asynchronous suspension>
+#3 runTest (%test%)
+<asynchronous suspension>
+#4 main (%test%)
+<asynchronous suspension>""",
+ """
+#0 baz (%test%)
+#1 bar (%test%)
+<asynchronous suspension>
+#2 foo (%test%)
+<asynchronous suspension>
+#3 Stream.singleWhere.<anonymous closure> (stream.dart)
+<asynchronous suspension>
+#4 runTest (%test%)
+<asynchronous suspension>
+#5 main (%test%)
+<asynchronous suspension>""",
+ """
+#0 baz (%test%)
+<asynchronous suspension>
+#1 bar (%test%)
+<asynchronous suspension>
+#2 foo (%test%)
+<asynchronous suspension>
+#3 Stream.singleWhere.<anonymous closure> (stream.dart)
+<asynchronous suspension>
+#4 runTest (%test%)
+<asynchronous suspension>
+#5 main (%test%)
+<asynchronous suspension>""",
+ """
+#0 baz (%test%)
+#1 foo (%test%)
+<asynchronous suspension>
+#2 Stream.singleWhere.<anonymous closure> (stream.dart)
+<asynchronous suspension>
+#3 runTest (%test%)
+<asynchronous suspension>
+#4 main (%test%)
+<asynchronous suspension>""",
+ """
+#0 baz (%test%)
+<asynchronous suspension>
+#1 foo (%test%)
+<asynchronous suspension>
+#2 Stream.singleWhere.<anonymous closure> (stream.dart)
+<asynchronous suspension>
+#3 runTest (%test%)
+<asynchronous suspension>
+#4 main (%test%)
+<asynchronous suspension>""",
+ """
+#0 foo (%test%)
+<asynchronous suspension>
#1 Stream.firstWhere.<anonymous closure> (stream.dart)
<asynchronous suspension>
#2 runTest (%test%)
@@ -1442,5 +1589,82 @@
<asynchronous suspension>
#5 main (%test%)
<asynchronous suspension>""",
+ """
+#0 Stream.reduce.<anonymous closure> (stream.dart)
+<asynchronous suspension>
+#1 runTest (%test%)
+<asynchronous suspension>
+#2 main (%test%)
+<asynchronous suspension>""",
+ """
+#0 Stream.first.<anonymous closure> (stream.dart)
+<asynchronous suspension>
+#1 runTest (%test%)
+<asynchronous suspension>
+#2 main (%test%)
+<asynchronous suspension>""",
+ """
+#0 Stream.last.<anonymous closure> (stream.dart)
+<asynchronous suspension>
+#1 runTest (%test%)
+<asynchronous suspension>
+#2 main (%test%)
+<asynchronous suspension>""",
+ """
+#0 Stream.single.<anonymous closure> (stream.dart)
+<asynchronous suspension>
+#1 runTest (%test%)
+<asynchronous suspension>
+#2 main (%test%)
+<asynchronous suspension>""",
+ """
+#0 Stream.single.<anonymous closure> (stream.dart)
+<asynchronous suspension>
+#1 runTest (%test%)
+<asynchronous suspension>
+#2 main (%test%)
+<asynchronous suspension>""",
+ """
+#0 Stream.single.<anonymous closure> (stream.dart)
+<asynchronous suspension>
+#1 runTest (%test%)
+<asynchronous suspension>
+#2 main (%test%)
+<asynchronous suspension>""",
+ """
+#0 Stream.singleWhere.<anonymous closure> (stream.dart)
+<asynchronous suspension>
+#1 runTest (%test%)
+<asynchronous suspension>
+#2 main (%test%)
+<asynchronous suspension>""",
+ """
+#0 Stream.singleWhere.<anonymous closure>.<anonymous closure> (stream.dart)
+<asynchronous suspension>
+#1 runTest (%test%)
+<asynchronous suspension>
+#2 main (%test%)
+<asynchronous suspension>""",
+ """
+#0 Stream.firstWhere.<anonymous closure> (stream.dart)
+<asynchronous suspension>
+#1 runTest (%test%)
+<asynchronous suspension>
+#2 main (%test%)
+<asynchronous suspension>""",
+ """
+#0 Stream.lastWhere.<anonymous closure> (stream.dart)
+<asynchronous suspension>
+#1 runTest (%test%)
+<asynchronous suspension>
+#2 main (%test%)
+<asynchronous suspension>""",
+ """
+#0 Stream.elementAt.<anonymous closure> (stream.dart)
+<asynchronous suspension>
+#1 runTest (%test%)
+<asynchronous suspension>
+#2 main (%test%)
+<asynchronous suspension>""",
];
// CURRENT EXPECTATIONS END
diff --git a/sdk/lib/async/stream.dart b/sdk/lib/async/stream.dart
index 488573c..f400c84 100644
--- a/sdk/lib/async/stream.dart
+++ b/sdk/lib/async/stream.dart
@@ -1064,6 +1064,7 @@
/// print(result); // 28
/// ```
Future<T> reduce(T combine(T previous, T element)) {
+ @pragma('vm:awaiter-link')
_Future<T> result = _Future<T>();
bool seenFirst = false;
late T value;
@@ -1072,7 +1073,7 @@
onError: result._completeError,
onDone: () {
if (!seenFirst) {
- var stack = StackTrace.empty;
+ var stack = StackTrace.current;
var error = IterableElementError.noElement();
_trySetStackTrace(error, stack);
_completeWithErrorCallback(result, error, stack);
@@ -1643,12 +1644,13 @@
/// Except for the type of the error, this method is equivalent to
/// `this.elementAt(0)`.
Future<T> get first {
+ @pragma('vm:awaiter-link')
_Future<T> future = _Future<T>();
StreamSubscription<T> subscription = this.listen(
null,
onError: future._completeError,
onDone: () {
- var stack = StackTrace.empty;
+ var stack = StackTrace.current;
var error = IterableElementError.noElement();
_trySetStackTrace(error, stack);
_completeWithErrorCallback(future, error, stack);
@@ -1670,6 +1672,7 @@
/// If this stream is empty (the done event is the first event),
/// the returned future completes with an error.
Future<T> get last {
+ @pragma('vm:awaiter-link')
_Future<T> future = _Future<T>();
late T result;
bool foundResult = false;
@@ -1684,7 +1687,7 @@
future._complete(result);
return;
}
- var stack = StackTrace.empty;
+ var stack = StackTrace.current;
var error = IterableElementError.noElement();
_trySetStackTrace(error, stack);
_completeWithErrorCallback(future, error, stack);
@@ -1703,6 +1706,7 @@
/// If this [Stream] is empty or has more than one element,
/// the returned future completes with an error.
Future<T> get single {
+ @pragma('vm:awaiter-link')
_Future<T> future = _Future<T>();
late T result;
bool foundResult = false;
@@ -1714,7 +1718,7 @@
future._complete(result);
return;
}
- var stack = StackTrace.empty;
+ var stack = StackTrace.current;
var error = IterableElementError.noElement();
_trySetStackTrace(error, stack);
_completeWithErrorCallback(future, error, stack);
@@ -1724,7 +1728,7 @@
subscription.onData((T value) {
if (foundResult) {
// This is the second element we get.
- var stack = StackTrace.empty;
+ var stack = StackTrace.current;
var error = IterableElementError.tooMany();
_trySetStackTrace(error, stack);
_cancelAndErrorWithReplacement(subscription, future, error, stack);
@@ -1773,6 +1777,7 @@
/// print(result); // -1
/// ```
Future<T> firstWhere(bool test(T element), {T orElse()?}) {
+ @pragma('vm:awaiter-link')
_Future<T> future = _Future();
StreamSubscription<T> subscription = this.listen(
null,
@@ -1782,7 +1787,7 @@
_runUserCode(orElse, future._complete, future._completeError);
return;
}
- var stack = StackTrace.empty;
+ var stack = StackTrace.current;
var error = IterableElementError.noElement();
_trySetStackTrace(error, stack);
_completeWithErrorCallback(future, error, stack);
@@ -1826,6 +1831,7 @@
/// print(result); // -1
/// ```
Future<T> lastWhere(bool test(T element), {T orElse()?}) {
+ @pragma('vm:awaiter-link')
_Future<T> future = _Future();
late T result;
bool foundResult = false;
@@ -1841,7 +1847,7 @@
_runUserCode(orElse, future._complete, future._completeError);
return;
}
- var stack = StackTrace.empty;
+ var stack = StackTrace.current;
var error = IterableElementError.noElement();
_trySetStackTrace(error, stack);
_completeWithErrorCallback(future, error, stack);
@@ -1893,6 +1899,7 @@
/// // Throws.
/// ```
Future<T> singleWhere(bool test(T element), {T orElse()?}) {
+ @pragma('vm:awaiter-link')
_Future<T> future = _Future<T>();
late T result;
bool foundResult = false;
@@ -1908,7 +1915,7 @@
_runUserCode(orElse, future._complete, future._completeError);
return;
}
- var stack = StackTrace.empty;
+ var stack = StackTrace.current;
var error = IterableElementError.noElement();
_trySetStackTrace(error, stack);
_completeWithErrorCallback(future, error, stack);
@@ -1920,7 +1927,7 @@
_runUserCode(() => test(value), (bool isMatch) {
if (isMatch) {
if (foundResult) {
- var stack = StackTrace.empty;
+ var stack = StackTrace.current;
var error = IterableElementError.tooMany();
_trySetStackTrace(error, stack);
_cancelAndErrorWithReplacement(subscription, future, error, stack);
@@ -1950,6 +1957,7 @@
/// with a [RangeError].
Future<T> elementAt(int index) {
RangeError.checkNotNegative(index, "index");
+ @pragma('vm:awaiter-link')
_Future<T> result = _Future<T>();
int elementIndex = 0;
StreamSubscription<T> subscription;
@@ -1964,7 +1972,7 @@
indexable: this,
name: "index",
),
- StackTrace.empty,
+ StackTrace.current,
);
},
cancelOnError: true,
