v8/test/mjsunit/harmony/async-debug-caught-exception.js
littledan cd049c2c76 Fix crash from turning on DevTools in the middle of catch prediction
If DevTools is turned on in the middle of doing some things with async
functions, then more items may be popped from the Promise stack than were
pushed to it. In this sort of case, it's OK to have a catch misprediction,
but a crash is unacceptable. This patch defensively handles this edge
case where the Promise stack is unexpectedly empty for that reason.

BUG=v8:5167

Review-Url: https://codereview.chromium.org/2361333003
Cr-Commit-Position: refs/heads/master@{#39705}
2016-09-24 03:31:13 +00:00

145 lines
3.3 KiB
JavaScript

// Copyright 2016 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Flags: --allow-natives-syntax --harmony-async-await --expose-debug-as debug
Debug = debug.Debug
var exception = null;
var log;
function listener(event, exec_state, event_data, data) {
if (event != Debug.DebugEvent.Exception) return;
try {
var line = exec_state.frame(0).sourceLineText();
var match = /Exception (\w)/.exec(line);
assertNotNull(match);
log.push(match[1]);
} catch (e) {
exception = e;
}
}
async function thrower() {
throw "a"; // Exception a
}
async function caught_throw() {
try {
await thrower();
} catch (e) {
assertEquals("a", e);
}
}
// Caught throw, events on any exception.
log = [];
Debug.setListener(listener);
Debug.setBreakOnException();
caught_throw();
%RunMicrotasks();
Debug.setListener(null);
Debug.clearBreakOnException();
assertEquals(["a"], log);
assertNull(exception);
// Caught throw, events on uncaught exception.
log = [];
Debug.setListener(listener);
Debug.setBreakOnUncaughtException();
caught_throw();
%RunMicrotasks();
Debug.setListener(null);
Debug.clearBreakOnUncaughtException();
assertEquals([], log);
assertNull(exception);
var reject = Promise.reject("b");
async function caught_reject() {
try {
await reject;
} catch (e) {
assertEquals("b", e);
}
}
// Caught reject, events on any exception.
log = [];
Debug.setListener(listener);
Debug.setBreakOnException();
caught_reject();
%RunMicrotasks();
Debug.setListener(null);
Debug.clearBreakOnException();
assertEquals([], log);
assertNull(exception);
// Caught reject, events on uncaught exception.
log = [];
Debug.setListener(listener);
Debug.setBreakOnUncaughtException();
caught_reject();
%RunMicrotasks();
Debug.setListener(null);
Debug.clearBreakOnUncaughtException();
assertEquals([], log);
assertNull(exception);
log = [];
Debug.setListener(listener);
Debug.setBreakOnException();
// "rethrown" uncaught exceptions in return don't cause another event
async function propagate_inner() { return thrower(); }
async function propagate_outer() { return propagate_inner(); }
propagate_outer();
%RunMicrotasks();
assertEquals(["a"], log);
assertNull(exception);
// Also don't propagate if an await interceded
log = [];
async function propagate_await() { await 1; return thrower(); }
async function propagate_await_outer() { return propagate_await(); }
propagate_await_outer();
%RunMicrotasks();
assertEquals(["a"], log);
assertNull(exception);
Debug.clearBreakOnException();
Debug.setBreakOnUncaughtException();
log = [];
Promise.resolve().then(() => Promise.reject()).catch(() => log.push("d")); // Exception c
%RunMicrotasks();
assertEquals(["d"], log);
assertNull(exception);
Debug.clearBreakOnUncaughtException();
Debug.setListener(null);
// If devtools is turned on in the middle, then catch prediction
// could be wrong (here, it mispredicts the exception as caught),
// but shouldn't crash.
log = [];
var resolve;
var turnOnListenerPromise = new Promise(r => resolve = r);
async function confused() {
await turnOnListenerPromise;
throw foo
}
confused();
Promise.resolve().then(() => {
Debug.setListener(listener);
Debug.setBreakOnUncaughtException();
resolve();
});
assertEquals([], log);