| // Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| import 'dart:async'; |
| |
| import 'chain.dart'; |
| import 'lazy_chain.dart'; |
| import 'lazy_trace.dart'; |
| import 'trace.dart'; |
| import 'utils.dart'; |
| |
| /// A function that handles errors in the zone wrapped by [Chain.capture]. |
| typedef void _ChainHandler(error, Chain chain); |
| |
| /// A class encapsulating the zone specification for a [Chain.capture] zone. |
| /// |
| /// Until they're materialized and exposed to the user, stack chains are tracked |
| /// as linked lists of [Trace]s using the [_Node] class. These nodes are stored |
| /// in three distinct ways: |
| /// |
| /// * When a callback is registered, a node is created and stored as a captured |
| /// local variable until the callback is run. |
| /// |
| /// * When a callback is run, its captured node is set as the [_currentNode] so |
| /// it can be available to [Chain.current] and to be linked into additional |
| /// chains when more callbacks are scheduled. |
| /// |
| /// * When a callback throws an error or a Future or Stream emits an error, the |
| /// current node is associated with that error's stack trace using the |
| /// [_chains] expando. |
| /// |
| /// Since [ZoneSpecification] can't be extended or even implemented, in order to |
| /// get a real [ZoneSpecification] instance it's necessary to call [toSpec]. |
| class StackZoneSpecification { |
| /// An opaque object used as a zone value to disable chain tracking in a given |
| /// zone. |
| /// |
| /// If `Zone.current[disableKey]` is `true`, no stack chains will be tracked. |
| static final disableKey = new Object(); |
| |
| /// Whether chain-tracking is disabled in the current zone. |
| bool get _disabled => Zone.current[disableKey] == true; |
| |
| /// The expando that associates stack chains with [StackTrace]s. |
| /// |
| /// The chains are associated with stack traces rather than errors themselves |
| /// because it's a common practice to throw strings as errors, which can't be |
| /// used with expandos. |
| /// |
| /// The chain associated with a given stack trace doesn't contain a node for |
| /// that stack trace. |
| final _chains = new Expando<_Node>("stack chains"); |
| |
| /// The error handler for the zone. |
| /// |
| /// If this is null, that indicates that any unhandled errors should be passed |
| /// to the parent zone. |
| final _ChainHandler _onError; |
| |
| /// The most recent node of the current stack chain. |
| _Node _currentNode; |
| |
| /// Whether this is an error zone. |
| final bool _errorZone; |
| |
| StackZoneSpecification(this._onError, {bool errorZone: true}) |
| : _errorZone = errorZone; |
| |
| /// Converts [this] to a real [ZoneSpecification]. |
| ZoneSpecification toSpec() { |
| return new ZoneSpecification( |
| handleUncaughtError: _errorZone ? _handleUncaughtError : null, |
| registerCallback: _registerCallback, |
| registerUnaryCallback: _registerUnaryCallback, |
| registerBinaryCallback: _registerBinaryCallback, |
| errorCallback: _errorCallback); |
| } |
| |
| /// Returns the current stack chain. |
| /// |
| /// By default, the first frame of the first trace will be the line where |
| /// [currentChain] is called. If [level] is passed, the first trace will start |
| /// that many frames up instead. |
| Chain currentChain([int level = 0]) => _createNode(level + 1).toChain(); |
| |
| /// Returns the stack chain associated with [trace], if one exists. |
| /// |
| /// The first stack trace in the returned chain will always be [trace] |
| /// (converted to a [Trace] if necessary). If there is no chain associated |
| /// with [trace], this just returns a single-trace chain containing [trace]. |
| Chain chainFor(StackTrace trace) { |
| if (trace is Chain) return trace; |
| trace ??= StackTrace.current; |
| |
| var previous = _chains[trace] ?? _currentNode; |
| if (previous == null) { |
| // If there's no [_currentNode], we're running synchronously beneath |
| // [Chain.capture] and we should fall back to the VM's stack chaining. We |
| // can't use [Chain.from] here because it'll just call [chainFor] again. |
| if (trace is Trace) return new Chain([trace]); |
| return new LazyChain(() => new Chain.parse(trace.toString())); |
| } else { |
| if (trace is! Trace) { |
| var original = trace; |
| trace = new LazyTrace(() => new Trace.parse(_trimVMChain(original))); |
| } |
| |
| return new _Node(trace, previous).toChain(); |
| } |
| } |
| |
| /// Tracks the current stack chain so it can be set to [_currentChain] when |
| /// [f] is run. |
| ZoneCallback<R> _registerCallback<R>( |
| Zone self, ZoneDelegate parent, Zone zone, R f()) { |
| if (f == null || _disabled) return parent.registerCallback(zone, f); |
| var node = _createNode(1); |
| return parent.registerCallback(zone, () => _run(f, node)); |
| } |
| |
| /// Tracks the current stack chain so it can be set to [_currentChain] when |
| /// [f] is run. |
| ZoneUnaryCallback<R, T> _registerUnaryCallback<R, T>( |
| Zone self, ZoneDelegate parent, Zone zone, R f(T arg)) { |
| if (f == null || _disabled) return parent.registerUnaryCallback(zone, f); |
| var node = _createNode(1); |
| return parent.registerUnaryCallback(zone, (arg) { |
| return _run(() => f(arg), node); |
| }); |
| } |
| |
| /// Tracks the current stack chain so it can be set to [_currentChain] when |
| /// [f] is run. |
| ZoneBinaryCallback<R, T1, T2> _registerBinaryCallback<R, T1, T2>( |
| Zone self, ZoneDelegate parent, Zone zone, Function f) { |
| if (f == null || _disabled) return parent.registerBinaryCallback(zone, f); |
| |
| var node = _createNode(1); |
| return parent.registerBinaryCallback(zone, (arg1, arg2) { |
| return _run(() => f(arg1, arg2), node); |
| }); |
| } |
| |
| /// Looks up the chain associated with [stackTrace] and passes it either to |
| /// [_onError] or [parent]'s error handler. |
| void _handleUncaughtError( |
| Zone self, ZoneDelegate parent, Zone zone, error, StackTrace stackTrace) { |
| if (_disabled) { |
| parent.handleUncaughtError(zone, error, stackTrace); |
| return; |
| } |
| |
| var stackChain = chainFor(stackTrace); |
| if (_onError == null) { |
| parent.handleUncaughtError(zone, error, stackChain); |
| return; |
| } |
| |
| // TODO(nweiz): Currently this copies a lot of logic from [runZoned]. Just |
| // allow [runBinary] to throw instead once issue 18134 is fixed. |
| try { |
| self.parent.runBinary(_onError, error, stackChain); |
| } catch (newError, newStackTrace) { |
| if (identical(newError, error)) { |
| parent.handleUncaughtError(zone, error, stackChain); |
| } else { |
| parent.handleUncaughtError(zone, newError, newStackTrace); |
| } |
| } |
| } |
| |
| /// Attaches the current stack chain to [stackTrace], replacing it if |
| /// necessary. |
| AsyncError _errorCallback(Zone self, ZoneDelegate parent, Zone zone, |
| Object error, StackTrace stackTrace) { |
| if (_disabled) return parent.errorCallback(zone, error, stackTrace); |
| |
| // Go up two levels to get through [_CustomZone.errorCallback]. |
| if (stackTrace == null) { |
| stackTrace = _createNode(2).toChain(); |
| } else { |
| if (_chains[stackTrace] == null) _chains[stackTrace] = _createNode(2); |
| } |
| |
| var asyncError = parent.errorCallback(zone, error, stackTrace); |
| return asyncError == null ? new AsyncError(error, stackTrace) : asyncError; |
| } |
| |
| /// Creates a [_Node] with the current stack trace and linked to |
| /// [_currentNode]. |
| /// |
| /// By default, the first frame of the first trace will be the line where |
| /// [_createNode] is called. If [level] is passed, the first trace will start |
| /// that many frames up instead. |
| _Node _createNode([int level = 0]) => |
| new _Node(_currentTrace(level + 1), _currentNode); |
| |
| // TODO(nweiz): use a more robust way of detecting and tracking errors when |
| // issue 15105 is fixed. |
| /// Runs [f] with [_currentNode] set to [node]. |
| /// |
| /// If [f] throws an error, this associates [node] with that error's stack |
| /// trace. |
| T _run<T>(T f(), _Node node) { |
| var previousNode = _currentNode; |
| _currentNode = node; |
| try { |
| return f(); |
| } catch (e, stackTrace) { |
| _chains[stackTrace] = node; |
| rethrow; |
| } finally { |
| _currentNode = previousNode; |
| } |
| } |
| |
| /// Like [new Trace.current], but if the current stack trace has VM chaining |
| /// enabled, this only returns the innermost sub-trace. |
| Trace _currentTrace([int level]) { |
| level ??= 0; |
| var stackTrace = StackTrace.current; |
| return new LazyTrace(() { |
| var text = _trimVMChain(stackTrace); |
| var trace = new Trace.parse(text); |
| // JS includes a frame for the call to StackTrace.current, but the VM |
| // doesn't, so we skip an extra frame in a JS context. |
| return new Trace(trace.frames.skip(level + (inJS ? 2 : 1)), |
| original: text); |
| }); |
| } |
| |
| /// Removes the VM's stack chains from the native [trace], since we're |
| /// generating our own and we don't want duplicate frames. |
| String _trimVMChain(StackTrace trace) { |
| var text = trace.toString(); |
| var index = text.indexOf(vmChainGap); |
| return index == -1 ? text : text.substring(0, index); |
| } |
| } |
| |
| /// A linked list node representing a single entry in a stack chain. |
| class _Node { |
| /// The stack trace for this link of the chain. |
| final Trace trace; |
| |
| /// The previous node in the chain. |
| final _Node previous; |
| |
| _Node(StackTrace trace, [this.previous]) : trace = new Trace.from(trace); |
| |
| /// Converts this to a [Chain]. |
| Chain toChain() { |
| var nodes = <Trace>[]; |
| var node = this; |
| while (node != null) { |
| nodes.add(node.trace); |
| node = node.previous; |
| } |
| return new Chain(nodes); |
| } |
| } |