when/monitor/PromiseMonitor.js

/** @license MIT License (c) copyright 2010-2014 original author or authors */
/** @author Brian Cavalier */
/** @author John Hann */

(function(define) { 'use strict';
define(function(require) {

	var defaultStackJumpSeparator = 'from execution context:';
	var defaultStackFilter = /[\s\(\/\\](node|module|timers)\.js:|when([\/\\]{1,2}(lib|monitor|es6-shim)[\/\\]{1,2}|\.js)|(new\sPromise)\b|(\b(PromiseMonitor|ConsoleReporter|Scheduler|RunHandlerTask|ProgressTask|Promise|.*Handler)\.[\w_]\w\w+\b)|\b(tryCatch\w+|getHandler\w*)\b/i;

	var setTimer = require('../lib/env').setTimer;
	var error = require('./error');

	var executionContext = [];

	function PromiseMonitor(reporter) {
		this.logDelay = 0;
		this.stackFilter = defaultStackFilter;
		this.stackJumpSeparator = defaultStackJumpSeparator;
		this.filterDuplicateFrames = true;

		this._reporter = reporter;
		if(typeof reporter.configurePromiseMonitor === 'function') {
			reporter.configurePromiseMonitor(this);
		}

		this._traces = [];
		this._traceTask = 0;

		var self = this;
		this._doLogTraces = function() {
			self._logTraces();
		};
	}

	PromiseMonitor.prototype.monitor = function(Promise) {
		var self = this;
		Promise.createContext = function(p, context) {
			p.context = self.createContext(p, context);
		};

		Promise.enterContext = function(p) {
			executionContext.push(p.context);
		};

		Promise.exitContext = function() {
			executionContext.pop();
		};

		Promise.onPotentiallyUnhandledRejection = function(rejection, extraContext) {
			return self.addTrace(rejection, extraContext);
		};

		Promise.onPotentiallyUnhandledRejectionHandled = function(rejection) {
			return self.removeTrace(rejection);
		};

		Promise.onFatalRejection = function(rejection, extraContext) {
			return self.fatal(rejection, extraContext);
		};

		return this;
	};

	PromiseMonitor.prototype.createContext = function(at, parentContext) {
		var context = {
			parent: parentContext || executionContext[executionContext.length - 1],
			stack: void 0
		};
		error.captureStack(context, at.constructor);
		return context;
	};

	PromiseMonitor.prototype.addTrace = function(handler, extraContext) {
		var t, i;

		for(i = this._traces.length-1; i >= 0; --i) {
			t = this._traces[i];
			if(t.handler === handler) {
				break;
			}
		}

		if(i >= 0) {
			t.extraContext = extraContext;
		} else {
			this._traces.push({
				handler: handler,
				extraContext: extraContext
			});
		}

		this.logTraces();
	};

	PromiseMonitor.prototype.removeTrace = function(/*handler*/) {
		this.logTraces();
	};

	PromiseMonitor.prototype.fatal = function(handler, extraContext) {
		var err = new Error();
		err.stack = this._createLongTrace(handler.value, handler.context, extraContext).join('\n');
		setTimer(function() {
			throw err;
		}, 0);
	};

	PromiseMonitor.prototype.logTraces = function() {
		if(!this._traceTask) {
			this._traceTask = setTimer(this._doLogTraces, this.logDelay);
		}
	};

	PromiseMonitor.prototype._logTraces = function() {
		this._traceTask = void 0;
		this._traces = this._traces.filter(filterHandled);
		this._reporter.log(this.formatTraces(this._traces));
	};


	PromiseMonitor.prototype.formatTraces = function(traces) {
		return traces.map(function(t) {
			return this._createLongTrace(t.handler.value, t.handler.context, t.extraContext);
		}, this);
	};

	PromiseMonitor.prototype._createLongTrace = function(e, context, extraContext) {
		var trace = error.parse(e) || [String(e) + ' (WARNING: non-Error used)'];
		trace = filterFrames(this.stackFilter, trace, 0);
		this._appendContext(trace, context);
		this._appendContext(trace, extraContext);
		return this.filterDuplicateFrames ? this._removeDuplicates(trace) : trace;
	};

	PromiseMonitor.prototype._removeDuplicates = function(trace) {
		var seen = {};
		var sep = this.stackJumpSeparator;
		var count = 0;
		return trace.reduceRight(function(deduped, line, i) {
			if(i === 0) {
				deduped.unshift(line);
			} else if(line === sep) {
				if(count > 0) {
					deduped.unshift(line);
					count = 0;
				}
			} else if(!seen[line]) {
				seen[line] = true;
				deduped.unshift(line);
				++count;
			}
			return deduped;
		}, []);
	};

	PromiseMonitor.prototype._appendContext = function(trace, context) {
		trace.push.apply(trace, this._createTrace(context));
	};

	PromiseMonitor.prototype._createTrace = function(traceChain) {
		var trace = [];
		var stack;

		while(traceChain) {
			stack = error.parse(traceChain);

			if (stack) {
				stack = filterFrames(this.stackFilter, stack);
				appendStack(trace, stack, this.stackJumpSeparator);
			}

			traceChain = traceChain.parent;
		}

		return trace;
	};

	function appendStack(trace, stack, separator) {
		if (stack.length > 1) {
			stack[0] = separator;
			trace.push.apply(trace, stack);
		}
	}

	function filterFrames(stackFilter, stack) {
		return stack.filter(function(frame) {
			return !stackFilter.test(frame);
		});
	}

	function filterHandled(t) {
		return !t.handler.handled;
	}

	return PromiseMonitor;
});
}(typeof define === 'function' && define.amd ? define : function(factory) { module.exports = factory(require); }));