8000 Cache SourceMapConsumer Promise for performance · stacktracejs/stacktrace-gps@170bb4a · GitHub
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eriweneriwen
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Cache SourceMapConsumer Promise for performance
This allows us to avoid multiple SourceMapConsumers for the same source map URL. Issue: #41
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-23
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‎spec/stacktrace-gps-spec.js

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Original file line numberDiff line numberDiff line change
@@ -42,6 +42,29 @@ describe('StackTraceGPS', function() {
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});
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});
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describe('#_getSourceMapConsumer', function() {
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it('avoids duplicate SourceMapConsumers', function(done) {
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var sourceMap = '{"version":3,"sources":["./test.js"],"names":["foo","bar","baz","eval"],"mappings":"AAAA,GAAIA,KAAM,YACV,SAASC,QACT,GAAIC,KAAMC,KAAK","file":"test.min.js"}';
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var sourceMapUrl = 'http://localhost:9999/test.js.map';
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jasmine.Ajax.stubRequest(sourceMapUrl).andReturn({responseText: sourceMap});
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var stackTraceGPS = new StackTraceGPS();
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stackTraceGPS._getSourceMapConsumer(sourceMapUrl).then(callback, done.fail);
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stackTraceGPS._getSourceMapConsumer(sourceMapUrl).then(callback, done.fail);
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var callCount = 0;
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function callback() {
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callCount++;
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if (callCount === 1) {
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expect(stackTraceGPS.sourceMapConsumerCache[sourceMapUrl]).toBeTruthy();
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} else if (callCount === 2) {
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expect(Object.keys(stackTraceGPS.sourceMapConsumerCache).length).toBe(1);
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done();
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}
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}
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});
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});
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describe('#findFunctionName', function() {
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it('rejects given non-object StackFrame', function(done) {
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StackTraceGPS().findFunctionName('').then(done.fail, done); // jshint ignore:line

‎stacktrace-gps.js

Lines changed: 38 additions & 23 deletions
Original file line numberDiff line numberDiff line change
@@ -134,7 +134,6 @@
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}
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}
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function _extractLocationInfoFromSourceMapSource(stackframe, sourceMapConsumer, sourceCache) {
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return new Promise(function(resolve, reject) {
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var loc = sourceMapConsumer.originalPositionFor({
@@ -143,11 +142,14 @@
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});
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if (loc.source) {
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// cache mapped sources
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var mappedSource = sourceMapConsumer.sourceContentFor(loc.source);
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if (mappedSource) {
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sourceCache[loc.source] = mappedSource;
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}
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resolve(
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// given stackframe and source location, update stackframe
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new StackFrame({
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functionName: loc.name || stackframe.functionName,
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args: stackframe.args,
@@ -216,6 +218,37 @@
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}.bind(this));
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};
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/**
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* Creating SourceMapConsumers is expensive, so this wraps the creation of a
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* SourceMapConsumer in a per-instance cache.
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*
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* @param sourceMappingURL = {String} URL to fetch source map from
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* @param defaultSourceRoot = Default source root for source map if undefined
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* @returns {Promise} that resolves a SourceMapConsumer
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*/
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this._getSourceMapConsumer = function _getSourceMapConsumer(sourceMappingURL, defaultSourceRoot) {
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return new Promise(function(resolve, reject) {
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if (this.sourceMapConsumerCache[sourceMappingURL]) {
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resolve(this.sourceMapConsumerCache[sourceMappingURL]);
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} else {
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var sourceMapConsumerPromise = new Promise(function(resolve) {
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return this._get(sourceMappingURL).then(function(sourceMapSource) {
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if (typeof sourceMapSource === 'string') {
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sourceMapSource = _parseJson(sourceMapSource.replace(/^\)\]\}'/, ''));
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}
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if (typeof sourceMapSource.sourceRoot === 'undefined') {
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sourceMapSource.sourceRoot = defaultSourceRoot;
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}
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resolve(new SourceMap.SourceMapConsumer(sourceMapSource));
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}, reject);
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}.bind(this));
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this.sourceMapConsumerCache[sourceMappingURL] = sourceMapConsumerPromise;
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resolve(sourceMapConsumerPromise);
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}
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}.bind(this));
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};
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/**
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* Given a StackFrame, enhance function name and use source maps for a
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* better StackFrame.
@@ -278,40 +311,22 @@
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_ensureStackFrameIsLegit(stackframe);
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var sourceCache = this.sourceCache;
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var sourceMapConsumerCache = this.sourceMapConsumerCache;
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var fileName = stackframe.fileName;
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this._get(fileName).then(function(source) {
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var sourceMappingURL = _findSourceMappingURL(source);
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var isDataUrl = sourceMappingURL.substr(0, 5) === 'data:';
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var base = fileName.substring(0, fileName.lastIndexOf('/') + 1);
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var defaultSourceRoot = fileName.substring(0, fileName.lastIndexOf('/') + 1);
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if (sourceMappingURL[0] !== '/' && !isDataUrl && !(/^https?:\/\/|^\/\//i).test(sourceMappingURL)) {
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sourceMappingURL = base + sourceMappingURL;
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}
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var cachedSourceMapConsumer = sourceMapConsumerCache[sourceMappingURL];
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if (cachedSourceMapConsumer !== undefined) {
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return _extractLocationInfoFromSourceMapSource(stackframe, cachedSourceMapConsumer, sourceCache)
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.then(resolve)['catch'](function() {
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resolve(stackframe);
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});
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sourceMappingURL = defaultSourceRoot + sourceMappingURL;
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}
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300-
return this._get(sourceMappingURL).then(function(sourceMapSource) {
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if (typeof sourceMapSource === 'string') {
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sourceMapSource = _parseJson(sourceMapSource.replace(/^\)\]\}'/, ''));
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}
304-
if (typeof sourceMapSource.sourceRoot === 'undefined') {
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sourceMapSource.sourceRoot = base;
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}
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var sourceMapConsumer = new SourceMap.SourceMapConsumer(sourceMapSource);
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sourc 76BD eMapConsumerCache[sourceMappingURL] = sourceMapConsumer;
324+
return this._getSourceMapConsumer(sourceMappingURL, defaultSourceRoot).then(function(sourceMapConsumer) {
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return _extractLocationInfoFromSourceMapSource(stackframe, sourceMapConsumer, sourceCache)
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.then(resolve)['catch'](function() {
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resolve(stackframe);
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});
314-
}, reject)['catch'](reject);
329+
});
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}.bind(this), reject)['catch'](reject);
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}.bind(this));
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};

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