Bug 1291877 - Source map optimization in console due to Unique Locations. r=jsantell

--HG--
extra : rebase_source : 890ed6da1a3ea2406334ed7565e9b1a79a14ebee

devtools/client/framework/source-map-service.js

@@ -19,6 +19,7 @@ const { LocationStore, serialize, deserialize } = require("./location-store");
 function SourceMapService(target) {
   this._target = target;
   this._locationStore = new LocationStore();
+  this._isNotSourceMapped = new Map();
 
   EventEmitter.decorate(this);
 
@@ -37,10 +38,11 @@ function SourceMapService(target) {
 }
 
 /**
- * Clears the store containing the cached resolved locations and promises
+ * Clears the store containing the cached promised locations
  */
 SourceMapService.prototype.reset = function () {
   this._locationStore.clear();
+  this._isNotSourceMapped.clear();
 };
 
 SourceMapService.prototype.destroy = function () {
@@ -49,15 +51,24 @@ SourceMapService.prototype.destroy = function () {
   this._target.off("navigate", this.reset);
   this._target.off("will-navigate", this.reset);
   this._target.off("close", this.destroy);
-  this._target = this._locationStore = null;
+  this._target = this._locationStore = this._isNotSourceMapped = null;
 };
 
 /**
- * Sets up listener for the callback to update the FrameView and tries to resolve location
+ * Sets up listener for the callback to update the FrameView
+ * and tries to resolve location, if it is source-mappable
  * @param location
  * @param callback
  */
 SourceMapService.prototype.subscribe = function (location, callback) {
+  // A valid candidate location for source-mapping should have a url and line.
+  // Abort if there's no `url`, which means it's unsourcemappable anyway,
+  // like an eval script.
+  // From previous attempts to source-map locations, we also determine if a location
+  // is not source-mapped.
+  if (!location.url || !location.line || this._isNotSourceMapped.get(location.url)) {
+    return;
+  }
   this.on(serialize(location), callback);
   this._locationStore.set(location);
   this._resolveAndUpdate(location);
@@ -80,7 +91,7 @@ SourceMapService.prototype.unsubscribe = function (location, callback) {
 
 /**
  * Tries to resolve the location and if successful,
- * emits the resolved location and caches it
+ * emits the resolved location
  * @param location
  * @private
  */
@@ -96,46 +107,48 @@ SourceMapService.prototype._resolveAndUpdate = function (location) {
 };
 
 /**
- * Validates the location model,
- * checks if there is existing promise to resolve location, if so returns cached promise
- * if not promised to resolve,
- * tries to resolve location and returns a promised location
+ * Checks if there is existing promise to resolve location, if so returns cached promise
+ * if not, tries to resolve location and returns a promised location
  * @param location
  * @return Promise<Object>
  * @private
  */
 SourceMapService.prototype._resolveLocation = Task.async(function* (location) {
-  // Location must have a url and a line
-  if (!location.url || !location.line) {
-    return null;
-  }
+  let resolvedLocation;
   const cachedLocation = this._locationStore.get(location);
   if (cachedLocation) {
-    return cachedLocation;
+    resolvedLocation = cachedLocation;
   } else {
     const promisedLocation = resolveLocation(this._target, location);
     if (promisedLocation) {
       this._locationStore.set(location, promisedLocation);
-      return promisedLocation;
+      resolvedLocation = promisedLocation;
     }
   }
+  return resolvedLocation;
 });
 
 /**
  * Checks if the `source-updated` event is fired from the target.
  * Checks to see if location store has the source url in its cache,
  * if so, tries to update each stale location in the store.
+ * Determines if the source should be source-mapped or not.
  * @param _
  * @param sourceEvent
  * @private
  */
 SourceMapService.prototype._onSourceUpdated = function (_, sourceEvent) {
   let { type, source } = sourceEvent;
+
   // If we get a new source, and it's not a source map, abort;
   // we can have no actionable updates as this is just a new normal source.
-  // Also abort if there's no `url`, which means it's unsourcemappable anyway,
-  // like an eval script.
-  if (!source.url || type === "newSource" && !source.isSourceMapped) {
+  // Check Source Actor for sourceMapURL property (after Firefox 48)
+  // If not present, utilize isSourceMapped and isPrettyPrinted properties
+  // to estimate if a source is not source-mapped.
+  const isNotSourceMapped = !(source.sourceMapURL ||
+    source.isSourceMapped || source.isPrettyPrinted);
+  if (type === "newSource" && isNotSourceMapped) {
+    this._isNotSourceMapped.set(source.url, true);
     return;
   }
   let sourceUrl = null;
@@ -180,7 +193,7 @@ function resolveLocation(target, location) {
 }
 
 /**
- * Returns if the original location and resolved location are the same
+ * Returns true if the original location and resolved location are the same
  * @param location
  * @param resolvedLocation
  * @returns {boolean}