DevTools: carefully cleanup javascript sourcemaps

This patch starts to detach JavaScript sourcemaps as the
associated scripts go away (e.g. parent frame got detached).

This patch makes javascript sourcemap management similar to
CSS domain:
- debuggerModel now has sourceMapManager
- CompilerScriptMapping listens only to SourceMapManager events

A few key differences arose:
- We make sure that there's only one sourceMap per
  (executionContext, script.sourceURL, script.sourceMapURL).
  This is to support "browsersync" scenario and "hot script reload".
- Since CompilerScriptMapping has a need for stubProjects,
  SourceMapManager is taught to send SourceMapWillAttach and
  SourceMapFailedToAttach events.

BUG=670180, 685552
R=dgozman

Review-Url: https://codereview.chromium.org/2784413003
Cr-Commit-Position: refs/heads/master@{#461303}

front_end/bindings/BlackboxManager.js

@@ -132,7 +132,7 @@ Bindings.BlackboxManager = class {
 
   /**
    * @param {!SDK.Script} script
-   * @param {?SDK.TextSourceMap} sourceMap
+   * @param {?SDK.SourceMap} sourceMap
    * @return {!Promise<undefined>}
    */
   sourceMapLoaded(script, sourceMap) {

front_end/bindings/DebuggerWorkspaceBinding.js

@@ -233,7 +233,7 @@ Bindings.DebuggerWorkspaceBinding = class extends Common.Object {
 
   /**
    * @param {!SDK.Script} script
-   * @return {?SDK.TextSourceMap}
+   * @return {?SDK.SourceMap}
    */
   sourceMapForScript(script) {
     var modelData = this._debuggerModelToData.get(script.debuggerModel);
@@ -370,9 +370,6 @@ Bindings.DebuggerWorkspaceBinding.ModelData = class {
     var script = /** @type {!SDK.Script} */ (event.data);
     this._defaultMapping.addScript(script);
     this._resourceMapping.addScript(script);
-
-    if (Common.moduleSetting('jsSourceMapsEnabled').get())
-      this._compilerMapping.addScript(script);
   }
 
   /**

front_end/bindings/ResourceScriptMapping.js

@@ -425,7 +425,7 @@ Bindings.ResourceScriptFile = class extends Common.Object {
   addSourceMapURL(sourceMapURL) {
     if (!this._script)
       return;
-    this._script.addSourceMapURL(sourceMapURL);
+    this._script.debuggerModel.setSourceMapURL(this._script, sourceMapURL);
   }
 
   /**

front_end/platform/utilities.js

@@ -1213,12 +1213,14 @@ Multimap.prototype = {
   /**
    * @param {K} key
    * @param {V} value
+   * @return {boolean}
    */
   remove: function(key, value) {
     var values = this.get(key);
-    values.delete(value);
+    var result = values.delete(value);
     if (!values.size)
       this._map.delete(key);
+    return result;
   },
 
   /**

front_end/sdk/DebuggerModel.js

@@ -42,6 +42,11 @@ SDK.DebuggerModel = class extends SDK.SDKModel {
     this._agent = target.debuggerAgent();
     this._runtimeModel = /** @type {!SDK.RuntimeModel} */ (target.model(SDK.RuntimeModel));
 
+    /** @type {!SDK.SourceMapManager<!SDK.Script>} */
+    this._sourceMapManager = new SDK.SourceMapManager(target);
+    /** @type {!Map<string, !SDK.Script>} */
+    this._sourceMapIdToScript = new Map();
+
     /** @type {?SDK.DebuggerPausedDetails} */
     this._debuggerPausedDetails = null;
     /** @type {!Object.<string, !SDK.Script>} */
@@ -65,6 +70,28 @@ SDK.DebuggerModel = class extends SDK.SDKModel {
 
     /** @type {!Map<string, string>} */
     this._stringMap = new Map();
+    this._sourceMapManager.setEnabled(Common.moduleSetting('jsSourceMapsEnabled').get());
+    Common.moduleSetting('jsSourceMapsEnabled')
+        .addChangeListener(event => this._sourceMapManager.setEnabled(/** @type {boolean} */ (event.data)));
+  }
+
+  /**
+   * @param {string} executionContextId
+   * @param {string} sourceURL
+   * @param {?string} sourceMapURL
+   * @return {?string}
+   */
+  static _sourceMapId(executionContextId, sourceURL, sourceMapURL) {
+    if (!sourceMapURL)
+      return null;
+    return executionContextId + ':' + sourceURL + ':' + sourceMapURL;
+  }
+
+  /**
+   * @return {!SDK.SourceMapManager<!SDK.Script>}
+   */
+  sourceMapManager() {
+    return this._sourceMapManager;
   }
 
   /**
@@ -314,6 +341,10 @@ SDK.DebuggerModel = class extends SDK.SDKModel {
   }
 
   _reset() {
+    for (var scriptWithSourceMap of this._sourceMapIdToScript.values())
+      this._sourceMapManager.detachSourceMap(scriptWithSourceMap);
+    this._sourceMapIdToScript.clear();
+
     this._scripts = {};
     this._scriptsBySourceURL.clear();
     this._stringMap.clear();
@@ -486,6 +517,18 @@ SDK.DebuggerModel = class extends SDK.SDKModel {
       this.dispatchEventToListeners(SDK.DebuggerModel.Events.ParsedScriptSource, script);
     else
       this.dispatchEventToListeners(SDK.DebuggerModel.Events.FailedToParseScriptSource, script);
+
+    var sourceMapId = SDK.DebuggerModel._sourceMapId(script.executionContextId, script.sourceURL, script.sourceMapURL);
+    if (sourceMapId && !hasSyntaxError) {
+      // Consecutive script evaluations in the same execution context with the same sourceURL
+      // and sourceMappingURL should result in source map reloading.
+      var previousScript = this._sourceMapIdToScript.get(sourceMapId);
+      if (previousScript)
+        this._sourceMapManager.detachSourceMap(previousScript);
+      this._sourceMapIdToScript.set(sourceMapId, script);
+      this._sourceMapManager.attachSourceMap(script, script.sourceURL, script.sourceMapURL);
+    }
+
     var isDiscardable = hasSyntaxError && script.isAnonymousScript();
     if (isDiscardable) {
       this._discardableScripts.push(script);
@@ -494,6 +537,38 @@ SDK.DebuggerModel = class extends SDK.SDKModel {
     return script;
   }
 
+  /**
+   * @param {!SDK.Script} script
+   * @param {string} newSourceMapURL
+   */
+  setSourceMapURL(script, newSourceMapURL) {
+    var sourceMapId = SDK.DebuggerModel._sourceMapId(script.executionContextId, script.sourceURL, script.sourceMapURL);
+    if (sourceMapId && this._sourceMapIdToScript.get(sourceMapId) === script)
+      this._sourceMapIdToScript.delete(sourceMapId);
+    this._sourceMapManager.detachSourceMap(script);
+
+    script.sourceMapURL = newSourceMapURL;
+    sourceMapId = SDK.DebuggerModel._sourceMapId(script.executionContextId, script.sourceURL, script.sourceMapURL);
+    if (!sourceMapId)
+      return;
+    this._sourceMapIdToScript.set(sourceMapId, script);
+    this._sourceMapManager.attachSourceMap(script, script.sourceURL, script.sourceMapURL);
+  }
+
+  /**
+   * @param {!SDK.ExecutionContext} executionContext
+   */
+  executionContextDestroyed(executionContext) {
+    var sourceMapIds = Array.from(this._sourceMapIdToScript.keys());
+    for (var sourceMapId of sourceMapIds) {
+      var script = this._sourceMapIdToScript.get(sourceMapId);
+      if (script.executionContextId === executionContext.id) {
+        this._sourceMapIdToScript.delete(sourceMapId);
+        this._sourceMapManager.detachSourceMap(script);
+      }
+    }
+  }
+
   /**
    * @param {!SDK.Script} script
    */
@@ -772,6 +847,7 @@ SDK.DebuggerModel = class extends SDK.SDKModel {
    * @override
    */
   dispose() {
+    this._sourceMapManager.dispose();
     Common.moduleSetting('pauseOnExceptionEnabled').removeChangeListener(this._pauseOnExceptionStateChanged, this);
     Common.moduleSetting('pauseOnCaughtException').removeChangeListener(this._pauseOnExceptionStateChanged, this);
     Common.moduleSetting('enableAsyncStackTraces').removeChangeListener(this.asyncStackTracesStateChanged, this);
@@ -847,8 +923,7 @@ SDK.DebuggerModel.Events = {
   DiscardedAnonymousScriptSource: Symbol('DiscardedAnonymousScriptSource'),
   GlobalObjectCleared: Symbol('GlobalObjectCleared'),
   CallFrameSelected: Symbol('CallFrameSelected'),
-  ConsoleCommandEvaluatedInSelectedCallFrame: Symbol('ConsoleCommandEvaluatedInSelectedCallFrame'),
-  SourceMapURLAdded: Symbol('SourceMapURLAdded')
+  ConsoleCommandEvaluatedInSelectedCallFrame: Symbol('ConsoleCommandEvaluatedInSelectedCallFrame')
 };
 
 /** @enum {string} */

front_end/sdk/RuntimeModel.js

@@ -123,6 +123,7 @@ SDK.RuntimeModel = class extends SDK.SDKModel {
     var executionContext = this._executionContextById.get(executionContextId);
     if (!executionContext)
       return;
+    this.debuggerModel().executionContextDestroyed(executionContext);
     this._executionContextById.delete(executionContextId);
     this.dispatchEventToListeners(SDK.RuntimeModel.Events.ExecutionContextDestroyed, executionContext);
   }

front_end/sdk/SourceMapManager.js

@@ -131,6 +131,8 @@ SDK.SourceMapManager = class extends SDK.SDKObject {
     if (!this._isEnabled)
       return;
 
+    this.dispatchEventToListeners(SDK.SourceMapManager.Events.SourceMapWillAttach, client);
+
     if (this._sourceMapByURL.has(sourceMapURL)) {
       attach.call(this, sourceMapURL, client);
       return;
@@ -169,8 +171,13 @@ SDK.SourceMapManager = class extends SDK.SDKObject {
       this._sourceMapLoadedForTest();
       var clients = this._sourceMapURLToLoadingClients.get(sourceMapURL);
       this._sourceMapURLToLoadingClients.removeAll(sourceMapURL);
-      if (!sourceMap || !clients.size)
+      if (!clients.size)
+        return;
+      if (!sourceMap) {
+        for (var client of clients)
+          this.dispatchEventToListeners(SDK.SourceMapManager.Events.SourceMapFailedToAttach, client);
         return;
+      }
       this._sourceMapByURL.set(sourceMapURL, sourceMap);
       for (var client of clients)
         attach.call(this, sourceMapURL, client);
@@ -217,7 +224,8 @@ SDK.SourceMapManager = class extends SDK.SDKObject {
     if (!sourceMapURL)
       return;
     if (!this._sourceMapURLToClients.hasValue(sourceMapURL, client)) {
-      this._sourceMapURLToLoadingClients.remove(sourceMapURL, client);
+      if (this._sourceMapURLToLoadingClients.remove(sourceMapURL, client))
+        this.dispatchEventToListeners(SDK.SourceMapManager.Events.SourceMapFailedToAttach, client);
       return;
     }
     this._sourceMapURLToClients.remove(sourceMapURL, client);
@@ -238,6 +246,8 @@ SDK.SourceMapManager = class extends SDK.SDKObject {
 };
 
 SDK.SourceMapManager.Events = {
+  SourceMapWillAttach: Symbol('SourceMapWillAttach'),
+  SourceMapFailedToAttach: Symbol('SourceMapFailedToAttach'),
   SourceMapAttached: Symbol('SourceMapAttached'),
   SourceMapDetached: Symbol('SourceMapDetached'),
   SourceMapChanged: Symbol('SourceMapChanged')