DevTools: carefully cleanup javascript sourcemaps

third_party/WebKit/Source/devtools/front_end/sdk/DebuggerModel.js

Index: third_party/WebKit/Source/devtools/front_end/sdk/DebuggerModel.js
diff --git a/third_party/WebKit/Source/devtools/front_end/sdk/DebuggerModel.js b/third_party/WebKit/Source/devtools/front_end/sdk/DebuggerModel.js
index 72693cadfdd036e221785df59aa9a22d9f65462d..055d5a1a36c41825173a561824c7066bb866d166 100644
--- a/third_party/WebKit/Source/devtools/front_end/sdk/DebuggerModel.js
+++ b/third_party/WebKit/Source/devtools/front_end/sdk/DebuggerModel.js
@@ -41,6 +41,13 @@ SDK.DebuggerModel = class extends SDK.SDKModel {
     target.registerDebuggerDispatcher(new SDK.DebuggerDispatcher(this));
     this._agent = target.debuggerAgent();
     this._runtimeModel = /** @type {!SDK.RuntimeModel} */ (target.model(SDK.RuntimeModel));
+    this._runtimeModel.addEventListener(
+        SDK.RuntimeModel.Events.ExecutionContextDestroyed, this._executionContextDestroyed, this);
+
+    /** @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;
@@ -65,6 +72,28 @@ 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;
   }
 
   /**
@@ -318,6 +347,10 @@ SDK.DebuggerModel = class extends SDK.SDKModel {
     this._scriptsBySourceURL.clear();
     this._stringMap.clear();
     this._discardableScripts = [];
+
+    for (var scriptWithSourceMap of this._sourceMapIdToScript.values())
+      this._sourceMapManager.detachSourceMap(scriptWithSourceMap);

[dgozman, 2017/03/31 21:57:41]

Let's do this before clearing scripts.

[lushnikov, 2017/03/31 23:53:10]

Done.

+    this._sourceMapIdToScript.clear();
   }
 
   /**
@@ -486,6 +519,16 @@ 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) {
+      var previousSourceMapClient = this._sourceMapIdToScript.get(sourceMapId);

[dgozman, 2017/03/31 21:57:41]

Let's add a comment.

[lushnikov, 2017/03/31 23:53:10]

Done.

+      if (previousSourceMapClient)

[dgozman, 2017/03/31 21:57:40]

previousScript

[lushnikov, 2017/03/31 23:53:10]

Done.

+        this._sourceMapManager.detachSourceMap(previousSourceMapClient);
+      this._sourceMapIdToScript.set(sourceMapId, script);
+      this._sourceMapManager.attachSourceMap(script, script.sourceURL, script.sourceMapURL);
+    }
+
     var isDiscardable = hasSyntaxError && script.isAnonymousScript();
     if (isDiscardable) {
       this._discardableScripts.push(script);
@@ -496,6 +539,35 @@ SDK.DebuggerModel = class extends SDK.SDKModel {
 
   /**
    * @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)

[dgozman, 2017/03/31 21:57:41]

Figure out null vs undefined vs empty string.

[lushnikov, 2017/03/31 23:53:10]

Not loading sourceMaps for all falsy values of souceMapId works fine here.

+      return;
+    this._sourceMapIdToScript.set(sourceMapId, script);
+    this._sourceMapManager.attachSourceMap(script, script.sourceURL, script.sourceMapURL);
+  }
+
+  /**
+   * @param {!Common.Event} event
+   */
+  _executionContextDestroyed(event) {
+    var executionContext = /** @type {!SDK.ExecutionContext} */ (event.data);
+    for (var script of this._sourceMapIdToScript.values()) {
+      if (script.executionContextId === executionContext.id)
+        this._sourceMapManager.detachSourceMap(script);

[dgozman, 2017/03/31 21:57:41]

Remove from this._sourceMapIdToScript as well.

[lushnikov, 2017/03/31 23:53:10]

Done.

+    }
+  }
+
+  /**
+   * @param {!SDK.Script} script
    */
   _registerScript(script) {
     this._scripts[script.scriptId] = script;
@@ -772,6 +844,9 @@ SDK.DebuggerModel = class extends SDK.SDKModel {
    * @override
    */
   dispose() {
+    this._sourceMapManager.dispose();
+    this._runtimeModel.removeEventListener(

[dgozman, 2017/03/31 21:57:40]

Let's turn this into direct call 'executionContextDestroyed()'.

[lushnikov, 2017/03/31 23:53:10]

Done.

+        SDK.RuntimeModel.Events.ExecutionContextDestroyed, this._executionContextDestroyed, this);
     Common.moduleSetting('pauseOnExceptionEnabled').removeChangeListener(this._pauseOnExceptionStateChanged, this);
     Common.moduleSetting('pauseOnCaughtException').removeChangeListener(this._pauseOnExceptionStateChanged, this);
     Common.moduleSetting('enableAsyncStackTraces').removeChangeListener(this.asyncStackTracesStateChanged, this);
@@ -847,8 +922,7 @@ SDK.DebuggerModel.Events = {
   DiscardedAnonymousScriptSource: Symbol('DiscardedAnonymousScriptSource'),
   GlobalObjectCleared: Symbol('GlobalObjectCleared'),
   CallFrameSelected: Symbol('CallFrameSelected'),
-  ConsoleCommandEvaluatedInSelectedCallFrame: Symbol('ConsoleCommandEvaluatedInSelectedCallFrame'),
-  SourceMapURLAdded: Symbol('SourceMapURLAdded')
+  ConsoleCommandEvaluatedInSelectedCallFrame: Symbol('ConsoleCommandEvaluatedInSelectedCallFrame')
 };
 
 /** @enum {string} */