Bug 859170 - Fix for hang when trying to expand a very long message in the web console output; r=past

browser/devtools/webconsole/test/Makefile.in

@@ -120,6 +120,7 @@ MOCHITEST_BROWSER_FILES = \
 	browser_console_variables_view.js \
 	browser_console_variables_view_while_debugging.js \
 	browser_console.js \
+	browser_longstring_hang.js \
 	head.js \
 	$(NULL)
 
@@ -221,6 +222,7 @@ MOCHITEST_BROWSER_FILES += \
 	test-bug-821877-csperrors.html \
 	test-bug-821877-csperrors.html^headers^ \
 	test-eval-in-stackframe.html \
+	test-bug-859170-longstring-hang.html \
 	$(NULL)
 
 include $(topsrcdir)/config/rules.mk

browser/devtools/webconsole/test/browser_longstring_hang.js

@@ -0,0 +1,88 @@
+/* vim:set ts=2 sw=2 sts=2 et: */
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that very long strings do not hang the browser.
+
+function test()
+{
+  waitForExplicitFinish();
+
+  let DebuggerServer = Cu.import("resource://gre/modules/devtools/dbg-server.jsm",
+                                 {}).DebuggerServer;
+
+  addTab("http://example.com/browser/browser/devtools/webconsole/test/test-bug-859170-longstring-hang.html");
+
+  let hud = null;
+
+  gBrowser.selectedBrowser.addEventListener("load", function onLoad() {
+    gBrowser.selectedBrowser.removeEventListener("load", onLoad, true);
+    openConsole(null, performTest);
+  }, true);
+
+  function performTest(aHud)
+  {
+    hud = aHud;
+
+    info("wait for the initial long string");
+
+    waitForMessages({
+      webconsole: hud,
+      messages: [
+        {
+          name: "find 'foobar', no 'foobaz', in long string output",
+          text: "foobar",
+          noText: "foobaz",
+          category: CATEGORY_WEBDEV,
+          longString: true,
+        },
+      ],
+    }).then(onInitialString);
+  }
+
+  function onInitialString(aResults)
+  {
+    let msg = [...aResults[0].matched][0];
+    ok(msg, "console.log result message element");
+
+    let clickable = msg.querySelector(".longStringEllipsis");
+    ok(clickable, "long string ellipsis is shown");
+
+    scrollToVisible(clickable);
+
+    executeSoon(() => {
+      EventUtils.synthesizeMouse(clickable, 2, 2, {}, hud.iframeWindow);
+
+      info("wait for long string expansion");
+
+      waitForMessages({
+        webconsole: hud,
+        messages: [
+          {
+            name: "find 'foobaz' after expand, but no 'boom!' at the end",
+            text: "foobaz",
+            noText: "boom!",
+            category: CATEGORY_WEBDEV,
+            longString: false,
+          },
+          {
+            text: "too long to be displayed",
+            longString: false,
+          },
+        ],
+      }).then(finishTest);
+    });
+  }
+
+  function scrollToVisible(aNode)
+  {
+    let richListBoxNode = aNode.parentNode;
+    while (richListBoxNode.tagName != "richlistbox") {
+      richListBoxNode = richListBoxNode.parentNode;
+    }
+
+    let boxObject = richListBoxNode.scrollBoxObject;
+    let nsIScrollBoxObject = boxObject.QueryInterface(Ci.nsIScrollBoxObject);
+    nsIScrollBoxObject.ensureElementIsVisible(aNode);
+  }
+}

browser/devtools/webconsole/test/head.js

@@ -875,20 +875,28 @@ function waitForMessages(aOptions)
   let listenerAdded = false;
   let deferred = Promise.defer();
 
+  function checkText(aRule, aText)
+  {
+    let result;
+    if (typeof aRule == "string") {
+      result = aText.indexOf(aRule) > -1;
+    }
+    else if (aRule instanceof RegExp) {
+      result = aRule.test(aText);
+    }
+    return result;
+  }
+
   function checkMessage(aRule, aElement)
   {
-    if (aRule.text) {
-      let elemText = getMessageElementText(aElement);
-      let matched = false;
-      if (typeof aRule.text == "string") {
-        matched = elemText.indexOf(aRule.text) > -1;
-      }
-      else if (aRule.text instanceof RegExp) {
-        matched = aRule.text.test(elemText);
-      }
-      if (!matched) {
-        return false;
-      }
+    let elemText = getMessageElementText(aElement);
+
+    if (aRule.text && !checkText(aRule.text, elemText)) {
+      return false;
+    }
+
+    if (aRule.noText && checkText(aRule.noText, elemText)) {
+      return false;
     }
 
     if (aRule.category) {
@@ -910,6 +918,11 @@ function waitForMessages(aOptions)
       }
     }
 
+    let longString = !!aElement.querySelector(".longStringEllipsis");
+    if ("longString" in aRule && aRule.longString != longString) {
+      return false;
+    }
+
     let count = aRule.count || 1;
     if (!aRule.matched) {
       aRule.matched = new Set();
@@ -945,6 +958,7 @@ function waitForMessages(aOptions)
     if (rulesMatched == rules.length) {
       if (listenerAdded) {
         webconsole.ui.off("messages-added", onMessagesAdded);
+        webconsole.ui.off("messages-updated", onMessagesAdded);
       }
       gPendingOutputTest--;
       deferred.resolve(rules);
@@ -964,7 +978,7 @@ function waitForMessages(aOptions)
 
     for (let rule of rules) {
       if (!rule._ruleMatched) {
-        console.log("failed to match rule: " + displayRule(rule));
+        ok(false, "failed to match rule: " + displayRule(rule));
       }
     }
   }
@@ -980,6 +994,7 @@ function waitForMessages(aOptions)
       listenerAdded = true;
       registerCleanupFunction(testCleanup);
       webconsole.ui.on("messages-added", onMessagesAdded);
+      webconsole.ui.on("messages-updated", onMessagesAdded);
     }
   });
 

browser/devtools/webconsole/test/test-bug-859170-longstring-hang.html

@@ -0,0 +1,23 @@
+<!DOCTYPE html>
+<html lang="en">
+  <head><meta charset="utf-8">
+    <title>Web Console test for bug 859170 - very long strings hang the browser</title>
+    <!-- Any copyright is dedicated to the Public Domain.
+         http://creativecommons.org/publicdomain/zero/1.0/ -->
+<script type="application/javascript">
+(function() {
+var longString = "abbababazomglolztest";
+for (var i = 0; i < 10; i++) {
+  longString += longString + longString;
+}
+
+longString = "foobar" + (new Array(20000)).join("a") + "foobaz" +
+             longString + "boom!";
+console.log(longString);
+})();
+</script>
+  </head>
+  <body>
+    <p>Web Console test for bug 859170 - very long strings hang the browser.</p>
+  </body>
+</html>

browser/devtools/webconsole/webconsole.js

@@ -171,6 +171,9 @@ const FILTER_PREFS_PREFIX = "devtools.webconsole.filter.";
 // The minimum font size.
 const MIN_FONT_SIZE = 10;
 
+// The maximum length of strings to be displayed by the Web Console.
+const MAX_LONG_STRING_LENGTH = 200000;
+
 const PREF_CONNECTION_TIMEOUT = "devtools.debugger.remote-timeout";
 
 /**
@@ -1319,7 +1322,7 @@ WebConsoleFrame.prototype = {
   },
 
   /**
-   * Inform user that the Web Console API has been replaced by a script
+   * Inform user that the window.console API has been replaced by a script
    * in a content page.
    */
   logWarningAboutReplacedAPI: function WCF_logWarningAboutReplacedAPI()
@@ -1329,6 +1332,16 @@ WebConsoleFrame.prototype = {
     this.outputMessage(CATEGORY_JS, node);
   },
 
+  /**
+   * Inform user that the string he tries to view is too long.
+   */
+  logWarningAboutStringTooLong: function WCF_logWarningAboutStringTooLong()
+  {
+    let node = this.createMessageNode(CATEGORY_JS, SEVERITY_WARNING,
+                                      l10n.getStr("longStringTooLong"));
+    this.outputMessage(CATEGORY_JS, node);
+  },
+
   /**
    * Handle the network events coming from the remote Web Console.
    *
@@ -1695,11 +1708,17 @@ WebConsoleFrame.prototype = {
     let hudIdSupportsString = WebConsoleUtils.supportsString(this.hudId);
 
     // Output the current batch of messages.
-    let newOrUpdatedNodes = new Set();
+    let newMessages = new Set();
+    let updatedMessages = new Set();
     for (let item of batch) {
       let result = this._outputMessageFromQueue(hudIdSupportsString, item);
       if (result) {
-        newOrUpdatedNodes.add(result.isRepeated || result.node);
+        if (result.isRepeated) {
+          updatedMessages.add(result.isRepeated);
+        }
+        else {
+          newMessages.add(result.node);
+        }
         if (result.visible && result.node == this.outputNode.lastChild) {
           lastVisibleNode = result.node;
         }
@@ -1743,7 +1762,12 @@ WebConsoleFrame.prototype = {
       scrollBox.scrollTop -= oldScrollHeight - scrollBox.scrollHeight;
     }
 
-    this.emit("messages-added", newOrUpdatedNodes);
+    if (newMessages.size) {
+      this.emit("messages-added", newMessages);
+    }
+    if (updatedMessages.size) {
+      this.emit("messages-updated", updatedMessages);
+    }
 
     // If the queue is not empty, schedule another flush.
     if (this._outputQueue.length > 0) {
@@ -2255,7 +2279,8 @@ WebConsoleFrame.prototype = {
     }
 
     let longString = this.webConsoleClient.longString(aActor);
-    longString.substring(longString.initial.length, longString.length,
+    let toIndex = Math.min(longString.length, MAX_LONG_STRING_LENGTH);
+    longString.substring(longString.initial.length, toIndex,
       function WCF__onSubstring(aResponse) {
         if (aResponse.error) {
           Cu.reportError("WCF__longStringClick substring failure: " +
@@ -2271,7 +2296,13 @@ WebConsoleFrame.prototype = {
             aMessage.category == CATEGORY_OUTPUT) {
           aMessage.clipboardText = aMessage.textContent;
         }
-      });
+
+        this.emit("messages-updated", new Set([aMessage]));
+
+        if (toIndex != longString.length) {
+          this.logWarningAboutStringTooLong();
+        }
+      }.bind(this));
   },
 
   /**
@@ -3468,7 +3499,8 @@ JSTerm.prototype = {
     }
 
     let client = this.webConsoleClient.longString(grip);
-    client.substring(grip.initial.length, grip.length, (aResponse) => {
+    let toIndex = Math.min(grip.length, MAX_LONG_STRING_LENGTH);
+    client.substring(grip.initial.length, toIndex, (aResponse) => {
       if (aResponse.error) {
         Cu.reportError("JST__fetchVarLongString substring failure: " +
                        aResponse.error + ": " + aResponse.message);
@@ -3479,6 +3511,10 @@ JSTerm.prototype = {
       aVar.setGrip(grip.initial + aResponse.substring);
       aVar.hideArrow();
       aVar._retrieved = true;
+
+      if (toIndex != grip.length) {
+        this.hud.logWarningAboutStringTooLong();
+      }
     });
   },
 

browser/locales/en-US/chrome/browser/devtools/webconsole.properties

@@ -180,6 +180,10 @@ ToolboxWebconsole.tooltip=Web Console
 # from the server.
 longStringEllipsis=[…]
 
+# LOCALIZATION NOTE (longStringTooLong): The string displayed after the user
+# tries to expand a long string.
+longStringTooLong=The string you are trying to view is too long to be displayed by the Web Console.
+
 # LOCALIZATION NOTE (executeEmptyInput): This is displayed when the user tries
 # to execute code, but the input is empty.
 executeEmptyInput=No value to execute.