Bug 1499070 - Fix timestamp for evaluation result; r=Honza.

When sending a command to the server, a timestamp is
computed before evaluating the string, and is then
sent back to the client in the packet.
However, if top-level await, or somme :commands, the
evaluation takes more time, which means the timestamp
is now innacurate.
For those cases, we update the timestamp before sending
the packet to the client.

Differential Revision: https://phabricator.services.mozilla.com/D8734

--HG--
extra : moz-landing-system : lando

devtools/client/webconsole/components/JSTerm.js

@@ -550,6 +550,7 @@ class JSTerm extends Component {
     const { ConsoleCommand } = require("devtools/client/webconsole/types");
     const cmdMessage = new ConsoleCommand({
       messageText: executeString,
+      timeStamp: Date.now(),
     });
     this.hud.proxy.dispatchMessageAdd(cmdMessage);
 

devtools/client/webconsole/components/message-types/ConsoleCommand.js

@@ -35,6 +35,7 @@ function ConsoleCommand(props) {
     type,
     level,
     messageText,
+    timeStamp,
   } = message;
 
   // This uses a Custom Element to syntax highlight when possible. If it's not
@@ -48,6 +49,7 @@ function ConsoleCommand(props) {
     messageBody,
     serviceContainer,
     indent,
+    timeStamp,
     timestampsVisible,
   });
 }

devtools/client/webconsole/test/mochitest/browser_jsterm_await.js

@@ -39,6 +39,17 @@ async function performTests() {
   is(messagesText, `${simpleAwait} - Array [ "await1" ]`,
     "The output contains the the expected messages");
 
+  // Check that the timestamp of the result is accurate
+  const {
+    visibleMessages,
+    messagesById
+  } = hud.ui.consoleOutput.getStore().getState().messages;
+  const [commandId, resultId] = visibleMessages;
+  const delta = messagesById.get(resultId).timeStamp -
+    messagesById.get(commandId).timeStamp;
+  ok(delta >= 500,
+    `The result has a timestamp at least 500ms (${delta}ms) older than the command`);
+
   info("Check that assigning the result of a top-level await expression works");
   await executeAndWaitForResultMessage(
     `x = await new Promise(r => setTimeout(() => r("await2"), 500))`,

devtools/client/webconsole/types.js

@@ -22,6 +22,7 @@ exports.ConsoleCommand = function(props) {
     groupId: null,
     indent: 0,
     private: false,
+    timeStamp: null,
   }, props);
 };
 

devtools/server/actors/webconsole.js

@@ -976,11 +976,14 @@ WebConsoleActor.prototype =
    *         `resultID` field, with a sanitized helperResult field.
    */
   _waitForResultAndSend: async function(response) {
+    let updateTimestamp = false;
+
     // Wait for asynchronous command completion before sending back the response
     if (
       response.helperResult && typeof response.helperResult.then == "function"
     ) {
       response.helperResult = await response.helperResult;
+      updateTimestamp = true;
     } else if (response.awaitResult && typeof response.awaitResult.then === "function") {
       let result;
       try {
@@ -1000,6 +1003,14 @@ WebConsoleActor.prototype =
 
       // Remove the promise from the response object.
       delete response.awaitResult;
+
+      updateTimestamp = true;
+    }
+
+    if (updateTimestamp) {
+      // We need to compute the timestamp again as the one in the response was set before
+      // doing the evaluation, which is now innacurate since we waited for a bit.
+      response.timestamp = Date.now();
     }
 
     // Finally, send an unsolicited evaluationResult packet with