Throttle new sources

[jasonLaster]

Associated Issue: #4705

Summary of Changes

This throttles the firefox newSource event so that we fire at most one newSources action every 50ms.

• Not sure if we need a test
• Not sure if we want to debounce in the event or the actions. Events seem easier now

The performance savings is significant ⏲

No throttling, w/o the editor fix

~ 9 seconds. Lots of thrashing here :P

Throttling w/o the editor fix

3 seconds. The editor update holds up the main thread so we also do more newSources calls :) vicious cycle

Throttling w/ the editor fix

1.5 sec

[codehag]

this is really good work. i tried it out, quite an impressive improvement

[codehag]

do we need this?

[jasonLaster]

it should be in its own PR probably. It can throw, and that breaks things

[codehag]

maybe we can send the promises all at once using Promise.all? especially with the queue work. and if we move to sagas we can use forks

[codehag]

damp benchmark:

test result averages for 11dc3161e3e39159e9fa2520b76f5a5d0a0783b8:
    simple.jsdebugger.open.DAMP: 1719.7275000000045ms
    simple.jsdebugger.reload.DAMP: 409.27750000000015ms
    simple.jsdebugger.close.DAMP: 127.70750000000044ms
    complicated.jsdebugger.open.DAMP: 2556.3025000000016ms
    complicated.jsdebugger.reload.DAMP: 1324.5275000000038ms
    complicated.jsdebugger.close.DAMP: 4235.457499999997ms

test result averages for f59026d3d047fbbb984580ea2d01a9bc5cb11553:
    simple.jsdebugger.open.DAMP: 1530.5324999999975ms
    simple.jsdebugger.reload.DAMP: 361.75750000000335ms
    simple.jsdebugger.close.DAMP: 135.4349999999995ms
    complicated.jsdebugger.open.DAMP: 2409.629999999999ms
    complicated.jsdebugger.reload.DAMP: 1293.0750000000007ms
    complicated.jsdebugger.close.DAMP: 4672.5625ms

difference between 11dc3161e3e39159e9fa2520b76f5a5d0a0783b8 and  f59026d3d047fbbb984580ea2d01a9bc5cb11553:
    simple.jsdebugger.open.DAMP: -11.6418% difference
    simple.jsdebugger.reload.DAMP: -12.3263% difference
    simple.jsdebugger.close.DAMP: +5.87324% difference
    complicated.jsdebugger.open.DAMP: -5.90715% difference
    complicated.jsdebugger.reload.DAMP: -2.40315% difference
    complicated.jsdebugger.close.DAMP: +9.81374% difference

my computer was struggling a bit so some of the values are higher than normal

[jasonLaster]

Yep. I tried to break this work up a bit so that we can land it piecemeal. This logic will be touched in another PR

[jasonLaster]

Just checked CI: two mochitests, and one lint error. This should be pretty close :)

[jasonLaster]

browser_dbg-breakpoints-cond
browser_dbg-breaking

[jasonLaster]

looks like it's failing because we're not selecting the source or waiting for the source to be selected..

diff --git a/src/actions/pause/paused.js b/src/actions/pause/paused.js
index c4c8b4e..7a29545 100644
--- a/src/actions/pause/paused.js
+++ b/src/actions/pause/paused.js
@@ -51,6 +51,7 @@ export function paused(pauseInfo: Pause) {
     }
 
     const { line, column } = frame.location;
+    debugger;
     await dispatch(
       selectSource(frame.location.sourceId, { location: { line, column } })
     );
diff --git a/src/actions/sources.js b/src/actions/sources.js
index ddb437b..44f656a 100644
--- a/src/actions/sources.js
+++ b/src/actions/sources.js
@@ -66,6 +66,12 @@ async function checkPendingBreakpoints(state, dispatch, sourceId) {
 
   // load the source text if there is a pending breakpoint for it
   await dispatch(loadSourceText(source));

 }
 
diff --git a/src/test/mochitest/browser_dbg-breaking.js b/src/test/mochitest/browser_dbg-breaking.js
index a4fdfa7..61263ee 100644
--- a/src/test/mochitest/browser_dbg-breaking.js
+++ b/src/test/mochitest/browser_dbg-breaking.js
@@ -13,7 +13,9 @@ add_task(async function() {
   reload(dbg);
   await waitForPaused(dbg);
 
-  await waitForLoadedSource(dbg, "doc-scripts.html");
+  await waitForSelectedSource(dbg, "doc-scripts.html");
+  debugger
+  // await waitForever()
   assertPausedLocation(dbg);
   await resume(dbg);
 

[jasonLaster]

Got this working on the plane, turned out we had a sneaky timing w/ pause and sources. Now that we're throttling the newSources action, we need to flush it before firing the pause action.

There were also some small nits in there too. Should be ready to go!

[codehag]

looks good, thanks!