Settings sync should debounce requests when a request is in progress

[Tyriar]

On a slow responding server, several requests get fired before proceeding ones have finished. For the following log I think the behavior should be:

[2020-02-24 07:29:36.999] Fire sync request
[2020-02-24 07:29:58.309] Queue a request
[2020-02-24 07:30:06.612] Queue a request (does nothing, one's already queued)
[2020-02-24 07:30:08.798] Queue a request (does nothing, one's already queued)
[2020-02-24 07:30:10.024] Queue a request (does nothing, one's already queued)
[2020-02-24 07:30:12.788] Queue a request (does nothing, one's already queued)
[2020-02-24 07:30:38.955] Queue a request (does nothing, one's already queued)
[2020-02-24 07:31:36.999] Abandon request as it's taken over 2 minutes
[2020-02-24 07:31:36.999] Fire sync request as it has been queued
[2020-02-24 07:31:51.136] Queue a request (does nothing, one's already queued)
[2020-02-24 07:31:52.629] Queue a request (does nothing, one's already queued)
[2020-02-24 07:32:09.359] Queue a request (does nothing, one's already queued)
[2020-02-24 07:32:12.146] Queue a request (does nothing, one's already queued)
...

Actual sync log:

[2020-02-24 07:29:36.999] [userDataSync] [info] Auto Sync: Triggered.
[2020-02-24 07:29:58.309] [userDataSync] [info] Auto Sync: Triggered.
[2020-02-24 07:30:06.612] [userDataSync] [info] Auto Sync: Triggered.
[2020-02-24 07:30:08.798] [userDataSync] [info] Auto Sync: Triggered.
[2020-02-24 07:30:10.024] [userDataSync] [info] Auto Sync: Triggered.
[2020-02-24 07:30:12.788] [userDataSync] [info] Auto Sync: Triggered.
[2020-02-24 07:30:38.955] [userDataSync] [info] Auto Sync: Triggered.
[2020-02-24 07:31:51.136] [userDataSync] [info] Auto Sync: Triggered.
[2020-02-24 07:31:52.629] [userDataSync] [info] Auto Sync: Triggered.
[2020-02-24 07:32:09.359] [userDataSync] [info] Auto Sync: Triggered.
[2020-02-24 07:32:12.146] [userDataSync] [info] Auto Sync: Triggered.
[2020-02-24 07:32:18.444] [userDataSync] [error] Unknown (UserDataSyncError) undefined: Server returned 500
    at d.manifest (file:///C:/Users/daimms.REDMOND/AppData/Local/Programs/Microsoft VS Code Insiders/resources/app/out/vs/code/electron-browser/sharedProcess/sharedProcessMain.js:446:798)
    at async m.sync (file:///C:/Users/daimms.REDMOND/AppData/Local/Programs/Microsoft VS Code Insiders/resources/app/out/vs/code/electron-browser/sharedProcess/sharedProcessMain.js:441:8)
    at async l.sync (file:///C:/Users/daimms.REDMOND/AppData/Local/Programs/Microsoft VS Code Insiders/resources/app/out/vs/code/electron-browser/sharedProcess/sharedProcessMain.js:431:979)
[2020-02-24 07:32:26.674] [userDataSync] [error] Unknown (UserDataSyncError) undefined: Server returned 500
    at d.manifest (file:///C:/Users/daimms.REDMOND/AppData/Local/Programs/Microsoft VS Code Insiders/resources/app/out/vs/code/electron-browser/sharedProcess/sharedProcessMain.js:446:798)
    at async m.sync (file:///C:/Users/daimms.REDMOND/AppData/Local/Programs/Microsoft VS Code Insiders/resources/app/out/vs/code/electron-browser/sharedProcess/sharedProcessMain.js:441:8)
    at async l.sync (file:///C:/Users/daimms.REDMOND/AppData/Local/Programs/Microsoft VS Code Insiders/resources/app/out/vs/code/electron-browser/sharedProcess/sharedProcessMain.js:431:979)
[2020-02-24 07:32:28.864] [userDataSync] [error] Unknown (UserDataSyncError) undefined: Server returned 500
    at d.manifest (file:///C:/Users/daimms.REDMOND/AppData/Local/Programs/Microsoft VS Code Insiders/resources/app/out/vs/code/electron-browser/sharedProcess/sharedProcessMain.js:446:798)
    at async m.sync (file:///C:/Users/daimms.REDMOND/AppData/Local/Programs/Microsoft VS Code Insiders/resources/app/out/vs/code/electron-browser/sharedProcess/sharedProcessMain.js:441:8)
    at async l.sync (file:///C:/Users/daimms.REDMOND/AppData/Local/Programs/Microsoft VS Code Insiders/resources/app/out/vs/code/electron-browser/sharedProcess/sharedProcessMain.js:431:979)
[2020-02-24 07:32:30.082] [userDataSync] [error] Unknown (UserDataSyncError) undefined: Server returned 500
    at d.manifest (file:///C:/Users/daimms.REDMOND/AppData/Local/Programs/Microsoft VS Code Insiders/resources/app/out/vs/code/electron-browser/sharedProcess/sharedProcessMain.js:446:798)
    at async m.sync (file:///C:/Users/daimms.REDMOND/AppData/Local/Programs/Microsoft VS Code Insiders/resources/app/out/vs/code/electron-browser/sharedProcess/sharedProcessMain.js:441:8)
    at async l.sync (file:///C:/Users/daimms.REDMOND/AppData/Local/Programs/Microsoft VS Code Insiders/resources/app/out/vs/code/electron-browser/sharedProcess/sharedProcessMain.js:431:979)
[2020-02-24 07:32:32.854] [userDataSync] [error] Unknown (UserDataSyncError) undefined: Server returned 500
    at d.manifest (file:///C:/Users/daimms.REDMOND/AppData/Local/Programs/Microsoft VS Code Insiders/resources/app/out/vs/code/electron-browser/sharedProcess/sharedProcessMain.js:446:798)
    at async m.sync (file:///C:/Users/daimms.REDMOND/AppData/Local/Programs/Microsoft VS Code Insiders/resources/app/out/vs/code/electron-browser/sharedProcess/sharedProcessMain.js:441:8)
    at async l.sync (file:///C:/Users/daimms.REDMOND/AppData/Local/Programs/Microsoft VS Code Insiders/resources/app/out/vs/code/electron-browser/sharedProcess/sharedProcessMain.js:431:979)
[2020-02-24 07:32:59.021] [userDataSync] [error] Unknown (UserDataSyncError) undefined: Server returned 500
    at d.manifest (file:///C:/Users/daimms.REDMOND/AppData/Local/Programs/Microsoft VS Code Insiders/resources/app/out/vs/code/electron-browser/sharedProcess/sharedProcessMain.js:446:798)
    at async m.sync (file:///C:/Users/daimms.REDMOND/AppData/Local/Programs/Microsoft VS Code Insiders/resources/app/out/vs/code/electron-browser/sharedProcess/sharedProcessMain.js:441:8)
    at async l.sync (file:///C:/Users/daimms.REDMOND/AppData/Local/Programs/Microsoft VS Code Insiders/resources/app/out/vs/code/electron-browser/sharedProcess/sharedProcessMain.js:431:979)

[sandy081]

Syncing each areas are queued but not the manifest request.

[ericblade]

FWIW -- I just activated Settings Sync on what used to be my main machine, but I've been using a different one for quite a while. My newer machine picked up all the settings and extensions that I never bothered to install on it, which lead to a continuous repeating crash in Extension Host.

To attempt to nail down which extension was at fault, I went through the entire extensions list (about 120 extensions) and disabled them individually. At some point during this, VSCode threw up a warning that I was blocked from settings sync for spamming it.

Therefore, I think that debounce is really something that needs to be added.. I shouldn't be able to spam the server to the point where I'm locked out because I'm trying to fix the app being broken. :-)

[sandy081]

Currently requests are queued but not debounced. Will improve it.

[sandy081]

Each Settings Sync activity is debounced for 2 seconds and queued until the current sync is finished. Also when if the client manages to exceed the client side rate limit, settings sync is suspended until restarting VS Code.