Try canceling TS Server geterr requests when document changes

[mjbvz]

From microsoft/TypeScript#19458 (comment)

TS would like us to try cancelling the TS Server geterr requests if the document changes before a response is returned

[mjbvz]

See microsoft/TypeScript#19458 for verification steps. Basically, in a file that requires sass.js, confirm that you can get completions in a timely manner. Previously completions blocked until geterr returned, which could take several seconds

[isidorn]

I actually still get this with the latest insiders
I am using vscode ts version 2.9.1

[mjbvz]

Yeah, the full fix for this looks like it is move to TS 3.0

To verify the specific fix on our side:

• Set "typescript.tsserver.trace": "verbose"
• Reload vs code
• Open the file with the sass.js require and quickly type something to trigger completions
• Open the output panel and go to typescript section
• Look for the getErr requests and note the request number (55 here):

[Trace  - 11:14:40 PM] Sending request: geterr (55). Response expected: yes. Current queue length: 0
Arguments: {
    "delay": 0,
    "files": [
        "/Users/matb/projects/san/sub/foo.js"
    ]
}

• Look for the geterr request being cancelled when a change request is sent if it has not completed yet:

[Trace  - 11:14:40 PM] Sending request: change (56). Response expected: no. Current queue length: 0
Arguments: {
    "file": "/Users/matb/projects/san/sub/foo.js",
    "line": 3,
    "offset": 4,
    "endLine": 3,
    "endOffset": 4,
    "insertString": "a"
}
[Trace  - 11:14:40 PM] TypeScript Service: trying to cancel ongoing request with sequence number 55