313575 - unnecessary qi's to nsISeekableStream from nsFastLoadFile

Status: RESOLVED FIXED

(Core :: XPCOM, defect)

Description

[Brian Ryner (not reading)]

nsFastLoadFileReader/Writer/Updater repeatedly QI the input and/or output stream to nsISeekableStream.  In many cases this happens even if no seek is required for the read being performed.  We can optimize this by QI'ing to nsISeekableStream when the input or output stream is set and keeping the pointer around.  We can also take advantage of the fact that the underlying nsBinaryInput/OutputStream is keeping a similar cached interface pointer for nsIStreamBufferAccess.

Comment 1

[Brian Ryner (not reading)]

Attachment: patch

Comment 2

[Brendan Eich [:brendan]]

Comment on attachment 200587 [details] [diff] [review]
patch

Nice, I was severely COMtaminated when I wrote fastload.  Nit:

>@@ -556,6 +568,8 @@ class nsFastLoadFileUpdater
> 
>   protected:
>     nsCOMPtr<nsIInputStream> mInputStream;

Blank line here to match style elsewhere in both existing file and your added members in reader and writer.

>+    // Kept in sync with mInputStream to avoid repeated QI
>+    nsCOMPtr<nsISeekableStream> mSeekableInput;
> };
> 
> NS_COM nsresult

Thanks,

/be

Comment 3

[Brian Ryner (not reading)]

checked in.