Bug 26405

Summary:	Performance improvements in read_block()
Product:	XCB	Reporter:	Markus Fleschutz <markus.fleschutz>
Component:	Library	Assignee:	xcb mailing list dummy <xcb>
Status:	RESOLVED NOTABUG	QA Contact:	xcb mailing list dummy <xcb>
Severity:	enhancement
Priority:	medium
Version:	1.1
Hardware:	All
OS:	All
Whiteboard:
i915 platform:		i915 features:

Description Markus Fleschutz 2010-02-03 01:46:14 UTC

in libxcb-1.5/src/xcb_in.c: read_block() should read: (replace the new ELSE by else)

...
        if(ret > 0)
            done += ret;
        ELSE if(ret < 0 && errno == EAGAIN)
        {
...
        }
        ELSE if(ret <= 0)
             return ret;
...

This saves 2 if() on partial read.

Comment 1 Julien Danjou 2010-02-03 01:55:52 UTC

I agree for the first else, but the second seems like a bad idea:
poll or select might return 0.

Comment 2 Bart Massey 2010-02-03 16:57:51 UTC

Inspection of the assembly code convinces me that the compiler does the right thing here, as I expected.  So there's no performance issue.  The style of the existing code isn't so bad, I think.  I tried some restructurings, and couldn't find one so much better that it was worth a patch.  So for now I think we'll leave the elses off.

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