[HTTPCORE-701] A little confuse for the H2 update window function

• Type: Improvement
• Status: Closed
• Priority: Trivial
• Resolution: Information Provided
• Affects Version/s: 5.1
• Component/s: HttpCore
• Assignee: Unassigned
• Reporter: Kaven Stone
• Created: 28/Nov/21 11:15
• Updated: 30/Nov/21 02:09
• Resolved: 29/Nov/21 10:47

Description

I just read the update window logic for http2, and the function is a little confuse for me.

1. for the two TODO:  The first TODO, it revert the min value as to the the max value, this if for what situation?
2. The seconde TODO:  needs to be removed ,  and that will remove what?

 

The soure code in httpcore5-h2\src\main\java\org\apache\hc\core5\http2\impl\nio\AbstractH2StreamMultiplexer.java is as below:

private int updateWindow(final AtomicInteger window, final int delta) throws ArithmeticException {
for (; {
final int current = window.get();
long newValue = (long) current + delta;

//TODO: work-around for what looks like a bug in Ngnix (1.11)
// Tolerate if the update window exceeded by one
if (newValue == 0x80000000L)

{ newValue = Integer.MAX_VALUE; }

//TODO: needs to be removed

if (Math.abs(newValue) > 0x7fffffffL)

{ throw new ArithmeticException("Update causes flow control window to exceed " + Integer.MAX_VALUE); }

if (window.compareAndSet(current, (int) newValue))

{ return (int) newValue; }

}
}