Re: [JGIT PATCH 2/2] Allow core.packedGitLimit to exceed "2 g"

From: Shawn O. Pearce <spearce@spearce.org>
Date: Jun 13, 2009, 19:19 UTC
Message-ID: <20090613191943.GS16497@spearce.org>
In-Reply-To: <4A335B9A.7080808@pelagic.nl>

Ferry Huberts <ferry.huberts@pelagic.nl> wrote:

> Shawn O. Pearce wrote:
> > A 64 bit JVM might actually be able to dedicate more than 2 GiB of

Please don't quote everything if you are only replying to a tiny part.

Show 15 quoted lines

> >  	private static int tableSize(final WindowCacheConfig cfg) {
> >  		final int wsz = cfg.getPackedGitWindowSize();
> > -		final int limit = cfg.getPackedGitLimit();
> > +		final long limit = cfg.getPackedGitLimit();
> >  		if (wsz <= 0)
> >  			throw new IllegalArgumentException("Invalid window size");
> >  		if (limit < wsz)
> >  			throw new IllegalArgumentException("Window size must be < limit");
> > -		return 5 * (limit / wsz) / 2;
> > +		return (int) Math.min(5 * (limit / wsz) / 2, 2000000000);
> 
> Math.min returns a long because the prototype Math.min(long,long) will
> be chosen. The cast can then overflow and fail. Better change the return
> type to a long:
> + return Math.min(5 * (limit / wsz) / 2, 2000000000L);

If you looked at that, 2,000,000,000 is within the range of an int. We select the smallest value. The first argument expression is computed as a long, so we shouldn't ever overflow and cause the first argument to be negative. If the first argument is larger than 2 billion, then it does risk overflow, but the 2nd argument is smaller, so it is returned.

The code is fine as is.

-- 
Shawn.