[ccache] globally unique hashes

[Reuben Hawkins]

Hi ccache developers,

I was wondering if the hash values generated by ccache are globally unique.
I was thinking about adding a multicast feature where after not finding a
cached object file in the local cache, but before trying to compile the
file, ccache will multicast to it's neighbors the hash value to see if
another local machine has the cached object file corresponding the the hash
value.  For this to work, however, I would think the hash values MUST be
globally unique across platforms and compilers.  Is that the case?

BTW, the reason for this feature is...

a) I've been assigned a 5 day project to do whatever I'm interested in
b) our computer all do nightly builds and build throughout the day, but
headers are now changing so frequently that local caches are marginalized
c) distcc takes too much configuration/coordination, however, multicasting
takes zero configuration/coordination

Thanks in advance,
Reuben