interfaceHash reads too far into data
anacrolix opened this issue · comments
interfaceHash calls fmt.Sprintf("%v", x) which can cause it to read into mutable data triggering the race detector. The hashing used by Go's built-in map key types would be more appropriate (for instance pointer types would just use a hash of the pointer value). I tried to implement this using Go's internal interhash, but it just triggers nil deference errors that I couldn't figure out.
Here's how I tried to use interhash: anacrolix@70355c2
Hi,
Great thinking! I think the problem was that it is an empty interface,
which is a special case in the runtime. So, you need to use
nilinterhash instead.
See
https://github.com/teh-cmc/go-internals/blob/master/chapter2_interfaces/README.md#the-empty-interface
I pushed a new commit on master with the update:
80d0820
Please let me know what the race detector thinks.
Thanks!
// Tobias
Den fre 25 okt. 2019 kl 02:42 skrev Matt Joiner <notifications@github.com>:
… Here's how I tried to use interhash: ***@***.***
<anacrolix@70355c2>
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The race detector seems happy, and all my tests are passing. I'm not sure why it needed to handle the nil case.
I think the problem is that eface does not have the tab element that is
present on iface so interhash would crash on line 142 here:
https://golang.org/src/runtime/alg.go
Den fre 25 okt. 2019 kl 12:29 skrev Matt Joiner <notifications@github.com>:
… The race detector seems happy, and all my tests are passing. I'm not sure
why it needed to handle the nil case.
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Fantastic, thanks!