perf(mux) use RWMutex

[btc]

@jbenet

[jbenet]

i dont think that was mine? maybe.

[whyrusleeping]

Uhmm.... dont do that. RWMutexes Standard lock operation takes twice as long as a normal mutex. The only proper use case for it is frequent reads with infrequent writes, GetBandwidth will be called rather infrequently.

[whyrusleeping]

confusing branch name too, lol. Today is still the 27th...

[btc]

Uhmm.... dont do that. RWMutexes Standard lock operation takes twice as long as a normal mutex. The only proper use case for it is frequent reads with infrequent writes, GetBandwidth will be called rather infrequently.

Ah. I didn't know that.

confusing branch name too, lol. Today is still the 27th...

And (omg), I started naming branches 2014-10-28 last night.

[btc]

reverted

#219

[jbenet]

RWMutexes Standard lock operation takes twice as long as a normal mutex.

@whyrusleeping where did you get this stat from?

GetBandwidth will be called rather infrequently.

watch this not be true later on :] maybe add a note referencing this conversation.

[whyrusleeping]

Take a look at the source:

RWMutex:
http://golang.org/src/pkg/sync/rwmutex.go?s=1966:1991#L62

Mutex:
http://golang.org/src/pkg/sync/mutex.go?s=1078:1100#L31

And also run some benchmarks.
The RWMutex does more work than the standard mutex, and also uses a standard mutex internally to protect the waitcounts which allows it to starve out readers.

[whyrusleeping]

Also, unless we are checking the bandwidth way more often than we are receiving a packet, this will still hold true.