context: Always call returned cancel funcs

[cryptix]

This PR follows up on #822.

• core/commands/id.go: ctx, _ := context.WithTimeout(context.TODO(), time.Second*5)
• core/commands/ping.go: ctx, _ := context.WithTimeout(ctx, kPingTimeout)
• core/commands/ping.go: ctx, _ := context.WithTimeout(ctx, kPingTimeout)
• core/corenet/net.go: ctx, _ := context.WithTimeout(nd.Context(), time.Second*30)
• diagnostics/diag.go: ctx, _ := context.WithTimeout(context.TODO(), timeout)
• exchange/bitswap/bitswap.go: child, _ := context.WithTimeout(ctx, providerRequestTimeout)
• exchange/bitswap/bitswap.go: hasBlockCtx, _ := context.WithTimeout(ctx, hasBlockTimeout)
• merkledag/merkledag.go: ctx, _ := context.WithTimeout(context.TODO(), time.Minute)
• namesys/publisher.go: timectx, _ := context.WithDeadline(ctx, time.Now().Add(time.Second*10))
• p2p/net/swarm/swarm_dial.go: ctxT, _ := context.WithTimeout(ctx, s.dialT)
• pin/pin.go: ctx, _ := context.WithTimeout(context.Background(), time.Second*60)
• routing/dht/dht.go: ctx, _ := context.WithTimeout(dht.Context(), time.Second*5)
• unixfs/tar/reader.go: ctx, _ := context.WithTimeout(context.TODO(), time.Second*60)

[cryptix]

I guess 3e6effc cancels in the wrong place.

==================
WARNING: DATA RACE
Write by goroutine 149:
  sync.raceWrite()
      /usr/local/go/src/pkg/sync/race.go:41 +0x35
  sync.(*WaitGroup).Wait()
      /usr/local/go/src/pkg/sync/waitgroup.go:122 +0x176
  github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-ctxgroup.(*contextGroup).closeLogic()
      /workspace/race/src/github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-ctxgroup/ctxgroup.go:202 +0xba
  github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-ctxgroup.*contextGroup.(github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-ctxgroup.closeLogic)��fm()
      /workspace/race/src/github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-ctxgroup/ctxgroup.go:192 +0x33
  sync.(*Once).Do()
      /usr/local/go/src/pkg/sync/once.go:40 +0xb1

Previous read by goroutine 121:
  sync.raceRead()
      /usr/local/go/src/pkg/sync/race.go:37 +0x35
  sync.(*WaitGroup).Add()
      /usr/local/go/src/pkg/sync/waitgroup.go:60 +0xbe
  github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-ctxgroup.(*contextGroup).AddChildFunc()
      /workspace/race/src/github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-ctxgroup/ctxgroup.go:168 +0x4d
  github.com/jbenet/go-ipfs/routing/dht.(*dhtQueryRunner).Run()
      /workspace/race/src/github.com/jbenet/go-ipfs/routing/dht/query.go:110 +0x45d
  github.com/jbenet/go-ipfs/routing/dht.(*dhtQuery).Run()
      /workspace/race/src/github.com/jbenet/go-ipfs/routing/dht/query.go:59 +0xe1
  github.com/jbenet/go-ipfs/routing/dht.func��009()
      /workspace/race/src/github.com/jbenet/go-ipfs/routing/dht/lookup.go:83 +0x119

Goroutine 149 (running) created at:
  github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-ctxgroup.(*contextGroup).internalClose()
      /workspace/race/src/github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-ctxgroup/ctxgroup.go:192 +0x92
  github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-ctxgroup.(*contextGroup).closeOnContextDone()
      /workspace/race/src/github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-ctxgroup/ctxgroup.go:211 +0xa9

Goroutine 121 (running) created at:
  github.com/jbenet/go-ipfs/routing/dht.(*IpfsDHT).GetClosestPeers()
      /workspace/race/src/github.com/jbenet/go-ipfs/routing/dht/lookup.go:87 +0xa24
  github.com/jbenet/go-ipfs/routing/dht.(*IpfsDHT).Provide()
      /workspace/race/src/github.com/jbenet/go-ipfs/routing/dht/routing.go:151 +0x342
  github.com/jbenet/go-ipfs/exchange/bitswap/network.(*impl).Provide()
      /workspace/race/src/github.com/jbenet/go-ipfs/exchange/bitswap/network/ipfs_impl.go:138 +0xa8
  github.com/jbenet/go-ipfs/exchange/bitswap.(*Bitswap).provideWorker()
      /workspace/race/src/github.com/jbenet/go-ipfs/exchange/bitswap/workers.go:72 +0x2c8
  github.com/jbenet/go-ipfs/exchange/bitswap.func��013()
      /workspace/race/src/github.com/jbenet/go-ipfs/exchange/bitswap/workers.go:37 +0x6e
  github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/goprocess.func��005()
      /workspace/race/src/github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/goprocess/impl-mutex.go:96 +0xa8
==================
2015-03-07 11:01:13.291539 ERROR bitswap <autogenerated>:24: context canceled
2015-03-07 11:01:13.292278 ERROR bitswap <autogenerated>:24: context canceled
2015-03-07 11:02:58.251986 CRITICAL boguskey <autogenerated>:21: TestBogusPrivateKey.Sign -- this better be a test!
PASS
Found 1 data race(s)
FAIL    github.com/jbenet/go-ipfs/test/integration  288.244s

src

[jbenet]

@cryptix yeah im doing it the hard way (proc)

[cryptix]

still faults with same race. Need some insight here - maybe FindProvidersAsync() has to cancel - cc @whyrusleeping

[jbenet]

@cryptix oh!! thats the race im fixing in #877 -- i thought you had rebase on top of mine. im about to push a fix

[cryptix]

not sure - i rebased on master, is it in there?

[jbenet]

@cryptix no not yet-- a few min. its in tests now, i think i got it this time around. want to CR it? #877

[jbenet]

#877 landed-- you can rebase now

[cryptix]

@jbenet perfect, all green! 😄. not sure if i can move the cancel() back up before the <-done. waiting for @whyrusleeping

[jbenet]

@cryptix this LGTM so far. also not sure about moving the cancel() before <-done.

[cryptix]

not sure about moving the cancel() before <-done.

I reseted to the commit before - race tests passed, looks like #877 fixed this one.

[jbenet]

@cryptix yay :)

[jbenet]

@cryptix @whyrusleeping though i merged-- pls CR!

[cryptix]

LGTM