syncutil: add AssertRHeld methods to RWMutex implementations

[nvb]

This mirrors the AssertHeld methods we have on these mutexes and extends them for read locks. These serve as both a useful assertion and good documentation (because they compile away for real builds).

#39119 reminded me that I had been sitting on this commit since June as part of a larger change that won't be making it in any time soon.

Release note: None

[cockroach-teamcity]

This change is 

[ajwerner]

Reviewed 4 of 4 files at r1.
Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @nvanbenschoten)

---

pkg/util/syncutil/mutex_sync_race_test.go, line 70 at r1 (raw file):

	m.Unlock()

	func() {

If you feel like adopting require this could be:

require.PanicsWithValue(t, "mutex is not read locked", m.AssertRHeld)

[nvb]

bors r=ajwerner

Reviewable status: complete! 0 of 0 LGTMs obtained (and 1 stale) (waiting on @ajwerner)

---

pkg/util/syncutil/mutex_sync_race_test.go, line 70 at r1 (raw file):

Previously, ajwerner wrote…

If you feel like adopting require this could be:

require.PanicsWithValue(t, "mutex is not read locked", m.AssertRHeld)

Nice! Done.

[craig]

Build failed (retrying...)

• GitHub CI (Cockroach)

[nvb]

bors r-

Write at 0x00c000b2cdfc by goroutine 178:
  sync/atomic.AddInt32()
      /usr/local/go/src/runtime/race_amd64.s:269 +0xb
  github.com/cockroachdb/cockroach/pkg/util/syncutil.(*RWMutex).RLock()
      /go/src/github.com/cockroachdb/cockroach/pkg/util/syncutil/mutex_sync_race.go:75 +0x54
  github.com/cockroachdb/cockroach/pkg/config.(*SystemConfig).getZoneEntry()
      /go/src/github.com/cockroachdb/cockroach/pkg/config/system.go:299 +0x5e
  github.com/cockroachdb/cockroach/pkg/config.(*SystemConfig).getZoneConfigForKey()
      /go/src/github.com/cockroachdb/cockroach/pkg/config/system.go:334 +0x5e
  github.com/cockroachdb/cockroach/pkg/config.(*SystemConfig).GetZoneConfigForKey()
      /go/src/github.com/cockroachdb/cockroach/pkg/config/system.go:279 +0x159
  github.com/cockroachdb/cockroach/pkg/storage.(*Store).systemGossipUpdate.func2()
      /go/src/github.com/cockroachdb/cockroach/pkg/storage/store.go:1698 +0xf6
  github.com/cockroachdb/cockroach/pkg/storage.(*storeReplicaVisitor).Visit()
      /go/src/github.com/cockroachdb/cockroach/pkg/storage/store.go:350 +0x2e2
  github.com/cockroachdb/cockroach/pkg/storage.(*Store).systemGossipUpdate()
      /go/src/github.com/cockroachdb/cockroach/pkg/storage/store.go:1696 +0x23c
  github.com/cockroachdb/cockroach/pkg/storage.(*Store).Start.func2()
      /go/src/github.com/cockroachdb/cockroach/pkg/storage/store.go:1409 +0x95
  github.com/cockroachdb/cockroach/pkg/util/stop.(*Stopper).RunWorker.func1()
      /go/src/github.com/cockroachdb/cockroach/pkg/util/stop/stopper.go:196 +0x15f

Previous read at 0x00c000b2cdfc by goroutine 156:
  reflect.typedmemmove()
      /usr/local/go/src/runtime/mbarrier.go:177 +0x0
  reflect.packEface()
      /usr/local/go/src/reflect/value.go:119 +0x104
  reflect.valueInterface()
      /usr/local/go/src/reflect/value.go:1009 +0x170
  reflect.deepValueEqual()
      /usr/local/go/src/reflect/deepequal.go:132 +0xa61
  reflect.deepValueEqual()
      /usr/local/go/src/reflect/deepequal.go:101 +0xc7a
  reflect.deepValueEqual()
      /usr/local/go/src/reflect/deepequal.go:101 +0xc7a
  reflect.deepValueEqual()
      /usr/local/go/src/reflect/deepequal.go:101 +0xc7a
  reflect.deepValueEqual()
      /usr/local/go/src/reflect/deepequal.go:98 +0x1866
  reflect.DeepEqual()
      /usr/local/go/src/reflect/deepequal.go:196 +0x2f1
  github.com/cockroachdb/cockroach/pkg/storage_test.TestStoreGossipSystemData.func4()
      /go/src/github.com/cockroachdb/cockroach/pkg/storage/client_lease_test.go:208 +0x1f5
  github.com/cockroachdb/cockroach/pkg/testutils.SucceedsSoonError.func1()
      /go/src/github.com/cockroachdb/cockroach/pkg/testutils/soon.go:48 +0x52
  github.com/cockroachdb/cockroach/pkg/util/retry.ForDuration()
      /go/src/github.com/cockroachdb/cockroach/pkg/util/retry/retry.go:184 +0xf4
  github.com/cockroachdb/cockroach/pkg/testutils.SucceedsSoonError()
      /go/src/github.com/cockroachdb/cockroach/pkg/testutils/soon.go:54 +0x11a
  github.com/cockroachdb/cockroach/pkg/testutils.SucceedsSoon()
      /go/src/github.com/cockroachdb/cockroach/pkg/testutils/soon.go:34 +0x59
  github.com/cockroachdb/cockroach/pkg/storage_test.TestStoreGossipSystemData()
      /go/src/github.com/cockroachdb/cockroach/pkg/storage/client_lease_test.go:207 +0xbcf
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:865 +0x163

[craig]

Canceled

[nvb]

bors r+

[craig]

Build succeeded

• GitHub CI (Cockroach)