ring: make ring.Buffer generic

[ajwerner]

Epic: none

Release note: None

[cockroach-teamcity]

This change is 

[andreimatei]

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

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pkg/util/tracing/crdbspan.go line 157 at r4 (raw file):

	// verbose recording because of the span limit) are not part of this buffer;
	// they're in finishedChildren.Root.StructuredRecords.
	structured sizeLimitedBuffer[*tracingpb.StructuredRecord]

do these need to be pointers any more or were they only pointer because they had to be boxed in interface{} anyway?

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pkg/util/tracing/tracer.go line 970 at r4 (raw file):

	tagsAlloc             [3]attribute.KeyValue
	childrenAlloc         [4]childRef
	structuredEventsAlloc [3]*tracingpb.StructuredRecord

do

[ajwerner]

Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @andreimatei)

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pkg/util/tracing/crdbspan.go line 157 at r4 (raw file):

Previously, andreimatei (Andrei Matei) wrote…

do these need to be pointers any more or were they only pointer because they had to be boxed in interface{} anyway?

I think they want to be pointers because the protoutil.Message interface is implemented on the pointer and they're constructed as pointers, no? Also, for better or for worse, the ring.Buffer doesn't have a mechanism to get a pointer into the buffer itself. If it did you'd have to be careful about lifecycles. I think it's better to leave them as pointers in this PR.

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pkg/util/tracing/tracer.go line 970 at r4 (raw file):

Previously, andreimatei (Andrei Matei) wrote…

do

?

[andreimatei]

Reviewable status: complete! 1 of 0 LGTMs obtained

[ajwerner]

TFTR!

bors r+

[craig]

Build failed (retrying...):

• Bazel Essential CI (Cockroach)

[craig]

Build succeeded:

• Bazel Essential CI (Cockroach)