Unify dropping approach on over limited span

[XSAM]

The SDK will discard attributes, links and events if they beyond the configured limit, but we have different approaches in SDK.

It drops the oldest attributes, links and events.

opentelemetry-go/sdk/trace/span.go

Lines 545 to 547 in 0fe65e6

	span.attributes = newAttributesMap(cfg.SpanLimits.AttributeCountLimit)
	span.messageEvents = newEvictedQueue(cfg.SpanLimits.EventCountLimit)
	span.links = newEvictedQueue(cfg.SpanLimits.LinkCountLimit)

But drop the newest attributes in events and links.

opentelemetry-go/sdk/trace/span.go

Lines 303 to 307 in 0fe65e6

	// Discard over limited attributes
	if len(c.Attributes) > s.spanLimits.AttributePerEventCountLimit {
	s.addDroppedAttributeCount(len(c.Attributes) - s.spanLimits.AttributePerEventCountLimit)
	c.Attributes = c.Attributes[:s.spanLimits.AttributePerEventCountLimit]
	}

opentelemetry-go/sdk/trace/span.go

Lines 433 to 437 in 0fe65e6

	// Discard over limited attributes
	if len(link.Attributes) > s.spanLimits.AttributePerLinkCountLimit {
	s.addDroppedAttributeCount(len(link.Attributes) - s.spanLimits.AttributePerLinkCountLimit)
	link.Attributes = link.Attributes[:s.spanLimits.AttributePerLinkCountLimit]
	}

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Though the specification does not describe how to discard over limited data on span, I think we need to unify our dropping approach at least to prevent "random drop".

I slightly prefer this comment, which suggests we should drop the newest data.

[MrAlias]

Removing the "help wanted" until we have consensus on a solution.

FWIW, I as well prefer the "drop newest data" approach as well described in the linked comment. Particularly because "the attributes required for "identifying" the traced operation are usually set at the very beginning of a span".

[github-actions]

This issue has been closed as inactive because it has been stale for 2 years with no activity.