Add support for pipelined_get in Dalli meta protocol instrumentation

[genya0407]

Is your feature request related to a problem? Please describe.

When using Dalli (v3.2.0+) with the meta protocol enabled, the pipelined_get method is not currently instrumented.

Feature Description

Support pipelined_get instrumentation for meta protocol for Dalli instrumentation.
It appears that updating the following code would solve this.

newrelic-ruby-agent/lib/new_relic/agent/instrumentation/memcache/dalli.rb

Lines 54 to 58 in 0c49161

	if supports_binary_protocol?
	::Dalli::Protocol::Binary
	else
	::Dalli::Server
	end.class_eval do

For example:

if supports_meta_protocol? # check Dalli's version is larger than or equal to 3.2.0
  ::Dalli::Protocol::Base # with this, both meta and binary protocol are instrumented
elsif supports_binary_protocol?
  ::Dalli::Protocol::Binary
else
  ::Dalli::Server
end.class_eval do

Describe Alternatives

• Implementing monkey patches in the user's project
• Using binary protocol
  • Note: Since AWS Elasticache does not support the binary protocol, it is impossible to switch protocols when using it.

Additional context

I see that the meta protocol is not currently supported, so this problem might be a known issue.

• Support Dalli 5.0 #3446
• Add support for Dalli::Protocol::Meta #3131

Priority

Nice to Have

[Newrelic-Boomi]

https://new-relic.atlassian.net/browse/NR-523033

[kaylareopelle]

Hi @genya0407! Thank you for bringing this to our attention. We let this slip by the wayside, and I appreciate you opening an issue for it. We have some work to do on Dalli to support 5.0 and we can consider this when we pick up that initiative. We'll keep you posted when we start looking into it and may reach out with some questions.