fix: Update max instrument length from 63 to 255 (#1883)

* fix: Update max instrument length from 63 to 255

The current specification states that the max instrument length is 255
chars:
https://opentelemetry.io/docs/specs/otel/metrics/api/#instrument-name-syntax

This commit updates the Ruby sdk to reflect this!

* Update metrics_api/lib/opentelemetry/metrics/meter.rb

Co-authored-by: Kayla Reopelle <[email protected]>

* Update metrics_sdk/lib/opentelemetry/sdk/metrics/meter.rb

Co-authored-by: Kayla Reopelle <[email protected]>

* Update metrics_sdk/test/opentelemetry/sdk/metrics/meter_test.rb

Co-authored-by: Kayla Reopelle <[email protected]>

* Include forward slash in instrument name test

* Use percent literal for regexes with forward slash

* Remove redundant escape inside regex literal

---------

Co-authored-by: Kayla Reopelle <[email protected]>

Author: nat-sch

metrics_api/lib/opentelemetry/metrics/meter.rb

@@ -16,7 +16,7 @@ class Meter
       UP_DOWN_COUNTER = Instrument::UpDownCounter.new
       OBSERVABLE_UP_DOWN_COUNTER = Instrument::ObservableUpDownCounter.new
 
-      NAME_REGEX = /\A[a-zA-Z][-.\w]{0,62}\z/
+      NAME_REGEX = %r{\A[a-zA-Z][-./\w]{0,254}\z}
 
       private_constant(:COUNTER, :OBSERVABLE_COUNTER, :HISTOGRAM, :GAUGE, :OBSERVABLE_GAUGE, :UP_DOWN_COUNTER, :OBSERVABLE_UP_DOWN_COUNTER)
 

metrics_sdk/lib/opentelemetry/sdk/metrics/meter.rb

@@ -11,7 +11,7 @@ module SDK
     module Metrics
       # {Meter} is the SDK implementation of {OpenTelemetry::Metrics::Meter}.
       class Meter < OpenTelemetry::Metrics::Meter
-        NAME_REGEX = /\A[a-zA-Z][-.\w]{0,62}\z/
+        NAME_REGEX = %r{\A[a-zA-Z][-./\w]{0,254}\z}
 
         # @api private
         #

metrics_sdk/test/opentelemetry/sdk/metrics/meter_test.rb

@@ -185,14 +185,14 @@
       _(-> { meter.create_counter('1_counter') }).must_raise(INSTRUMENT_NAME_ERROR)
     end
 
-    it 'instrument name must not exceed 63 character limit' do
-      long_name = 'a' * 63
+    it 'instrument name must not exceed 255 character limit' do
+      long_name = 'a' * 255
       meter.create_counter(long_name)
       _(-> { meter.create_counter(long_name + 'a') }).must_raise(INSTRUMENT_NAME_ERROR)
     end
 
-    it 'instrument name must belong to alphanumeric characters, _, ., and -' do
-      meter.create_counter('a_-..-_a')
+    it 'instrument name must belong to alphanumeric characters, _, ., -, and /' do
+      meter.create_counter('a_/-..-/_a')
       _(-> { meter.create_counter('a@') }).must_raise(INSTRUMENT_NAME_ERROR)
       _(-> { meter.create_counter('a!') }).must_raise(INSTRUMENT_NAME_ERROR)
     end