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Return string for trace_id and span_id from Correlation::Identifier #3322

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merged 8 commits into from
Jan 26, 2024
Merged

Return string for trace_id and span_id from Correlation::Identifier #3322

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92fbc34
Return string for trace id
TonyCTHsu Dec 12, 2023
2735aea
Return string for span id
TonyCTHsu Dec 12, 2023
5849dc8
Use `Datadog::Tracing::Utils::TraceId.next_id` in test
TonyCTHsu Dec 12, 2023
996bba3
Fix tracer spec
TonyCTHsu Dec 12, 2023
c8bf1dc
Merge branch '2.0' into tonycthsu/correlation-string
TonyCTHsu Jan 23, 2024
988934b
Remove redundant fields
TonyCTHsu Jan 23, 2024
48c8b77
Fix removed span_id in test
TonyCTHsu Jan 24, 2024
5e1a480
Lint
TonyCTHsu Jan 24, 2024
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35 changes: 4 additions & 31 deletions lib/datadog/tracing/correlation.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,8 @@ module Datadog
module Tracing
# Contains behavior for managing correlations with tracing
# e.g. Retrieve a correlation to the current trace for logging, etc.
# This class is for usage with log correlation.
# To continue from a trace, users should use TraceDigest instead.
module Correlation
# Represents current trace state with key identifiers
# @public_api
Expand All @@ -21,42 +23,21 @@ class Identifier
:env,
:service,
:span_id,
:span_name,
:span_resource,
:span_service,
:span_type,
:trace_name,
:trace_resource,
:trace_service,
:version

# @!visibility private
def initialize(
env: nil,
service: nil,
span_id: nil,
span_name: nil,
span_resource: nil,
span_service: nil,
span_type: nil,
trace_id: nil,
trace_name: nil,
trace_resource: nil,
trace_service: nil,
version: nil
)
# Dup and freeze strings so they aren't modified by reference.
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Let's document that "this class is for usage with log correlation. To continue from a trace, users should use TraceDigest instead."

@env = Core::Utils::SafeDup.frozen_dup(env || Datadog.configuration.env)
@service = Core::Utils::SafeDup.frozen_dup(service || Datadog.configuration.service)
@span_id = span_id || 0
@span_name = Core::Utils::SafeDup.frozen_dup(span_name)
@span_resource = Core::Utils::SafeDup.frozen_dup(span_resource)
@span_service = Core::Utils::SafeDup.frozen_dup(span_service)
@span_type = Core::Utils::SafeDup.frozen_dup(span_type)
@span_id = (span_id || 0).to_s
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@TonyCTHsu I don't remember: why are we converting the numbers to strings?

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@marcotc's question suggests that we should include that in the release notes somewhere.

Apparently, Ruby integers can natively handle 128-bit numbers, so I agree. It's not clear why we need to convert them to strings.

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@marcotc @ekump The value returned by those methods are meant to be injected into log entries.

Hence, returning string instead of integer provides finer control for implementing different encoding.

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The value returned by those methods are meant to be injected into log entries

Is that the only supported use for the return value? This is part of the public API, so should we be considering more generic usage?

Generally speaking, I don't think public API methods should be too opinionated on what is done with their return values (within reason) and we should be returning values as the types that best reflect what they are. This contributes to an API being predictable and intuitive for an engineer to use. If I know trace_ids are 128-bit integers, and I see a method called trace_id I would assume/expect it to return an integer.

It should be the responsibility of the calling method to convert it to a string and/or encode it a particular way unless we have a good reason to do otherwise.

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@ekump we have the method #to_log_format which is a helper method you use when you want to inject the correlation into your logs safely, that method is opinionated.

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@marcotc marcotc Dec 15, 2023 •
edited
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Here an interesting bit, OTel uses 128-bit trace ids as well, but it represents them as 16-char strings.
OTel always passes these 16 bytes around or, if needed to be converted to a printable string, converts it to hex representation.

@trace_id = trace_id || 0
@trace_name = Core::Utils::SafeDup.frozen_dup(trace_name)
@trace_resource = Core::Utils::SafeDup.frozen_dup(trace_resource)
@trace_service = Core::Utils::SafeDup.frozen_dup(trace_service)
@version = Core::Utils::SafeDup.frozen_dup(version || Datadog.configuration.version)
end

Expand Down Expand Up @@ -90,13 +71,12 @@ def to_log_format
end
end

# DEV-2.0: This public method was returning an Integer, but with 128 bit trace id it would return a String.
def trace_id
if Datadog.configuration.tracing.trace_id_128_bit_logging_enabled &&
!Tracing::Utils::TraceId.to_high_order(@trace_id).zero?
Kernel.format('%032x', @trace_id)
else
Tracing::Utils::TraceId.to_low_order(@trace_id)
Tracing::Utils::TraceId.to_low_order(@trace_id).to_s
end
end
end
Expand All @@ -113,14 +93,7 @@ def identifier_from_digest(digest)

Identifier.new(
span_id: digest.span_id,
span_name: digest.span_name,
span_resource: digest.span_resource,
span_service: digest.span_service,
span_type: digest.span_type,
trace_id: digest.trace_id,
trace_name: digest.trace_name,
trace_resource: digest.trace_resource,
trace_service: digest.trace_service
)
end
end
Expand Down
81 changes: 16 additions & 65 deletions spec/datadog/tracing/correlation_spec.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -46,15 +46,8 @@
expect(identifier).to have_attributes(
env: default_env,
service: default_service,
span_id: 0,
span_name: nil,
span_resource: nil,
span_service: nil,
span_type: nil,
trace_id: 0,
trace_name: nil,
trace_resource: nil,
trace_service: nil,
span_id: '0',
trace_id: '0',
version: default_version
)
end
Expand Down Expand Up @@ -88,29 +81,15 @@
expect(identifier).to have_attributes(
env: default_env,
service: default_service,
span_id: span_id,
span_name: span_name,
span_resource: span_resource,
span_service: span_service,
span_type: span_type,
trace_id: low_order_trace_id(trace_id),
trace_name: trace_name,
trace_resource: trace_resource,
trace_service: trace_service,
span_id: span_id.to_s,
trace_id: low_order_trace_id(trace_id).to_s,
version: default_version
)
end

it 'has frozen copies of strings' do
expect(identifier.env).to be_a_frozen_copy_of(default_env)
expect(identifier.service).to be_a_frozen_copy_of(default_service)
expect(identifier.span_name).to be_a_frozen_copy_of(span_name)
expect(identifier.span_resource).to be_a_frozen_copy_of(span_resource)
expect(identifier.span_service).to be_a_frozen_copy_of(span_service)
expect(identifier.span_type).to be_a_frozen_copy_of(span_type)
expect(identifier.trace_name).to be_a_frozen_copy_of(trace_name)
expect(identifier.trace_resource).to be_a_frozen_copy_of(trace_resource)
expect(identifier.trace_service).to be_a_frozen_copy_of(trace_service)
expect(identifier.version).to be_a_frozen_copy_of(default_version)
end
end
Expand All @@ -125,15 +104,8 @@
expect(identifier).to have_attributes(
env: default_env,
service: default_service,
span_id: 0,
span_name: nil,
span_resource: nil,
span_service: nil,
span_type: nil,
trace_id: 0,
trace_name: nil,
trace_resource: nil,
trace_service: nil,
span_id: '0',
trace_id: '0',
version: default_version
)
end
Expand All @@ -153,14 +125,7 @@
env: env,
service: service,
span_id: span_id,
span_name: span_name,
span_resource: span_resource,
span_service: span_service,
span_type: span_type,
trace_id: trace_id,
trace_name: trace_name,
trace_resource: trace_resource,
trace_service: trace_service,
version: version
)
end
Expand All @@ -169,29 +134,15 @@
expect(identifier).to have_attributes(
env: env,
service: service,
span_id: span_id,
span_name: span_name,
span_resource: span_resource,
span_service: span_service,
span_type: span_type,
trace_id: low_order_trace_id(trace_id),
trace_name: trace_name,
trace_resource: trace_resource,
trace_service: trace_service,
span_id: span_id.to_s,
trace_id: low_order_trace_id(trace_id).to_s,
version: version
)
end

it 'has frozen copies of strings' do
expect(identifier.env).to be_a_frozen_copy_of(env)
expect(identifier.service).to be_a_frozen_copy_of(service)
expect(identifier.span_name).to be_a_frozen_copy_of(span_name)
expect(identifier.span_resource).to be_a_frozen_copy_of(span_resource)
expect(identifier.span_service).to be_a_frozen_copy_of(span_service)
expect(identifier.span_type).to be_a_frozen_copy_of(span_type)
expect(identifier.trace_name).to be_a_frozen_copy_of(trace_name)
expect(identifier.trace_resource).to be_a_frozen_copy_of(trace_resource)
expect(identifier.trace_service).to be_a_frozen_copy_of(trace_service)
expect(identifier.version).to be_a_frozen_copy_of(version)
end
end
Expand Down Expand Up @@ -509,22 +460,22 @@ def have_attribute(attribute)
context 'when given 64 bit trace id' do
it 'returns to lower 64 bits of trace id' do
trace_id = 0xaaaaaaaaaaaaaaaa
expected_trace_id = 0xaaaaaaaaaaaaaaaa

identifier = described_class.new(trace_id: trace_id)

expect(identifier.trace_id).to eq(expected_trace_id)
# `0xaaaaaaaaaaaaaaaa.to_s` => '12297829382473034410'
expect(identifier.trace_id).to eq('12297829382473034410')
end
end

context 'when given 128 bit trace id' do
it 'returns to lower 64 bits of trace id' do
trace_id = 0xaaaaaaaaaaaaaaaaffffffffffffffff
expected_trace_id = 0xffffffffffffffff

identifier = described_class.new(trace_id: trace_id)

expect(identifier.trace_id).to eq(expected_trace_id)
# `0xffffffffffffffff.to_s` => '18446744073709551615'
expect(identifier.trace_id).to eq('18446744073709551615')
end
end
end
Expand All @@ -537,11 +488,11 @@ def have_attribute(attribute)
context 'when given 64 bit trace id' do
it 'returns lower 64 bits of trace id' do
trace_id = 0xaaaaaaaaaaaaaaaa
expected_trace_id = 0xaaaaaaaaaaaaaaaa

identifier = described_class.new(trace_id: trace_id)

expect(identifier.trace_id).to eq(expected_trace_id)
# `0xaaaaaaaaaaaaaaaa.to_s` => '12297829382473034410'
expect(identifier.trace_id).to eq('12297829382473034410')
end
end

Expand All @@ -559,11 +510,11 @@ def have_attribute(attribute)
context 'when given > 64 bit trace id but high order is 0' do
it 'returns to lower 64 bits of trace id' do
trace_id = 0x00000000000000000aaaaaaaaaaaaaaaa
expected_trace_id = 0xaaaaaaaaaaaaaaaa

identifier = described_class.new(trace_id: trace_id)

expect(identifier.trace_id).to eq(expected_trace_id)
# `0xaaaaaaaaaaaaaaaa.to_s` => '12297829382473034410'
expect(identifier.trace_id).to eq('12297829382473034410')
end
end
end
Expand Down
8 changes: 4 additions & 4 deletions spec/datadog/tracing/tracer_spec.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -739,16 +739,16 @@
it 'produces an Identifier with data' do
is_expected.to be_a_kind_of(Datadog::Tracing::Correlation::Identifier)
expect(active_correlation.trace_id)
.to eq(low_order_trace_id(span.trace_id))
expect(active_correlation.span_id).to eq(span.id)
.to eq(low_order_trace_id(span.trace_id).to_s)
expect(active_correlation.span_id).to eq(span.id.to_s)
end
end

context 'when no trace is active' do
it 'produces an empty Identifier' do
is_expected.to be_a_kind_of(Datadog::Tracing::Correlation::Identifier)
expect(active_correlation.trace_id).to eq 0
expect(active_correlation.span_id).to eq 0
expect(active_correlation.trace_id).to eq '0'
expect(active_correlation.span_id).to eq '0'
end
end

Expand Down
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