196 lines
6.9 KiB
Ruby
196 lines
6.9 KiB
Ruby
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# frozen_string_literal: true
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module Jaeger
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class Tracer
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def initialize(reporter:, sampler:, injectors:, extractors:)
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@reporter = reporter
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@sampler = sampler
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@injectors = injectors
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@extractors = extractors
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@scope_manager = ScopeManager.new
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end
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# @return [ScopeManager] the current ScopeManager, which may be a no-op
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# but may not be nil.
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attr_reader :scope_manager
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# @return [Span, nil] the active span. This is a shorthand for
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# `scope_manager.active.span`, and nil will be returned if
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# Scope#active is nil.
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def active_span
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scope = scope_manager.active
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scope.span if scope
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end
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# Starts a new span.
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#
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# This is similar to #start_active_span, but the returned Span will not
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# be registered via the ScopeManager.
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#
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# @param operation_name [String] The operation name for the Span
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# @param child_of [SpanContext, Span] SpanContext that acts as a parent to
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# the newly-started Span. If a Span instance is provided, its
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# context is automatically substituted. See [Reference] for more
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# information.
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#
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# If specified, the `references` parameter must be omitted.
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# @param references [Array<Reference>] An array of reference
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# objects that identify one or more parent SpanContexts.
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# @param start_time [Time] When the Span started, if not now
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# @param tags [Hash] Tags to assign to the Span at start time
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# @param ignore_active_scope [Boolean] whether to create an implicit
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# References#CHILD_OF reference to the ScopeManager#active.
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#
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# @return [Span] The newly-started Span
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def start_span(operation_name,
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child_of: nil,
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references: nil,
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start_time: Time.now,
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tags: {},
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ignore_active_scope: false,
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**)
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context, sampler_tags = prepare_span_context(
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operation_name: operation_name,
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child_of: child_of,
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references: references,
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ignore_active_scope: ignore_active_scope
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)
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Span.new(
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context,
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operation_name,
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@reporter,
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start_time: start_time,
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references: references,
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tags: tags.merge(sampler_tags)
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)
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end
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# Creates a newly started and activated Scope
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#
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# If the Tracer's ScopeManager#active is not nil, no explicit references
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# are provided, and `ignore_active_scope` is false, then an inferred
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# References#CHILD_OF reference is created to the ScopeManager#active's
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# SpanContext when start_active is invoked.
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#
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# @param operation_name [String] The operation name for the Span
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# @param child_of [SpanContext, Span] SpanContext that acts as a parent to
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# the newly-started Span. If a Span instance is provided, its
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# context is automatically substituted. See [Reference] for more
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# information.
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#
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# If specified, the `references` parameter must be omitted.
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# @param references [Array<Reference>] An array of reference
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# objects that identify one or more parent SpanContexts.
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# @param start_time [Time] When the Span started, if not now
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# @param tags [Hash] Tags to assign to the Span at start time
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# @param ignore_active_scope [Boolean] whether to create an implicit
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# References#CHILD_OF reference to the ScopeManager#active.
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# @param finish_on_close [Boolean] whether span should automatically be
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# finished when Scope#close is called
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# @yield [Scope] If an optional block is passed to start_active it will
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# yield the newly-started Scope. If `finish_on_close` is true then the
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# Span will be finished automatically after the block is executed.
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# @return [Scope] The newly-started and activated Scope
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def start_active_span(operation_name,
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child_of: nil,
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references: nil,
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start_time: Time.now,
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tags: {},
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ignore_active_scope: false,
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finish_on_close: true,
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**)
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span = start_span(
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operation_name,
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child_of: child_of,
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references: references,
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start_time: start_time,
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tags: tags,
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ignore_active_scope: ignore_active_scope
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)
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scope = @scope_manager.activate(span, finish_on_close: finish_on_close)
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if block_given?
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begin
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yield scope
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ensure
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scope.close
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end
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end
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scope
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end
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# Inject a SpanContext into the given carrier
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#
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# @param span_context [SpanContext]
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# @param format [OpenTracing::FORMAT_TEXT_MAP, OpenTracing::FORMAT_BINARY, OpenTracing::FORMAT_RACK]
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# @param carrier [Carrier] A carrier object of the type dictated by the specified `format`
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def inject(span_context, format, carrier)
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@injectors.fetch(format).each do |injector|
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injector.inject(span_context, carrier)
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end
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end
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# Extract a SpanContext in the given format from the given carrier.
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#
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# @param format [OpenTracing::FORMAT_TEXT_MAP, OpenTracing::FORMAT_BINARY, OpenTracing::FORMAT_RACK]
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# @param carrier [Carrier] A carrier object of the type dictated by the specified `format`
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# @return [SpanContext] the extracted SpanContext or nil if none could be found
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def extract(format, carrier)
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@extractors
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.fetch(format)
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.lazy
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.map { |extractor| extractor.extract(carrier) }
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.reject(&:nil?)
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.first
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end
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private
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def prepare_span_context(operation_name:, child_of:, references:, ignore_active_scope:)
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context =
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context_from_child_of(child_of) ||
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context_from_references(references) ||
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context_from_active_scope(ignore_active_scope)
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if context
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[SpanContext.create_from_parent_context(context), {}]
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else
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trace_id = TraceId.generate
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is_sampled, tags = @sampler.sample?(
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trace_id: trace_id,
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operation_name: operation_name
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)
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span_context = SpanContext.new(
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trace_id: trace_id,
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span_id: trace_id,
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flags: is_sampled ? SpanContext::Flags::SAMPLED : SpanContext::Flags::NONE
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)
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[span_context, tags]
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end
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end
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def context_from_child_of(child_of)
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return nil unless child_of
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child_of.respond_to?(:context) ? child_of.context : child_of
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end
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def context_from_references(references)
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return nil if !references || references.none?
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# Prefer CHILD_OF reference if present
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ref = references.detect do |reference|
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reference.type == OpenTracing::Reference::CHILD_OF
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end
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(ref || references[0]).context
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end
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def context_from_active_scope(ignore_active_scope)
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return if ignore_active_scope
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active_scope = @scope_manager.active
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active_scope.span.context if active_scope
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end
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end
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end
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