feat: add extract_from and extract_span_context

src/api/Project.toml

@@ -1,7 +1,7 @@
 name = "OpenTelemetryAPI"
 uuid = "4f63ef3d-5940-44e7-a611-2d97696cffc9"
 authors = ["Jun Tian <[email protected]>"]
-version = "0.5.1"
+version = "0.5.2"
 
 [deps]
 Dates = "ade2ca70-3891-5945-98fb-dc099432e06a"

src/api/ext/OpenTelemetryAPIHTTPExt.jl

@@ -216,8 +216,4 @@ function OpenTelemetryAPI.uninstrument!(::Val{:HTTP})
     )
 end
 
-function __init__()
-    println("$(@__MODULE__) is loaded!")
-end
-
 end

src/api/src/propagator/trace_context_textmap_propagator.jl

@@ -7,19 +7,30 @@ This propagator follows the [W3C format](https://www.w3.org/TR/trace-context/#tr
 """
 struct TraceContextTextMapPropagator <: AbstractPropagator end
 
+function generate_w3c_traceparent(trace_id, span_id, trace_flag_sampled)
+    return "00-$(string(trace_id, base=16, pad=32))-$(string(span_id, base=16,pad=16))-$(trace_flag_sampled ? "01" : "00")"
+end
+
+function generate_w3c_traceparent(sc::SpanContext)
+    return generate_w3c_traceparent(sc.trace_id, sc.span_id, sc.trace_flag.sampled)
+end
+
+function generate_w3c_context(sc::SpanContext)
+    return generate_w3c_traceparent(sc), string(sc.trace_state)
+end
+
 function inject_context!(
     carrier::Union{
         AbstractVector{<:Pair{<:AbstractString,<:AbstractString}},
         AbstractDict{<:AbstractString,<:AbstractString},
     },
     propagator::TraceContextTextMapPropagator,
-    ctx::Context = current_context(),
+    ctx::Context = current_context()
 )
     sc = span_context(ctx)
     if !isnothing(sc)
-        s_trace_parent = "00-$(string(sc.trace_id, base=16, pad=32))-$(string(sc.span_id, base=16,pad=16))-$(sc.trace_flag.sampled ? "01" : "00")"
+        s_trace_parent, s_trace_state = generate_w3c_context(sc)
         push!(carrier, "traceparent" => s_trace_parent)
-        s_trace_state = string(sc.trace_state)
         if !isempty(s_trace_state)
             push!(carrier, "tracestate" => s_trace_state)
         end
@@ -31,7 +42,7 @@ end
 function inject_context!(
     carrier::T,
     ::TraceContextTextMapPropagator,
-    ctx::Context = current_context(),
+    ctx::Context = current_context()
 ) where {T}
     @warn "unknown carrier type $T"
     carrier
@@ -43,10 +54,53 @@ TRACEPARENT_HEADER_FORMAT =
     r"^[ \t]*(?P<version>[0-9a-f]{2})-(?P<trace_id>[0-9a-f]{32})-(?P<span_id>[0-9a-f]{16})-(?P<trace_flag>[0-9a-f]{2})(?P<rest>-.*)?[ \t]*$"
 
 function extract_context(
-    carrier::AbstractDict{<:AbstractString,<:AbstractString},
+    carrier::Union{
+        AbstractDict{<:AbstractString,<:AbstractString},
+        AbstractVector{<:Pair{<:AbstractString,<:AbstractString}}
+    },
     propagator::TraceContextTextMapPropagator,
     ctx::Context = current_context(),
 )
+    trace_id, span_id, trace_flag, trace_state = extract_from(carrier)
+    return if (
+        trace_id === nothing || 
+        span_id === nothing || 
+        trace_flag === nothing
+    )
+        ctx
+    else
+        merge(
+            ctx,
+            Context(Dict(
+                SPAN_KEY_IN_CONTEXT => NonRecordingSpan(
+                    "",
+                    SpanContext(span_id, trace_id, false, trace_flag, trace_state),
+                    nothing,
+                )
+            )),
+        )
+    end
+end
+
+function extract_span_context(
+    carrier::Union{
+        AbstractDict{<:AbstractString,<:AbstractString},
+        AbstractVector{<:Pair{<:AbstractString,<:AbstractString}}
+    }
+)
+    trace_id, span_id, trace_flag, trace_state = extract_from(carrier)
+    return if (
+        trace_id === nothing || 
+        span_id === nothing || 
+        trace_flag === nothing
+    )
+        nothing
+    else
+        SpanContext(span_id, trace_id, false, trace_flag, trace_state)
+    end
+end
+
+function extract_from(carrier::AbstractDict{<:AbstractString,<:AbstractString})
     trace_id = nothing
     span_id = nothing
     trace_flag = nothing
@@ -70,15 +124,10 @@ function extract_context(
             end
         end
     end
-
-    return _extract_context(trace_id, span_id, trace_flag, trace_state, propagator, ctx)
+    return trace_id, span_id, trace_flag, trace_state
 end
 
-function extract_context(
-    carrier::AbstractVector{<:Pair{<:AbstractString,<:AbstractString}},
-    propagator::TraceContextTextMapPropagator,
-    ctx::Context = current_context(),
-)
+function extract_from(carrier::AbstractVector{<:Pair{<:AbstractString,<:AbstractString}})
     trace_id = nothing
     span_id = nothing
     trace_flag = nothing
@@ -100,37 +149,9 @@ function extract_context(
             end
         end
     end
-
-    return _extract_context(trace_id, span_id, trace_flag, trace_state, propagator, ctx)
+    return trace_id, span_id, trace_flag, trace_state
 end
 
-function _extract_context(
-    trace_id,
-    span_id,
-    trace_flag,
-    trace_state,
-    propagator::TraceContextTextMapPropagator,
-    ctx::Context = current_context(),
-)
-    return if (
-        trace_id === nothing || 
-        span_id === nothing || 
-        trace_flag === nothing
-    )
-        ctx
-    else
-        merge(
-            ctx,
-            Context(Dict(
-                SPAN_KEY_IN_CONTEXT => NonRecordingSpan(
-                    "",
-                    SpanContext(span_id, trace_id, false, trace_flag, trace_state),
-                    nothing,
-                )
-            )),
-        )
-    end
-end
 
 # fallback
 function extract_context(
@@ -141,3 +162,4 @@ function extract_context(
     @warn "unknown carrier type $T"
     ctx
 end
+