support zone context propagation in traceContext and traceContextSync

Author: blakeroberts-wk

example/zone_context_manager.dart

@@ -3,9 +3,12 @@ import 'dart:async';
 import 'package:opentelemetry/api.dart';
 import 'package:opentelemetry/sdk.dart'
     show ConsoleExporter, SimpleSpanProcessor, TracerProviderBase;
-import 'package:opentelemetry/src/api/context/zone_context.dart';
 import 'package:opentelemetry/src/experimental_api.dart'
-    show globalContextManager, registerGlobalContextManager, ZoneContextManager;
+    show
+        globalContextManager,
+        registerGlobalContextManager,
+        ZoneContext,
+        ZoneContextManager;
 
 void main(List<String> args) async {
   final tp =

lib/src/api/context/context.dart

@@ -71,7 +71,9 @@ abstract class Context {
 
   /// Execute a function [fn] within this [Context] and return its result.
   @Deprecated(
-      'This method will be removed in 0.19.0. Propagate [Context] as an argument to [fn].')
+      'This method will be removed in 0.19.0. Propagate [Context] as an '
+      'argument to [fn] and call [fn] directly or use '
+      '[(context as ZoneContext).run((_) => fn(this))] instead.')
   R execute<R>(R Function() fn);
 
   /// Get the [Span] attached to this [Context], or an invalid, [Span] if no such

lib/src/api/context/map_context.dart

@@ -43,6 +43,8 @@ class MapContext implements Context {
   @override
   Span get span => spanFromContext(this);
 
+  /// Call [fn] with this [MapContext] and return its result.
+  @experimental
   R run<R>(R Function(Context context) fn) => fn(this);
 
   /// Get the [SpanContext] from this [MapContext], or an invalid [SpanContext] if no such

lib/src/api/context/zone_context.dart

@@ -59,6 +59,8 @@ class ZoneContext implements Context {
   @override
   R execute<R>(R Function() fn) => _zone.run(() => fn());
 
+  /// Call [fn] in this [ZoneContext]'s [Zone] and return its result.
+  @experimental
   R run<R>(R Function(Context context) fn) => _zone.run(() => fn(this));
 
   /// Get the [Span] attached to this [ZoneContext], or an invalid, [Span] if no such

lib/src/api/open_telemetry.dart

@@ -9,7 +9,7 @@ import 'propagation/noop_text_map_propagator.dart';
 import 'trace/noop_tracer_provider.dart';
 
 import '../../api.dart' as api;
-import '../experimental_api.dart' show globalContextManager;
+import '../experimental_api.dart' show globalContextManager, ZoneContext;
 
 final api.TracerProvider _noopTracerProvider = NoopTracerProvider();
 final api.TextMapPropagator _noopTextMapPropagator = NoopTextMapPropagator();
@@ -79,8 +79,13 @@ Future<T> traceContext<T>(String name, Future<T> Function(api.Context) fn,
   }
 
   final span = tracer.startSpan(name, context: context);
+  context = api.contextWithSpan(context, span);
   try {
-    return await fn(api.contextWithSpan(context, span));
+    // TODO: remove this check once `run` exists on context interface
+    if (context is ZoneContext) {
+      return await context.run((context) => fn(context));
+    }
+    return await fn(context);
   } catch (e, s) {
     span
       ..setStatus(api.StatusCode.error, e.toString())
@@ -93,7 +98,7 @@ Future<T> traceContext<T>(String name, Future<T> Function(api.Context) fn,
 
 /// Use [traceSync] instead of [trace] when [fn] is not an async function.
 @Deprecated(
-    'This method will be removed in 0.19.0. Use [traceSyncContext] instead.')
+    'This method will be removed in 0.19.0. Use [traceContextSync] instead.')
 R traceSync<R>(String name, R Function() fn,
     {api.Context? context, api.Tracer? tracer}) {
   context ??= globalContextManager.active;
@@ -120,9 +125,9 @@ R traceSync<R>(String name, R Function() fn,
   }
 }
 
-/// Use [traceSyncContext] instead of [traceContext] when [fn] is not an async function.
+/// Use [traceContextSync] instead of [traceContext] when [fn] is not an async function.
 @experimental
-R traceSyncContext<R>(String name, R Function(api.Context) fn,
+R traceContextSync<R>(String name, R Function(api.Context) fn,
     {api.Context? context,
     api.Tracer? tracer,
     bool newRoot = false,
@@ -136,12 +141,19 @@ R traceSyncContext<R>(String name, R Function(api.Context) fn,
   }
 
   final span = tracer.startSpan(name, context: context);
+  context = api.contextWithSpan(context, span);
   try {
-    final r = fn(api.contextWithSpan(context, span));
+    var r;
+    // TODO: remove this check once `run` exists on context interface
+    if (context is ZoneContext) {
+      r = context.run((context) => fn(context));
+    } else {
+      r = fn(context);
+    }
 
     if (r is Future) {
       throw ArgumentError.value(fn, 'fn',
-          'Use traceSyncContext to trace functions that do not return a [Future].');
+          'Use traceContextSync to trace functions that do not return a [Future].');
     }
 
     return r;

lib/src/experimental_api.dart

@@ -9,6 +9,7 @@ import 'package:meta/meta.dart';
 export 'api/context/context_manager.dart'
     show ContextManager, registerGlobalContextManager, globalContextManager;
 export 'api/context/noop_context_manager.dart' show NoopContextManager;
+export 'api/context/zone_context.dart' show ZoneContext;
 export 'api/context/zone_context_manager.dart' show ZoneContextManager;
 export 'api/metrics/counter.dart' show Counter;
 export 'api/metrics/meter_provider.dart' show MeterProvider;