Context prop combined

adapters/faraday/lib/opentelemetry/adapters/faraday/middlewares/tracer_middleware.rb

@@ -35,13 +35,8 @@ def disable_span_reporting?(_env)
 
           attr_reader :app
 
-          # Outbound requests should only need to inject the current span.
           def propagate_context(span, env)
-            propagator.inject(span.context, env.request_headers)
-          end
-
-          def propagator
-            OpenTelemetry.tracer_factory.http_text_format
+            OpenTelemetry.propagation.inject(env.request_headers)
           end
 
           def tracer

adapters/sinatra/lib/opentelemetry/adapters/sinatra/middlewares/tracer_middleware.rb

@@ -32,7 +32,7 @@ def call(env)
           attr_reader :app
 
           def parent_context(env)
-            OpenTelemetry.tracer_factory.http_text_format.extract(env)
+            OpenTelemetry.propagation.extract(env)
           end
 
           def tracer

api/lib/opentelemetry.rb

@@ -8,7 +8,7 @@
 
 require 'opentelemetry/error'
 require 'opentelemetry/context'
-require 'opentelemetry/distributed_context'
+require 'opentelemetry/correlation_context'
 require 'opentelemetry/internal'
 require 'opentelemetry/instrumentation'
 require 'opentelemetry/metrics'
@@ -23,7 +23,7 @@
 module OpenTelemetry
   extend self
 
-  attr_writer :tracer_factory, :meter_factory, :distributed_context_manager
+  attr_writer :tracer_factory, :meter_factory, :correlations
 
   attr_accessor :logger
 
@@ -39,17 +39,23 @@ def meter_factory
     @meter_factory ||= Metrics::MeterFactory.new
   end
 
-  # @return [Object, DistributedContext::Manager] registered distributed
-  #   context manager or a default no-op implementation of the manager
-  def distributed_context_manager
-    @distributed_context_manager ||= DistributedContext::Manager.new
-  end
-
   # @return [Instrumentation::Registry] registry containing all known
   #  instrumentation
   def instrumentation_registry
     @instrumentation_registry ||= Instrumentation::Registry.new
   end
 
+  # @return [Object, CorrelationContext::Manager] registered
+  #   correlation context manager or a default no-op implementation of the
+  #   manager.
+  def correlations
+    @correlations ||= CorrelationContext::Manager.new
+  end
+
+  # @return [Context::Propagation::Propagation] an instance of the propagation API
+  def propagation
+    @propagation ||= Context::Propagation::Propagation.new
+  end
+
   self.logger = Logger.new(STDOUT)
 end

api/lib/opentelemetry/context.rb

@@ -4,28 +4,146 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
+require 'opentelemetry/context/key'
+require 'opentelemetry/context/propagation'
+
 module OpenTelemetry
-  # The Context module provides per-thread storage.
-  module Context
-    extend self
+  # Manages context on a per-fiber basis
+  class Context
+    KEY = :__opentelemetry_context__
+    EMPTY_ENTRIES = {}.freeze
+
+    class << self
+      # Returns a key used to index a value in a Context
+      #
+      # @param [String] name The key name
+      # @return [Context::Key]
+      def create_key(name)
+        Key.new(name)
+      end
+
+      # Returns current context, which is never nil
+      #
+      # @return [Context]
+      def current
+        Thread.current[KEY] ||= ROOT
+      end
+
+      # Sets the current context
+      #
+      # @param [Context] ctx The context to be made active
+      def current=(ctx)
+        Thread.current[KEY] = ctx
+      end
+
+      # Executes a block with ctx as the current context. It restores
+      # the previous context upon exiting.
+      #
+      # @param [Context] ctx The context to be made active
+      def with_current(ctx)
+        prev = ctx.attach
+        yield
+      ensure
+        ctx.detach(prev)
+      end
+
+      # Execute a block in a new context with key set to value. Restores the
+      # previous context after the block executes.
+
+      # @param [String] key The lookup key
+      # @param [Object] value The object stored under key
+      # @param [Callable] Block to execute in a new context
+      def with_value(key, value)
+        ctx = current.set_value(key, value)
+        prev = ctx.attach
+        yield value
+      ensure
+        ctx.detach(prev)
+      end
+
+      # Execute a block in a new context where its values are merged with the
+      # incoming values. Restores the previous context after the block executes.
+
+      # @param [String] key The lookup key
+      # @param [Hash] values Will be merged with values of the current context
+      #  and returned in a new context
+      # @param [Callable] Block to execute in a new context
+      def with_values(values)
+        ctx = current.set_values(values)
+        prev = ctx.attach
+        yield values
+      ensure
+        ctx.detach(prev)
+      end
+
+      # Returns the value associated with key in the current context
+      #
+      # @param [String] key The lookup key
+      def value(key)
+        current.value(key)
+      end
+
+      def clear
+        self.current = ROOT
+      end
 
-    def get(key)
-      storage[key]
+      def empty
+        new(nil, EMPTY_ENTRIES)
+      end
     end
 
-    def with(key, value)
-      store = storage
-      previous = store[key]
-      store[key] = value
-      yield value
-    ensure
-      store[key] = previous
+    def initialize(parent, entries)
+      @parent = parent
+      @entries = entries.freeze
     end
 
-    private
+    # Returns the corresponding value (or nil) for key
+    #
+    # @param [Key] key The lookup key
+    # @return [Object]
+    def value(key)
+      @entries[key]
+    end
+
+    alias [] value
+
+    # Returns a new Context where entries contains the newly added key and value
+    #
+    # @param [Key] key The key to store this value under
+    # @param [Object] value Object to be stored under key
+    # @return [Context]
+    def set_value(key, value)
+      new_entries = @entries.dup
+      new_entries[key] = value
+      Context.new(self, new_entries)
+    end
+
+    # Returns a new Context with the current context's entries merged with the
+    #   new entries
+    #
+    # @param [Hash] values The values to be merged with the current context's
+    #   entries.
+    # @param [Object] value Object to be stored under key
+    # @return [Context]
+    def set_values(values) # rubocop:disable Naming/AccessorMethodName:
+      Context.new(self, @entries.merge(values))
+    end
 
-    def storage
-      Thread.current[:__opentelemetry__] ||= {}
+    # @api private
+    def attach
+      prev = self.class.current
+      self.class.current = self
+      prev
     end
+
+    # @api private
+    def detach(ctx_to_attach = nil)
+      OpenTelemetry.logger.warn 'Calls to detach should match corresponding calls to attach' if self.class.current != self
+
+      ctx_to_attach ||= @parent || ROOT
+      ctx_to_attach.attach
+    end
+
+    ROOT = empty.freeze
   end
 end

api/lib/opentelemetry/context/key.rb

@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+# Copyright 2019 OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+module OpenTelemetry
+  class Context
+    # The Key class provides mechanisms to index and access values from a
+    # Context
+    class Key
+      attr_reader :name
+
+      # @api private
+      # Use Context.create_key to obtain a Key instance.
+      def initialize(name)
+        @name = name
+      end
+
+      # Returns the value indexed by this Key in the specified context
+      #
+      # @param [optional Context] context The Context to lookup the key from.
+      #   Defaults to +Context.current+.
+      def get(context = Context.current)
+        context[self]
+      end
+    end
+  end
+end

api/lib/opentelemetry/context/propagation.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+# Copyright 2019 OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+require 'opentelemetry/context/propagation/default_getter'
+require 'opentelemetry/context/propagation/default_setter'
+require 'opentelemetry/context/propagation/propagation'
+
+module OpenTelemetry
+  class Context
+    # The propagation module contains APIs and utilities to interact with context
+    # and propagate across process boundaries.
+    module Propagation
+    end
+  end
+end

api/lib/opentelemetry/context/propagation/default_getter.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+# Copyright 2019 OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+module OpenTelemetry
+  class Context
+    module Propagation
+      # The default getter module provides a common method for reading
+      # a key from a carrier that implements +[]+
+      module DefaultGetter
+        DEFAULT_GETTER = ->(carrier, key) { carrier[key] }
+        private_constant :DEFAULT_GETTER
+
+        # Returns a callable that can read a key from a carrier that implements
+        # +[]+. Useful for extract operations.
+        #
+        # @return [Callable]
+        def default_getter
+          DEFAULT_GETTER
+        end
+      end
+    end
+  end
+end

api/lib/opentelemetry/context/propagation/default_setter.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+# Copyright 2019 OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+module OpenTelemetry
+  class Context
+    module Propagation
+      # The default setter module provides a common method for writing
+      # a key into a carrier that implements +[]=+
+      module DefaultSetter
+        DEFAULT_SETTER = ->(carrier, key, value) { carrier[key] = value }
+        private_constant :DEFAULT_SETTER
+
+        # Returns a callable that can write a key into a carrier that implements
+        # +[]=+. Useful for inject operations.
+        #
+        # @return [Callable]
+        def default_setter
+          DEFAULT_SETTER
+        end
+      end
+    end
+  end
+end