Remove setters and getters

Fixes open-telemetry#1644

Author: ocelotl

opentelemetry-api/src/opentelemetry/baggage/propagation/__init__.py

@@ -31,7 +31,6 @@ class W3CBaggagePropagator(textmap.TextMapPropagator):
 
     def extract(
         self,
-        getter: textmap.Getter[textmap.TextMapPropagatorT],
         carrier: textmap.TextMapPropagatorT,
         context: typing.Optional[Context] = None,
     ) -> Context:
@@ -44,11 +43,14 @@ def extract(
         if context is None:
             context = get_current()
 
-        header = _extract_first_element(
-            getter.get(carrier, self._BAGGAGE_HEADER_NAME)
-        )
+        value = carrier.get(self._BAGGAGE_HEADER_NAME)
 
-        if not header or len(header) > self._MAX_HEADER_LENGTH:
+        if value is None:
+            header = None
+        else:
+            header = next(iter(value), None)
+
+        if header is None or len(header) > self._MAX_HEADER_LENGTH:
             return context
 
         baggage_entries = header.split(",")
@@ -73,7 +75,6 @@ def extract(
 
     def inject(
         self,
-        set_in_carrier: textmap.Setter[textmap.TextMapPropagatorT],
         carrier: textmap.TextMapPropagatorT,
         context: typing.Optional[Context] = None,
     ) -> None:
@@ -83,28 +84,14 @@ def inject(
         `opentelemetry.propagators.textmap.TextMapPropagator.inject`
         """
         baggage_entries = baggage.get_all(context=context)
-        if not baggage_entries:
-            return
 
-        baggage_string = _format_baggage(baggage_entries)
-        set_in_carrier(carrier, self._BAGGAGE_HEADER_NAME, baggage_string)
+        if baggage_entries:
+            carrier[self._BAGGAGE_HEADER_NAME] = ",".join(
+                key + "=" + urllib.parse.quote_plus(str(value))
+                for key, value in baggage_entries.items()
+            )
 
     @property
     def fields(self) -> typing.Set[str]:
         """Returns a set with the fields set in `inject`."""
         return {self._BAGGAGE_HEADER_NAME}
-
-
-def _format_baggage(baggage_entries: typing.Mapping[str, object]) -> str:
-    return ",".join(
-        key + "=" + urllib.parse.quote_plus(str(value))
-        for key, value in baggage_entries.items()
-    )
-
-
-def _extract_first_element(
-    items: typing.Optional[typing.Iterable[textmap.TextMapPropagatorT]],
-) -> typing.Optional[textmap.TextMapPropagatorT]:
-    if items is None:
-        return None
-    return next(iter(items), None)

opentelemetry-api/src/opentelemetry/propagate/__init__.py

@@ -40,23 +40,12 @@
     PROPAGATOR = propagators.get_global_textmap()
 
 
-    def get_header_from_flask_request(request, key):
-        return request.headers.get_all(key)
-
-    def set_header_into_requests_request(request: requests.Request,
-                                            key: str, value: str):
-        request.headers[key] = value
-
     def example_route():
-        context = PROPAGATOR.extract(
-            get_header_from_flask_request,
-            flask.request
-        )
+        context = PROPAGATOR.extract(flask.request)
         request_to_downstream = requests.Request(
             "GET", "http://httpbin.org/get"
         )
         PROPAGATOR.inject(
-            set_header_into_requests_request,
             request_to_downstream,
             context=context
         )
@@ -82,7 +71,6 @@ def example_route():
 
 
 def extract(
-    getter: textmap.Getter[textmap.TextMapPropagatorT],
     carrier: textmap.TextMapPropagatorT,
     context: typing.Optional[Context] = None,
 ) -> Context:
@@ -99,26 +87,22 @@ def extract(
         context: an optional Context to use. Defaults to current
             context if not set.
     """
-    return get_global_textmap().extract(getter, carrier, context)
+    return get_global_textmap().extract(carrier, context)
 
 
 def inject(
-    set_in_carrier: textmap.Setter[textmap.TextMapPropagatorT],
     carrier: textmap.TextMapPropagatorT,
     context: typing.Optional[Context] = None,
 ) -> None:
     """Uses the configured propagator to inject a Context into the carrier.
 
     Args:
-        set_in_carrier: A setter function that can set values
-            on the carrier.
-        carrier: An object that contains a representation of HTTP
-            headers. Should be paired with set_in_carrier, which
-            should know how to set header values on the carrier.
+        carrier: A dict-like object that contains a representation of HTTP
+            headers.
         context: an optional Context to use. Defaults to current
             context if not set.
     """
-    get_global_textmap().inject(set_in_carrier, carrier, context)
+    get_global_textmap().inject(carrier, context)
 
 
 try:

opentelemetry-api/src/opentelemetry/propagators/composite.py

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
-import typing
+from typing import Optional, Set, Sequence
 
 from opentelemetry.context.context import Context
 from opentelemetry.propagators import textmap
@@ -29,32 +29,31 @@ class CompositeHTTPPropagator(textmap.TextMapPropagator):
     """
 
     def __init__(
-        self, propagators: typing.Sequence[textmap.TextMapPropagator]
+        self, propagators: Sequence[textmap.TextMapPropagator]
     ) -> None:
         self._propagators = propagators
 
     def extract(
         self,
-        getter: textmap.Getter[textmap.TextMapPropagatorT],
         carrier: textmap.TextMapPropagatorT,
-        context: typing.Optional[Context] = None,
+        context: Optional[Context] = None,
     ) -> Context:
-        """Run each of the configured propagators with the given context and carrier.
+        """Run each of the configured propagators with the given context and
+        carrier.
         Propagators are run in the order they are configured, if multiple
-        propagators write the same context key, the propagator later in the list
-        will override previous propagators.
+        propagators write the same context key, the propagator later in the
+        list will override previous propagators.
 
         See `opentelemetry.propagators.textmap.TextMapPropagator.extract`
         """
         for propagator in self._propagators:
-            context = propagator.extract(getter, carrier, context)
+            context = propagator.extract(carrier, context)
         return context  # type: ignore
 
     def inject(
         self,
-        set_in_carrier: textmap.Setter[textmap.TextMapPropagatorT],
         carrier: textmap.TextMapPropagatorT,
-        context: typing.Optional[Context] = None,
+        context: Optional[Context] = None,
     ) -> None:
         """Run each of the configured propagators with the given context and carrier.
         Propagators are run in the order they are configured, if multiple
@@ -64,10 +63,10 @@ def inject(
         See `opentelemetry.propagators.textmap.TextMapPropagator.inject`
         """
         for propagator in self._propagators:
-            propagator.inject(set_in_carrier, carrier, context)
+            propagator.inject(carrier, context)
 
     @property
-    def fields(self) -> typing.Set[str]:
+    def fields(self) -> Set[str]:
         """Returns a set with the fields set in `inject`.
 
         See

opentelemetry-api/src/opentelemetry/propagators/textmap.py

@@ -18,66 +18,6 @@
 from opentelemetry.context.context import Context
 
 TextMapPropagatorT = typing.TypeVar("TextMapPropagatorT")
-CarrierValT = typing.Union[typing.List[str], str]
-
-Setter = typing.Callable[[TextMapPropagatorT, str, str], None]
-
-
-class Getter(typing.Generic[TextMapPropagatorT]):
-    """This class implements a Getter that enables extracting propagated
-    fields from a carrier.
-    """
-
-    def get(
-        self, carrier: TextMapPropagatorT, key: str
-    ) -> typing.Optional[typing.List[str]]:
-        """Function that can retrieve zero
-        or more values from the carrier. In the case that
-        the value does not exist, returns None.
-
-        Args:
-            carrier: An object which contains values that are used to
-                    construct a Context.
-            key: key of a field in carrier.
-        Returns: first value of the propagation key or None if the key doesn't
-                exist.
-        """
-        raise NotImplementedError()
-
-    def keys(self, carrier: TextMapPropagatorT) -> typing.List[str]:
-        """Function that can retrieve all the keys in a carrier object.
-
-        Args:
-            carrier: An object which contains values that are
-                used to construct a Context.
-        Returns:
-            list of keys from the carrier.
-        """
-        raise NotImplementedError()
-
-
-class DictGetter(Getter[typing.Dict[str, CarrierValT]]):
-    def get(
-        self, carrier: typing.Dict[str, CarrierValT], key: str
-    ) -> typing.Optional[typing.List[str]]:
-        """Getter implementation to retrieve a value from a dictionary.
-
-        Args:
-            carrier: dictionary in which header
-            key: the key used to get the value
-        Returns:
-            A list with a single string with the value if it exists, else None.
-        """
-        val = carrier.get(key, None)
-        if val is None:
-            return None
-        if isinstance(val, typing.Iterable) and not isinstance(val, str):
-            return list(val)
-        return [val]
-
-    def keys(self, carrier: typing.Dict[str, CarrierValT]) -> typing.List[str]:
-        """Keys implementation that returns all keys from a dictionary."""
-        return list(carrier.keys())
 
 
 class TextMapPropagator(abc.ABC):
@@ -92,7 +32,6 @@ class TextMapPropagator(abc.ABC):
     @abc.abstractmethod
     def extract(
         self,
-        getter: Getter[TextMapPropagatorT],
         carrier: TextMapPropagatorT,
         context: typing.Optional[Context] = None,
     ) -> Context:
@@ -103,9 +42,6 @@ def extract(
         Context value and return it.
 
         Args:
-            getter: a function that can retrieve zero
-                or more values from the carrier. In the case that
-                the value does not exist, return an empty list.
             carrier: and object which contains values that are
                 used to construct a Context. This object
                 must be paired with an appropriate getter
@@ -120,23 +56,16 @@ def extract(
     @abc.abstractmethod
     def inject(
         self,
-        set_in_carrier: Setter[TextMapPropagatorT],
         carrier: TextMapPropagatorT,
         context: typing.Optional[Context] = None,
     ) -> None:
         """Inject values from a Context into a carrier.
 
         inject enables the propagation of values into HTTP clients or
         other objects which perform an HTTP request. Implementations
-        should use the set_in_carrier method to set values on the
-        carrier.
 
         Args:
-            set_in_carrier: A setter function that can set values
-                on the carrier.
-            carrier: An object that a place to define HTTP headers.
-                Should be paired with set_in_carrier, which should
-                know how to set header values on the carrier.
+            carrier: An dict-like object where to store HTTP headers.
             context: an optional Context to use. Defaults to current
                 context if not set.