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Documenting Spans and Transactions (#2358)
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Added some docstrings and also did some minor cleanup for better readability of the code.

---------

Co-authored-by: Ivana Kellyerova <ivana.kellyerova@sentry.io>
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@antonpirker @sentrivana
antonpirker and sentrivana committed Sep 11, 2023
1 parent 34232eb commit 44ba734
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Showing 3 changed files with 111 additions and 22 deletions.
16 changes: 13 additions & 3 deletions sentry_sdk/hub.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -479,6 +479,7 @@ def start_span(self, span=None, instrumenter=INSTRUMENTER.SENTRY, **kwargs):
if instrumenter != configuration_instrumenter:
return NoOpSpan()

# THIS BLOCK IS DEPRECATED
# TODO: consider removing this in a future release.
# This is for backwards compatibility with releases before
# start_transaction existed, to allow for a smoother transition.
Expand All @@ -487,24 +488,33 @@ def start_span(self, span=None, instrumenter=INSTRUMENTER.SENTRY, **kwargs):
"Deprecated: use start_transaction to start transactions and "
"Transaction.start_child to start spans."
)

if isinstance(span, Transaction):
logger.warning(deprecation_msg)
return self.start_transaction(span)

if "transaction" in kwargs:
logger.warning(deprecation_msg)
name = kwargs.pop("transaction")
return self.start_transaction(name=name, **kwargs)

# THIS BLOCK IS DEPRECATED
# We do not pass a span into start_span in our code base, so I deprecate this.
if span is not None:
deprecation_msg = "Deprecated: passing a span into `start_span` is deprecated and will be removed in the future."
logger.warning(deprecation_msg)
return span

kwargs.setdefault("hub", self)

span = self.scope.span
if span is not None:
return span.start_child(**kwargs)
active_span = self.scope.span
if active_span is not None:
new_child_span = active_span.start_child(**kwargs)
return new_child_span

# If there is already a trace_id in the propagation context, use it.
# This does not need to be done for `start_child` above because it takes
# the trace_id from the parent span.
if "trace_id" not in kwargs:
traceparent = self.get_traceparent()
trace_id = traceparent.split("-")[0] if traceparent else None
Expand Down
113 changes: 94 additions & 19 deletions sentry_sdk/tracing.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -80,6 +80,9 @@ def add(self, span):


class Span(object):
"""A span holds timing information of a block of code.
Spans can have multiple child spans thus forming a span tree."""

__slots__ = (
"trace_id",
"span_id",
Expand Down Expand Up @@ -201,6 +204,9 @@ def __exit__(self, ty, value, tb):
@property
def containing_transaction(self):
# type: () -> Optional[Transaction]
"""The ``Transaction`` that this span belongs to.
The ``Transaction`` is the root of the span tree,
so one could also think of this ``Transaction`` as the "root span"."""

# this is a getter rather than a regular attribute so that transactions
# can return `self` here instead (as a way to prevent them circularly
Expand Down Expand Up @@ -237,12 +243,15 @@ def start_child(self, instrumenter=INSTRUMENTER.SENTRY, **kwargs):
)
if span_recorder:
span_recorder.add(child)

return child

def new_span(self, **kwargs):
# type: (**Any) -> Span
"""Deprecated: use :py:meth:`sentry_sdk.tracing.Span.start_child` instead."""
logger.warning("Deprecated: use Span.start_child instead of Span.new_span.")
"""DEPRECATED: use :py:meth:`sentry_sdk.tracing.Span.start_child` instead."""
logger.warning(
"Deprecated: use Span.start_child instead of Span.new_span. This will be removed in the future."
)
return self.start_child(**kwargs)

@classmethod
Expand All @@ -254,12 +263,15 @@ def continue_from_environ(
# type: (...) -> Transaction
"""
Create a Transaction with the given params, then add in data pulled from
the 'sentry-trace' and 'baggage' headers from the environ (if any)
the ``sentry-trace`` and ``baggage`` headers from the environ (if any)
before returning the Transaction.
This is different from `continue_from_headers` in that it assumes header
names in the form "HTTP_HEADER_NAME" - such as you would get from a wsgi
environ - rather than the form "header-name".
This is different from :py:meth:`~sentry_sdk.tracing.Span.continue_from_headers`
in that it assumes header names in the form ``HTTP_HEADER_NAME`` -
such as you would get from a WSGI/ASGI environ -
rather than the form ``header-name``.
:param environ: The ASGI/WSGI environ to pull information from.
"""
if cls is Span:
logger.warning(
Expand All @@ -277,7 +289,9 @@ def continue_from_headers(
# type: (...) -> Transaction
"""
Create a transaction with the given params (including any data pulled from
the 'sentry-trace' and 'baggage' headers).
the ``sentry-trace`` and ``baggage`` headers).
:param headers: The dictionary with the HTTP headers to pull information from.
"""
# TODO move this to the Transaction class
if cls is Span:
Expand Down Expand Up @@ -311,8 +325,8 @@ def continue_from_headers(
def iter_headers(self):
# type: () -> Iterator[Tuple[str, str]]
"""
Creates a generator which returns the span's `sentry-trace` and `baggage` headers.
If the span's containing transaction doesn't yet have a `baggage` value,
Creates a generator which returns the span's ``sentry-trace`` and ``baggage`` headers.
If the span's containing transaction doesn't yet have a ``baggage`` value,
this will cause one to be generated and stored.
"""
yield SENTRY_TRACE_HEADER_NAME, self.to_traceparent()
Expand All @@ -330,10 +344,10 @@ def from_traceparent(
):
# type: (...) -> Optional[Transaction]
"""
DEPRECATED: Use :py:meth:`sentry_sdk.tracing.Transaction.continue_from_headers`.
DEPRECATED: Use :py:meth:`sentry_sdk.tracing.Span.continue_from_headers`.
Create a `Transaction` with the given params, then add in data pulled from
the given 'sentry-trace' header value before returning the `Transaction`.
Create a ``Transaction`` with the given params, then add in data pulled from
the given ``sentry-trace`` header value before returning the ``Transaction``.
"""
logger.warning(
"Deprecated: Use Transaction.continue_from_headers(headers, **kwargs) "
Expand Down Expand Up @@ -364,6 +378,9 @@ def to_traceparent(self):

def to_baggage(self):
# type: () -> Optional[Baggage]
"""Returns the :py:class:`~sentry_sdk.tracing_utils.Baggage`
associated with this ``Span``, if any. (Taken from the root of the span tree.)
"""
if self.containing_transaction:
return self.containing_transaction.get_baggage()
return None
Expand Down Expand Up @@ -422,8 +439,21 @@ def is_success(self):

def finish(self, hub=None, end_timestamp=None):
# type: (Optional[sentry_sdk.Hub], Optional[datetime]) -> Optional[str]
# XXX: would be type: (Optional[sentry_sdk.Hub]) -> None, but that leads
# Note: would be type: (Optional[sentry_sdk.Hub]) -> None, but that leads
# to incompatible return types for Span.finish and Transaction.finish.
"""Sets the end timestamp of the span.
Additionally it also creates a breadcrumb from the span,
if the span represents a database or HTTP request.
:param hub: The hub to use for this transaction.
If not provided, the current hub will be used.
:param end_timestamp: Optional timestamp that should
be used as timestamp instead of the current time.
:return: Always ``None``. The type is ``Optional[str]`` to match
the return value of :py:meth:`sentry_sdk.tracing.Transaction.finish`.
"""

if self.timestamp is not None:
# This span is already finished, ignore.
return None
Expand All @@ -446,6 +476,8 @@ def finish(self, hub=None, end_timestamp=None):

def to_json(self):
# type: () -> Dict[str, Any]
"""Returns a JSON-compatible representation of the span."""

rv = {
"trace_id": self.trace_id,
"span_id": self.span_id,
Expand Down Expand Up @@ -491,6 +523,9 @@ def get_trace_context(self):


class Transaction(Span):
"""The Transaction is the root element that holds all the spans
for Sentry performance instrumentation."""

__slots__ = (
"name",
"source",
Expand All @@ -512,6 +547,19 @@ def __init__(
**kwargs # type: Any
):
# type: (...) -> None
"""Constructs a new Transaction.
:param name: Identifier of the transaction.
Will show up in the Sentry UI.
:param parent_sampled: Whether the parent transaction was sampled.
If True this transaction will be kept, if False it will be discarded.
:param baggage: The W3C baggage header value.
(see https://www.w3.org/TR/baggage/)
:param source: A string describing the source of the transaction name.
This will be used to determine the transaction's type.
See https://develop.sentry.dev/sdk/event-payloads/transaction/#transaction-annotations
for more information. Default "custom".
"""
# TODO: consider removing this in a future release.
# This is for backwards compatibility with releases before Transaction
# existed, to allow for a smoother transition.
Expand All @@ -522,7 +570,7 @@ def __init__(
)
name = kwargs.pop("transaction")

Span.__init__(self, **kwargs)
super(Transaction, self).__init__(**kwargs)

self.name = name
self.source = source
Expand Down Expand Up @@ -568,6 +616,9 @@ def __exit__(self, ty, value, tb):
@property
def containing_transaction(self):
# type: () -> Transaction
"""The root element of the span tree.
In the case of a transaction it is the transaction itself.
"""

# Transactions (as spans) belong to themselves (as transactions). This
# is a getter rather than a regular attribute to avoid having a circular
Expand All @@ -576,6 +627,17 @@ def containing_transaction(self):

def finish(self, hub=None, end_timestamp=None):
# type: (Optional[sentry_sdk.Hub], Optional[datetime]) -> Optional[str]
"""Finishes the transaction and sends it to Sentry.
All finished spans in the transaction will also be sent to Sentry.
:param hub: The hub to use for this transaction.
If not provided, the current hub will be used.
:param end_timestamp: Optional timestamp that should
be used as timestamp instead of the current time.
:return: The event ID if the transaction was sent to Sentry,
otherwise None.
"""
if self.timestamp is not None:
# This transaction is already finished, ignore.
return None
Expand Down Expand Up @@ -610,7 +672,7 @@ def finish(self, hub=None, end_timestamp=None):
)
self.name = "<unlabeled transaction>"

Span.finish(self, hub, end_timestamp)
super(Transaction, self).finish(hub, end_timestamp)

if not self.sampled:
# At this point a `sampled = None` should have already been resolved
Expand Down Expand Up @@ -661,15 +723,26 @@ def set_measurement(self, name, value, unit=""):

def set_context(self, key, value):
# type: (str, Any) -> None
"""Sets a context. Transactions can have multiple contexts
and they should follow the format described in the "Contexts Interface"
documentation.
:param key: The name of the context.
:param value: The information about the context.
"""
self._contexts[key] = value

def set_http_status(self, http_status):
# type: (int) -> None
"""Sets the status of the Transaction according to the given HTTP status.
:param http_status: The HTTP status code."""
super(Transaction, self).set_http_status(http_status)
self.set_context("response", {"status_code": http_status})

def to_json(self):
# type: () -> Dict[str, Any]
"""Returns a JSON-compatible representation of the transaction."""
rv = super(Transaction, self).to_json()

rv["name"] = self.name
Expand All @@ -680,10 +753,12 @@ def to_json(self):

def get_baggage(self):
# type: () -> Baggage
"""
The first time a new baggage with sentry items is made,
it will be frozen.
"""
"""Returns the :py:class:`~sentry_sdk.tracing_utils.Baggage`
associated with the Transaction.
The first time a new baggage with Sentry items is made,
it will be frozen."""

if not self._baggage or self._baggage.mutable:
self._baggage = Baggage.populate_from_transaction(self)

Expand Down
4 changes: 4 additions & 0 deletions sentry_sdk/tracing_utils.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -215,6 +215,10 @@ def _format_sql(cursor, sql):


class Baggage(object):
"""
The W3C Baggage header information (see https://www.w3.org/TR/baggage/).
"""

__slots__ = ("sentry_items", "third_party_items", "mutable")

SENTRY_PREFIX = "sentry-"
Expand Down

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