# Copyright 2017, OpenCensus Authors
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
try:
from collections.abc import MutableMapping
from collections.abc import Sequence
except ImportError:
from collections import MutableMapping
from collections import Sequence
from collections import OrderedDict
from collections import deque
from datetime import datetime
from itertools import chain
import threading
from opencensus.common import utils
from opencensus.trace import attributes as attributes_module
from opencensus.trace import base_span
from opencensus.trace import link as link_module
from opencensus.trace import stack_trace as stack_trace_module
from opencensus.trace import status as status_module
from opencensus.trace import time_event
from opencensus.trace.span_context import generate_span_id
from opencensus.trace.tracers import base
# https://github.com/census-instrumentation/opencensus-specs/blob/master/trace/TraceConfig.md # noqa
MAX_NUM_ATTRIBUTES = 32
MAX_NUM_ANNOTATIONS = 32
MAX_NUM_MESSAGE_EVENTS = 128
MAX_NUM_LINKS = 32
[docs]class BoundedList(Sequence):
"""An append only list with a fixed max size."""
def __init__(self, maxlen):
self.dropped = 0
self._dq = deque(maxlen=maxlen)
self._lock = threading.Lock()
def __repr__(self):
return ("{}({}, maxlen={})"
.format(
type(self).__name__,
list(self._dq),
self._dq.maxlen
))
def __getitem__(self, index):
return self._dq[index]
def __len__(self):
return len(self._dq)
def __iter__(self):
return iter(self._dq)
def append(self, item):
with self._lock:
if len(self._dq) == self._dq.maxlen:
self.dropped += 1
self._dq.append(item)
def extend(self, seq):
with self._lock:
to_drop = len(seq) + len(self._dq) - self._dq.maxlen
if to_drop > 0:
self.dropped += to_drop
self._dq.extend(seq)
@classmethod
def from_seq(cls, maxlen, seq):
seq = tuple(seq)
if len(seq) > maxlen:
raise ValueError
bounded_list = cls(maxlen)
bounded_list._dq = deque(seq, maxlen=maxlen)
return bounded_list
[docs]class BoundedDict(MutableMapping):
"""A dict with a fixed max capacity."""
def __init__(self, maxlen):
self.maxlen = maxlen
self.dropped = 0
self._dict = OrderedDict()
self._lock = threading.Lock()
def __repr__(self):
return ("{}({}, maxlen={})"
.format(
type(self).__name__,
dict(self._dict),
self.maxlen
))
def __getitem__(self, key):
return self._dict[key]
def __setitem__(self, key, value):
with self._lock:
if key in self._dict:
del self._dict[key]
elif len(self._dict) == self.maxlen:
del self._dict[next(iter(self._dict.keys()))]
self.dropped += 1
self._dict[key] = value
def __delitem__(self, key):
del self._dict[key]
def __iter__(self):
return iter(self._dict)
def __len__(self):
return len(self._dict)
@classmethod
def from_map(cls, maxlen, mapping):
mapping = OrderedDict(mapping)
if len(mapping) > maxlen:
raise ValueError
bounded_dict = cls(maxlen)
bounded_dict._dict = mapping
return bounded_dict
class SpanKind(object):
UNSPECIFIED = 0
SERVER = 1
CLIENT = 2
[docs]class Span(base_span.BaseSpan):
"""A span is an individual timed event which forms a node of the trace
tree. Each span has its name, span id and parent id. The parent id
indicates the causal relationships between the individual spans in a
single distributed trace. Span that does not have a parent id is called
root span. All spans associated with a specific trace also share a common
trace id. Spans do not need to be continuous, there can be gaps between
two spans.
:type name: str
:param name: The name of the span.
:type parent_span: :class:`~opencensus.trace.span.Span`
:param parent_span: (Optional) Parent span.
:type attributes: dict
:param attributes: Collection of attributes associated with the span.
Attribute keys must be less than 128 bytes.
Attribute values must be less than 16 kilobytes.
:type start_time: str
:param start_time: (Optional) Start of the time interval (inclusive)
during which the trace data was collected from the
application.
:type end_time: str
:param end_time: (Optional) End of the time interval (inclusive) during
which the trace data was collected from the application.
:type span_id: int
:param span_id: Identifier for the span, unique within a trace.
:type stack_trace: :class: `~opencensus.trace.stack_trace.StackTrace`
:param stack_trace: (Optional) A call stack appearing in a trace
:type annotations: list(:class:`opencensus.trace.time_event.Annotation`)
:param annotations: (Optional) The list of span annotations.
:type message_events:
list(:class:`opencensus.trace.time_event.MessageEvent`)
:param message_events: (Optional) The list of span message events.
:type links: list
:param links: (Optional) Links associated with the span. You can have up
to 128 links per Span.
:type status: :class: `~opencensus.trace.status.Status`
:param status: (Optional) An optional final status for this span.
:type same_process_as_parent_span: bool
:param same_process_as_parent_span: (Optional) A highly recommended but not
required flag that identifies when a
trace crosses a process boundary.
True when the parent_span belongs to
the same process as the current span.
:type context_tracer: :class:`~opencensus.trace.tracers.context_tracer.
ContextTracer`
:param context_tracer: The tracer that holds a stack of spans. If this is
not None, then when exiting a span, use the end_span
method in the tracer class to finish a span. If no
tracer is passed in, then just finish the span using
the finish method in the Span class.
:type span_kind: int
:param span_kind: (Optional) Highly recommended flag that denotes the type
of span (valid values defined by :class:
`opencensus.trace.span.SpanKind`)
"""
def __init__(
self,
name,
parent_span=None,
attributes=None,
start_time=None,
end_time=None,
span_id=None,
stack_trace=None,
annotations=None,
message_events=None,
links=None,
status=None,
same_process_as_parent_span=None,
context_tracer=None,
span_kind=SpanKind.UNSPECIFIED):
self.name = name
self.parent_span = parent_span
self.start_time = start_time
self.end_time = end_time
if span_id is None:
span_id = generate_span_id()
if attributes is None:
self.attributes = BoundedDict(MAX_NUM_ATTRIBUTES)
else:
self.attributes = BoundedDict.from_map(
MAX_NUM_ATTRIBUTES, attributes)
# Do not manipulate spans directly using the methods in Span Class,
# make sure to use the Tracer.
if parent_span is None:
parent_span = base.NullContextManager()
if annotations is None:
self.annotations = BoundedList(MAX_NUM_ANNOTATIONS)
else:
self.annotations = BoundedList.from_seq(MAX_NUM_LINKS, annotations)
if message_events is None:
self.message_events = BoundedList(MAX_NUM_MESSAGE_EVENTS)
else:
self.message_events = BoundedList.from_seq(
MAX_NUM_LINKS, message_events)
if links is None:
self.links = BoundedList(MAX_NUM_LINKS)
else:
self.links = BoundedList.from_seq(MAX_NUM_LINKS, links)
self.span_id = span_id
self.stack_trace = stack_trace
self.status = status
self.same_process_as_parent_span = same_process_as_parent_span
self._child_spans = []
self.context_tracer = context_tracer
self.span_kind = span_kind
for callback in Span._on_create_callbacks:
callback(self)
_on_create_callbacks = []
@staticmethod
def on_create(callback):
Span._on_create_callbacks.append(callback)
@property
def children(self):
"""The child spans of the current span."""
return self._child_spans
[docs] def span(self, name='child_span'):
"""Create a child span for the current span and append it to the child
spans list.
:type name: str
:param name: (Optional) The name of the child span.
:rtype: :class: `~opencensus.trace.span.Span`
:returns: A child Span to be added to the current span.
"""
child_span = Span(name, parent_span=self)
self._child_spans.append(child_span)
return child_span
[docs] def add_attribute(self, attribute_key, attribute_value):
"""Add attribute to span.
:type attribute_key: str
:param attribute_key: Attribute key.
:type attribute_value:str
:param attribute_value: Attribute value.
"""
self.attributes[attribute_key] = attribute_value
[docs] def add_annotation(self, description, **attrs):
"""Add an annotation to span.
:type description: str
:param description: A user-supplied message describing the event.
The maximum length for the description is 256 bytes.
:type attrs: kwargs
:param attrs: keyworded arguments e.g. failed=True, name='Caching'
"""
self.annotations.append(time_event.Annotation(
datetime.utcnow(),
description,
attributes_module.Attributes(attrs)
))
[docs] def add_message_event(self, message_event):
"""Add a message event to this span.
:type message_event: :class:`opencensus.trace.time_event.MessageEvent`
:param message_event: The message event to attach to this span.
"""
self.message_events.append(message_event)
[docs] def add_link(self, link):
"""Add a Link.
:type link: :class: `~opencensus.trace.link.Link`
:param link: A Link object.
"""
if isinstance(link, link_module.Link):
self.links.append(link)
else:
raise TypeError("Type Error: received {}, but requires Link.".
format(type(link).__name__))
[docs] def start(self):
"""Set the start time for a span."""
self.start_time = utils.to_iso_str()
[docs] def finish(self):
"""Set the end time for a span."""
self.end_time = utils.to_iso_str()
def __iter__(self):
"""Iterate through the span tree."""
for span in chain(*(map(iter, self.children))):
yield span
yield self
def __enter__(self):
"""Start a span."""
self.start()
return self
def __exit__(self, exception_type, exception_value, traceback):
"""Finish a span."""
if traceback is not None:
self.stack_trace =\
stack_trace_module.StackTrace.from_traceback(traceback)
if exception_value is not None:
self.status = status_module.Status.from_exception(exception_value)
if self.context_tracer is not None:
self.context_tracer.end_span()
return
self.finish()