Files
2020-04-08 10:39:44 -07:00

395 lines
12 KiB
Python

import math
import random
import sys
import traceback
from .compat import StringIO, stringify, iteritems, numeric_types, time_ns, is_integer
from .constants import NUMERIC_TAGS, MANUAL_DROP_KEY, MANUAL_KEEP_KEY
from .ext import SpanTypes, errors, priority, net, http
from .internal.logger import get_logger
log = get_logger(__name__)
if sys.version_info.major < 3:
_getrandbits = random.SystemRandom().getrandbits
else:
_getrandbits = random.getrandbits
class Span(object):
__slots__ = [
# Public span attributes
'service',
'name',
'resource',
'span_id',
'trace_id',
'parent_id',
'meta',
'error',
'metrics',
'span_type',
'start_ns',
'duration_ns',
'tracer',
# Sampler attributes
'sampled',
# Internal attributes
'_context',
'finished',
'_parent',
'__weakref__',
]
def __init__(
self,
tracer,
name,
service=None,
resource=None,
span_type=None,
trace_id=None,
span_id=None,
parent_id=None,
start=None,
context=None,
):
"""
Create a new span. Call `finish` once the traced operation is over.
:param ddtrace.Tracer tracer: the tracer that will submit this span when
finished.
:param str name: the name of the traced operation.
:param str service: the service name
:param str resource: the resource name
:param str span_type: the span type
:param int trace_id: the id of this trace's root span.
:param int parent_id: the id of this span's direct parent span.
:param int span_id: the id of this span.
:param int start: the start time of request as a unix epoch in seconds
:param object context: the Context of the span.
"""
# required span info
self.name = name
self.service = service
self.resource = resource or name
self.span_type = span_type.value if isinstance(span_type, SpanTypes) else span_type
# tags / metatdata
self.meta = {}
self.error = 0
self.metrics = {}
# timing
self.start_ns = time_ns() if start is None else int(start * 1e9)
self.duration_ns = None
# tracing
self.trace_id = trace_id or _new_id()
self.span_id = span_id or _new_id()
self.parent_id = parent_id
self.tracer = tracer
# sampling
self.sampled = True
self._context = context
self._parent = None
# state
self.finished = False
@property
def start(self):
"""The start timestamp in Unix epoch seconds."""
return self.start_ns / 1e9
@start.setter
def start(self, value):
self.start_ns = int(value * 1e9)
@property
def duration(self):
"""The span duration in seconds."""
if self.duration_ns is not None:
return self.duration_ns / 1e9
@duration.setter
def duration(self, value):
self.duration_ns = value * 1e9
def finish(self, finish_time=None):
"""Mark the end time of the span and submit it to the tracer.
If the span has already been finished don't do anything
:param int finish_time: The end time of the span in seconds.
Defaults to now.
"""
if self.finished:
return
self.finished = True
if self.duration_ns is None:
ft = time_ns() if finish_time is None else int(finish_time * 1e9)
# be defensive so we don't die if start isn't set
self.duration_ns = ft - (self.start_ns or ft)
if self._context:
try:
self._context.close_span(self)
except Exception:
log.exception('error recording finished trace')
else:
# if a tracer is available to process the current context
if self.tracer:
try:
self.tracer.record(self._context)
except Exception:
log.exception('error recording finished trace')
def set_tag(self, key, value=None):
""" Set the given key / value tag pair on the span. Keys and values
must be strings (or stringable). If a casting error occurs, it will
be ignored.
"""
# Special case, force `http.status_code` as a string
# DEV: `http.status_code` *has* to be in `meta` for metrics
# calculated in the trace agent
if key == http.STATUS_CODE:
value = str(value)
# Determine once up front
is_an_int = is_integer(value)
# Explicitly try to convert expected integers to `int`
# DEV: Some integrations parse these values from strings, but don't call `int(value)` themselves
INT_TYPES = (net.TARGET_PORT, )
if key in INT_TYPES and not is_an_int:
try:
value = int(value)
is_an_int = True
except (ValueError, TypeError):
pass
# Set integers that are less than equal to 2^53 as metrics
if is_an_int and abs(value) <= 2 ** 53:
self.set_metric(key, value)
return
# All floats should be set as a metric
elif isinstance(value, float):
self.set_metric(key, value)
return
# Key should explicitly be converted to a float if needed
elif key in NUMERIC_TAGS:
try:
# DEV: `set_metric` will try to cast to `float()` for us
self.set_metric(key, value)
except (TypeError, ValueError):
log.debug('error setting numeric metric %s:%s', key, value)
return
elif key == MANUAL_KEEP_KEY:
self.context.sampling_priority = priority.USER_KEEP
return
elif key == MANUAL_DROP_KEY:
self.context.sampling_priority = priority.USER_REJECT
return
try:
self.meta[key] = stringify(value)
if key in self.metrics:
del self.metrics[key]
except Exception:
log.debug('error setting tag %s, ignoring it', key, exc_info=True)
def _remove_tag(self, key):
if key in self.meta:
del self.meta[key]
def get_tag(self, key):
""" Return the given tag or None if it doesn't exist.
"""
return self.meta.get(key, None)
def set_tags(self, tags):
""" Set a dictionary of tags on the given span. Keys and values
must be strings (or stringable)
"""
if tags:
for k, v in iter(tags.items()):
self.set_tag(k, v)
def set_meta(self, k, v):
self.set_tag(k, v)
def set_metas(self, kvs):
self.set_tags(kvs)
def set_metric(self, key, value):
# This method sets a numeric tag value for the given key. It acts
# like `set_meta()` and it simply add a tag without further processing.
# FIXME[matt] we could push this check to serialization time as well.
# only permit types that are commonly serializable (don't use
# isinstance so that we convert unserializable types like numpy
# numbers)
if type(value) not in numeric_types:
try:
value = float(value)
except (ValueError, TypeError):
log.debug('ignoring not number metric %s:%s', key, value)
return
# don't allow nan or inf
if math.isnan(value) or math.isinf(value):
log.debug('ignoring not real metric %s:%s', key, value)
return
if key in self.meta:
del self.meta[key]
self.metrics[key] = value
def set_metrics(self, metrics):
if metrics:
for k, v in iteritems(metrics):
self.set_metric(k, v)
def get_metric(self, key):
return self.metrics.get(key)
def to_dict(self):
d = {
'trace_id': self.trace_id,
'parent_id': self.parent_id,
'span_id': self.span_id,
'service': self.service,
'resource': self.resource,
'name': self.name,
'error': self.error,
}
# a common mistake is to set the error field to a boolean instead of an
# int. let's special case that here, because it's sure to happen in
# customer code.
err = d.get('error')
if err and type(err) == bool:
d['error'] = 1
if self.start_ns:
d['start'] = self.start_ns
if self.duration_ns:
d['duration'] = self.duration_ns
if self.meta:
d['meta'] = self.meta
if self.metrics:
d['metrics'] = self.metrics
if self.span_type:
d['type'] = self.span_type
return d
def set_traceback(self, limit=20):
""" If the current stack has an exception, tag the span with the
relevant error info. If not, set the span to the current python stack.
"""
(exc_type, exc_val, exc_tb) = sys.exc_info()
if (exc_type and exc_val and exc_tb):
self.set_exc_info(exc_type, exc_val, exc_tb)
else:
tb = ''.join(traceback.format_stack(limit=limit + 1)[:-1])
self.set_tag(errors.ERROR_STACK, tb) # FIXME[gabin] Want to replace 'error.stack' tag with 'python.stack'
def set_exc_info(self, exc_type, exc_val, exc_tb):
""" Tag the span with an error tuple as from `sys.exc_info()`. """
if not (exc_type and exc_val and exc_tb):
return # nothing to do
self.error = 1
# get the traceback
buff = StringIO()
traceback.print_exception(exc_type, exc_val, exc_tb, file=buff, limit=20)
tb = buff.getvalue()
# readable version of type (e.g. exceptions.ZeroDivisionError)
exc_type_str = '%s.%s' % (exc_type.__module__, exc_type.__name__)
self.set_tag(errors.ERROR_MSG, exc_val)
self.set_tag(errors.ERROR_TYPE, exc_type_str)
self.set_tag(errors.ERROR_STACK, tb)
def _remove_exc_info(self):
""" Remove all exception related information from the span. """
self.error = 0
self._remove_tag(errors.ERROR_MSG)
self._remove_tag(errors.ERROR_TYPE)
self._remove_tag(errors.ERROR_STACK)
def pprint(self):
""" Return a human readable version of the span. """
lines = [
('name', self.name),
('id', self.span_id),
('trace_id', self.trace_id),
('parent_id', self.parent_id),
('service', self.service),
('resource', self.resource),
('type', self.span_type),
('start', self.start),
('end', '' if not self.duration else self.start + self.duration),
('duration', '%fs' % (self.duration or 0)),
('error', self.error),
('tags', '')
]
lines.extend((' ', '%s:%s' % kv) for kv in sorted(self.meta.items()))
return '\n'.join('%10s %s' % l for l in lines)
@property
def context(self):
"""
Property that provides access to the ``Context`` associated with this ``Span``.
The ``Context`` contains state that propagates from span to span in a
larger trace.
"""
return self._context
def __enter__(self):
return self
def __exit__(self, exc_type, exc_val, exc_tb):
try:
if exc_type:
self.set_exc_info(exc_type, exc_val, exc_tb)
self.finish()
except Exception:
log.exception('error closing trace')
def __repr__(self):
return '<Span(id=%s,trace_id=%s,parent_id=%s,name=%s)>' % (
self.span_id,
self.trace_id,
self.parent_id,
self.name,
)
def _new_id():
"""Generate a random trace_id or span_id"""
return _getrandbits(64)