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# Copyright 2014 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
import base64
import gzip
import hashlib
import io
import logging
import zlib
from metrics import Metric
from telemetry.page import page_test
# All network metrics are Chrome only for now.
from telemetry.core.backends.chrome_inspector import inspector_network
from telemetry.value import scalar
class NetworkMetricException(page_test.MeasurementFailure):
pass
class HTTPResponse(object):
""" Represents an HTTP response from a timeline event."""
def __init__(self, event):
self._response = (
inspector_network.InspectorNetworkResponseData.FromTimelineEvent(event))
self._remote_port = None
if 'response' in event.args and 'remotePort' in event.args['response']:
self._remote_port = event.args['response']['remotePort']
self._content_length = None
@property
def response(self):
return self._response
@property
def remote_port(self):
return self._remote_port
@property
def url_signature(self):
return hashlib.md5(self.response.url).hexdigest()
@property
def content_length(self):
if self._content_length is None:
self._content_length = self.GetContentLength()
return self._content_length
@property
def has_original_content_length(self):
return 'X-Original-Content-Length' in self.response.headers
@property
def original_content_length(self):
if self.has_original_content_length:
return int(self.response.GetHeader('X-Original-Content-Length'))
return 0
@property
def data_saving_rate(self):
if (self.response.served_from_cache or
not self.has_original_content_length or
self.original_content_length <= 0):
return 0.0
return (float(self.original_content_length - self.content_length) /
self.original_content_length)
def GetContentLengthFromBody(self):
resp = self.response
body, base64_encoded = resp.GetBody()
if not body:
return 0
# The binary data like images, etc is base64_encoded. Decode it to get
# the actualy content length.
if base64_encoded:
decoded = base64.b64decode(body)
return len(decoded)
encoding = resp.GetHeader('Content-Encoding')
if not encoding:
return len(body)
# The response body returned from a timeline event is always decompressed.
# So, we need to compress it to get the actual content length if headers
# say so.
encoding = encoding.lower()
if encoding == 'gzip':
return self.GetGizppedBodyLength(body)
elif encoding == 'deflate':
return len(zlib.compress(body, 9))
else:
raise NetworkMetricException, (
'Unknown Content-Encoding %s for %s' % (encoding, resp.url))
def GetContentLength(self):
cl = 0
try:
cl = self.GetContentLengthFromBody()
except Exception, e:
logging.warning('Fail to get content length for %s from body: %s',
self.response.url[:100], e)
if cl == 0:
resp = self.response
cl_header = resp.GetHeader('Content-Length')
if cl_header:
cl = int(cl_header)
else:
body, _ = resp.GetBody()
if body:
cl = len(body)
return cl
@staticmethod
def GetGizppedBodyLength(body):
if not body:
return 0
bio = io.BytesIO()
try:
with gzip.GzipFile(fileobj=bio, mode="wb", compresslevel=9) as f:
f.write(body.encode('utf-8'))
except Exception, e:
logging.warning('Fail to gzip response body: %s', e)
raise e
return len(bio.getvalue())
class NetworkMetric(Metric):
"""A network metric based on timeline events."""
def __init__(self):
super(NetworkMetric, self).__init__()
# Whether to add detailed result for each sub-resource in a page.
self.add_result_for_resource = False
self.compute_data_saving = False
self._events = None
def Start(self, page, tab):
self._events = None
tab.StartTimelineRecording()
def Stop(self, page, tab):
assert self._events is None
tab.StopTimelineRecording()
def IterResponses(self, tab):
if self._events is None:
self._events = tab.timeline_model.GetAllEventsOfName('HTTPResponse')
if len(self._events) == 0:
return
for e in self._events:
yield self.ResponseFromEvent(e)
def ResponseFromEvent(self, event):
return HTTPResponse(event)
def AddResults(self, tab, results):
content_length = 0
original_content_length = 0
for resp in self.IterResponses(tab):
# Ignore content length calculation for cache hit.
if resp.response.served_from_cache:
continue
resource = resp.response.url
resource_signature = resp.url_signature
cl = resp.content_length
if resp.has_original_content_length:
ocl = resp.original_content_length
if ocl < cl:
logging.warning('original content length (%d) is less than content '
'length (%d) for resource %s', ocl, cl, resource)
if self.add_result_for_resource:
results.AddValue(scalar.ScalarValue(
results.current_page,
'resource_data_saving_' + resource_signature, 'percent',
resp.data_saving_rate * 100))
results.AddValue(scalar.ScalarValue(
results.current_page,
'resource_original_content_length_' + resource_signature, 'bytes',
ocl))
original_content_length += ocl
else:
original_content_length += cl
if self.add_result_for_resource:
results.AddValue(scalar.ScalarValue(
results.current_page,
'resource_content_length_' + resource_signature, 'bytes', cl))
content_length += cl
results.AddValue(scalar.ScalarValue(
results.current_page, 'content_length', 'bytes', content_length))
results.AddValue(scalar.ScalarValue(
results.current_page, 'original_content_length', 'bytes',
original_content_length))
if self.compute_data_saving:
if (original_content_length > 0 and
original_content_length >= content_length):
saving = (float(original_content_length-content_length) * 100 /
original_content_length)
results.AddValue(scalar.ScalarValue(
results.current_page, 'data_saving', 'percent', saving))
else:
results.AddValue(scalar.ScalarValue(
results.current_page, 'data_saving', 'percent', 0.0))
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