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# Copyright 2013 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.
"""Extract histogram names from the description XML file.
For more information on the format of the XML file, which is self-documenting,
see histograms.xml; however, here is a simple example to get you started. The
XML below will generate the following five histograms:
<histogram name="HistogramTime" units="milliseconds">
<summary>A brief description.</summary>
<details>This is a more thorough description of this histogram.</details>
<histogram name="HistogramEnum" enum="MyEnumType">
<summary>This histogram sports an enum value type.</summary>
<enum name="MyEnumType">
<summary>This is an example enum type, where the values mean little.</summary>
<int value="1" label="FIRST_VALUE">This is the first value.</int>
<int value="2" label="SECOND_VALUE">This is the second value.</int>
<histogram_suffixes name="BrowserType">
<group name="Chrome"/>
<group name="IE"/>
<group name="Firefox"/>
<affected-histogram name="HistogramEnum"/>
import copy
import logging
import xml.dom.minidom
'Please list the metric\'s owners. Add more owner tags as needed.')
class Error(Exception):
def _JoinChildNodes(tag):
"""Join child nodes into a single text.
Applicable to leafs like 'summary' and 'detail'.
tag: parent node
a string with concatenated nodes' text representation.
return ''.join(c.toxml() for c in tag.childNodes).strip()
def _NormalizeString(s):
"""Replaces all whitespace sequences with a single space.
The function properly handles multi-line strings.
s: The string to normalize, (' \\n a b c\\n d ').
The normalized string (a b c d).
return ' '.join(s.split())
def _NormalizeAllAttributeValues(node):
"""Recursively normalizes all tag attribute values in the given tree.
node: The minidom node to be normalized.
The normalized minidom node.
if node.nodeType == xml.dom.minidom.Node.ELEMENT_NODE:
for a in node.attributes.keys():
node.attributes[a].value = _NormalizeString(node.attributes[a].value)
for c in node.childNodes:
return node
def _ExpandHistogramNameWithSuffixes(suffix_name, histogram_name,
"""Creates a new histogram name based on a histogram suffix.
suffix_name: The suffix string to apply to the histogram name. May be empty.
histogram_name: The name of the histogram. May be of the form
Group.BaseName or BaseName.
histogram_suffixes_node: The histogram_suffixes XML node.
A string with the expanded histogram name.
Error: if the expansion can't be done.
if histogram_suffixes_node.hasAttribute('separator'):
separator = histogram_suffixes_node.getAttribute('separator')
separator = '_'
if histogram_suffixes_node.hasAttribute('ordering'):
ordering = histogram_suffixes_node.getAttribute('ordering')
ordering = 'suffix'
if ordering not in ['prefix', 'suffix']:
logging.error('ordering needs to be prefix or suffix, value is %s',
raise Error()
if not suffix_name:
return histogram_name
if ordering == 'suffix':
return histogram_name + separator + suffix_name
# For prefixes, the suffix_name is inserted between the "cluster" and the
# "remainder", e.g. Foo.BarHist expanded with gamma becomes Foo.gamma_BarHist.
sections = histogram_name.split('.')
if len(sections) <= 1:
'Prefix Field Trial expansions require histogram names which include a '
'dot separator. Histogram name is %s, and Field Trial is %s',
histogram_name, histogram_suffixes_node.getAttribute('name'))
raise Error()
cluster = sections[0] + '.'
remainder = '.'.join(sections[1:])
return cluster + suffix_name + separator + remainder
def _ExtractEnumsFromXmlTree(tree):
"""Extract all <enum> nodes in the tree into a dictionary."""
enums = {}
have_errors = False
last_name = None
for enum in tree.getElementsByTagName('enum'):
if enum.getAttribute('type') != 'int':
logging.error('Unknown enum type %s', enum.getAttribute('type'))
have_errors = True
name = enum.getAttribute('name')
if last_name is not None and name.lower() < last_name.lower():
logging.error('Enums %s and %s are not in alphabetical order',
last_name, name)
have_errors = True
last_name = name
if name in enums:
logging.error('Duplicate enum %s', name)
have_errors = True
last_int_value = None
enum_dict = {}
enum_dict['name'] = name
enum_dict['values'] = {}
for int_tag in enum.getElementsByTagName('int'):
value_dict = {}
int_value = int(int_tag.getAttribute('value'))
if last_int_value is not None and int_value < last_int_value:
logging.error('Enum %s int values %d and %d are not in numerical order',
name, last_int_value, int_value)
have_errors = True
last_int_value = int_value
if int_value in enum_dict['values']:
logging.error('Duplicate enum value %d for enum %s', int_value, name)
have_errors = True
value_dict['label'] = int_tag.getAttribute('label')
value_dict['summary'] = _JoinChildNodes(int_tag)
enum_dict['values'][int_value] = value_dict
summary_nodes = enum.getElementsByTagName('summary')
if summary_nodes:
enum_dict['summary'] = _NormalizeString(_JoinChildNodes(summary_nodes[0]))
enums[name] = enum_dict
return enums, have_errors
def _ExtractOwners(xml_node):
"""Extract all owners into a list from owner tag under |xml_node|."""
owners = []
for owner_node in xml_node.getElementsByTagName('owner'):
owner_entry = _NormalizeString(_JoinChildNodes(owner_node))
if OWNER_FIELD_PLACEHOLDER not in owner_entry:
return owners
def _ExtractHistogramsFromXmlTree(tree, enums):
"""Extract all <histogram> nodes in the tree into a dictionary."""
# Process the histograms. The descriptions can include HTML tags.
histograms = {}
have_errors = False
last_name = None
for histogram in tree.getElementsByTagName('histogram'):
name = histogram.getAttribute('name')
if last_name is not None and name.lower() < last_name.lower():
logging.error('Histograms %s and %s are not in alphabetical order',
last_name, name)
have_errors = True
last_name = name
if name in histograms:
logging.error('Duplicate histogram definition %s', name)
have_errors = True
histograms[name] = histogram_entry = {}
# Find <owner> tag.
owners = _ExtractOwners(histogram)
if owners:
histogram_entry['owners'] = owners
# Find <summary> tag.
summary_nodes = histogram.getElementsByTagName('summary')
if summary_nodes:
histogram_entry['summary'] = _NormalizeString(
histogram_entry['summary'] = 'TBD'
# Find <obsolete> tag.
obsolete_nodes = histogram.getElementsByTagName('obsolete')
if obsolete_nodes:
reason = _JoinChildNodes(obsolete_nodes[0])
histogram_entry['obsolete'] = reason
# Handle units.
if histogram.hasAttribute('units'):
histogram_entry['units'] = histogram.getAttribute('units')
# Find <details> tag.
details_nodes = histogram.getElementsByTagName('details')
if details_nodes:
histogram_entry['details'] = _NormalizeString(
# Handle enum types.
if histogram.hasAttribute('enum'):
enum_name = histogram.getAttribute('enum')
if enum_name not in enums:
logging.error('Unknown enum %s in histogram %s', enum_name, name)
have_errors = True
histogram_entry['enum'] = enums[enum_name]
return histograms, have_errors
def _UpdateHistogramsWithSuffixes(tree, histograms):
"""Process <histogram_suffixes> tags and combine with affected histograms.
The histograms dictionary will be updated in-place by adding new histograms
created by combining histograms themselves with histogram_suffixes targeting
these histograms.
tree: XML dom tree.
histograms: a dictionary of histograms previously extracted from the tree;
True if any errors were found.
have_errors = False
# TODO(yiyaoliu): Remove this part after fieldtrial is not used any more.
if tree.getElementsByTagName('histogram_suffixes'):
histogram_suffix_tag = 'histogram_suffixes'
suffix_tag = 'suffix'
with_tag = 'with-suffix'
histogram_suffix_tag = 'fieldtrial'
suffix_tag = 'group'
with_tag = 'with-group'
# Verify order of histogram_suffixes fields first.
last_name = None
for histogram_suffixes in tree.getElementsByTagName(histogram_suffix_tag):
name = histogram_suffixes.getAttribute('name')
if last_name is not None and name.lower() < last_name.lower():
logging.error('histogram_suffixes %s and %s are not in alphabetical '
'order', last_name, name)
have_errors = True
last_name = name
# histogram_suffixes can depend on other histogram_suffixes, so we need to be
# careful. Make a temporary copy of the list of histogram_suffixes to use as a
# queue. histogram_suffixes whose dependencies have not yet been processed
# will get relegated to the back of the queue to be processed later.
reprocess_queue = []
def GenerateHistogramSuffixes():
for f in tree.getElementsByTagName(histogram_suffix_tag):
yield 0, f
for r, f in reprocess_queue:
yield r, f
for reprocess_count, histogram_suffixes in GenerateHistogramSuffixes():
# Check dependencies first
dependencies_valid = True
affected_histograms = histogram_suffixes.getElementsByTagName(
for affected_histogram in affected_histograms:
histogram_name = affected_histogram.getAttribute('name')
if histogram_name not in histograms:
# Base histogram is missing
dependencies_valid = False
missing_dependency = histogram_name
if not dependencies_valid:
reprocess_queue.append((reprocess_count + 1, histogram_suffixes))
logging.error('histogram_suffixes %s is missing its dependency %s',
have_errors = True
name = histogram_suffixes.getAttribute('name')
suffix_nodes = histogram_suffixes.getElementsByTagName(suffix_tag)
suffix_labels = {}
for suffix in suffix_nodes:
suffix_labels[suffix.getAttribute('name')] = suffix.getAttribute('label')
# Find owners list under current histogram_suffixes tag.
owners = _ExtractOwners(histogram_suffixes)
last_histogram_name = None
for affected_histogram in affected_histograms:
histogram_name = affected_histogram.getAttribute('name')
if (last_histogram_name is not None
and histogram_name.lower() < last_histogram_name.lower()):
logging.error('Affected histograms %s and %s of histogram_suffixes %s '
'are not in alphabetical order',
last_histogram_name, histogram_name, name)
have_errors = True
last_histogram_name = histogram_name
with_suffixes = affected_histogram.getElementsByTagName(with_tag)
if with_suffixes:
suffixes_to_add = with_suffixes
suffixes_to_add = suffix_nodes
for suffix in suffixes_to_add:
suffix_name = suffix.getAttribute('name')
new_histogram_name = _ExpandHistogramNameWithSuffixes(
suffix_name, histogram_name, histogram_suffixes)
if new_histogram_name != histogram_name:
histograms[new_histogram_name] = copy.deepcopy(
suffix_label = suffix_labels.get(suffix_name, '')
# TODO(yiyaoliu): Rename these to be consistent with the new naming.
# It is kept unchanged for now to be it's used by dashboards.
if 'fieldtrial_groups' not in histograms[new_histogram_name]:
histograms[new_histogram_name]['fieldtrial_groups'] = []
if 'fieldtrial_names' not in histograms[new_histogram_name]:
histograms[new_histogram_name]['fieldtrial_names'] = []
if 'fieldtrial_labels' not in histograms[new_histogram_name]:
histograms[new_histogram_name]['fieldtrial_labels'] = []
# If no owners are added for this histogram-suffixes, it inherits the
# owners of its parents.
if owners:
histograms[new_histogram_name]['owners'] = owners
except Error:
have_errors = True
return have_errors
def ExtractHistogramsFromFile(file_handle):
"""Compute the histogram names and descriptions from the XML representation.
file_handle: A file or file-like with XML content.
a tuple of (histograms, status) where histograms is a dictionary mapping
histogram names to dictionaries containing histogram descriptions and status
is a boolean indicating if errros were encoutered in processing.
tree = xml.dom.minidom.parse(file_handle)
enums, enum_errors = _ExtractEnumsFromXmlTree(tree)
histograms, histogram_errors = _ExtractHistogramsFromXmlTree(tree, enums)
update_errors = _UpdateHistogramsWithSuffixes(tree, histograms)
return histograms, enum_errors or histogram_errors or update_errors
def ExtractHistograms(filename):
"""Load histogram definitions from a disk file.
filename: a file path to load data from.
a dictionary of histogram descriptions.
Error: if the file is not well-formatted.
with open(filename, 'r') as f:
histograms, had_errors = ExtractHistogramsFromFile(f)
if had_errors:
logging.error('Error parsing %s', filename)
raise Error()
return histograms
def ExtractNames(histograms):
return sorted(histograms.keys())