gecko/toolkit/components/telemetry/gen-histogram-data.py

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# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
# Write out histogram information for C++. The histograms are defined
# in a file provided as a command-line argument.
from __future__ import with_statement
import sys
import histogram_tools
import itertools
banner = """/* This file is auto-generated, see gen-histogram-data.py. */
"""
# Write out the gHistograms array.
class StringTable:
def __init__(self):
self.current_index = 0;
self.table = {}
def c_strlen(self, string):
return len(string) + 1
def stringIndex(self, string):
if string in self.table:
return self.table[string]
else:
result = self.current_index
self.table[string] = result
self.current_index += self.c_strlen(string)
return result
def writeDefinition(self, f, name):
entries = self.table.items()
entries.sort(key=lambda x:x[1])
# Avoid null-in-string warnings with GCC and potentially
# overlong string constants; write everything out the long way.
def explodeToCharArray(string):
def toCChar(s):
if s == "'":
return "'\\''"
else:
return "'%s'" % s
return ", ".join(map(toCChar, string))
f.write("const char %s[] = {\n" % name)
for (string, offset) in entries[:-1]:
f.write(" /* %5d */ %s, '\\0',\n"
% (offset, explodeToCharArray(string)))
f.write(" /* %5d */ %s, '\\0' };\n\n"
% (entries[-1][1], explodeToCharArray(entries[-1][0])))
def print_array_entry(histogram, name_index, desc_index):
cpp_guard = histogram.cpp_guard()
if cpp_guard:
print "#if defined(%s)" % cpp_guard
print " { %s, %s, %s, %s, %d, %d }," \
% (histogram.low(), histogram.high(),
histogram.n_buckets(), histogram.nsITelemetry_kind(),
name_index, desc_index)
if cpp_guard:
print "#endif"
def write_histogram_table(histograms):
table = StringTable()
print "const TelemetryHistogram gHistograms[] = {"
for histogram in histograms:
name_index = table.stringIndex(histogram.name())
desc_index = table.stringIndex(histogram.description())
print_array_entry(histogram, name_index, desc_index)
print "};"
strtab_name = "gHistogramStringTable"
table.writeDefinition(sys.stdout, strtab_name)
static_assert("sizeof(%s) <= UINT16_MAX" % strtab_name,
"index overflow")
# Write out static asserts for histogram data. We'd prefer to perform
# these checks in this script itself, but since several histograms
# (generally enumerated histograms) use compile-time constants for
# their upper bounds, we have to let the compiler do the checking.
def static_assert(expression, message):
print "MOZ_STATIC_ASSERT(%s, \"%s\");" % (expression, message)
def static_asserts_for_boolean(histogram):
pass
def static_asserts_for_flag(histogram):
pass
def static_asserts_for_enumerated(histogram):
n_values = histogram.high()
static_assert("%s > 2" % n_values,
"Not enough values for %s" % histogram.name())
def shared_static_asserts(histogram):
name = histogram.name()
low = histogram.low()
high = histogram.high()
n_buckets = histogram.n_buckets()
static_assert("%s < %s" % (low, high), "low >= high for %s" % name)
static_assert("%s > 2" % n_buckets, "Not enough values for %s" % name)
static_assert("%s >= 1" % low, "Incorrect low value for %s" % name)
static_assert("%s > %s" % (high, n_buckets),
"high must be > number of buckets for %s; you may want an enumerated histogram" % name)
def static_asserts_for_linear(histogram):
shared_static_asserts(histogram)
def static_asserts_for_exponential(histogram):
shared_static_asserts(histogram)
def write_histogram_static_asserts(histograms):
print """
// Perform the checks at the beginning of HistogramGet at
// compile time, so that incorrect histogram definitions
// give compile-time errors, not runtime errors."""
table = {
'boolean' : static_asserts_for_boolean,
'flag' : static_asserts_for_flag,
'enumerated' : static_asserts_for_enumerated,
'linear' : static_asserts_for_linear,
'exponential' : static_asserts_for_exponential,
}
for histogram in histograms:
histogram_tools.table_dispatch(histogram.kind(), table,
lambda f: f(histogram))
def write_debug_histogram_ranges(histograms):
ranges_lengths = []
# Collect all the range information from individual histograms.
# Write that information out as well.
print "#ifdef DEBUG"
print "const int gBucketLowerBounds[] = {"
for histogram in histograms:
ranges = []
try:
ranges = histogram.ranges()
except histogram_tools.DefinitionException:
pass
ranges_lengths.append(len(ranges))
# Note that we do not test cpp_guard here. We do this so we
# will have complete information about all the histograms in
# this array. Just having information about the ranges of
# histograms is not platform-specific; if there are histograms
# that have platform-specific constants in their definitions,
# those histograms will fail in the .ranges() call above and
# we'll have a zero-length array to deal with here.
if len(ranges) > 0:
print ','.join(map(str, ranges)), ','
else:
print '/* Skipping %s */' % histogram.name()
print "};"
# Write the offsets into gBucketLowerBounds.
print "struct bounds { int offset; int length; };"
print "const struct bounds gBucketLowerBoundIndex[] = {"
offset = 0
for (histogram, range_length) in itertools.izip(histograms, ranges_lengths):
cpp_guard = histogram.cpp_guard()
# We do test cpp_guard here, so that histogram IDs are valid
# indexes into this array.
if cpp_guard:
print "#if defined(%s)" % cpp_guard
print "{ %d, %d }," % (offset, range_length)
if cpp_guard:
print "#endif"
offset += range_length
print "};"
print "#endif"
def main(argv):
filename = argv[0]
histograms = list(histogram_tools.from_file(filename))
print banner
write_histogram_table(histograms)
write_histogram_static_asserts(histograms)
write_debug_histogram_ranges(histograms)
main(sys.argv[1:])