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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/.
from mozparsers.shared_telemetry_utils import ParserError
from perfecthash import PerfectHash
PHFSIZE = 1024
import sys
import buildconfig
from mozparsers import parse_histograms
banner = """/* This file is auto-generated, see gen_histogram_phf.py. */
"""
header = """
#ifndef mozilla_TelemetryHistogramNameMap_h
#define mozilla_TelemetryHistogramNameMap_h
#include "mozilla/PerfectHash.h"
namespace mozilla {
namespace Telemetry {
"""
footer = """
} // namespace mozilla
} // namespace Telemetry
#endif // mozilla_TelemetryHistogramNameMap_h
"""
def main(output, *filenames):
"""
Generate a Perfect Hash Table for the Histogram name -> Histogram ID lookup.
The table is immutable once generated and we can avoid any dynamic memory allocation.
"""
output.write(banner)
output.write(header)
try:
histograms = list(parse_histograms.from_files(filenames))
histograms = [
h for h in histograms if h.record_on_os(buildconfig.substs["OS_TARGET"])
]
except ParserError as ex:
print("\nError processing histograms:\n" + str(ex) + "\n")
sys.exit(1)
histograms = [
(bytearray(hist.name(), "ascii"), idx) for (idx, hist) in enumerate(histograms)
]
name_phf = PerfectHash(histograms, PHFSIZE)
output.write(
name_phf.cxx_codegen(
name="HistogramIDByNameLookup",
entry_type="uint32_t",
lower_entry=lambda x: str(x[1]),
key_type="const nsACString&",
key_bytes="aKey.BeginReading()",
key_length="aKey.Length()",
)
)
output.write(footer)
if __name__ == "__main__":
main(sys.stdout, *sys.argv[1:])
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