toolkit/components/telemetry/build_scripts/gen_histogram_phf.py

   1 # This Source Code Form is subject to the terms of the Mozilla Public
   2 # License, v. 2.0. If a copy of the MPL was not distributed with this
   3 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
   4
   5 from mozparsers.shared_telemetry_utils import ParserError
   6 from perfecthash import PerfectHash
   7
   8 PHFSIZE = 1024
   9
  10 import sys
  11
  12 import buildconfig
  13 from mozparsers import parse_histograms
  14
  15 banner = """/* This file is auto-generated, see gen_histogram_phf.py.  */
  16 """
  17
  18 header = """
  19 #ifndef mozilla_TelemetryHistogramNameMap_h
  20 #define mozilla_TelemetryHistogramNameMap_h
  21
  22 #include "mozilla/PerfectHash.h"
  23
  24 namespace mozilla {
  25 namespace Telemetry {
  26 """
  27
  28 footer = """
  29 } // namespace mozilla
  30 } // namespace Telemetry
  31 #endif // mozilla_TelemetryHistogramNameMap_h
  32 """
  33
  34
  35 def main(output, *filenames):
  36     """
  37     Generate a Perfect Hash Table for the Histogram name -> Histogram ID lookup.
  38     The table is immutable once generated and we can avoid any dynamic memory allocation.
  39     """
  40
  41     output.write(banner)
  42     output.write(header)
  43
  44     try:
  45         histograms = list(parse_histograms.from_files(filenames))
  46         histograms = [
  47             h for h in histograms if h.record_on_os(buildconfig.substs["OS_TARGET"])
  48         ]
  49     except ParserError as ex:
  50         print("\nError processing histograms:\n" + str(ex) + "\n")
  51         sys.exit(1)
  52
  53     histograms = [
  54         (bytearray(hist.name(), "ascii"), idx) for (idx, hist) in enumerate(histograms)
  55     ]
  56     name_phf = PerfectHash(histograms, PHFSIZE)
  57
  58     output.write(
  59         name_phf.cxx_codegen(
  60             name="HistogramIDByNameLookup",
  61             entry_type="uint32_t",
  62             lower_entry=lambda x: str(x[1]),
  63             key_type="const nsACString&",
  64             key_bytes="aKey.BeginReading()",
  65             key_length="aKey.Length()",
  66         )
  67     )
  68
  69     output.write(footer)
  70
  71
  72 if __name__ == "__main__":
  73     main(sys.stdout, *sys.argv[1:])