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Commit 55b7ba06 authored by Anas Sulaiman's avatar Anas Sulaiman
Browse files

Fix non-deterministic python compilation

Timestamps in pyc files and zip archives were causing cache misses in RBE.

Bug: b/322788229
Test: Ran a few local builds and verified improved cache hit rate for metalava actions.
Change-Id: I9375694d26a107f5c0c43bbd685bd8e86349d187
parent a8a5f642
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+19 −9
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@
import argparse
import py_compile
import os
import sys
import shutil
import tempfile
import zipfile
@@ -23,22 +24,31 @@ import zipfile
# This file needs to support both python 2 and 3.


def process_one_file(name, inf, outzip):
    if not name.endswith('.py'):
        outzip.writestr(name, inf.read())
def process_one_file(info, infile, outzip):
    if not info.filename.endswith('.py'):
        outzip.writestr(info, infile.read())
        return

    # Unfortunately py_compile requires the input/output files to be written
    # out to disk.
    with tempfile.NamedTemporaryFile(prefix="Soong_precompile_", delete=False) as tmp:
        shutil.copyfileobj(inf, tmp)
        shutil.copyfileobj(infile, tmp)
        in_name = tmp.name
    with tempfile.NamedTemporaryFile(prefix="Soong_precompile_", delete=False) as tmp:
        out_name = tmp.name
    try:
        py_compile.compile(in_name, out_name, name, doraise=True)
        # Ensure deterministic pyc by using the hash rather than timestamp.
        # This is required to improve caching in accelerated builds.
        # Only works on Python 3.7+ (see https://docs.python.org/3/library/py_compile.html#py_compile.PycInvalidationMode)
        # which should cover most updated branches and developer machines.
        if sys.version_info >= (3, 7):
            py_compile.compile(in_name, out_name, info.filename, doraise=True, invalidation_mode=py_compile.PycInvalidationMode.CHECKED_HASH)
        else:
            py_compile.compile(in_name, out_name, info.filename, doraise=True)
        with open(out_name, 'rb') as f:
            outzip.writestr(name + 'c', f.read())
            info.filename = info.filename + 'c'
            # Use ZipInfo rather than str to reuse timestamps for deterministic zip files.
            outzip.writestr(info, f.read())
    finally:
        os.remove(in_name)
        os.remove(out_name)
@@ -52,9 +62,9 @@ def main():

    with open(args.dst_zip, 'wb') as outf, open(args.src_zip, 'rb') as inf:
        with zipfile.ZipFile(outf, mode='w') as outzip, zipfile.ZipFile(inf, mode='r') as inzip:
            for name in inzip.namelist():
                with inzip.open(name, mode='r') as inzipf:
                    process_one_file(name, inzipf, outzip)
            for info in inzip.infolist():
                with inzip.open(info.filename, mode='r') as inzipf:
                    process_one_file(info, inzipf, outzip)


if __name__ == "__main__":