async def find_interpreter(
interpreter_constraints: InterpreterConstraints,
pex_runtime_env: PexRuntimeEnvironment) -> PythonExecutable:
formatted_constraints = " OR ".join(
str(constraint) for constraint in interpreter_constraints)
result = await Get(
ProcessResult,
PexCliProcess(
description=
f"Find interpreter for constraints: {formatted_constraints}",
subcommand=(),
# Here, we run the Pex CLI with no requirements, which just selects an interpreter.
# Normally, this would start an isolated repl. By passing `--`, we force the repl to
# instead act as an interpreter (the selected one) and tell us about itself. The upshot
# is we run the Pex interpreter selection logic unperturbed but without resolving any
# distributions.
extra_args=(
*interpreter_constraints.generate_pex_arg_list(),
"--",
"-c",
# N.B.: The following code snippet must be compatible with Python 2.7 and
# Python 3.5+.
#
# When hashing, we pick 8192 for efficiency of reads and fingerprint updates
# (writes) since it's a common OS buffer size and an even multiple of the
# hash block size.
dedent("""\
import hashlib, os, sys
python = os.path.realpath(sys.executable)
print(python)
hasher = hashlib.sha256()
with open(python, "rb") as fp:
for chunk in iter(lambda: fp.read(8192), b""):
hasher.update(chunk)
print(hasher.hexdigest())
"""),
),
level=LogLevel.DEBUG,
# NB: We want interpreter discovery to re-run fairly frequently
# (PER_RESTART_SUCCESSFUL), but not on every run of Pants (NEVER, which is effectively
# per-Session). See #10769 for a solution that is less of a tradeoff.
cache_scope=ProcessCacheScope.PER_RESTART_SUCCESSFUL,
),
)
path, fingerprint = result.stdout.decode().strip().splitlines()
if pex_runtime_env.verbosity > 0:
log_output = result.stderr.decode()
if log_output:
logger.info("%s", log_output)
return PythonExecutable(path=path, fingerprint=fingerprint)
async def find_interpreter(
interpreter_constraints: PexInterpreterConstraints
) -> PythonExecutable:
formatted_constraints = " OR ".join(
str(constraint) for constraint in interpreter_constraints)
process = await Get(
Process,
PexCliProcess(
description=
f"Find interpreter for constraints: {formatted_constraints}",
# Here, we run the Pex CLI with no requirements, which just selects an interpreter.
# Normally, this would start an isolated repl. By passing `--`, we force the repl to
# instead act as an interpreter (the selected one) and tell us about itself. The upshot
# is we run the Pex interpreter selection logic unperturbed but without resolving any
# distributions.
argv=(
*interpreter_constraints.generate_pex_arg_list(),
"--",
"-c",
# N.B.: The following code snippet must be compatible with Python 2.7 and
# Python 3.5+.
dedent("""\
import hashlib
import os
import sys
python = os.path.realpath(sys.executable)
print(python)
hasher = hashlib.sha256()
with open(python, "rb") as fp:
# We pick 8192 for efficiency of reads and fingerprint updates
# (writes) since it's a common OS buffer size and an even
# multiple of the hash block size.
for chunk in iter(lambda: fp.read(8192), b""):
hasher.update(chunk)
print(hasher.hexdigest())
"""),
),
level=LogLevel.DEBUG,
),
)
result = await Get(
ProcessResult,
UncacheableProcess(process=process, scope=ProcessScope.PER_SESSION))
path, fingerprint = result.stdout.decode().strip().splitlines()
return PythonExecutable(path=path, fingerprint=fingerprint)