zstd/tests/rateLimiter.py

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#! /usr/bin/env python3
# ################################################################
# Copyright (c) 2018-present, Facebook, Inc.
# All rights reserved.
#
# This source code is licensed under both the BSD-style license (found in the
# LICENSE file in the root directory of this source tree) and the GPLv2 (found
# in the COPYING file in the root directory of this source tree).
# ##########################################################################
# Rate limiter, replacement for pv
# this rate limiter does not "catch up" after a blocking period
# Limitations:
# - only accepts limit speed in MB/s
import sys
import time
rate = float(sys.argv[1]) * 1024 * 1024
start = time.time()
total_read = 0
buf = " "
while len(buf):
now = time.time()
to_read = max(int(rate * (now - start) - total_read), 1)
buf = sys.stdin.read(to_read)
write_start = time.time()
sys.stdout.write(buf)
write_end = time.time()
start += write_end - write_start
total_read += len(buf)