38 lines
1.2 KiB
Python
Executable File
38 lines
1.2 KiB
Python
Executable File
#!/usr/bin/env python3
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# ################################################################
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# Copyright (c) 2018-present, Facebook, Inc.
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# All rights reserved.
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#
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# This source code is licensed under both the BSD-style license (found in the
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# LICENSE file in the root directory of this source tree) and the GPLv2 (found
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# in the COPYING file in the root directory of this source tree).
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# ##########################################################################
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# Rate limiter, replacement for pv
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# this rate limiter does not "catch up" after a blocking period
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# Limitations:
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# - only accepts limit speed in MB/s
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import sys
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import time
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MB = 1024 * 1024
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rate = float(sys.argv[1]) * MB
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rate *= 1.25 # compensation for excluding write time (experimentally determined)
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start = time.time()
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total_read = 0
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buf = " "
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while len(buf):
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now = time.time()
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to_read = max(int(rate * (now - start) - total_read), 1)
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max_buf_size = 1 * MB
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to_read = min(to_read, max_buf_size)
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buf = sys.stdin.buffer.read(to_read)
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write_start = time.time()
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sys.stdout.buffer.write(buf)
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write_end = time.time()
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start += write_end - write_start # exclude write delay
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total_read += len(buf)
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