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Bigger buffer for the Command Line interface. #39

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Merged
merged 2 commits into from
Feb 19, 2021
Merged

Bigger buffer for the Command Line interface. #39

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eece4fc
Slightly increase buffer size in the CLI application for 6% speed imp…
rhpvorderman Feb 19, 2021
00c9791
Update changelog
rhpvorderman Feb 19, 2021
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3 changes: 3 additions & 0 deletions CHANGELOG.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,9 @@ Changelog

version 0.5.0-dev
-----------------
+ The command-line interface now reads in blocks of 32K instead of 8K. This
improves performance by about 6% when compressing and 11% when decompressing.
A hidden ``-b`` flag was added to adjust the buffer size for benchmarks.
+ A ``-c`` or ``--stdout`` flag was added to the CLI interface of isal.igzip.
This allows it to behave more like the ``gzip`` or ``pigz`` command line
interfaces.
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12 changes: 7 additions & 5 deletions src/isal/igzip.py
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Expand Up @@ -27,8 +27,6 @@
import os
import sys

import _compression

from . import isal_zlib

__all__ = ["IGzipFile", "open", "compress", "decompress", "BadGzipFile"]
Expand All @@ -37,8 +35,6 @@
_COMPRESS_LEVEL_TRADEOFF = isal_zlib.ISAL_DEFAULT_COMPRESSION
_COMPRESS_LEVEL_BEST = isal_zlib.ISAL_BEST_COMPRESSION

BUFFER_SIZE = _compression.BUFFER_SIZE

try:
BadGzipFile = gzip.BadGzipFile
except AttributeError: # Versions lower than 3.8 do not have BadGzipFile
Expand Down Expand Up @@ -278,6 +274,12 @@ def main():
help="Decompress the file instead of compressing.")
parser.add_argument("-c", "--stdout", action="store_true",
help="write on standard output")
# -b flag not taken by either gzip or igzip. Hidden attribute. Above 32K
# diminishing returns hit. _compression.BUFFER_SIZE = 8k. But 32K is about
# ~6% faster.
parser.add_argument("-b", "--buffer-size",
default=32 * 1024, type=int,
help=argparse.SUPPRESS)
args = parser.parse_args()

compresslevel = args.compresslevel or _COMPRESS_LEVEL_TRADEOFF
Expand Down Expand Up @@ -310,7 +312,7 @@ def main():

try:
while True:
block = in_file.read(BUFFER_SIZE)
block = in_file.read(args.buffer_size)
if block == b"":
break
out_file.write(block)
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