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Performance improvement: use struct.unpack instead of manually constructing bytes when possible

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This commit is contained in:
Anze 2022-05-08 17:54:05 +02:00
parent b10dc5faef
commit 77da7b16b6
1 changed files with 13 additions and 5 deletions
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18
netflow/v9.py
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@ -228,11 +228,19 @@ class V9DataFlowSet:
continue
new_record.data[fkey] = ip.compressed
else:
# Better solution than struct.unpack with variable field length
fdata = 0
for idx, byte in enumerate(reversed(bytearray(dataslice))):
fdata += byte << (idx * 8)
new_record.data[fkey] = fdata
# For performance reasons, we use struct.unpack for known lengths:
if flen == 4:
new_record.data[fkey], = struct.unpack('!L', dataslice)
elif flen == 2:
new_record.data[fkey], = struct.unpack('!H', dataslice)
elif flen == 1:
new_record.data[fkey], = struct.unpack('!B', dataslice)
else:
# Caveat: this code assumes little-endian system (like x86)
fdata = 0
for idx, byte in enumerate(reversed(bytearray(dataslice))):
fdata += byte << (idx * 8)
new_record.data[fkey] = fdata
offset += flen