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Improve performance of Python serialization. Patch from Will Pierce.

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This commit is contained in:
kenton@google.com 2009-04-18 02:01:27 +00:00
parent 6dcd46c8d2
commit a8e8ccf29c
2 changed files with 14 additions and 6 deletions
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2
CONTRIBUTORS.txt
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@ -65,3 +65,5 @@ Patch contributors:
* Added generation of field number constants.
Wink Saville <wink@google.com>
* Fixed initialization ordering problem in logging code.
Will Pierce <willp@nuclei.com>
* Small patch improving performance of in Python serialization.

18
python/google/protobuf/internal/wire_format.py
View File

@ -227,13 +227,19 @@ def TagByteSize(field_number):
# Private helper function for the *ByteSize() functions above.
def _VarUInt64ByteSizeNoTag(uint64):
"""Returns the bytes required to serialize a single varint.
"""Returns the number of bytes required to serialize a single varint
using boundary value comparisons. (unrolled loop optimization -WPierce)
uint64 must be unsigned.
"""
if uint64 <= 0x7f: return 1
if uint64 <= 0x3fff: return 2
if uint64 <= 0x1fffff: return 3
if uint64 <= 0xfffffff: return 4
if uint64 <= 0x7ffffffff: return 5
if uint64 <= 0x3ffffffffff: return 6
if uint64 <= 0x1ffffffffffff: return 7
if uint64 <= 0xffffffffffffff: return 8
if uint64 <= 0x7fffffffffffffff: return 9
if uint64 > UINT64_MAX:
raise message.EncodeError('Value out of range: %d' % uint64)
bytes = 1
while uint64 > 0x7f:
bytes += 1
uint64 >>= 7
return bytes
return 10