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core/types, rlp: optimize derivesha (#21728)

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This PR contains a minor optimization in derivesha, by exposing the RLP
int-encoding and making use of it to write integers directly to a
buffer (an RLP integer is known to never require more than 9 bytes
total). rlp.AppendUint64 might be useful in other places too.

The code assumes, just as before, that the hasher (a trie) will copy the
key internally, which it does when doing keybytesToHex(key).

Co-authored-by: Felix Lange <fjl@twurst.com>
This commit is contained in:
Martin Holst Swende
2020-11-04 19:29:24 +01:00
committed by GitHub
parent 36bb7ac083
commit 175506e7fd
3 changed files with 117 additions and 12 deletions
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71
rlp/raw.go
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@ -180,3 +180,74 @@ func readSize(b []byte, slen byte) (uint64, error) {
}
return s, nil
}
// AppendUint64 appends the RLP encoding of i to b, and returns the resulting slice.
func AppendUint64(b []byte, i uint64) []byte {
if i == 0 {
return append(b, 0x80)
} else if i < 128 {
return append(b, byte(i))
}
switch {
case i < (1 << 8):
return append(b, 0x81, byte(i))
case i < (1 << 16):
return append(b, 0x82,
byte(i>>8),
byte(i),
)
case i < (1 << 24):
return append(b, 0x83,
byte(i>>16),
byte(i>>8),
byte(i),
)
case i < (1 << 32):
return append(b, 0x84,
byte(i>>24),
byte(i>>16),
byte(i>>8),
byte(i),
)
case i < (1 << 40):
return append(b, 0x85,
byte(i>>32),
byte(i>>24),
byte(i>>16),
byte(i>>8),
byte(i),
)
case i < (1 << 48):
return append(b, 0x86,
byte(i>>40),
byte(i>>32),
byte(i>>24),
byte(i>>16),
byte(i>>8),
byte(i),
)
case i < (1 << 56):
return append(b, 0x87,
byte(i>>48),
byte(i>>40),
byte(i>>32),
byte(i>>24),
byte(i>>16),
byte(i>>8),
byte(i),
)
default:
return append(b, 0x88,
byte(i>>56),
byte(i>>48),
byte(i>>40),
byte(i>>32),
byte(i>>24),
byte(i>>16),
byte(i>>8),
byte(i),
)
}
}