tyrelr commented on a change in pull request #9304:
URL: https://github.com/apache/arrow/pull/9304#discussion_r563336446
##########
File path: rust/arrow/src/buffer.rs
##########
@@ -1188,6 +1209,57 @@ impl Drop for SetLenOnDrop<'_> {
}
}
+/// Creating a `MutableBuffer` instance by setting bits according to the
boolean values
+impl std::iter::FromIterator<bool> for MutableBuffer {
+ fn from_iter<I>(iter: I) -> Self
+ where
+ I: IntoIterator<Item = bool>,
+ {
+ let mut iterator = iter.into_iter();
+ let mut result = {
+ let byte_capacity: usize =
iterator.size_hint().0.saturating_add(7) / 8;
+ MutableBuffer::new(byte_capacity)
+ };
+
+ while let Some(value) = iterator.next() {
+ //we have the first bit of the byte
+ let mut exhausted = false;
+ let mut byte_accum: u8 = match value {
Review comment:
That approach seems to be worse in the micro-benchmark, but better for
the comparison kernel.
```
critcmp master-67d0c2e3 bool-38d4e395 bool-11dd14af -t 10
group bool-11dd14af
bool-38d4e395 master-67d0c2e3
----- -------------
------------- ---------------
Buffer::from_iter bool 1.66 10.2±0.02ms ? B/sec
1.00 6.2±0.01ms ? B/sec
MutableBuffer iter bitset 1.00 56.0±0.11ms ? B/sec
1.12 62.5±0.13ms ? B/sec
MutableBuffer::from_iter bool 1.45 8.9±0.02ms ? B/sec
1.00 6.1±0.01ms ? B/sec
add 512 1.06 225.1±1.05ns ? B/sec
1.00 212.9±0.56ns ? B/sec 1.38 293.0±1.54ns ? B/sec
array_from_vec 256 1.00 629.6±2.56ns ? B/sec
1.03 649.4±1.78ns ? B/sec 1.11 701.7±1.29ns ? B/sec
cast int64 to int32 512 1.00 2.2±0.01µs ? B/sec
1.14 2.5±0.01µs ? B/sec 1.02 2.3±0.01µs ? B/sec
cast time32s to time32ms 512 1.23 901.3±2.65ns ? B/sec
1.01 736.1±1.17ns ? B/sec 1.00 731.5±1.15ns ? B/sec
cast timestamp_ms to timestamp_ns 512 1.17 1211.8±2.48ns ? B/sec
1.00 1036.8±1.71ns ? B/sec 1.11 1149.7±2.41ns ? B/sec
eq Float32 1.00 84.6±0.08µs ? B/sec
1.05 89.2±0.28µs ? B/sec 1.49 125.9±0.23µs ? B/sec
eq scalar Float32 1.02 71.2±0.08µs ? B/sec
1.12 78.2±0.18µs ? B/sec 1.00 69.8±0.07µs ? B/sec
from_slice 1.00 488.4±0.92µs ? B/sec
1.81 883.0±1.48µs ? B/sec 1.76 861.2±1.55µs ? B/sec
from_slice prepared 1.00 480.7±1.00µs ? B/sec
1.15 552.1±1.44µs ? B/sec 1.18 564.8±0.85µs ? B/sec
gt scalar Float32 1.24 64.8±0.06µs ? B/sec
1.37 71.5±0.07µs ? B/sec 1.00 52.4±0.06µs ? B/sec
gt_eq Float32 1.00 72.3±0.26µs ? B/sec
1.04 75.3±0.09µs ? B/sec 1.72 124.2±0.09µs ? B/sec
lt scalar Float32 1.07 65.5±0.09µs ? B/sec
1.15 70.9±0.13µs ? B/sec 1.00 61.4±0.09µs ? B/sec
lt_eq Float32 1.00 72.0±0.07µs ? B/sec
1.03 74.2±0.08µs ? B/sec 1.71 123.1±0.23µs ? B/sec
lt_eq scalar Float32 1.00 58.0±0.10µs ? B/sec
1.05 61.1±0.07µs ? B/sec 1.52 88.3±0.15µs ? B/sec
min nulls 512 1.11 2.1±0.01µs ? B/sec
1.03 1961.9±13.05ns ? B/sec 1.00 1908.7±19.95ns ? B/sec
multiply 512 1.34 350.1±0.66ns ? B/sec
1.30 339.1±0.32ns ? B/sec 1.00 261.6±0.30ns ? B/sec
mutable 3.79 1630.3±2.29µs ? B/sec
1.00 429.8±1.01µs ? B/sec 1.02 436.7±1.19µs ? B/sec
mutable extend 2.45 2.0±0.00ms ? B/sec
1.00 835.7±3.31µs ? B/sec 1.01 846.4±1.40µs ? B/sec
mutable iter extend_from_slice 2.20 2.2±0.00ms ? B/sec
1.00 1007.3±1.72µs ? B/sec
mutable str nulls 1024 1.16 5.4±0.01ms ? B/sec
1.00 4.7±0.01ms ? B/sec 1.05 4.9±0.01ms ? B/sec
neq scalar Float32 1.12 71.3±0.12µs ? B/sec
1.23 78.2±0.08µs ? B/sec 1.00 63.6±0.18µs ? B/sec
not 1.13 1145.6±1.91ns ? B/sec
1.13 1146.5±1.20ns ? B/sec 1.00 1014.1±0.90ns ? B/sec
subtract 512 1.02 258.8±1.15ns ? B/sec
1.40 354.9±0.66ns ? B/sec
```
I may try playing with the benchmarks to see if I'm missing a black-box
that's causing an unrealistic optimization...
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