eerhardt commented on code in PR #13810:
URL: https://github.com/apache/arrow/pull/13810#discussion_r1148367033
##########
csharp/src/Apache.Arrow/Arrays/PrimitiveArrayBuilder.cs:
##########
@@ -141,15 +141,17 @@ public TBuilder Append(ReadOnlySpan<T> span)
{
int len = ValueBuffer.Length;
ValueBuffer.Append(span);
- ValidityBuffer.AppendRange(Enumerable.Repeat(true,
ValueBuffer.Length - len));
+ int additionalBitsCount = ValueBuffer.Length - len;
+
ValidityBuffer.Reserve(additionalBitsCount).AppendRange(Enumerable.Repeat(true,
additionalBitsCount));
Review Comment:
If you really wanted to optimize this, we should get rid of the
`Enumerable.Repeat` as well.
##########
csharp/src/Apache.Arrow/ArrowBuffer.BitmapBuilder.cs:
##########
@@ -89,6 +89,37 @@ public BitmapBuilder Append(bool value)
return this;
}
+ /// <summary>
+ /// Append a span of bits.
+ /// </summary>
+ /// <param name="source">Source of bit span.</param>
+ /// <param name="validBits">Number of valid bits in the bit
span</param>
+ /// <returns>Returns the builder (for fluent-style
composition).</returns>
+ public BitmapBuilder Append(ReadOnlySpan<byte> source, int
validBits)
+ {
+ var length = source.IsEmpty ? validBits :
Math.Min(source.Length * 8, validBits);
Review Comment:
Since this is a public API, I think we should we do parameter validation
that ensures `validBits` <= `source.Length * 8`. Or we make it internal.
##########
csharp/src/Apache.Arrow/ArrowBuffer.BitmapBuilder.cs:
##########
@@ -89,6 +89,37 @@ public BitmapBuilder Append(bool value)
return this;
}
+ /// <summary>
+ /// Append a span of bits.
+ /// </summary>
+ /// <param name="source">Source of bit span.</param>
+ /// <param name="validBits">Number of valid bits in the bit
span</param>
+ /// <returns>Returns the builder (for fluent-style
composition).</returns>
+ public BitmapBuilder Append(ReadOnlySpan<byte> source, int
validBits)
+ {
+ var length = source.IsEmpty ? validBits :
Math.Min(source.Length * 8, validBits);
+
+ // Check if memory copy can be used from the source array
(performance optimization for byte-aligned coping)
+ if (!source.IsEmpty && this.Length % 8 == 0)
+ {
+ EnsureAdditionalCapacity(length * 8);
+ source.Slice(0,
BitUtility.ByteCount(length)).CopyTo(Span.Slice(Length / 8));
+
+ Length += length;
+ SetBitCount = BitUtility.CountBits(Span, 0, Length);
Review Comment:
Do we really need to count all the bits again? Can't we just count the bits
that were appended and add it to the existing number?
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