mr-smidge commented on a change in pull request #7654:
URL: https://github.com/apache/arrow/pull/7654#discussion_r456557580
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File path: csharp/src/Apache.Arrow/Arrays/Date64Array.cs
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@@ -15,56 +15,94 @@
using Apache.Arrow.Types;
using System;
-using System.Collections.Generic;
-using Apache.Arrow.Memory;
namespace Apache.Arrow
{
+ /// <summary>
+ /// The <see cref="Date64Array"/> class holds an array of dates in the
<c>Date64</c> format, where each date is
+ /// stored as the number of milliseconds since the dawn of (UNIX) time,
excluding leap seconds.
+ /// </summary>
public class Date64Array: PrimitiveArray<long>
{
+ private static readonly DateTime _epoch = new DateTime(1970, 1, 1, 0,
0, 0, DateTimeKind.Unspecified);
+
public Date64Array(
ArrowBuffer valueBuffer, ArrowBuffer nullBitmapBuffer,
int length, int nullCount, int offset)
: this(new ArrayData(Date64Type.Default, length, nullCount, offset,
new[] { nullBitmapBuffer, valueBuffer }))
{ }
- public class Builder : PrimitiveArrayBuilder<DateTimeOffset, long,
Date64Array, Builder>
+ /// <summary>
+ /// The <see cref="Builder"/> class can be used to fluently build <see
cref="Date64Array"/> objects.
+ /// </summary>
+ public class Builder : DateArrayBuilder<long, Date64Array, Builder>
{
- internal class DateBuilder: PrimitiveArrayBuilder<long,
Date64Array, DateBuilder>
+ private class DateBuilder: PrimitiveArrayBuilder<long,
Date64Array, DateBuilder>
{
protected override Date64Array Build(
ArrowBuffer valueBuffer, ArrowBuffer nullBitmapBuffer,
int length, int nullCount, int offset) =>
new Date64Array(valueBuffer, nullBitmapBuffer, length,
nullCount, offset);
- }
+ }
+ /// <summary>
+ /// Construct a new instance of the <see cref="Builder"/> class.
+ /// </summary>
public Builder() : base(new DateBuilder()) { }
- protected override long ConvertTo(DateTimeOffset value)
+ protected override long Convert(DateTime dateTime)
+ {
+ return (long)(dateTime - _epoch).TotalMilliseconds;
+ }
+
+ protected override long Convert(DateTimeOffset dateTimeOffset)
{
- return value.ToUnixTimeMilliseconds();
+ return (long)(dateTimeOffset.Date - _epoch).TotalMilliseconds;
Review comment:
I've restored this to use `.ToUnixTimeMilliseconds()` (and with the
conversion in the other direction).
However, I'm not sure whether it is such a good idea to make the same change
in `Date32Array`. My personal opinion is that `(dateTime - _epoch).TotalDays`
is more readable as a day count than having to make a trip into milliseconds
and then convert again. Involving milliseconds may also distract the reader
into momentarily thinking about leap seconds, when they are not relevant for a
day count.
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