jacek-lewandowski commented on code in PR #2464:
URL: https://github.com/apache/cassandra/pull/2464#discussion_r1263496147
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src/java/org/apache/cassandra/db/DeletionTime.java:
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@@ -195,42 +195,100 @@ public static Serializer getSerializer(Version version)
return legacySerializer;
}
- // Serializer for Usigned Integer ldt
+ /* Serializer for Usigned Integer ldt
+ *
+ * ldt is encoded as a uint in seconds since unix epoch, it can go up o
2106-02-07T06:28:13+00:00 only.
+ * Since mfda is micros since the Unix Epoch with 7 bytes we can encode
2^56 ~= 1142 years. That leaves
+ * 1 free byte we can use to store flags for sentinel values with some
space saving.
+ *
+ * Currently only a flag for the LIVE ldt is being used.
+ */
public static class Serializer implements ISerializer<DeletionTime>
{
+ private final static int IS_LIVE_DELETION = 0x01;
+ // Long.MAX_VALUE sentinel value equivalent in 7bytes
+ public final static long MAX_MFDA = (1L << (7 * 8)) - 1;
+
public void serialize(DeletionTime delTime, DataOutputPlus out) throws
IOException
{
- out.writeInt(delTime.localDeletionTimeUnsignedInteger);
- out.writeLong(delTime.markedForDeleteAt());
+ if (delTime.equals(LIVE))
+ out.writeByte(IS_LIVE_DELETION);
+ else
+ {
+ if (delTime.markedForDeleteAt() > MAX_MFDA &&
delTime.markedForDeleteAt() != Long.MAX_VALUE)
+ throw new IOException("Value too high for markForDeleteAt
to encode in 7 bytes: " + delTime.markedForDeleteAt());
+ // The flags byte is all zeros atm here, so we can write a
long directly
+ out.writeLong(delTime.markedForDeleteAt() == Long.MAX_VALUE ?
MAX_MFDA : delTime.markedForDeleteAt());
Review Comment:
I thought that reducing the number of written bytes in certain cases is the
reason for introducing a flag?
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