use FastISODateParser.parseAsEpochMilli

Compared to FastISODateParser.parse, which returns an
OffsetDateTime object, parseAsEpochMilli returns the
epoch time millis. The performance improvement for
date parsing alone is roughly 100% (8m dates/s to
18m dates/s).
Insertion speed improved from 13-14s for 1.6m entries
to 11.5-12.5s.

pdb-api/src/main/java/org/lucares/pdb/api/Entry.java

@@ -1,6 +1,8 @@
 package org.lucares.pdb.api;
 
+import java.time.Instant;
 import java.time.OffsetDateTime;
+import java.time.ZoneOffset;
 import java.time.format.DateTimeFormatter;
 
 public class Entry {
@@ -9,30 +11,26 @@ public class Entry {
 	 * A special {@link Entry} that can be used as poison object for
 	 * {@link BlockingQueueIterator}.
 	 */
-	public static final Entry POISON = new Entry(OffsetDateTime.MIN, -1, null);
+	public static final Entry POISON = new Entry(Long.MIN_VALUE, -1, null);
 
 	private final long value;
 
 	private final Tags tags;
 
-	private final OffsetDateTime date;
+	private final long epochMilli;
 
-	public Entry(final OffsetDateTime date, final long value, final Tags tags) {
-		this.date = date;
+	public Entry(final long epochMilli, final long value, final Tags tags) {
+		this.epochMilli = epochMilli;
 		this.tags = tags;
 		this.value = value;
 	}
 
-	public OffsetDateTime getDate() {
-		return date;
-	}
-
 	public long getValue() {
 		return value;
 	}
 
 	public long getEpochMilli() {
-		return date.toInstant().toEpochMilli();
+		return epochMilli;
 	}
 
 	public Tags getTags() {
@@ -45,7 +43,7 @@ public class Entry {
 			return "POISON ENTRY";
 		}
 
-		final OffsetDateTime date = getDate();
+		final OffsetDateTime date = Instant.ofEpochMilli(epochMilli).atOffset(ZoneOffset.UTC);
 		return date.format(DateTimeFormatter.ISO_ZONED_DATE_TIME) + " = " + value + " (" + tags.asString() + ")";
 	}
 
@@ -53,7 +51,7 @@ public class Entry {
 	public int hashCode() {
 		final int prime = 31;
 		int result = 1;
-		result = prime * result + ((date == null) ? 0 : date.hashCode());
+		result = prime * result + (int) (epochMilli ^ (epochMilli >>> 32));
 		result = prime * result + ((tags == null) ? 0 : tags.hashCode());
 		result = prime * result + (int) (value ^ (value >>> 32));
 		return result;
@@ -68,10 +66,7 @@ public class Entry {
 		if (getClass() != obj.getClass())
 			return false;
 		final Entry other = (Entry) obj;
-		if (date == null) {
-			if (other.date != null)
-				return false;
-		} else if (!date.equals(other.date))
+		if (epochMilli != other.epochMilli)
 			return false;
 		if (tags == null) {
 			if (other.tags != null)
@@ -82,5 +77,4 @@ public class Entry {
 			return false;
 		return true;
 	}
-
 }