ColumnEncodingUtils add comments and test

scalar-labs · Dec 17, 2024 · 152e196 · 152e196
1 parent 523b009
commit 152e196
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Showing 2 changed files with 57 additions and 25 deletions.
diff --git a/core/src/main/java/com/scalar/db/storage/ColumnEncodingUtils.java b/core/src/main/java/com/scalar/db/storage/ColumnEncodingUtils.java
@@ -18,53 +18,59 @@ public static long encode(DateColumn column) {
     return column.getDateValue().toEpochDay();
   }
 
+  public static LocalDate decodeDate(long epochDay) {
+    return LocalDate.ofEpochDay(epochDay);
+  }
+
   public static long encode(TimeColumn column) {
     assert column.getTimeValue() != null;
     return column.getTimeValue().toNanoOfDay();
   }
 
+  public static LocalTime decodeTime(long nanoOfDay) {
+    return LocalTime.ofNanoOfDay(nanoOfDay);
+  }
+
   public static long encode(TimestampColumn column) {
     assert column.getTimestampValue() != null;
-
     return encodeInstant(column.getTimestampValue().toInstant(ZoneOffset.UTC));
   }
 
-  @SuppressWarnings("JavaInstantGetSecondsGetNano")
+  public static LocalDateTime decodeTimestamp(long longTimestamp) {
+    long nanoOfSeconds = longTimestamp % 1000 * 1_000_000;
+    // Invert the nanoOfSeconds when the encoded instant is negative, that is for a date before 1970
+    if (longTimestamp < 0) {
+      nanoOfSeconds *= -1;
+    }
+    return LocalDateTime.ofEpochSecond(
+        longTimestamp / 1000, Math.toIntExact(nanoOfSeconds), ZoneOffset.UTC);
+  }
+
   public static long encode(TimestampTZColumn column) {
     assert column.getTimestampTZValue() != null;
-
     return encodeInstant(column.getTimestampTZValue());
   }
 
+  @SuppressWarnings("JavaInstantGetSecondsGetNano")
   private static long encodeInstant(Instant instant) {
+    // Encoding format : <epochSecond><millisecondOfSecond>
+    // The rightmost three digits are the number of milliseconds from the start of the
+    // second, the other digits on the left are the epochSecond
+    // For example:
+    // - if epochSecond=12345 and millisecondOfSecond=789, then the encoded value will be 12345789
+    // - if epochSecond=-12345 and millisecondOfSecond=789, then the encoded value will be -12345789
+
     long encoded = instant.getEpochSecond() * 1000;
-    // Subtract the nanoOfSeconds when the epochSecond is negative, that is for a date before 1970
-    if (encoded >= 0) {
-      encoded += instant.getNano() / 1_000_000;
-    } else {
+    // Subtract the millisecondOfSeconds when the epochSecond is negative, that is for a date before
+    // 1970
+    if (encoded < 0) {
       encoded -= instant.getNano() / 1_000_000;
+    } else {
+      encoded += instant.getNano() / 1_000_000;
     }
     return encoded;
   }
 
-  public static LocalDate decodeDate(long epochDay) {
-    return LocalDate.ofEpochDay(epochDay);
-  }
-
-  public static LocalTime decodeTime(long nanoOfDay) {
-    return LocalTime.ofNanoOfDay(nanoOfDay);
-  }
-
-  public static LocalDateTime decodeTimestamp(long longTimestamp) {
-    long nanoOfSeconds = longTimestamp % 1000 * 1_000_000;
-    // Invert the nanoOfSeconds when the encoded instant is negative, that is for a date before 1970
-    if (longTimestamp < 0) {
-      nanoOfSeconds *= -1;
-    }
-    return LocalDateTime.ofEpochSecond(
-        longTimestamp / 1000, Math.toIntExact(nanoOfSeconds), ZoneOffset.UTC);
-  }
-
   public static Instant decodeTimestampTZ(long longTimestampTZ) {
     long nanoOfSeconds = longTimestampTZ % 1000 * 1_000_000;
     // Invert the nanoOfSeconds when the encoded instant is negative, that is for a date before 1970

diff --git a/core/src/test/java/com/scalar/db/storage/ColumnEncodingUtilsTest.java b/core/src/test/java/com/scalar/db/storage/ColumnEncodingUtilsTest.java
@@ -180,4 +180,30 @@ public void decodeTimestampTZ_ShouldWorkProperly() {
         .isEqualTo(LocalDateTime.of(1234, 10, 1, 12, 34, 56, 0).toInstant(ZoneOffset.UTC));
     assertThat(epoch).isEqualTo(Instant.EPOCH);
   }
+
+  @Test
+  public void encodeThenDecodeTimestamp_WithMinAndMaxValues_ShouldWorkProperly() {
+    // Arrange
+    TimestampColumn min = TimestampColumn.of("timestamp", TimestampColumn.MIN_VALUE);
+    TimestampColumn max = TimestampColumn.of("timestamp", TimestampColumn.MAX_VALUE);
+
+    // Act Assert
+    assertThat(ColumnEncodingUtils.decodeTimestamp(ColumnEncodingUtils.encode(min)))
+        .isEqualTo(TimestampColumn.MIN_VALUE);
+    assertThat(ColumnEncodingUtils.decodeTimestamp(ColumnEncodingUtils.encode(max)))
+        .isEqualTo(TimestampColumn.MAX_VALUE);
+  }
+
+  @Test
+  public void encodeThenDecodeTimestampTZ_WithMinAndMaxValues_ShouldWorkProperly() {
+    // Arrange
+    TimestampTZColumn min = TimestampTZColumn.of("timestampTZ", TimestampTZColumn.MIN_VALUE);
+    TimestampTZColumn max = TimestampTZColumn.of("timestampTZ", TimestampTZColumn.MAX_VALUE);
+
+    // Act Assert
+    assertThat(ColumnEncodingUtils.decodeTimestampTZ(ColumnEncodingUtils.encode(min)))
+        .isEqualTo(TimestampTZColumn.MIN_VALUE);
+    assertThat(ColumnEncodingUtils.decodeTimestampTZ(ColumnEncodingUtils.encode(max)))
+        .isEqualTo(TimestampTZColumn.MAX_VALUE);
+  }
 }