[Remove] Old Translog Checkpoint Format (#1884)

This commit removes support for old translog checkpoint formats prior to 7.0.0.

Signed-off-by: Nicholas Walter Knize <nknize@apache.org>

server/src/main/java/org/opensearch/index/translog/Checkpoint.java

@@ -64,13 +64,10 @@ final class Checkpoint {
     final long minTranslogGeneration;
     final long trimmedAboveSeqNo;
 
-    private static final int VERSION_6_0_0 = 2; // introduction of global checkpoints
     private static final int CURRENT_VERSION = 3; // introduction of trimmed above seq#
 
     private static final String CHECKPOINT_CODEC = "ckp";
 
-    // size of 6.4.0 checkpoint
-
     static final int V3_FILE_SIZE = CodecUtil.headerLength(CHECKPOINT_CODEC) + Integer.BYTES  // ops
         + Long.BYTES // offset
         + Long.BYTES // generation
@@ -78,17 +75,7 @@ final class Checkpoint {
         + Long.BYTES // maximum sequence number
         + Long.BYTES // global checkpoint
         + Long.BYTES // minimum translog generation in the translog
-        + Long.BYTES // maximum reachable (trimmed) sequence number, introduced in 6.4.0
+        + Long.BYTES // maximum reachable (trimmed) sequence number
-        + CodecUtil.footerLength();
-
-    // size of 6.0.0 checkpoint
-    static final int V2_FILE_SIZE = CodecUtil.headerLength(CHECKPOINT_CODEC) + Integer.BYTES  // ops
-        + Long.BYTES // offset
-        + Long.BYTES // generation
-        + Long.BYTES // minimum sequence number
-        + Long.BYTES // maximum sequence number
-        + Long.BYTES // global checkpoint
-        + Long.BYTES // minimum translog generation in the translog
         + CodecUtil.footerLength();
 
     /**
@@ -177,18 +164,6 @@ final class Checkpoint {
         return new Checkpoint(offset, numOps, generation, minSeqNo, maxSeqNo, globalCheckpoint, minTranslogGeneration, trimmedAboveSeqNo);
     }
 
-    static Checkpoint readCheckpointV2(final DataInput in) throws IOException {
-        final long offset = in.readLong();
-        final int numOps = in.readInt();
-        final long generation = in.readLong();
-        final long minSeqNo = in.readLong();
-        final long maxSeqNo = in.readLong();
-        final long globalCheckpoint = in.readLong();
-        final long minTranslogGeneration = in.readLong();
-        final long trimmedAboveSeqNo = SequenceNumbers.UNASSIGNED_SEQ_NO;
-        return new Checkpoint(offset, numOps, generation, minSeqNo, maxSeqNo, globalCheckpoint, minTranslogGeneration, trimmedAboveSeqNo);
-    }
-
     @Override
     public String toString() {
         return "Checkpoint{"
@@ -216,15 +191,10 @@ final class Checkpoint {
             try (IndexInput indexInput = dir.openInput(path.getFileName().toString(), IOContext.DEFAULT)) {
                 // We checksum the entire file before we even go and parse it. If it's corrupted we barf right here.
                 CodecUtil.checksumEntireFile(indexInput);
-                final int fileVersion = CodecUtil.checkHeader(indexInput, CHECKPOINT_CODEC, VERSION_6_0_0, CURRENT_VERSION);
+                final int fileVersion = CodecUtil.checkHeader(indexInput, CHECKPOINT_CODEC, CURRENT_VERSION, CURRENT_VERSION);
-                if (fileVersion == VERSION_6_0_0) {
+                assert fileVersion == CURRENT_VERSION : fileVersion;
-                    assert indexInput.length() == V2_FILE_SIZE : indexInput.length();
+                assert indexInput.length() == V3_FILE_SIZE : indexInput.length();
-                    return Checkpoint.readCheckpointV2(indexInput);
+                return Checkpoint.readCheckpointV3(indexInput);
-                } else {
-                    assert fileVersion == CURRENT_VERSION : fileVersion;
-                    assert indexInput.length() == V3_FILE_SIZE : indexInput.length();
-                    return Checkpoint.readCheckpointV3(indexInput);
-                }
             } catch (CorruptIndexException | NoSuchFileException | IndexFormatTooOldException | IndexFormatTooNewException e) {
                 throw new TranslogCorruptedException(path.toString(), e);
             }

server/src/test/java/org/opensearch/index/translog/TranslogTests.java

@@ -3461,22 +3461,7 @@ public class TranslogTests extends OpenSearchTestCase {
         expectThrows(
             TranslogCorruptedException.class,
             IndexFormatTooOldException.class,
-            () -> Checkpoint.read(getDataPath("/org/opensearch/index/checkpoint/v1.ckp.binary"))
+            () -> Checkpoint.read(getDataPath("/org/opensearch/index/checkpoint/v2.ckp.binary"))
-        );
-        assertThat(
-            Checkpoint.read(getDataPath("/org/opensearch/index/checkpoint/v2.ckp.binary")),
-            equalTo(
-                new Checkpoint(
-                    -1312746831014894010L,
-                    44230819,
-                    4168771208509507653L,
-                    6217263213205155568L,
-                    8590850694628654668L,
-                    3768575734506660560L,
-                    1476009383806516272L,
-                    SequenceNumbers.UNASSIGNED_SEQ_NO
-                )
-            )
         );
     }