[kafka] branch 1.0 updated: KAFKA-6857; Leader should reply with undefined offset if undefined leader epoch requested (#4967)

[jgus]

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jgus pushed a commit to branch 1.0
in repository https://gitbox.apache.org/repos/asf/kafka.git


The following commit(s) were added to refs/heads/1.0 by this push:
     new baaaa4f  KAFKA-6857; Leader should reply with undefined offset if 
undefined leader epoch requested (#4967)
baaaa4f is described below

commit baaaa4fc6cc66c7577e0cefc6a81e30650304690
Author: Anna Povzner <a...@confluent.io>
AuthorDate: Thu May 3 23:06:34 2018 -0700

    KAFKA-6857; Leader should reply with undefined offset if undefined leader 
epoch requested (#4967)
    
    The leader must explicitly check if requested leader epoch is undefined, 
and return undefined offset so that the follower can fall back to truncating to 
high watermark. Otherwise, if the leader also is not tracking leader epochs, it 
may return its LEO, which will the follower to truncate to the incorrect offset.
---
 .../scala/kafka/server/epoch/LeaderEpochFileCache.scala |  9 ++++++---
 .../kafka/server/epoch/LeaderEpochFileCacheTest.scala   | 17 ++++++++++++++++-
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/core/src/main/scala/kafka/server/epoch/LeaderEpochFileCache.scala 
b/core/src/main/scala/kafka/server/epoch/LeaderEpochFileCache.scala
index c4b5214..cb44798 100644
--- a/core/src/main/scala/kafka/server/epoch/LeaderEpochFileCache.scala
+++ b/core/src/main/scala/kafka/server/epoch/LeaderEpochFileCache.scala
@@ -96,10 +96,13 @@ class LeaderEpochFileCache(topicPartition: TopicPartition, 
leo: () => LogOffsetM
   override def endOffsetFor(requestedEpoch: Int): Long = {
     inReadLock(lock) {
       val offset =
-        if (requestedEpoch == latestEpoch) {
+        if (requestedEpoch == UNDEFINED_EPOCH) {
+          // this may happen if a bootstrapping follower sends a request with 
undefined epoch or
+          // a follower is on the older message format where leader epochs are 
not recorded
+          UNDEFINED_EPOCH_OFFSET
+        } else if (requestedEpoch == latestEpoch) {
           leo().messageOffset
-        }
-        else {
+        } else {
           val subsequentEpochs = epochs.filter(e => e.epoch > requestedEpoch)
           if (subsequentEpochs.isEmpty || requestedEpoch < epochs.head.epoch)
             UNDEFINED_EPOCH_OFFSET
diff --git 
a/core/src/test/scala/unit/kafka/server/epoch/LeaderEpochFileCacheTest.scala 
b/core/src/test/scala/unit/kafka/server/epoch/LeaderEpochFileCacheTest.scala
index 8460fe4..4a8df11 100644
--- a/core/src/test/scala/unit/kafka/server/epoch/LeaderEpochFileCacheTest.scala
+++ b/core/src/test/scala/unit/kafka/server/epoch/LeaderEpochFileCacheTest.scala
@@ -144,6 +144,21 @@ class LeaderEpochFileCacheTest {
   }
 
   @Test
+  def shouldReturnUnsupportedIfNoEpochRecordedAndUndefinedEpochRequested(){
+    val leo = 73
+    def leoFinder() = new LogOffsetMetadata(leo)
+
+    //Given
+    val cache = new LeaderEpochFileCache(tp, () => leoFinder, checkpoint)
+
+    //When (say a follower on older message format version) sends request for 
UNDEFINED_EPOCH
+    val offsetFor = cache.endOffsetFor(UNDEFINED_EPOCH)
+
+    //Then
+    assertEquals(UNDEFINED_EPOCH_OFFSET, offsetFor)
+  }
+
+  @Test
   def shouldReturnUnsupportedIfRequestedEpochLessThanFirstEpoch(){
     def leoFinder() = new LogOffsetMetadata(0)
 
@@ -664,4 +679,4 @@ class LeaderEpochFileCacheTest {
   def setUp() {
     checkpoint = new LeaderEpochCheckpointFile(TestUtils.tempFile())
   }
-}
\ No newline at end of file
+}

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