Fix default retention time value in offset commit

The retention time field of the offset commit request uses -1 to mean
"use the broker's default". Sarama uses the value 0 in the
`Config.Consumer.Offsets.Retenton` field to mean "use the broker's
default". Ensure that Sarama's default (0) is correctly mapped to the
broker's default (-1).

Fixes: IBM#2677
Signed-off-by: Adrian Preston <[email protected]>

offset_manager.go

@@ -318,9 +318,13 @@ func (om *offsetManager) constructRequest() *OffsetCommitRequest {
 
 	// request controlled retention was only supported from V2-V4 (it became
 	// broker-only after that) so if the user has set the config options then
-	// flow those through as retention time on the commit request
-	if r.Version >= 2 && r.Version < 5 && om.conf.Consumer.Offsets.Retention > 0 {
-		r.RetentionTime = int64(om.conf.Consumer.Offsets.Retention / time.Millisecond)
+	// flow those through as retention time on the commit request.
+	if r.Version >= 2 && r.Version < 5 {
+		// Map Sarama's default of 0 to Kafka's default of -1
+		r.RetentionTime = -1
+		if om.conf.Consumer.Offsets.Retention > 0 {
+			r.RetentionTime = int64(om.conf.Consumer.Offsets.Retention / time.Millisecond)
+		}
 	}
 
 	om.pomsLock.RLock()

offset_manager_test.go

@@ -2,6 +2,7 @@ package sarama
 
 import (
 	"errors"
+	"fmt"
 	"sync/atomic"
 	"testing"
 	"time"
@@ -572,3 +573,63 @@ func TestAbortPartitionOffsetManager(t *testing.T) {
 	safeClose(t, om)
 	safeClose(t, testClient)
 }
+
+// Validate that the constructRequest() method correctly maps Sarama's default for
+// Config.Consumer.Offsets.Retention to the equivalent Kafka value.
+func TestConstructRequestRetentionTime(t *testing.T) {
+	expectedRetention := func(version KafkaVersion, retention time.Duration) int64 {
+		switch {
+		case version.IsAtLeast(V2_1_0_0):
+			// version >= 2.1.0: Client specified retention time isn't supported in the
+			// offset commit request anymore, thus the retention time field set in the
+			// OffsetCommitRequest struct should be 0.
+			return 0
+		case version.IsAtLeast(V0_9_0_0):
+			// 0.9.0 <= version < 2.1.0: Retention time *is* supported in the offset commit
+			// request. Sarama's default retention times (0) must be mapped to the Kafka
+			// default (-1). Non-zero Sarama times are converted from time.Duration to
+			// an int64 millisecond value.
+			if retention > 0 {
+				return int64(retention / time.Millisecond)
+			} else {
+				return -1
+			}
+		default:
+			// version < 0.9.0: Client specified retention time is not supported in the offset
+			// commit request, thus the retention time field set in the OffsetCommitRequest
+			// struct should be 0.
+			return 0
+		}
+	}
+
+	for _, version := range SupportedVersions {
+		for _, retention := range []time.Duration{0, time.Millisecond} {
+			name := fmt.Sprintf("version %s retention: %s", version, retention)
+			t.Run(name, func(t *testing.T) {
+				// Perform necessary setup for calling the constructRequest() method. This
+				// test-case only cares about the code path that sets the retention time
+				// field in the returned request struct.
+				conf := NewTestConfig()
+				conf.Version = version
+				conf.Consumer.Offsets.Retention = retention
+				om := &offsetManager{
+					conf: conf,
+					poms: map[string]map[int32]*partitionOffsetManager{
+						"topic": {
+							0: {
+								dirty: true,
+							},
+						},
+					},
+				}
+
+				req := om.constructRequest()
+
+				expectedRetention := expectedRetention(version, retention)
+				if req.RetentionTime != expectedRetention {
+					t.Errorf("expected retention time %d, got: %d", expectedRetention, req.RetentionTime)
+				}
+			})
+		}
+	}
+}