pkg/kgo: allow marking using an offset

Currently marking is only available via records, expose a new function,
MarkCommitOffsets, to allow marking using offsets only.

Author: sudo-sturbia

pkg/kgo/consumer_group.go

@@ -2433,6 +2433,44 @@ func (cl *Client) MarkCommitRecords(rs ...*Record) {
 	}
 }
 
+// MarkCommitOffsets marks offsets to be available for autocommitting. This
+// function is only useful if you use the AutoCommitMarks config option, see
+// the documentation on that option for more details. This function does not
+// allow rewinds.
+func (cl *Client) MarkCommitOffsets(unmarked map[string]map[int32]EpochOffset) {
+	g := cl.consumer.g
+	if g == nil || !cl.cfg.autocommitMarks {
+		return
+	}
+
+	// protect g.uncommitted map
+	g.mu.Lock()
+	defer g.mu.Unlock()
+
+	if g.uncommitted == nil {
+		g.uncommitted = make(uncommitted)
+	}
+
+	for topic, partitions := range unmarked {
+		curPartitions := g.uncommitted[topic]
+		if curPartitions == nil {
+			curPartitions = make(map[int32]uncommit)
+			g.uncommitted[topic] = curPartitions
+		}
+
+		for partition, newHead := range partitions {
+			current := curPartitions[partition]
+			if current.head.Less(newHead) {
+				curPartitions[partition] = uncommit{
+					dirty:     current.dirty,
+					committed: current.committed,
+					head:      newHead,
+				}
+			}
+		}
+	}
+}
+
 // CommitUncommittedOffsets issues a synchronous offset commit for any
 // partition that has been consumed from that has uncommitted offsets.
 // Retryable errors are retried up to the configured retry limit, and any