1 files changed, 54 insertions, 0 deletions
diff --git a/weed/mq/pub_balancer/allocate.go b/weed/mq/pub_balancer/allocate.go
new file mode 100644
index 000000000..9b2113162
--- /dev/null
+++ b/weed/mq/pub_balancer/allocate.go
@@ -0,0 +1,54 @@
+package pub_balancer
+
+import (
+	cmap "github.com/orcaman/concurrent-map/v2"
+	"github.com/seaweedfs/seaweedfs/weed/glog"
+	"github.com/seaweedfs/seaweedfs/weed/pb/mq_pb"
+	"math/rand"
+)
+
+func allocateTopicPartitions(brokers cmap.ConcurrentMap[string, *BrokerStats], partitionCount int32) (assignments []*mq_pb.BrokerPartitionAssignment) {
+	// divide the ring into partitions
+	rangeSize := MaxPartitionCount / partitionCount
+	for i := int32(0); i < partitionCount; i++ {
+		assignment := &mq_pb.BrokerPartitionAssignment{
+			Partition: &mq_pb.Partition{
+				RingSize:   MaxPartitionCount,
+				RangeStart: int32(i * rangeSize),
+				RangeStop:  int32((i + 1) * rangeSize),
+			},
+		}
+		if i == partitionCount-1 {
+			assignment.Partition.RangeStop = MaxPartitionCount
+		}
+		assignments = append(assignments, assignment)
+	}
+
+	// pick the brokers
+	pickedBrokers := pickBrokers(brokers, partitionCount)
+
+	// assign the partitions to brokers
+	for i, assignment := range assignments {
+		assignment.LeaderBroker = pickedBrokers[i]
+	}
+	glog.V(0).Infof("allocate topic partitions %d: %v", len(assignments), assignments)
+	return
+}
+
+// for now: randomly pick brokers
+// TODO pick brokers based on the broker stats
+func pickBrokers(brokers cmap.ConcurrentMap[string, *BrokerStats], count int32) []string {
+	candidates := make([]string, 0, brokers.Count())
+	for brokerStatsItem := range brokers.IterBuffered() {
+		candidates = append(candidates, brokerStatsItem.Key)
+	}
+	pickedBrokers := make([]string, 0, count)
+	for i := int32(0); i < count; i++ {
+		p := rand.Int() % len(candidates)
+		if p < 0 {
+			p = -p
+		}
+		pickedBrokers = append(pickedBrokers, candidates[p])
+	}
+	return pickedBrokers
+}