WIP: implement maxSize alongside maxCapacity

WIP TBD

Signed-off-by: Francesco Romani <fromani@redhat.com>

Author: ffromani

pkg/pfpstatus/record/recorder.go

@@ -19,6 +19,7 @@ package record
 import (
 	"errors"
 	"time"
+	"unsafe"
 
 	"github.com/k8stopologyawareschedwg/podfingerprint"
 )
@@ -36,6 +37,28 @@ type RecordedStatus struct {
 	podfingerprint.Status
 	// RecordTime is a timestamp of when the RecordedStatus was added to the record
 	RecordTime time.Time `json:"recordTime"`
+	statusSize int       `json:"-"`
+}
+
+func cloneStatus(st podfingerprint.Status) (podfingerprint.Status, int) {
+	size := len(st.NodeName) + len(st.FingerprintExpected) + len(st.FingerprintComputed)
+	pods := make([]podfingerprint.NamespacedName, len(st.Pods))
+	for idx := 0; idx < len(st.Pods); idx++ {
+		pods[idx].Namespace = st.Pods[idx].Namespace
+		pods[idx].Name = st.Pods[idx].Name
+		size += len(pods[idx].Namespace) + len(pods[idx].Name)
+	}
+	ret := podfingerprint.Status{
+		FingerprintExpected: st.FingerprintExpected,
+		FingerprintComputed: st.FingerprintComputed,
+		Pods:                pods,
+		NodeName:            st.NodeName,
+	}
+	return ret, size
+}
+
+func (rs RecordedStatus) Size() int {
+	return rs.statusSize + int(unsafe.Sizeof(rs.RecordTime))
 }
 
 func (rs RecordedStatus) Equal(x RecordedStatus) bool {
@@ -51,6 +74,8 @@ type NodeRecorder struct {
 	timestamper func() time.Time
 	nodeName    string // shortcut
 	capacity    int
+	maxSize     int
+	size        int
 	statuses    []RecordedStatus
 }
 
@@ -62,6 +87,13 @@ func WithCapacity(capacity int) NodeOption {
 	}
 }
 
+func WithMaxSize(maxSize int) NodeOption {
+	return func(nr *NodeRecorder) {
+		nr.maxSize = maxSize
+		nr.capacity = 1
+	}
+}
+
 // NewNodeRecorder creates a new recorder for the given node with the given capacity.
 // The record is a ring buffer, so only the latest <capacity> Statuses are kept at any time.
 // The timestamper callback is used to mark times. Use `time.Now` if unsure.
@@ -91,14 +123,21 @@ func (nr *NodeRecorder) dropOldest() {
 	if nr.Len() < 1 {
 		return
 	}
+	nr.size -= nr.statuses[0].Size()
 	nr.statuses = nr.statuses[1:]
 }
 
 func (nr *NodeRecorder) makeRoom() {
-	if nr.Len() < nr.Cap() {
+	if nr.capacity > 1 && nr.Len() == nr.Cap() {
+		nr.dropOldest()
 		return
 	}
-	nr.dropOldest()
+	if nr.maxSize == 0 {
+		return
+	}
+	for nr.size > nr.maxSize {
+		nr.dropOldest()
+	}
 }
 
 // Push adds a new Status to the record, evicting the oldest Status if necessary.
@@ -113,16 +152,20 @@ func (nr *NodeRecorder) Push(st podfingerprint.Status) error {
 		return ErrMismatchingNode
 	}
 	ts := nr.timestamper()
+	cloned, size := cloneStatus(st)
 	item := RecordedStatus{
-		Status:     st.Clone(),
+		Status:     cloned,
 		RecordTime: ts,
+		statusSize: size,
 	}
 	if nr.capacity == 1 { // handle common special case, avoid any resize
 		nr.statuses[0] = item
+		nr.size = item.Size()
 		return nil
 	}
 	nr.makeRoom()
 	nr.statuses = append(nr.statuses, item)
+	nr.size += item.Size()
 	return nil
 }