Execute PLAN_AGGREGATOR.md

cmd/aggregator/merger.go

@@ -0,0 +1,70 @@
+package main
+
+import (
+	"sync"
+
+	st "git.ipng.ch/ipng/nginx-logtail/internal/store"
+	pb "git.ipng.ch/ipng/nginx-logtail/proto/logtailpb"
+)
+
+// Merger maintains per-collector maps and a running merged map using a delta
+// strategy: on each new snapshot from collector X, subtract X's old entries
+// and add the new ones. This is O(snapshot_size) rather than
+// O(N_collectors × snapshot_size).
+type Merger struct {
+	mu           sync.Mutex
+	perCollector map[string]map[string]int64 // source → label → count
+	merged       map[string]int64            // label → total across all collectors
+}
+
+func NewMerger() *Merger {
+	return &Merger{
+		perCollector: make(map[string]map[string]int64),
+		merged:       make(map[string]int64),
+	}
+}
+
+// Apply incorporates a snapshot from a collector, replacing that collector's
+// previous contribution in the merged map.
+func (m *Merger) Apply(snap *pb.Snapshot) {
+	addr := snap.Source
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	// Subtract the old contribution.
+	for label, count := range m.perCollector[addr] {
+		m.merged[label] -= count
+		if m.merged[label] <= 0 {
+			delete(m.merged, label)
+		}
+	}
+
+	// Build the new per-collector map and add to merged.
+	newMap := make(map[string]int64, len(snap.Entries))
+	for _, e := range snap.Entries {
+		newMap[e.Label] += e.Count
+		m.merged[e.Label] += e.Count
+	}
+	m.perCollector[addr] = newMap
+}
+
+// Zero removes a degraded collector's entire contribution from the merged map.
+func (m *Merger) Zero(addr string) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	for label, count := range m.perCollector[addr] {
+		m.merged[label] -= count
+		if m.merged[label] <= 0 {
+			delete(m.merged, label)
+		}
+	}
+	delete(m.perCollector, addr)
+}
+
+// TopK returns the top-k entries from the current merged view.
+func (m *Merger) TopK(k int) []st.Entry {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	return st.TopKFromMap(m.merged, k)
+}