From f064fb24429854a2b1cb6d19050ae44f2cffb306 Mon Sep 17 00:00:00 2001
From: Julio Capote <jcapote@gmail.com>
Date: Sun, 8 Jan 2023 10:08:13 -0500
Subject: only return most recent 50 items for outbox

---
 models/persister.go | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

(limited to 'models')

diff --git a/models/persister.go b/models/persister.go
index b4b9c49..94992de 100644
--- a/models/persister.go
+++ b/models/persister.go
@@ -2,6 +2,8 @@ package models
 
 import (
 	"github.com/dgraph-io/badger/v3"
+	lru "github.com/hashicorp/golang-lru/v2"
+
 	"go.uber.org/zap"
 )
 
@@ -115,6 +117,47 @@ func (p *Persister) CollectKeys(model model) ([][]byte, error) {
 	return keys, err
 }
 
+// CollectRecent grabs the last n from a collection in an efficient way
+func (p *Persister) CollectRecent(model model, n int) ([][]byte, error) {
+	keys, err := lru.New[string, string](n)
+	if err != nil {
+		return nil, err
+	}
+
+	err = p.db.View(func(txn *badger.Txn) error {
+		opts := badger.DefaultIteratorOptions
+		opts.PrefetchValues = false
+		it := txn.NewIterator(opts)
+		defer it.Close()
+		prefix := []byte(model.Keybase())
+		for it.Seek(prefix); it.ValidForPrefix(prefix); it.Next() {
+			keys.Add(string(it.Item().Key()), "")
+		}
+		return nil
+	})
+
+	var results [][]byte
+	for _, k := range keys.Keys() {
+		err := p.db.View(func(txn *badger.Txn) error {
+			var getErr error
+			item, getErr := txn.Get([]byte(k))
+			if getErr != nil {
+				return getErr
+			}
+			getErr = item.Value(func(v []byte) error {
+				results = append(results, v)
+				return nil
+			})
+			return nil
+		})
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return results, err
+}
+
 func (p *Persister) Find(model model) ([]byte, error) {
 	var result []byte
 	var item *badger.Item
-- 
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