From 07f13c61322d1ac72c0e67c813491b6404ca22d8 Mon Sep 17 00:00:00 2001
From: Stephen Buttolph <stephen@avalabs.org>
Date: Wed, 11 Sep 2024 11:41:54 -0400
Subject: [PATCH] Implement ExpiryEntry (#3382)

---
 vms/platformvm/state/expiry.go      | 57 ++++++++++++++++++++++++++
 vms/platformvm/state/expiry_test.go | 62 +++++++++++++++++++++++++++++
 2 files changed, 119 insertions(+)
 create mode 100644 vms/platformvm/state/expiry.go
 create mode 100644 vms/platformvm/state/expiry_test.go

diff --git a/vms/platformvm/state/expiry.go b/vms/platformvm/state/expiry.go
new file mode 100644
index 000000000000..d2b392b62f4b
--- /dev/null
+++ b/vms/platformvm/state/expiry.go
@@ -0,0 +1,57 @@
+// Copyright (C) 2019-2024, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package state
+
+import (
+	"encoding/binary"
+	"fmt"
+
+	"github.com/google/btree"
+
+	"github.com/ava-labs/avalanchego/database"
+	"github.com/ava-labs/avalanchego/ids"
+)
+
+// expiryEntry = [timestamp] + [validationID]
+const expiryEntryLength = database.Uint64Size + ids.IDLen
+
+var (
+	errUnexpectedExpiryEntryLength = fmt.Errorf("expected expiry entry length %d", expiryEntryLength)
+
+	_ btree.LessFunc[ExpiryEntry] = ExpiryEntry.Less
+)
+
+type ExpiryEntry struct {
+	Timestamp    uint64
+	ValidationID ids.ID
+}
+
+func (e *ExpiryEntry) Marshal() []byte {
+	data := make([]byte, expiryEntryLength)
+	binary.BigEndian.PutUint64(data, e.Timestamp)
+	copy(data[database.Uint64Size:], e.ValidationID[:])
+	return data
+}
+
+func (e *ExpiryEntry) Unmarshal(data []byte) error {
+	if len(data) != expiryEntryLength {
+		return errUnexpectedExpiryEntryLength
+	}
+
+	e.Timestamp = binary.BigEndian.Uint64(data)
+	copy(e.ValidationID[:], data[database.Uint64Size:])
+	return nil
+}
+
+// Invariant: Less produces the same ordering as the marshalled bytes.
+func (e ExpiryEntry) Less(o ExpiryEntry) bool {
+	switch {
+	case e.Timestamp < o.Timestamp:
+		return true
+	case e.Timestamp > o.Timestamp:
+		return false
+	default:
+		return e.ValidationID.Compare(o.ValidationID) == -1
+	}
+}
diff --git a/vms/platformvm/state/expiry_test.go b/vms/platformvm/state/expiry_test.go
new file mode 100644
index 000000000000..38a0d07f9ab0
--- /dev/null
+++ b/vms/platformvm/state/expiry_test.go
@@ -0,0 +1,62 @@
+// Copyright (C) 2019-2024, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package state
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"github.com/thepudds/fzgen/fuzzer"
+)
+
+func FuzzExpiryEntryMarshal(f *testing.F) {
+	f.Fuzz(func(t *testing.T, data []byte) {
+		require := require.New(t)
+
+		var entry ExpiryEntry
+		fz := fuzzer.NewFuzzer(data)
+		fz.Fill(&entry)
+
+		marshalledData := entry.Marshal()
+
+		var parsedEntry ExpiryEntry
+		require.NoError(parsedEntry.Unmarshal(marshalledData))
+		require.Equal(entry, parsedEntry)
+	})
+}
+
+func FuzzExpiryEntryLessAndMarshalOrdering(f *testing.F) {
+	f.Fuzz(func(t *testing.T, data []byte) {
+		var (
+			entry0 ExpiryEntry
+			entry1 ExpiryEntry
+		)
+		fz := fuzzer.NewFuzzer(data)
+		fz.Fill(&entry0, &entry1)
+
+		key0 := entry0.Marshal()
+		key1 := entry1.Marshal()
+		require.Equal(
+			t,
+			entry0.Less(entry1),
+			bytes.Compare(key0, key1) == -1,
+		)
+	})
+}
+
+func FuzzExpiryEntryUnmarshal(f *testing.F) {
+	f.Fuzz(func(t *testing.T, data []byte) {
+		require := require.New(t)
+
+		var entry ExpiryEntry
+		if err := entry.Unmarshal(data); err != nil {
+			require.ErrorIs(err, errUnexpectedExpiryEntryLength)
+			return
+		}
+
+		marshalledData := entry.Marshal()
+		require.Equal(data, marshalledData)
+	})
+}