From 220278ee89b556521e4bda7530460405a4ec467d Mon Sep 17 00:00:00 2001
From: Matt Joiner <anacrolix@gmail.com>
Date: Tue, 13 May 2025 20:45:24 +1000
Subject: [PATCH] Add a test for sizeof(Piece)

---
 piece.go           |  6 +++---
 requesting.go      |  2 +-
 struct_test.go     | 12 ------------
 testing.go         |  1 +
 type-sizes_test.go | 37 +++++++++++++++++++++++++++++++++++++
 5 files changed, 42 insertions(+), 16 deletions(-)
 delete mode 100644 struct_test.go
 create mode 100644 type-sizes_test.go

diff --git a/piece.go b/piece.go
index 17a4ed89..6e53fb25 100644
--- a/piece.go
+++ b/piece.go
@@ -4,11 +4,10 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"sync"
-
 	"github.com/anacrolix/chansync"
 	g "github.com/anacrolix/generics"
 	"github.com/anacrolix/missinggo/v2/bitmap"
+	"sync"
 
 	"github.com/anacrolix/torrent/merkle"
 	"github.com/anacrolix/torrent/metainfo"
@@ -22,7 +21,8 @@ type pieceVerifyCount = int64
 type Piece struct {
 	// The completed piece SHA1 hash, from the metainfo "pieces" field. Nil if the info is not V1
 	// compatible.
-	hash   *metainfo.Hash
+	hash *metainfo.Hash
+	// Not easy to use unique.Handle because we need this as a slice sometimes.
 	hashV2 g.Option[[32]byte]
 	t      *Torrent
 	index  pieceIndex
diff --git a/requesting.go b/requesting.go
index 0d72733d..00a8a659 100644
--- a/requesting.go
+++ b/requesting.go
@@ -4,7 +4,6 @@ import (
 	"context"
 	"encoding/gob"
 	"fmt"
-	"github.com/anacrolix/torrent/metainfo"
 	"reflect"
 	"runtime/pprof"
 	"time"
@@ -16,6 +15,7 @@ import (
 	"github.com/anacrolix/log"
 	"github.com/anacrolix/multiless"
 
+	"github.com/anacrolix/torrent/metainfo"
 	requestStrategy "github.com/anacrolix/torrent/request-strategy"
 	typedRoaring "github.com/anacrolix/torrent/typed-roaring"
 )
diff --git a/struct_test.go b/struct_test.go
deleted file mode 100644
index cee91e10..00000000
--- a/struct_test.go
+++ /dev/null
@@ -1,12 +0,0 @@
-package torrent
-
-import (
-	"testing"
-	"unsafe"
-)
-
-func TestStructSizes(t *testing.T) {
-	t.Log("[]*File", unsafe.Sizeof([]*File(nil)))
-	t.Log("Piece", unsafe.Sizeof(Piece{}))
-	t.Log("map[*peer]struct{}", unsafe.Sizeof(map[*Peer]struct{}(nil)))
-}
diff --git a/testing.go b/testing.go
index ac70b1c9..a4909273 100644
--- a/testing.go
+++ b/testing.go
@@ -5,6 +5,7 @@ import (
 	"time"
 
 	"github.com/anacrolix/log"
+
 	pp "github.com/anacrolix/torrent/peer_protocol"
 )
 
diff --git a/type-sizes_test.go b/type-sizes_test.go
new file mode 100644
index 00000000..116d2aa2
--- /dev/null
+++ b/type-sizes_test.go
@@ -0,0 +1,37 @@
+package torrent
+
+import (
+	"github.com/anacrolix/chansync"
+	"reflect"
+	"testing"
+
+	g "github.com/anacrolix/generics"
+	"github.com/go-quicktest/qt"
+)
+
+func testSizeof[T any](t *testing.T, max g.Option[uintptr]) {
+	ty := reflect.TypeFor[T]()
+	size := ty.Size()
+	t.Logf("%v has size %v", ty, size)
+	if max.Ok {
+		qt.Check(t, qt.IsTrue(size <= max.Value), qt.Commentf("size of %v is %v, expected <= %v", ty, size, max.Value))
+	}
+}
+
+func checkSizeLessThan[T any](t *testing.T, max uintptr) {
+	testSizeof[T](t, g.Some(max))
+}
+
+func justLogSizeof[T any](t *testing.T) {
+	testSizeof[T](t, g.None[uintptr]())
+}
+
+func TestTypeSizes(t *testing.T) {
+	justLogSizeof[[]*File](t)
+	checkSizeLessThan[Piece](t, 296)
+	justLogSizeof[map[*Peer]struct{}](t)
+	justLogSizeof[chansync.BroadcastCond](t)
+
+	justLogSizeof[g.Option[[32]byte]](t)
+	justLogSizeof[[]byte](t)
+}
-- 
2.51.0