From 21ac23a96f204dfb558a8d3071380c1d105a93ba Mon Sep 17 00:00:00 2001 From: Michael Anthony Knyszek Date: Wed, 4 Sep 2024 16:46:33 +0000 Subject: [PATCH] unique: don't retain uncloned input as key Currently the unique package tries to clone strings that get stored in its internal map to avoid retaining large strings. However, this falls over entirely due to the fact that the original string is *still* stored in the map as a key. Whoops. Fix this by storing the cloned value in the map instead. This change also adds a test which fails without this change. Change-Id: I1a6bb68ed79b869ea12ab6be061a5ae4b4377ddb Reviewed-on: https://go-review.googlesource.com/c/go/+/610738 Reviewed-by: Michael Pratt Auto-Submit: Michael Knyszek LUCI-TryBot-Result: Go LUCI --- src/unique/handle.go | 7 ++++--- src/unique/handle_test.go | 22 ++++++++++++++++++++++ 2 files changed, 26 insertions(+), 3 deletions(-) diff --git a/src/unique/handle.go b/src/unique/handle.go index 96d8fedb0c..abc620f60f 100644 --- a/src/unique/handle.go +++ b/src/unique/handle.go @@ -50,13 +50,13 @@ func Make[T comparable](value T) Handle[T] { toInsert *T // Keep this around to keep it alive. toInsertWeak weak.Pointer[T] ) - newValue := func() weak.Pointer[T] { + newValue := func() (T, weak.Pointer[T]) { if toInsert == nil { toInsert = new(T) *toInsert = clone(value, &m.cloneSeq) toInsertWeak = weak.Make(toInsert) } - return toInsertWeak + return *toInsert, toInsertWeak } var ptr *T for { @@ -64,7 +64,8 @@ func Make[T comparable](value T) Handle[T] { wp, ok := m.Load(value) if !ok { // Try to insert a new value into the map. - wp, _ = m.LoadOrStore(value, newValue()) + k, v := newValue() + wp, _ = m.LoadOrStore(k, v) } // Now that we're sure there's a value in the map, let's // try to get the pointer we need out of it. diff --git a/src/unique/handle_test.go b/src/unique/handle_test.go index ffb2be42b1..7d12edd467 100644 --- a/src/unique/handle_test.go +++ b/src/unique/handle_test.go @@ -9,7 +9,10 @@ import ( "internal/abi" "reflect" "runtime" + "strings" "testing" + "time" + "unsafe" ) // Set up special types. Because the internal maps are sharded by type, @@ -110,3 +113,22 @@ func checkMapsFor[T comparable](t *testing.T, value T) { } t.Errorf("failed to drain internal maps of %v", value) } + +func TestMakeClonesStrings(t *testing.T) { + s := strings.Clone("abcdefghijklmnopqrstuvwxyz") // N.B. Must be big enough to not be tiny-allocated. + ran := make(chan bool) + runtime.SetFinalizer(unsafe.StringData(s), func(_ *byte) { + ran <- true + }) + h := Make(s) + + // Clean up s (hopefully) and run the finalizer. + runtime.GC() + + select { + case <-time.After(1 * time.Second): + t.Fatal("string was improperly retained") + case <-ran: + } + runtime.KeepAlive(h) +} -- 2.48.1