tls: add gc-aware pthread slots

runtime/internal/clite/tls/tls_common.go

@@ -0,0 +1,88 @@
+//go:build llgo
+
+package tls
+
+import (
+	"unsafe"
+
+	c "github.com/goplus/llgo/runtime/internal/clite"
+	"github.com/goplus/llgo/runtime/internal/clite/pthread"
+)
+
+type Handle[T any] struct {
+	key        pthread.Key
+	destructor func(*T)
+}
+
+// Alloc creates a TLS handle backed by pthread TLS.
+func Alloc[T any](destructor func(*T)) Handle[T] {
+	var key pthread.Key
+	if ret := key.Create(slotDestructor[T]); ret != 0 {
+		c.Fprintf(c.Stderr, c.Str("tls: pthread_key_create failed (errno=%d)\n"), ret)
+		panic("tls: failed to create thread local storage key")
+	}
+	return Handle[T]{key: key, destructor: destructor}
+}
+
+// Get returns the value stored in the current thread's slot.
+func (h Handle[T]) Get() T {
+	if ptr := h.key.Get(); ptr != nil {
+		return (*slot[T])(ptr).value
+	}
+	var zero T
+	return zero
+}
+
+// Set stores v in the current thread's slot, creating it if necessary.
+func (h Handle[T]) Set(v T) {
+	s := h.ensureSlot()
+	s.value = v
+}
+
+// Clear zeroes the current thread's slot value without freeing the slot.
+func (h Handle[T]) Clear() {
+	if ptr := h.key.Get(); ptr != nil {
+		s := (*slot[T])(ptr)
+		var zero T
+		s.value = zero
+	}
+}
+
+func (h Handle[T]) ensureSlot() *slot[T] {
+	if ptr := h.key.Get(); ptr != nil {
+		return (*slot[T])(ptr)
+	}
+	size := unsafe.Sizeof(slot[T]{})
+	mem := c.Calloc(1, size)
+	if mem == nil {
+		panic("tls: failed to allocate thread slot")
+	}
+	s := (*slot[T])(mem)
+	s.destructor = h.destructor
+	if existing := h.key.Get(); existing != nil {
+		c.Free(mem)
+		return (*slot[T])(existing)
+	}
+	if ret := h.key.Set(mem); ret != 0 {
+		c.Free(mem)
+		c.Fprintf(c.Stderr, c.Str("tls: pthread_setspecific failed (errno=%d)\n"), ret)
+		panic("tls: failed to set thread local storage value")
+	}
+	registerSlot(s)
+	return s
+}
+
+func slotDestructor[T any](ptr c.Pointer) {
+	s := (*slot[T])(ptr)
+	if s == nil {
+		return
+	}
+	if s.destructor != nil {
+		s.destructor(&s.value)
+	}
+	deregisterSlot(s)
+	var zero T
+	s.value = zero
+	s.destructor = nil
+	c.Free(ptr)
+}