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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 00:47:55 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 00:47:55 +0000
commit26a029d407be480d791972afb5975cf62c9360a6 (patch)
treef435a8308119effd964b339f76abb83a57c29483 /js/public/RefCounted.h
parentInitial commit. (diff)
downloadfirefox-26a029d407be480d791972afb5975cf62c9360a6.tar.xz
firefox-26a029d407be480d791972afb5975cf62c9360a6.zip
Adding upstream version 124.0.1.upstream/124.0.1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'js/public/RefCounted.h')
-rw-r--r--js/public/RefCounted.h96
1 files changed, 96 insertions, 0 deletions
diff --git a/js/public/RefCounted.h b/js/public/RefCounted.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef js_RefCounted_h
+#define js_RefCounted_h
+
+#include "mozilla/Atomics.h"
+#include "mozilla/RefCountType.h"
+
+#include "js/Utility.h"
+
+// These types implement the same interface as mozilla::(Atomic)RefCounted and
+// must be used instead of mozilla::(Atomic)RefCounted for everything in
+// SpiderMonkey. There are two reasons:
+// - Release() needs to call js_delete, not delete
+// - SpiderMonkey does not have MOZILLA_INTERNAL_API defined which can lead
+// to ODR violations that show up as spurious leak reports when ref-counted
+// types are allocated by SpiderMonkey and released by Gecko (or vice versa).
+
+namespace js {
+
+template <typename T>
+class RefCounted {
+ static const MozRefCountType DEAD = 0xffffdead;
+
+ protected:
+ RefCounted() : mRefCnt(0) {}
+ ~RefCounted() { MOZ_ASSERT(mRefCnt == DEAD); }
+
+ public:
+ void AddRef() const {
+ MOZ_ASSERT(int32_t(mRefCnt) >= 0);
+ ++mRefCnt;
+ }
+
+ void Release() const {
+ MOZ_ASSERT(int32_t(mRefCnt) > 0);
+ MozRefCountType cnt = --mRefCnt;
+ if (0 == cnt) {
+#ifdef DEBUG
+ mRefCnt = DEAD;
+#endif
+ js_delete(const_cast<T*>(static_cast<const T*>(this)));
+ }
+ }
+
+ private:
+ mutable MozRefCountType mRefCnt;
+};
+
+template <typename T>
+class AtomicRefCounted {
+ // On 64-bit systems, if the refcount type is small (say, 32 bits), there's
+ // a risk that it could overflow. So require it to be large enough.
+
+ static_assert(sizeof(MozRefCountType) == sizeof(uintptr_t),
+ "You're at risk for ref count overflow.");
+
+ static const MozRefCountType DEAD = ~MozRefCountType(0xffff) | 0xdead;
+
+ protected:
+ AtomicRefCounted() = default;
+ ~AtomicRefCounted() { MOZ_ASSERT(mRefCnt == DEAD); }
+
+ public:
+ void AddRef() const {
+ ++mRefCnt;
+ MOZ_ASSERT(mRefCnt != DEAD);
+ }
+
+ void Release() const {
+ MOZ_ASSERT(mRefCnt != 0);
+ MozRefCountType cnt = --mRefCnt;
+ if (0 == cnt) {
+#ifdef DEBUG
+ mRefCnt = DEAD;
+#endif
+ js_delete(const_cast<T*>(static_cast<const T*>(this)));
+ }
+ }
+
+ bool hasOneRef() const {
+ MOZ_ASSERT(mRefCnt > 0);
+ return mRefCnt == 1;
+ }
+
+ private:
+ mutable mozilla::Atomic<MozRefCountType> mRefCnt{0};
+};
+
+} // namespace js
+
+#endif /* js_RefCounted_h */