gecko-dev/mfbt/tests/TestThreadSafeWeakPtr.cpp

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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/. */
#include "mozilla/RefPtr.h"
#include "mozilla/ThreadSafeWeakPtr.h"
using mozilla::SupportsThreadSafeWeakPtr;
using mozilla::ThreadSafeWeakPtr;
// To have a class C support weak pointers, inherit from
// SupportsThreadSafeWeakPtr<C>.
class C : public SupportsThreadSafeWeakPtr<C> {
public:
MOZ_DECLARE_THREADSAFEWEAKREFERENCE_TYPENAME(C)
MOZ_DECLARE_REFCOUNTED_TYPENAME(C)
int mNum;
C() : mNum(0) {}
~C() {
// Setting mNum in the destructor allows us to test against use-after-free
// below
mNum = 0xDEAD;
}
void act() {}
};
int main() {
RefPtr<C> c1 = new C;
MOZ_RELEASE_ASSERT(c1->mNum == 0);
// Get weak pointers to c1. The first time,
// a reference-counted ThreadSafeWeakReference object is created that
// can live beyond the lifetime of 'c1'. The ThreadSafeWeakReference
// object will be notified of 'c1's destruction.
ThreadSafeWeakPtr<C> w1(c1);
{
RefPtr<C> s1(w1);
// Test a weak pointer for validity before using it.
MOZ_RELEASE_ASSERT(s1);
MOZ_RELEASE_ASSERT(s1 == c1);
s1->mNum = 1;
s1->act();
}
// Test taking another ThreadSafeWeakPtr<C> to c1
ThreadSafeWeakPtr<C> w2(c1);
{
RefPtr<C> s2(w2);
MOZ_RELEASE_ASSERT(s2);
MOZ_RELEASE_ASSERT(s2 == c1);
MOZ_RELEASE_ASSERT(w1 == s2);
MOZ_RELEASE_ASSERT(s2->mNum == 1);
}
// Test that when a ThreadSafeWeakPtr is destroyed, it does not destroy the
// object that it points to, and it does not affect other ThreadSafeWeakPtrs
// pointing to the same object (e.g. it does not destroy the
// ThreadSafeWeakReference object).
{
ThreadSafeWeakPtr<C> w4local(c1);
MOZ_RELEASE_ASSERT(w4local == c1);
}
// Now w4local has gone out of scope. If that had destroyed c1, then the
// following would fail for sure (see C::~C()).
MOZ_RELEASE_ASSERT(c1->mNum == 1);
// Check that w4local going out of scope hasn't affected other
// ThreadSafeWeakPtr's pointing to c1
MOZ_RELEASE_ASSERT(w1 == c1);
MOZ_RELEASE_ASSERT(w2 == c1);
// Now construct another C object and test changing what object a
// ThreadSafeWeakPtr points to
RefPtr<C> c2 = new C;
c2->mNum = 2;
{
RefPtr<C> s2(w2);
MOZ_RELEASE_ASSERT(s2->mNum == 1); // w2 was pointing to c1
}
w2 = c2;
{
RefPtr<C> s2(w2);
MOZ_RELEASE_ASSERT(s2);
MOZ_RELEASE_ASSERT(s2 == c2);
MOZ_RELEASE_ASSERT(s2 != c1);
MOZ_RELEASE_ASSERT(w1 != s2);
MOZ_RELEASE_ASSERT(s2->mNum == 2);
}
// Destroying the underlying object clears weak pointers to it.
// It should not affect pointers that are not currently pointing to it.
c1 = nullptr;
MOZ_RELEASE_ASSERT(
!bool(w1), "Deleting an object should clear ThreadSafeWeakPtr's to it.");
MOZ_RELEASE_ASSERT(bool(w2),
"Deleting an object should not clear ThreadSafeWeakPtr "
"that are not pointing to it.");
c2 = nullptr;
MOZ_RELEASE_ASSERT(
!bool(w2), "Deleting an object should clear ThreadSafeWeakPtr's to it.");
}