Dave Zarzycki showed how the efficiency of shared_ptr could be significantly
increased. The following program is running 49% faster:
#include <iostream>
#include <memory>
#include <chrono>
#include <vector>
#include "chrono_io"
int main()
{
typedef std::chrono::high_resolution_clock Clock;
Clock::time_point t0 = Clock::now();
{
std::shared_ptr<int> p(new int (1));
std::vector<std::shared_ptr<int> > v(1000000, p);
v.insert(v.begin(), p);
v.insert(v.begin(), p);
v.insert(v.begin(), p);
v.insert(v.begin(), p);
}
Clock::time_point t1 = Clock::now();
std::cout << (t1-t0) << '\n';
}
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@119388 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/memory b/include/memory
index c016154..4752ba0 100644
--- a/include/memory
+++ b/include/memory
@@ -2535,7 +2535,7 @@
: __shared_owners_(__refs) {}
void __add_shared();
- void __release_shared();
+ bool __release_shared();
_LIBCPP_INLINE_VISIBILITY
long use_count() const {return __shared_owners_ + 1;}
};
diff --git a/src/memory.cpp b/src/memory.cpp
index 9918531..5bbf48e 100644
--- a/src/memory.cpp
+++ b/src/memory.cpp
@@ -50,11 +50,15 @@
increment(__shared_owners_);
}
-void
+bool
__shared_count::__release_shared()
{
if (decrement(__shared_owners_) == -1)
+ {
__on_zero_shared();
+ return true;
+ }
+ return false;
}
__shared_weak_count::~__shared_weak_count()
@@ -65,7 +69,6 @@
__shared_weak_count::__add_shared()
{
__shared_count::__add_shared();
- __add_weak();
}
void
@@ -77,8 +80,8 @@
void
__shared_weak_count::__release_shared()
{
- __shared_count::__release_shared();
- __release_weak();
+ if (__shared_count::__release_shared())
+ __release_weak();
}
void