Use atomic sharedptr operation (for C++11~20) instead of reflock

common/objectcachev2.h

@@ -37,7 +37,6 @@ class ObjectCacheV2 {
  const K key;
  std::shared_ptr<V> ref;
  photon::spinlock boxlock;
- photon::spinlock reflock;
  uint64_t lastcreate = 0;
  uint64_t timestamp = 0;
 
@@ -50,11 +49,12 @@ class ObjectCacheV2 {
  // other reader will get new one after updated
  std::shared_ptr<V> update(V* val, uint64_t ts = 0,
  std::shared_ptr<V>* newptr = nullptr) {
- SCOPED_LOCK(box->reflock);
  auto r = std::shared_ptr<V>(val);
- if (newptr) *newptr = r;
+ if (newptr)
+ std::atomic_store(newptr, r);
+ *newptr = r;
  box->lastcreate = ts;
- std::swap(r, box->ref);
+ r = std::atomic_exchange(&box->ref, r);
  return r;
  }
 
@@ -79,8 +79,7 @@ class ObjectCacheV2 {
 
  Updater writer() { return Updater(this); }
  std::shared_ptr<V> reader() {
- SCOPED_LOCK(reflock);
- return ref;
+ return std::atomic_load(&ref);
  }
  };
  struct ItemHash {
@@ -173,6 +172,7 @@ class ObjectCacheV2 {
  Borrow& operator=(Borrow&& rhs) {
  std::swap(_oc, rhs._oc);
  std::swap(_item, rhs._item);
+ _reader = std::atomic_exchange(&rhs._reader, _reader);
  std::swap(_reader, rhs._reader);
  std::swap(_recycle, rhs._recycle);
  return *this;

common/test/perf_objcache.cpp

@@ -40,7 +40,7 @@ void *task(void *arg) {
  for (const auto &x : k) {
  auto strx = std::to_string(x);
  auto b = oc->borrow(strx, [&strx] {
- photon::thread_usleep(1 * 1000);
+ // photon::thread_usleep(1 * 1000);
  // LOG_INFO("CTOR `", photon::now);
  return new std::string(strx);
  });
@@ -64,7 +64,7 @@ void test_objcache(OC<std::string, std::string *> &oc, const char *name) {
 
 template <template <class, class> class OC>
 void test(const char *name) {
- OC<std::string, std::string *> oc(-1UL);
+ OC<std::string, std::string *> oc(0);
  std::vector<std::thread> ths;
  photon::semaphore sem(0);
  for (int i = 0; i < 10; i++) {