Remove hazptr_priv_list

Summary: folly::ThreadLocal already maintains this list for us.  Add an accessor in folly::SingletonThreadLocal, and use it

Reviewed By: yfeldblum

Differential Revision: D7264843

fbshipit-source-id: 45278f7a074e50b96b451437c327de5d6713363a

folly/SingletonThreadLocal.h

@@ -59,7 +59,11 @@ namespace folly {
 template <
     typename T,
     typename Tag = detail::DefaultTag,
-    typename Make = detail::DefaultMake<T>>
+    typename Make = detail::DefaultMake<T>,
+    typename TLTag = _t<std::conditional<
+        std::is_same<Tag, detail::DefaultTag>::value,
+        void,
+        Tag>>>
 class SingletonThreadLocal {
  private:
   struct Wrapper;
@@ -123,10 +127,12 @@ class SingletonThreadLocal {
     }
   };
 
+  using WrapperTL = ThreadLocal<Wrapper, TLTag>;
+
   SingletonThreadLocal() = delete;
 
-  FOLLY_EXPORT FOLLY_NOINLINE static ThreadLocal<Wrapper>& getWrapperTL() {
-    static auto& entry = *detail::createGlobal<ThreadLocal<Wrapper>, Tag>();
+  FOLLY_EXPORT FOLLY_NOINLINE static WrapperTL& getWrapperTL() {
+    static auto& entry = *detail::createGlobal<WrapperTL, Tag>();
     return entry;
   }
 
@@ -153,5 +159,10 @@ class SingletonThreadLocal {
     return getWrapper();
 #endif
   }
+
+  // Must use a unique Tag, takes a lock that is one per Tag
+  static typename WrapperTL::Accessor accessAllThreads() {
+    return getWrapperTL().accessAllThreads();
+  }
 };
 } // namespace folly

folly/experimental/hazptr/hazptr-impl.h

@@ -184,7 +184,6 @@ class hazptr_priv {
     tail_ = nullptr;
     rcount_ = 0;
     active_ = true;
-    default_hazptr_domain().priv_add(this);
   }
 
   bool active() {
@@ -322,49 +321,6 @@ void hazptr_priv_init(hazptr_priv& priv);
 void hazptr_priv_shutdown(hazptr_priv& priv);
 bool hazptr_priv_try_retire(hazptr_obj* obj);
 
-inline void hazptr_priv_list::insert(hazptr_priv* rec) {
-  std::lock_guard<std::mutex> g(m_);
-  auto prev = head_ == nullptr ? rec : head_->prev();
-  auto next = head_ == nullptr ? rec : head_;
-  rec->set_next(next);
-  rec->set_prev(prev);
-  if (head_) {
-    prev->set_next(rec);
-    next->set_prev(rec);
-  } else {
-    head_ = rec;
-  }
-}
-
-inline void hazptr_priv_list::remove(hazptr_priv* rec) {
-  std::lock_guard<std::mutex> g(m_);
-  auto prev = rec->prev();
-  auto next = rec->next();
-  if (next == rec) {
-    DCHECK(prev == rec);
-    DCHECK(head_ == rec);
-    head_ = nullptr;
-  } else {
-    prev->set_next(next);
-    next->set_prev(prev);
-    if (head_ == rec) {
-      head_ = next;
-    }
-  }
-}
-
-inline void hazptr_priv_list::collect(hazptr_obj*& head, hazptr_obj*& tail) {
-  std::lock_guard<std::mutex> g(m_);
-  auto rec = head_;
-  while (rec) {
-    rec->collect(head, tail);
-    rec = rec->next();
-    if (rec == head_) {
-      break;
-    }
-  }
-}
-
 /** tls globals */
 
 struct hazptr_tls_globals_ {
@@ -386,8 +342,11 @@ struct hazptr_tls_globals_ {
     tls_state = TLS_DESTROYED;
   }
 };
+
+struct HazptrTag {};
+typedef folly::SingletonThreadLocal<hazptr_tls_globals_, HazptrTag> PrivList;
 FOLLY_ALWAYS_INLINE hazptr_tls_globals_& hazptr_tls_globals() {
-  return folly::SingletonThreadLocal<hazptr_tls_globals_, void>::get();
+  return PrivList::get();
 }
 
 /**
@@ -935,7 +894,9 @@ inline hazptr_domain::~hazptr_domain() {
 inline void hazptr_domain::cleanup() {
   hazptr_obj* h = nullptr;
   hazptr_obj* t = nullptr;
-  priv_.collect(h, t);
+  for (hazptr_tls_globals_& tls : PrivList::accessAllThreads()) {
+    tls.priv.collect(h, t);
+  }
   if (h) {
     DCHECK(t);
     pushRetired(h, t, 0);
@@ -943,14 +904,6 @@ inline void hazptr_domain::cleanup() {
   bulkReclaim();
 }
 
-inline void hazptr_domain::priv_add(hazptr_priv* rec) {
-  priv_.insert(rec);
-}
-
-inline void hazptr_domain::priv_remove(hazptr_priv* rec) {
-  priv_.remove(rec);
-}
-
 inline hazptr_rec* hazptr_domain::hazptrAcquire() {
   hazptr_rec* p;
   hazptr_rec* next;
@@ -1243,7 +1196,6 @@ inline void hazptr_priv_shutdown(hazptr_priv& priv) {
   if (!priv.empty()) {
     priv.push_all_to_domain();
   }
-  default_hazptr_domain().priv_remove(&priv);
 }
 
 inline bool hazptr_priv_try_retire(hazptr_obj* obj) {

folly/experimental/hazptr/hazptr.h

@@ -17,7 +17,6 @@
 #define HAZPTR_H
 
 #include <atomic>
-#include <mutex>
 
 /* Stand-in for C++17 std::pmr::memory_resource */
 #include <folly/experimental/hazptr/memory_resource.h>
@@ -53,16 +52,6 @@ class hazptr_local;
 /** hazptr_priv: Per-thread list of retired objects pushed in bulk to domain */
 class hazptr_priv;
 
-class hazptr_priv_list {
-  std::mutex m_;
-  hazptr_priv* head_{nullptr};
-
- public:
-  void insert(hazptr_priv* rec);
-  void remove(hazptr_priv* rec);
-  void collect(hazptr_obj*& head, hazptr_obj*& tail);
-};
-
 /** hazptr_domain: Class of hazard pointer domains. Each domain manages a set
  *  of hazard pointers and a set of retired objects. */
 class hazptr_domain {
@@ -74,7 +63,6 @@ class hazptr_domain {
    * involved in calculations related to the value of rcount_. */
   std::atomic<int> hcount_ = {0};
   std::atomic<int> rcount_ = {0};
-  hazptr_priv_list priv_;
 
  public:
   constexpr explicit hazptr_domain(
@@ -90,8 +78,6 @@ class hazptr_domain {
   template <typename T, typename D = std::default_delete<T>>
   void retire(T* obj, D reclaim = {});
   void cleanup();
-  void priv_add(hazptr_priv* rec);
-  void priv_remove(hazptr_priv* rec);
 
  private:
   friend class hazptr_obj_batch;