Revert "Using type-tags for test SingletonVaults"

[folly.git] / folly / Synchronized.h

diff --git a/folly/Synchronized.h b/folly/Synchronized.h
index 538bdbab5529269ba7cb8d6bf3c5bb2479fc7a16..20089816390ec38414bd97bc340dfbc8df620a16 100644 (file)
--- a/folly/Synchronized.h
+++ b/folly/Synchronized.h
@@ -27,8 +27,8 @@
 #include <type_traits>
 #include <mutex>
 #include <boost/thread.hpp>
-#include "folly/Preprocessor.h"
-#include "folly/Traits.h"
+#include <folly/Preprocessor.h>
+#include <folly/Traits.h>
 
 namespace folly {
 
@@ -49,7 +49,8 @@ struct HasLockUnlock {
   enum { value = IsOneOf<T,
          std::mutex, std::recursive_mutex,
          boost::mutex, boost::recursive_mutex, boost::shared_mutex
-#ifndef __APPLE__ // OSX doesn't have timed mutexes
+// OSX and Cygwin don't have timed mutexes
+#if !defined(__APPLE__) && !defined(__CYGWIN__)
         ,std::timed_mutex, std::recursive_timed_mutex,
          boost::timed_mutex, boost::recursive_timed_mutex
 #endif
@@ -97,7 +98,8 @@ acquireReadWrite(T& mutex) {
   mutex.lock();
 }
 
-#ifndef __APPLE__ // OSX doesn't have timed mutexes
+// OSX and Cygwin don't have timed mutexes
+#if !defined(__APPLE__) && !defined(__CYGWIN__)
 /**
  * Acquires a mutex for reading and writing with timeout by calling
  * .try_lock_for(). This applies to two of the std mutex classes as
@@ -196,36 +198,55 @@ struct Synchronized {
    */
   Synchronized() = default;
 
+ private:
+  static constexpr bool nxCopyCtor{
+      std::is_nothrow_copy_constructible<T>::value};
+  static constexpr bool nxMoveCtor{
+      std::is_nothrow_move_constructible<T>::value};
+
+  /**
+   * Helper constructors to enable Synchronized for
+   * non-default constructible types T.
+   * Guards are created in actual public constructors and are alive
+   * for the time required to construct the object
+   */
+  template <typename Guard>
+  Synchronized(const Synchronized& rhs,
+               const Guard& /*guard*/) noexcept(nxCopyCtor)
+      : datum_(rhs.datum_) {}
+
+  template <typename Guard>
+  Synchronized(Synchronized&& rhs, const Guard& /*guard*/) noexcept(nxMoveCtor)
+      : datum_(std::move(rhs.datum_)) {}
+
+ public:
   /**
    * Copy constructor copies the data (with locking the source and
    * all) but does NOT copy the mutex. Doing so would result in
    * deadlocks.
    */
-  Synchronized(const Synchronized& rhs) {
-    auto guard = rhs.operator->();
-    datum_ = rhs.datum_;
-  }
+  Synchronized(const Synchronized& rhs) noexcept(nxCopyCtor)
+      : Synchronized(rhs, rhs.operator->()) {}
 
   /**
    * Move constructor moves the data (with locking the source and all)
    * but does not move the mutex.
    */
-  Synchronized(Synchronized&& rhs) {
-    auto guard = rhs.operator->();
-    datum_ = std::move(rhs.datum_);
-  }
+  Synchronized(Synchronized&& rhs) noexcept(nxMoveCtor)
+      : Synchronized(std::move(rhs), rhs.operator->()) {}
 
   /**
    * Constructor taking a datum as argument copies it. There is no
    * need to lock the constructing object.
    */
-  explicit Synchronized(const T& rhs) : datum_(rhs) {}
+  explicit Synchronized(const T& rhs) noexcept(nxCopyCtor) : datum_(rhs) {}
 
   /**
    * Constructor taking a datum rvalue as argument moves it. Again,
    * there is no need to lock the constructing object.
    */
-  explicit Synchronized(T&& rhs) : datum_(std::move(rhs)) {}
+  explicit Synchronized(T&& rhs) noexcept(nxMoveCtor)
+      : datum_(std::move(rhs)) {}
 
   /**
    * The canonical assignment operator only assigns the data, NOT the
@@ -427,7 +448,7 @@ struct Synchronized {
       acquire();
     }
     ConstLockedPtr(const Synchronized* parent, unsigned int milliseconds) {
-      if (parent->mutex_.timed_lock(
+      if (parent->mutex_.timed_lock_shared(
             boost::posix_time::milliseconds(milliseconds))) {
         parent_ = parent;
         return;