/*
- * Copyright 2016 Facebook, Inc.
+ * Copyright 2017 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
#pragma once
+#include <folly/Likely.h>
#include <folly/LockTraits.h>
#include <folly/Preprocessor.h>
#include <folly/SharedMutex.h>
template <class LockedType, class LockPolicy = LockPolicyExclusive>
class LockedGuardPtr;
+/**
+ * Public version of LockInterfaceDispatcher that contains the MutexLevel enum
+ * for the passed in mutex type
+ *
+ * This is decoupled from MutexLevelValueImpl in LockTraits.h because this
+ * ensures that a heterogenous mutex with a different API can be used. For
+ * example - if a mutex does not have a lock_shared() method but the
+ * LockTraits specialization for it supports a static non member
+ * lock_shared(Mutex&) it can be used as a shared mutex and will provide
+ * rlock() and wlock() functions.
+ */
+template <class Mutex>
+using MutexLevelValue = detail::MutexLevelValueImpl<
+ true,
+ LockTraits<Mutex>::is_shared,
+ LockTraits<Mutex>::is_upgrade>;
+
/**
* SynchronizedBase is a helper parent class for Synchronized<T>.
*
* It provides wlock() and rlock() methods for shared mutex types,
* or lock() methods for purely exclusive mutex types.
*/
-template <class Subclass, bool is_shared>
+template <class Subclass, detail::MutexLevel level>
class SynchronizedBase;
/**
* accessing the data.
*/
template <class Subclass>
-class SynchronizedBase<Subclass, true> {
+class SynchronizedBase<Subclass, detail::MutexLevel::SHARED> {
public:
using LockedPtr = ::folly::LockedPtr<Subclass, LockPolicyExclusive>;
using ConstWLockedPtr =
}
};
+/**
+ * SynchronizedBase specialization for upgrade mutex types.
+ *
+ * This class provides all the functionality provided by the SynchronizedBase
+ * specialization for shared mutexes and a ulock() method that returns an
+ * upgradable lock RAII proxy
+ */
+template <class Subclass>
+class SynchronizedBase<Subclass, detail::MutexLevel::UPGRADE>
+ : public SynchronizedBase<Subclass, detail::MutexLevel::SHARED> {
+ public:
+ using UpgradeLockedPtr = ::folly::LockedPtr<Subclass, LockPolicyUpgrade>;
+ using ConstUpgradeLockedPtr =
+ ::folly::LockedPtr<const Subclass, LockPolicyUpgrade>;
+ using UpgradeLockedGuardPtr =
+ ::folly::LockedGuardPtr<Subclass, LockPolicyUpgrade>;
+ using ConstUpgradeLockedGuardPtr =
+ ::folly::LockedGuardPtr<const Subclass, LockPolicyUpgrade>;
+
+ /**
+ * Acquire an upgrade lock and return a LockedPtr that can be used to safely
+ * access the datum
+ *
+ * And the const version
+ */
+ UpgradeLockedPtr ulock() {
+ return UpgradeLockedPtr(static_cast<Subclass*>(this));
+ }
+ ConstUpgradeLockedPtr ulock() const {
+ return ConstUpgradeLockedPtr(static_cast<const Subclass*>(this));
+ }
+
+ /**
+ * Acquire an upgrade lock and return a LockedPtr that can be used to safely
+ * access the datum
+ *
+ * And the const version
+ */
+ template <class Rep, class Period>
+ UpgradeLockedPtr ulock(const std::chrono::duration<Rep, Period>& timeout) {
+ return UpgradeLockedPtr(static_cast<Subclass*>(this), timeout);
+ }
+ template <class Rep, class Period>
+ UpgradeLockedPtr ulock(
+ const std::chrono::duration<Rep, Period>& timeout) const {
+ return ConstUpgradeLockedPtr(static_cast<const Subclass*>(this), timeout);
+ }
+
+ /**
+ * Invoke a function while holding the lock.
+ *
+ * A reference to the datum will be passed into the function as its only
+ * argument.
+ *
+ * This can be used with a lambda argument for easily defining small critical
+ * sections in the code. For example:
+ *
+ * auto value = obj.withULock([](auto& data) {
+ * data.doStuff();
+ * return data.getValue();
+ * });
+ *
+ * This is probably not the function you want. If the intent is to read the
+ * data object and determine whether you should upgrade to a write lock then
+ * the withULockPtr() method should be called instead, since it gives access
+ * to the LockedPtr proxy (which can be upgraded via the
+ * moveFromUpgradeToWrite() method)
+ */
+ template <class Function>
+ auto withULock(Function&& function) const {
+ ConstUpgradeLockedGuardPtr guardPtr(static_cast<const Subclass*>(this));
+ return function(*guardPtr);
+ }
+
+ /**
+ * Invoke a function while holding the lock exclusively.
+ *
+ * This is similar to withULock(), but the function will be passed a
+ * LockedPtr rather than a reference to the data itself.
+ *
+ * This allows scopedUnlock() and getUniqueLock() to be called on the
+ * LockedPtr argument.
+ *
+ * This also allows you to upgrade the LockedPtr proxy to a write state so
+ * that changes can be made to the underlying data
+ */
+ template <class Function>
+ auto withULockPtr(Function&& function) {
+ return function(ulock());
+ }
+ template <class Function>
+ auto withULockPtr(Function&& function) const {
+ return function(ulock());
+ }
+};
+
/**
* SynchronizedBase specialization for non-shared mutex types.
*
* data.
*/
template <class Subclass>
-class SynchronizedBase<Subclass, false> {
+class SynchronizedBase<Subclass, detail::MutexLevel::UNIQUE> {
public:
using LockedPtr = ::folly::LockedPtr<Subclass, LockPolicyExclusive>;
using ConstLockedPtr =
template <class T, class Mutex = SharedMutex>
struct Synchronized : public SynchronizedBase<
Synchronized<T, Mutex>,
- LockTraits<Mutex>::is_shared> {
+ MutexLevelValue<Mutex>::value> {
private:
using Base =
- SynchronizedBase<Synchronized<T, Mutex>, LockTraits<Mutex>::is_shared>;
+ SynchronizedBase<Synchronized<T, Mutex>, MutexLevelValue<Mutex>::value>;
static constexpr bool nxCopyCtor{
std::is_nothrow_copy_constructible<T>::value};
static constexpr bool nxMoveCtor{
std::is_nothrow_move_constructible<T>::value};
+ // used to disable copy construction and assignment
+ class NonImplementedType;
+
public:
using LockedPtr = typename Base::LockedPtr;
using ConstLockedPtr = typename Base::ConstLockedPtr;
* Note that the copy constructor may throw because it acquires a lock in
* the contextualRLock() method
*/
- Synchronized(const Synchronized& rhs) /* may throw */
+ public:
+ /* implicit */ Synchronized(typename std::conditional<
+ std::is_copy_constructible<T>::value,
+ const Synchronized&,
+ NonImplementedType>::type rhs) /* may throw */
: Synchronized(rhs, rhs.contextualRLock()) {}
/**
/**
* Lets you construct non-movable types in-place. Use the constexpr
- * instance `construct_in_place` as the first argument.
+ * instance `in_place` as the first argument.
*/
template <typename... Args>
- explicit Synchronized(construct_in_place_t, Args&&... args)
+ explicit Synchronized(in_place_t, Args&&... args)
: datum_(std::forward<Args>(args)...) {}
/**
* mutex. It locks the two objects in ascending order of their
* addresses.
*/
- Synchronized& operator=(const Synchronized& rhs) {
+ Synchronized& operator=(typename std::conditional<
+ std::is_copy_assignable<T>::value,
+ const Synchronized&,
+ NonImplementedType>::type rhs) {
if (this == &rhs) {
// Self-assignment, pass.
} else if (this < &rhs) {
/**
* Attempts to acquire for a given number of milliseconds. If
- * acquisition is unsuccessful, the returned LockedPtr is NULL.
+ * acquisition is unsuccessful, the returned LockedPtr is nullptr.
*
* NOTE: This API is deprecated. Use lock(), wlock(), or rlock() instead.
* In the future it will be marked with a deprecation attribute to emit
/**
* Attempts to acquire for a given number of milliseconds. If
- * acquisition is unsuccessful, the returned ConstLockedPtr is NULL.
+ * acquisition is unsuccessful, the returned ConstLockedPtr is nullptr.
*
* NOTE: This API is deprecated. Use lock(), wlock(), or rlock() instead.
* In the future it will be marked with a deprecation attribute to emit
std::is_const<SynchronizedType>::value,
typename SynchronizedType::ConstLockedPtr,
typename SynchronizedType::LockedPtr>::type;
-} // detail
+} // namespace detail
/**
* A helper base class for implementing LockedPtr.
ScopedUnlocker<SynchronizedType, LockPolicy> scopedUnlock() {
return ScopedUnlocker<SynchronizedType, LockPolicy>(this);
}
+
+ /***************************************************************************
+ * Upgradable lock methods.
+ * These are disabled via SFINAE when the mutex is not upgradable
+ **************************************************************************/
+ /**
+ * Move the locked ptr from an upgrade state to an exclusive state. The
+ * current lock is left in a null state.
+ */
+ template <
+ typename SyncType = SynchronizedType,
+ typename = typename std::enable_if<
+ LockTraits<typename SyncType::MutexType>::is_upgrade>::type>
+ LockedPtr<SynchronizedType, LockPolicyFromUpgradeToExclusive>
+ moveFromUpgradeToWrite() {
+ auto* parent_to_pass_on = this->parent_;
+ this->parent_ = nullptr;
+ return LockedPtr<SynchronizedType, LockPolicyFromUpgradeToExclusive>(
+ parent_to_pass_on);
+ }
+
+ /**
+ * Move the locked ptr from an exclusive state to an upgrade state. The
+ * current lock is left in a null state.
+ */
+ template <
+ typename SyncType = SynchronizedType,
+ typename = typename std::enable_if<
+ LockTraits<typename SyncType::MutexType>::is_upgrade>::type>
+ LockedPtr<SynchronizedType, LockPolicyFromExclusiveToUpgrade>
+ moveFromWriteToUpgrade() {
+ auto* parent_to_pass_on = this->parent_;
+ this->parent_ = nullptr;
+ return LockedPtr<SynchronizedType, LockPolicyFromExclusiveToUpgrade>(
+ parent_to_pass_on);
+ }
+
+ /**
+ * Move the locked ptr from an upgrade state to a shared state. The
+ * current lock is left in a null state.
+ */
+ template <
+ typename SyncType = SynchronizedType,
+ typename = typename std::enable_if<
+ LockTraits<typename SyncType::MutexType>::is_upgrade>::type>
+ LockedPtr<SynchronizedType, LockPolicyFromUpgradeToShared>
+ moveFromUpgradeToRead() {
+ auto* parent_to_pass_on = this->parent_;
+ this->parent_ = nullptr;
+ return LockedPtr<SynchronizedType, LockPolicyFromUpgradeToShared>(
+ parent_to_pass_on);
+ }
+
+ /**
+ * Move the locked ptr from an exclusive state to a shared state. The
+ * current lock is left in a null state.
+ */
+ template <
+ typename SyncType = SynchronizedType,
+ typename = typename std::enable_if<
+ LockTraits<typename SyncType::MutexType>::is_upgrade>::type>
+ LockedPtr<SynchronizedType, LockPolicyFromExclusiveToShared>
+ moveFromWriteToRead() {
+ auto* parent_to_pass_on = this->parent_;
+ this->parent_ = nullptr;
+ return LockedPtr<SynchronizedType, LockPolicyFromExclusiveToShared>(
+ parent_to_pass_on);
+ }
};
/**
lhs.swap(rhs);
}
+/**
+ * Disambiguate the name var by concatenating the line number of the original
+ * point of expansion. This avoids shadowing warnings for nested
+ * SYNCHRONIZEDs. The name is consistent if used multiple times within
+ * another macro.
+ * Only for internal use.
+ */
+#define SYNCHRONIZED_VAR(var) FB_CONCATENATE(SYNCHRONIZED_##var##_, __LINE__)
+
/**
* SYNCHRONIZED is the main facility that makes Synchronized<T>
* helpful. It is a pseudo-statement that introduces a scope where the
*/
#define SYNCHRONIZED(...) \
FOLLY_PUSH_WARNING \
- FOLLY_GCC_DISABLE_WARNING(shadow) \
- if (bool SYNCHRONIZED_state = false) { \
+ FOLLY_GCC_DISABLE_WARNING("-Wshadow") \
+ FOLLY_MSVC_DISABLE_WARNING(4189) /* initialized but unreferenced */ \
+ FOLLY_MSVC_DISABLE_WARNING(4456) /* declaration hides local */ \
+ FOLLY_MSVC_DISABLE_WARNING(4457) /* declaration hides parameter */ \
+ FOLLY_MSVC_DISABLE_WARNING(4458) /* declaration hides member */ \
+ FOLLY_MSVC_DISABLE_WARNING(4459) /* declaration hides global */ \
+ FOLLY_GCC_DISABLE_NEW_SHADOW_WARNINGS \
+ if (bool SYNCHRONIZED_VAR(state) = false) { \
} else \
- for (auto SYNCHRONIZED_lockedPtr = \
+ for (auto SYNCHRONIZED_VAR(lockedPtr) = \
(FB_VA_GLUE(FB_ARG_2_OR_1, (__VA_ARGS__))).operator->(); \
- !SYNCHRONIZED_state; \
- SYNCHRONIZED_state = true) \
+ !SYNCHRONIZED_VAR(state); \
+ SYNCHRONIZED_VAR(state) = true) \
for (auto& FB_VA_GLUE(FB_ARG_1, (__VA_ARGS__)) = \
- *SYNCHRONIZED_lockedPtr.operator->(); \
- !SYNCHRONIZED_state; \
- SYNCHRONIZED_state = true) \
+ *SYNCHRONIZED_VAR(lockedPtr).operator->(); \
+ !SYNCHRONIZED_VAR(state); \
+ SYNCHRONIZED_VAR(state) = true) \
FOLLY_POP_WARNING
#define TIMED_SYNCHRONIZED(timeout, ...) \
- if (bool SYNCHRONIZED_state = false) { \
+ if (bool SYNCHRONIZED_VAR(state) = false) { \
} else \
- for (auto SYNCHRONIZED_lockedPtr = \
+ for (auto SYNCHRONIZED_VAR(lockedPtr) = \
(FB_VA_GLUE(FB_ARG_2_OR_1, (__VA_ARGS__))).timedAcquire(timeout); \
- !SYNCHRONIZED_state; \
- SYNCHRONIZED_state = true) \
+ !SYNCHRONIZED_VAR(state); \
+ SYNCHRONIZED_VAR(state) = true) \
for (auto FB_VA_GLUE(FB_ARG_1, (__VA_ARGS__)) = \
- (!SYNCHRONIZED_lockedPtr \
+ (!SYNCHRONIZED_VAR(lockedPtr) \
? nullptr \
- : SYNCHRONIZED_lockedPtr.operator->()); \
- !SYNCHRONIZED_state; \
- SYNCHRONIZED_state = true)
+ : SYNCHRONIZED_VAR(lockedPtr).operator->()); \
+ !SYNCHRONIZED_VAR(state); \
+ SYNCHRONIZED_VAR(state) = true)
/**
* Similar to SYNCHRONIZED, but only uses a read lock.
FB_VA_GLUE(FB_ARG_1, (__VA_ARGS__)), \
(FB_VA_GLUE(FB_ARG_2_OR_1, (__VA_ARGS__))).asConst())
-/**
- * Temporarily disables synchronization inside a SYNCHRONIZED block.
- *
- * Note: This macro is deprecated, and kind of broken. The input parameter
- * does not control what it unlocks--it always unlocks the lock acquired by the
- * most recent SYNCHRONIZED scope. If you have two nested SYNCHRONIZED blocks,
- * UNSYNCHRONIZED always unlocks the inner-most, even if you pass in the
- * variable name used in the outer SYNCHRONIZED block.
- *
- * This macro will be removed soon in a subsequent diff.
- */
-#define UNSYNCHRONIZED(name) \
- for (auto SYNCHRONIZED_state3 = SYNCHRONIZED_lockedPtr.scopedUnlock(); \
- !SYNCHRONIZED_state; \
- SYNCHRONIZED_state = true) \
- for (auto& name = *SYNCHRONIZED_state3.getSynchronized(); \
- !SYNCHRONIZED_state; \
- SYNCHRONIZED_state = true)
-
/**
* Synchronizes two Synchronized objects (they may encapsulate
* different data). Synchronization is done in increasing address of
* object order, so there is no deadlock risk.
*/
-#define SYNCHRONIZED_DUAL(n1, e1, n2, e2) \
- if (bool SYNCHRONIZED_state = false) { \
- } else \
- for (auto SYNCHRONIZED_ptrs = acquireLockedPair(e1, e2); \
- !SYNCHRONIZED_state; \
- SYNCHRONIZED_state = true) \
- for (auto& n1 = *SYNCHRONIZED_ptrs.first; !SYNCHRONIZED_state; \
- SYNCHRONIZED_state = true) \
- for (auto& n2 = *SYNCHRONIZED_ptrs.second; !SYNCHRONIZED_state; \
- SYNCHRONIZED_state = true)
+#define SYNCHRONIZED_DUAL(n1, e1, n2, e2) \
+ if (bool SYNCHRONIZED_VAR(state) = false) { \
+ } else \
+ for (auto SYNCHRONIZED_VAR(ptrs) = acquireLockedPair(e1, e2); \
+ !SYNCHRONIZED_VAR(state); \
+ SYNCHRONIZED_VAR(state) = true) \
+ for (auto& n1 = *SYNCHRONIZED_VAR(ptrs).first; !SYNCHRONIZED_VAR(state); \
+ SYNCHRONIZED_VAR(state) = true) \
+ for (auto& n2 = *SYNCHRONIZED_VAR(ptrs).second; \
+ !SYNCHRONIZED_VAR(state); \
+ SYNCHRONIZED_VAR(state) = true)
} /* namespace folly */
projects / folly.git / blobdiff