/*
- * 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.
* @author Xin Liu <xliux@fb.com>
*/
-#ifndef FOLLY_RWSPINLOCK_H_
-#define FOLLY_RWSPINLOCK_H_
+#pragma once
/*
========================================================================
#include <folly/Portability.h>
#include <folly/portability/Asm.h>
-#if defined(__GNUC__) && \
- (defined(__i386) || FOLLY_X64 || \
- defined(ARCH_K8))
-# define RW_SPINLOCK_USE_X86_INTRINSIC_
-# include <x86intrin.h>
+#if defined(__GNUC__) && (defined(__i386) || FOLLY_X64 || defined(ARCH_K8))
+#define RW_SPINLOCK_USE_X86_INTRINSIC_
+#include <x86intrin.h>
#elif defined(_MSC_VER) && defined(FOLLY_X64)
-# define RW_SPINLOCK_USE_X86_INTRINSIC_
+#define RW_SPINLOCK_USE_X86_INTRINSIC_
#else
-# undef RW_SPINLOCK_USE_X86_INTRINSIC_
+#undef RW_SPINLOCK_USE_X86_INTRINSIC_
#endif
// iOS doesn't define _mm_cvtsi64_si128 and friends
-#if (FOLLY_SSE >= 2) && !FOLLY_MOBILE
+#if (FOLLY_SSE >= 2) && !FOLLY_MOBILE && FOLLY_X64
#define RW_SPINLOCK_USE_SSE_INSTRUCTIONS_
#else
#undef RW_SPINLOCK_USE_SSE_INSTRUCTIONS_
#endif
+#include <algorithm>
#include <atomic>
#include <string>
-#include <algorithm>
+#include <thread>
-#include <sched.h>
#include <glog/logging.h>
#include <folly/Likely.h>
// Lockable Concept
void lock() {
- int count = 0;
+ uint_fast32_t count = 0;
while (!LIKELY(try_lock())) {
- if (++count > 1000) sched_yield();
+ if (++count > 1000) {
+ std::this_thread::yield();
+ }
}
}
// SharedLockable Concept
void lock_shared() {
- int count = 0;
+ uint_fast32_t count = 0;
while (!LIKELY(try_lock_shared())) {
- if (++count > 1000) sched_yield();
+ if (++count > 1000) {
+ std::this_thread::yield();
+ }
}
}
// UpgradeLockable Concept
void lock_upgrade() {
- int count = 0;
+ uint_fast32_t count = 0;
while (!try_lock_upgrade()) {
- if (++count > 1000) sched_yield();
+ if (++count > 1000) {
+ std::this_thread::yield();
+ }
}
}
void unlock_upgrade_and_lock() {
int64_t count = 0;
while (!try_unlock_upgrade_and_lock()) {
- if (++count > 1000) sched_yield();
+ if (++count > 1000) {
+ std::this_thread::yield();
+ }
}
}
class ReadHolder {
public:
- explicit ReadHolder(RWSpinLock* lock = nullptr) : lock_(lock) {
- if (lock_) lock_->lock_shared();
+ explicit ReadHolder(RWSpinLock* lock) : lock_(lock) {
+ if (lock_) {
+ lock_->lock_shared();
+ }
}
explicit ReadHolder(RWSpinLock& lock) : lock_(&lock) {
// down-grade
explicit ReadHolder(UpgradedHolder&& upgraded) : lock_(upgraded.lock_) {
upgraded.lock_ = nullptr;
- if (lock_) lock_->unlock_upgrade_and_lock_shared();
+ if (lock_) {
+ lock_->unlock_upgrade_and_lock_shared();
+ }
}
explicit ReadHolder(WriteHolder&& writer) : lock_(writer.lock_) {
writer.lock_ = nullptr;
- if (lock_) lock_->unlock_and_lock_shared();
+ if (lock_) {
+ lock_->unlock_and_lock_shared();
+ }
}
ReadHolder& operator=(ReadHolder&& other) {
ReadHolder(const ReadHolder& other) = delete;
ReadHolder& operator=(const ReadHolder& other) = delete;
- ~ReadHolder() { if (lock_) lock_->unlock_shared(); }
+ ~ReadHolder() {
+ if (lock_) {
+ lock_->unlock_shared();
+ }
+ }
void reset(RWSpinLock* lock = nullptr) {
- if (lock == lock_) return;
- if (lock_) lock_->unlock_shared();
+ if (lock == lock_) {
+ return;
+ }
+ if (lock_) {
+ lock_->unlock_shared();
+ }
lock_ = lock;
- if (lock_) lock_->lock_shared();
+ if (lock_) {
+ lock_->lock_shared();
+ }
}
void swap(ReadHolder* other) {
class UpgradedHolder {
public:
- explicit UpgradedHolder(RWSpinLock* lock = nullptr) : lock_(lock) {
- if (lock_) lock_->lock_upgrade();
+ explicit UpgradedHolder(RWSpinLock* lock) : lock_(lock) {
+ if (lock_) {
+ lock_->lock_upgrade();
+ }
}
explicit UpgradedHolder(RWSpinLock& lock) : lock_(&lock) {
explicit UpgradedHolder(WriteHolder&& writer) {
lock_ = writer.lock_;
writer.lock_ = nullptr;
- if (lock_) lock_->unlock_and_lock_upgrade();
+ if (lock_) {
+ lock_->unlock_and_lock_upgrade();
+ }
}
UpgradedHolder(UpgradedHolder&& other) noexcept : lock_(other.lock_) {
UpgradedHolder(const UpgradedHolder& other) = delete;
UpgradedHolder& operator =(const UpgradedHolder& other) = delete;
- ~UpgradedHolder() { if (lock_) lock_->unlock_upgrade(); }
+ ~UpgradedHolder() {
+ if (lock_) {
+ lock_->unlock_upgrade();
+ }
+ }
void reset(RWSpinLock* lock = nullptr) {
- if (lock == lock_) return;
- if (lock_) lock_->unlock_upgrade();
+ if (lock == lock_) {
+ return;
+ }
+ if (lock_) {
+ lock_->unlock_upgrade();
+ }
lock_ = lock;
- if (lock_) lock_->lock_upgrade();
+ if (lock_) {
+ lock_->lock_upgrade();
+ }
}
void swap(UpgradedHolder* other) {
class WriteHolder {
public:
- explicit WriteHolder(RWSpinLock* lock = nullptr) : lock_(lock) {
- if (lock_) lock_->lock();
+ explicit WriteHolder(RWSpinLock* lock) : lock_(lock) {
+ if (lock_) {
+ lock_->lock();
+ }
}
explicit WriteHolder(RWSpinLock& lock) : lock_(&lock) {
explicit WriteHolder(UpgradedHolder&& upgraded) {
lock_ = upgraded.lock_;
upgraded.lock_ = nullptr;
- if (lock_) lock_->unlock_upgrade_and_lock();
+ if (lock_) {
+ lock_->unlock_upgrade_and_lock();
+ }
}
WriteHolder(WriteHolder&& other) noexcept : lock_(other.lock_) {
WriteHolder(const WriteHolder& other) = delete;
WriteHolder& operator =(const WriteHolder& other) = delete;
- ~WriteHolder () { if (lock_) lock_->unlock(); }
+ ~WriteHolder() {
+ if (lock_) {
+ lock_->unlock();
+ }
+ }
void reset(RWSpinLock* lock = nullptr) {
- if (lock == lock_) return;
- if (lock_) lock_->unlock();
+ if (lock == lock_) {
+ return;
+ }
+ if (lock_) {
+ lock_->unlock();
+ }
lock_ = lock;
- if (lock_) lock_->lock();
+ if (lock_) {
+ lock_->lock();
+ }
}
void swap(WriteHolder* other) {
RWSpinLock* lock_;
};
- // Synchronized<> adaptors
- friend void acquireRead(RWSpinLock& l) { return l.lock_shared(); }
- friend void acquireReadWrite(RWSpinLock& l) { return l.lock(); }
- friend void releaseRead(RWSpinLock& l) { return l.unlock_shared(); }
- friend void releaseReadWrite(RWSpinLock& l) { return l.unlock(); }
-
private:
std::atomic<int32_t> bits_;
};
#ifdef RW_SPINLOCK_USE_SSE_INSTRUCTIONS_
static __m128i make128(const uint16_t v[4]) {
- return _mm_set_epi16(0, 0, 0, 0, v[3], v[2], v[1], v[0]);
+ return _mm_set_epi16(0, 0, 0, 0,
+ short(v[3]), short(v[2]), short(v[1]), short(v[0]));
}
static inline __m128i fromInteger(uint64_t from) {
- return _mm_cvtsi64_si128(from);
+ return _mm_cvtsi64_si128(int64_t(from));
}
static inline uint64_t toInteger(__m128i in) {
- return _mm_cvtsi128_si64(in);
+ return uint64_t(_mm_cvtsi128_si64(in));
}
static inline uint64_t addParallel(__m128i in, __m128i kDelta) {
return toInteger(_mm_add_epi16(in, kDelta));
#ifdef RW_SPINLOCK_USE_SSE_INSTRUCTIONS_
static __m128i make128(const uint8_t v[4]) {
- return _mm_set_epi8(0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, v[3], v[2], v[1], v[0]);
+ return _mm_set_epi8(
+ 0, 0, 0, 0,
+ 0, 0, 0, 0,
+ 0, 0, 0, 0,
+ char(v[3]), char(v[2]), char(v[1]), char(v[0]));
}
static inline __m128i fromInteger(uint32_t from) {
- return _mm_cvtsi32_si128(from);
+ return _mm_cvtsi32_si128(int32_t(from));
}
static inline uint32_t toInteger(__m128i in) {
- return _mm_cvtsi128_si32(in);
+ return uint32_t(_mm_cvtsi128_si32(in));
}
static inline uint32_t addParallel(__m128i in, __m128i kDelta) {
return toInteger(_mm_add_epi8(in, kDelta));
}
#endif
};
-} // detail
+} // namespace detail
-
-template<size_t kBitWidth, bool kFavorWriter=false>
+template <size_t kBitWidth, bool kFavorWriter = false>
class RWTicketSpinLockT {
typedef detail::RWTicketIntTrait<kBitWidth> IntTraitType;
typedef typename detail::RWTicketIntTrait<kBitWidth>::FullInt FullInt;
} ticket;
private: // Some x64-specific utilities for atomic access to ticket.
- template<class T> static T load_acquire(T* addr) {
+ template <class T> static T load_acquire(T* addr) {
T t = *addr; // acquire barrier
asm_volatile_memory();
return t;
}
- template<class T>
+ template <class T>
static void store_release(T* addr, T v) {
asm_volatile_memory();
*addr = v; // release barrier
bool try_lock() {
RWTicket t;
FullInt old = t.whole = load_acquire(&ticket.whole);
- if (t.users != t.write) return false;
+ if (t.users != t.write) {
+ return false;
+ }
++t.users;
return __sync_bool_compare_and_swap(&ticket.whole, old, t.whole);
}
* turns.
*/
void writeLockAggressive() {
- // sched_yield() is needed here to avoid a pathology if the number
+ // std::this_thread::yield() is needed here to avoid a pathology if the number
// of threads attempting concurrent writes is >= the number of real
// cores allocated to this process. This is less likely than the
// corresponding situation in lock_shared(), but we still want to
// avoid it
- int count = 0;
+ uint_fast32_t count = 0;
QuarterInt val = __sync_fetch_and_add(&ticket.users, 1);
while (val != load_acquire(&ticket.write)) {
asm_volatile_pause();
- if (UNLIKELY(++count > 1000)) sched_yield();
+ if (UNLIKELY(++count > 1000)) {
+ std::this_thread::yield();
+ }
}
}
// there are a lot of competing readers. The aggressive spinning
// can help to avoid starving writers.
//
- // We don't worry about sched_yield() here because the caller
+ // We don't worry about std::this_thread::yield() here because the caller
// has already explicitly abandoned fairness.
while (!try_lock()) {}
}
}
void lock_shared() {
- // sched_yield() is important here because we can't grab the
+ // std::this_thread::yield() is important here because we can't grab the
// shared lock if there is a pending writeLockAggressive, so we
// need to let threads that already have a shared lock complete
- int count = 0;
+ uint_fast32_t count = 0;
while (!LIKELY(try_lock_shared())) {
asm_volatile_pause();
- if (UNLIKELY((++count & 1023) == 0)) sched_yield();
+ if (UNLIKELY((++count & 1023) == 0)) {
+ std::this_thread::yield();
+ }
}
}
}
void unlock_shared() {
- QuarterInt val = __sync_fetch_and_add(&ticket.write, 1);
+ __sync_fetch_and_add(&ticket.write, 1);
}
class WriteHolder;
ReadHolder(ReadHolder const&) = delete;
ReadHolder& operator=(ReadHolder const&) = delete;
- explicit ReadHolder(RWSpinLock *lock = nullptr) :
- lock_(lock) {
- if (lock_) lock_->lock_shared();
+ explicit ReadHolder(RWSpinLock* lock) : lock_(lock) {
+ if (lock_) {
+ lock_->lock_shared();
+ }
}
explicit ReadHolder(RWSpinLock &lock) : lock_ (&lock) {
- if (lock_) lock_->lock_shared();
+ if (lock_) {
+ lock_->lock_shared();
+ }
}
// atomically unlock the write-lock from writer and acquire the read-lock
}
~ReadHolder() {
- if (lock_) lock_->unlock_shared();
+ if (lock_) {
+ lock_->unlock_shared();
+ }
}
void reset(RWSpinLock *lock = nullptr) {
- if (lock_) lock_->unlock_shared();
+ if (lock_) {
+ lock_->unlock_shared();
+ }
lock_ = lock;
- if (lock_) lock_->lock_shared();
+ if (lock_) {
+ lock_->lock_shared();
+ }
}
void swap(ReadHolder *other) {
WriteHolder(WriteHolder const&) = delete;
WriteHolder& operator=(WriteHolder const&) = delete;
- explicit WriteHolder(RWSpinLock *lock = nullptr) : lock_(lock) {
- if (lock_) lock_->lock();
+ explicit WriteHolder(RWSpinLock* lock) : lock_(lock) {
+ if (lock_) {
+ lock_->lock();
+ }
}
explicit WriteHolder(RWSpinLock &lock) : lock_ (&lock) {
- if (lock_) lock_->lock();
+ if (lock_) {
+ lock_->lock();
+ }
}
~WriteHolder() {
- if (lock_) lock_->unlock();
+ if (lock_) {
+ lock_->unlock();
+ }
}
void reset(RWSpinLock *lock = nullptr) {
- if (lock == lock_) return;
- if (lock_) lock_->unlock();
+ if (lock == lock_) {
+ return;
+ }
+ if (lock_) {
+ lock_->unlock();
+ }
lock_ = lock;
- if (lock_) lock_->lock();
+ if (lock_) {
+ lock_->lock();
+ }
}
void swap(WriteHolder *other) {
friend class ReadHolder;
RWSpinLock *lock_;
};
-
- // Synchronized<> adaptors.
- friend void acquireRead(RWTicketSpinLockT& mutex) {
- mutex.lock_shared();
- }
- friend void acquireReadWrite(RWTicketSpinLockT& mutex) {
- mutex.lock();
- }
- friend void releaseRead(RWTicketSpinLockT& mutex) {
- mutex.unlock_shared();
- }
- friend void releaseReadWrite(RWTicketSpinLockT& mutex) {
- mutex.unlock();
- }
};
typedef RWTicketSpinLockT<32> RWTicketSpinLock32;
#endif // RW_SPINLOCK_USE_X86_INTRINSIC_
-} // namespace folly
+} // namespace folly
#ifdef RW_SPINLOCK_USE_X86_INTRINSIC_
#undef RW_SPINLOCK_USE_X86_INTRINSIC_
#endif
-
-#endif // FOLLY_RWSPINLOCK_H_
projects / folly.git / blobdiff