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upd: [ipc] spin lock
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mutouyun
parent
985ef22f64
commit
4e4f22e3a8
@ -9,59 +9,18 @@
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#include <atomic>
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#include <thread>
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#include <chrono>
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#include <limits>
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#include <type_traits>
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#include <utility>
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#include "libimp/detect_plat.h"
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#include "libimp/export.h"
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#include "libipc/def.h"
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LIBIPC_NAMESPACE_BEG_
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/**
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* @brief Gives hint to processor that improves performance of spin-wait loops.
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*/
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#pragma push_macro("LIBIPC_LOCK_PAUSE_")
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#undef LIBIPC_LOCK_PAUSE_
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#if defined(LIBIPC_CC_MSVC)
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# include <Windows.h> // YieldProcessor
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/**
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* @brief Not for intel c++ compiler, so ignore http://software.intel.com/en-us/forums/topic/296168
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* @see http://msdn.microsoft.com/en-us/library/windows/desktop/ms687419(v=vs.85).aspx
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*/
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# define LIBIPC_LOCK_PAUSE_() YieldProcessor()
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#elif defined(LIBIPC_CC_GNUC)
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# if defined(LIBIPC_INSTR_X86_64)
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/**
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* @brief Intel(R) 64 and IA-32 Architectures Software Developer's Manual V2
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* PAUSE-Spin Loop Hint, 4-57
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* @see http://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.html?wapkw=instruction+set+reference
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*/
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# define LIBIPC_LOCK_PAUSE_() __asm__ __volatile__("pause")
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# elif defined(LIBIPC_INSTR_I64)
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/**
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* @brief Intel(R) Itanium(R) Architecture Developer's Manual, Vol.3
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* hint - Performance Hint, 3:145
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* @see http://www.intel.com/content/www/us/en/processors/itanium/itanium-architecture-vol-3-manual.html
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*/
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# define LIBIPC_LOCK_PAUSE_() __asm__ __volatile__ ("hint @pause")
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# elif defined(LIBIPC_INSTR_ARM)
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/**
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* @brief ARM Architecture Reference Manuals (YIELD)
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* @see http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.subset.architecture.reference/index.html
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*/
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# define LIBIPC_LOCK_PAUSE_() __asm__ __volatile__ ("yield")
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# endif
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#endif /*compilers*/
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#if !defined(LIBIPC_LOCK_PAUSE_)
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/**
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* @brief Just use a compiler fence, prevent compiler from optimizing loop
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*/
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# define LIBIPC_LOCK_PAUSE_() std::atomic_signal_fence(std::memory_order_seq_cst)
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#endif /*!defined(LIBIPC_LOCK_PAUSE_)*/
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LIBIPC_NAMESPACE_BEG_
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LIBIMP_EXPORT void pause() noexcept;
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/**
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* @brief Yield to other threads
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@ -71,7 +30,7 @@ template <typename K>
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inline void yield(K &k) noexcept {
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if (k < 4) { /* Do nothing */ }
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else
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if (k < 16) { LIBIPC_LOCK_PAUSE_(); }
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if (k < 16) { pause(); }
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else
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if (k < 32) { std::this_thread::yield(); }
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else {
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@ -96,86 +55,32 @@ inline void sleep(K &k, F &&f) {
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template <std::size_t N = 32, typename K>
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inline void sleep(K &k) {
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sleep<N>(k, [] {
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std::this_thread::sleep_for(std::chrono::milliseconds(1));
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std::this_thread::sleep_for(std::chrono::microseconds(1));
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});
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}
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/**
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* @brief Basic spin lock
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*/
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class spin_lock {
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class LIBIMP_EXPORT spin_lock {
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std::atomic<unsigned> lc_ {0};
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public:
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void lock(void) noexcept {
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for (unsigned k = 0;
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lc_.exchange(1, std::memory_order_acquire);
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yield(k)) ;
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}
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void unlock(void) noexcept {
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lc_.store(0, std::memory_order_release);
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}
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void lock() noexcept;
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void unlock() noexcept;
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};
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/**
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* @brief Support for shared mode spin lock
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*/
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class rw_lock {
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using lc_ui_t = unsigned;
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std::atomic<lc_ui_t> lc_ {0};
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enum : lc_ui_t {
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w_mask = (std::numeric_limits<std::make_signed_t<lc_ui_t>>::max)(), // b 0111 1111
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w_flag = w_mask + 1, // b 1000 0000
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};
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class LIBIMP_EXPORT rw_lock {
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std::atomic<unsigned> lc_ {0};
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public:
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rw_lock() noexcept = default;
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rw_lock(const rw_lock &) = delete;
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rw_lock &operator=(const rw_lock &) = delete;
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rw_lock(rw_lock &&) = delete;
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rw_lock &operator=(rw_lock &&) = delete;
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void lock() noexcept {
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for (unsigned k = 0;;) {
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auto old = lc_.fetch_or(w_flag, std::memory_order_acq_rel);
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if (!old) return; // got w-lock
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if (!(old & w_flag)) break; // other thread having r-lock
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yield(k); // other thread having w-lock
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}
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// wait for reading finished
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for (unsigned k = 0;
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lc_.load(std::memory_order_acquire) & w_mask;
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yield(k)) ;
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}
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void unlock() noexcept {
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lc_.store(0, std::memory_order_release);
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}
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void lock_shared() noexcept {
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auto old = lc_.load(std::memory_order_acquire);
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for (unsigned k = 0;;) {
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// if w_flag set, just continue
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if (old & w_flag) {
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yield(k);
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old = lc_.load(std::memory_order_acquire);
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}
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// otherwise try cas lc + 1 (set r-lock)
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else if (lc_.compare_exchange_weak(old, old + 1, std::memory_order_release)) {
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return;
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}
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// set r-lock failed, old has been updated
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}
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}
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void unlock_shared() noexcept {
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lc_.fetch_sub(1, std::memory_order_release);
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}
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void lock() noexcept;
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void unlock() noexcept;
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void lock_shared() noexcept;
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void unlock_shared() noexcept;
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};
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LIBIPC_NAMESPACE_END_
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#pragma pop_macro("LIBIPC_LOCK_PAUSE_")
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116
src/libipc/spin_lock.cpp
Normal file
116
src/libipc/spin_lock.cpp
Normal file
@ -0,0 +1,116 @@
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#include <limits>
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#include "libimp/detect_plat.h"
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#include "libipc/spin_lock.h"
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LIBIPC_NAMESPACE_BEG_
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#if defined(LIBIPC_CC_MSVC)
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# include <Windows.h> // YieldProcessor
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/**
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* @brief Not for intel c++ compiler, so ignore http://software.intel.com/en-us/forums/topic/296168
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* @see http://msdn.microsoft.com/en-us/library/windows/desktop/ms687419(v=vs.85).aspx
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*/
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# define LIBIPC_LOCK_PAUSE_() YieldProcessor()
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#elif defined(LIBIPC_CC_GNUC)
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# if defined(LIBIPC_INSTR_X86_64)
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/**
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* @brief Intel(R) 64 and IA-32 Architectures Software Developer's Manual V2
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* PAUSE-Spin Loop Hint, 4-57
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* @see http://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.html?wapkw=instruction+set+reference
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*/
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# define LIBIPC_LOCK_PAUSE_() __asm__ __volatile__("pause")
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# elif defined(LIBIPC_INSTR_I64)
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/**
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* @brief Intel(R) Itanium(R) Architecture Developer's Manual, Vol.3
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* hint - Performance Hint, 3:145
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* @see http://www.intel.com/content/www/us/en/processors/itanium/itanium-architecture-vol-3-manual.html
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*/
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# define LIBIPC_LOCK_PAUSE_() __asm__ __volatile__ ("hint @pause")
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# elif defined(LIBIPC_INSTR_ARM)
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/**
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* @brief ARM Architecture Reference Manuals (YIELD)
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* @see http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.subset.architecture.reference/index.html
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*/
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# define LIBIPC_LOCK_PAUSE_() __asm__ __volatile__ ("yield")
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# endif
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#endif /*compilers*/
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#if !defined(LIBIPC_LOCK_PAUSE_)
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/**
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* @brief Just use a compiler fence, prevent compiler from optimizing loop
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*/
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# define LIBIPC_LOCK_PAUSE_() std::atomic_signal_fence(std::memory_order_seq_cst)
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#endif /*!defined(LIBIPC_LOCK_PAUSE_)*/
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/**
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* @brief Gives hint to processor that improves performance of spin-wait loops.
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*/
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void pause() noexcept {
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LIBIPC_LOCK_PAUSE_();
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}
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/**
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* @brief Basic spin lock
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*/
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void spin_lock::lock() noexcept {
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for (unsigned k = 0;
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lc_.exchange(1, std::memory_order_acquire);
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yield(k)) ;
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}
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void spin_lock::unlock() noexcept {
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lc_.store(0, std::memory_order_release);
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}
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/// @brief Constants for shared mode spin lock
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enum : unsigned {
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w_mask = (std::numeric_limits<std::make_signed_t<unsigned>>::max)(), // b 0111 1111
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w_flag = w_mask + 1, // b 1000 0000
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};
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/**
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* @brief Support for shared mode spin lock
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*/
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void rw_lock::lock() noexcept {
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for (unsigned k = 0;;) {
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auto old = lc_.fetch_or(w_flag, std::memory_order_acq_rel);
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if (!old) return; // got w-lock
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if (!(old & w_flag)) break; // other thread having r-lock
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yield(k); // other thread having w-lock
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}
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// wait for reading finished
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for (unsigned k = 0;
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lc_.load(std::memory_order_acquire) & w_mask;
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yield(k)) ;
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}
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void rw_lock::unlock() noexcept {
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lc_.store(0, std::memory_order_release);
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}
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void rw_lock::lock_shared() noexcept {
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auto old = lc_.load(std::memory_order_acquire);
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for (unsigned k = 0;;) {
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// if w_flag set, just continue
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if (old & w_flag) {
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yield(k);
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old = lc_.load(std::memory_order_acquire);
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}
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// otherwise try cas lc + 1 (set r-lock)
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else if (lc_.compare_exchange_weak(old, old + 1, std::memory_order_release)) {
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return;
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}
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// set r-lock failed, old has been updated
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}
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}
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void rw_lock::unlock_shared() noexcept {
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lc_.fetch_sub(1, std::memory_order_release);
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}
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LIBIPC_NAMESPACE_END_
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