/*
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* =====================================================================================
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*
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* Filename: robust.h
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*
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* Description:
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*
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* Version: 1.0
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* Created: 2021年04月27日 10时04分29秒
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* Revision: none
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* Compiler: gcc
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*
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* Author: Li Chao (), lichao@aiotlink.com
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* Organization:
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*
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* =====================================================================================
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*/
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#ifndef ROBUST_Q31RCWYU
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#define ROBUST_Q31RCWYU
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#include "bh_util.h"
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#include "log.h"
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#include <atomic>
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#include <chrono>
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#include <memory>
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#include <mutex>
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#include <string>
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#include <sys/file.h>
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#include <sys/ipc.h>
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#include <sys/sem.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <unistd.h>
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namespace robust
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{
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using namespace std::chrono;
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using namespace std::chrono_literals;
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void QuickSleep();
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class CasMutex
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{
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typedef uint64_t locker_t;
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static inline locker_t this_locker() { return pthread_self(); }
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static const uint64_t kLockerMask = MaskBits(63);
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public:
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CasMutex() :
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meta_(0) {}
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int try_lock()
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{
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auto old = meta_.load();
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int r = 0;
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if (!Locked(old)) {
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r = MetaCas(old, Meta(1, this_locker()));
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}
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return r;
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}
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int lock()
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{
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int r = 0;
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do {
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r = try_lock();
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} while (r == 0);
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return r;
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}
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void unlock()
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{
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auto old = meta_.load();
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if (Locked(old) && Locker(old) == this_locker()) {
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MetaCas(old, Meta(0, this_locker()));
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}
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}
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private:
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std::atomic<uint64_t> meta_;
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bool Locked(uint64_t meta) { return (meta >> 63) == 1; }
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locker_t Locker(uint64_t meta) { return meta & kLockerMask; }
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uint64_t Meta(uint64_t lk, locker_t lid) { return (lk << 63) | lid; }
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bool MetaCas(uint64_t exp, uint64_t val) { return meta_.compare_exchange_strong(exp, val); }
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};
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class NullMutex
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{
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public:
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template <class... T>
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explicit NullMutex(T &&...t) {} // easy test.
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bool try_lock() { return true; }
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void lock() {}
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void unlock() {}
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};
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// flock + mutex
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class FMutex
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{
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public:
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typedef uint64_t id_t;
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FMutex(id_t id) :
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id_(id), fd_(Open(id_)), count_(0)
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{
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if (fd_ == -1) { throw "error create mutex!"; }
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}
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~FMutex() { Close(fd_); }
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bool try_lock();
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void lock();
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void unlock();
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private:
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static std::string GetPath(id_t id)
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{
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const std::string dir("/tmp/.bhome_mtx");
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mkdir(dir.c_str(), 0777);
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return dir + "/fm_" + std::to_string(id);
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}
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static int Open(id_t id) { return open(GetPath(id).c_str(), O_CREAT | O_RDONLY, 0666); }
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static int Close(int fd) { return close(fd); }
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id_t id_;
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int fd_;
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std::mutex mtx_;
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std::atomic<int32_t> count_;
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};
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union semun {
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int val; /* Value for SETVAL */
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struct semid_ds *buf; /* Buffer for IPC_STAT, IPC_SET */
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unsigned short *array; /* Array for GETALL, SETALL */
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struct seminfo *__buf; /* Buffer for IPC_INFO
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(Linux-specific) */
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};
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class SemMutex
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{
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public:
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SemMutex(key_t key) :
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key_(key), sem_id_(semget(key, 1, 0666))
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{
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if (sem_id_ == -1) { throw "error create semaphore."; }
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}
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~SemMutex() {}
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bool try_lock()
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{
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sembuf op = {0, -1, SEM_UNDO | IPC_NOWAIT};
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return semop(sem_id_, &op, 1) == 0;
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}
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void lock()
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{
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sembuf op = {0, -1, SEM_UNDO};
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semop(sem_id_, &op, 1);
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}
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void unlock()
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{
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sembuf op = {0, 1, SEM_UNDO};
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semop(sem_id_, &op, 1);
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}
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private:
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key_t key_;
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int sem_id_;
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};
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template <class Lock>
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class Guard
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{
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public:
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Guard(Lock &l) :
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l_(l) { l_.lock(); }
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~Guard() { l_.unlock(); }
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private:
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Guard(const Guard &);
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Guard(Guard &&);
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Lock &l_;
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};
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template <unsigned PowerSize = 4, class Int = int64_t>
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class AtomicQueue
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{
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public:
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typedef uint32_t size_type;
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typedef Int Data;
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typedef std::atomic<Data> AData;
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static_assert(sizeof(Data) == sizeof(AData));
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enum {
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power = PowerSize,
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capacity = (1 << power),
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mask = capacity - 1,
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};
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AtomicQueue() { memset(this, 0, sizeof(*this)); }
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size_type head() const { return head_.load(); }
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size_type tail() const { return tail_.load(); }
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bool like_empty() const { return head() == tail() && Empty(buf[head()]); }
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bool like_full() const { return head() == tail() && !Empty(buf[head()]); }
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bool push(const Data d, bool try_more = false)
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{
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bool r = false;
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size_type i = 0;
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do {
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auto pos = tail();
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if (tail_.compare_exchange_strong(pos, Next(pos))) {
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auto cur = buf[pos].load();
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r = Empty(cur) && buf[pos].compare_exchange_strong(cur, Enc(d));
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}
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} while (try_more && !r && ++i < capacity);
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return r;
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}
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bool pop(Data &d, bool try_more = false)
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{
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bool r = false;
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Data cur;
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size_type i = 0;
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do {
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auto pos = head();
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if (head_.compare_exchange_strong(pos, Next(pos))) {
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cur = buf[pos].load();
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r = !Empty(cur) && buf[pos].compare_exchange_strong(cur, 0);
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}
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} while (try_more && !r && ++i < capacity);
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if (r) { d = Dec(cur); }
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return r;
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}
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private:
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static_assert(std::is_integral<Data>::value, "Data must be integral type!");
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static_assert(std::is_signed<Data>::value, "Data must be signed type!");
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static_assert(PowerSize < 10, "RobustQ63 max size is 2^10!");
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static inline bool Empty(const Data d) { return (d & 1) == 0; } // lowest bit 1 means data ok.
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static inline Data Enc(const Data d) { return (d << 1) | 1; } // lowest bit 1 means data ok.
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static inline Data Dec(const Data d) { return d >> 1; } // lowest bit 1 means data ok.
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static size_type Next(const size_type index) { return (index + 1) & mask; }
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std::atomic<size_type> head_;
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std::atomic<size_type> tail_;
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AData buf[capacity];
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};
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template <class Int>
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class AtomicQueue<0, Int>
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{
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typedef Int Data;
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typedef std::atomic<Data> AData;
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static_assert(sizeof(Data) == sizeof(AData));
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public:
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AtomicQueue() { memset(this, 0, sizeof(*this)); }
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bool push(const Data d, bool try_more = false)
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{
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auto cur = buf.load();
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return Empty(cur) && buf.compare_exchange_strong(cur, Enc(d));
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}
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bool pop(Data &d, bool try_more = false)
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{
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Data cur = buf.load();
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bool r = !Empty(cur) && buf.compare_exchange_strong(cur, 0);
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if (r) { d = Dec(cur); }
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return r;
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}
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uint32_t head() const { return 0; }
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uint32_t tail() const { return 0; }
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private:
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static inline bool Empty(const Data d) { return (d & 1) == 0; } // lowest bit 1 means data ok.
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static inline Data Enc(const Data d) { return (d << 1) | 1; } // lowest bit 1 means data ok.
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static inline Data Dec(const Data d) { return d >> 1; } // lowest bit 1 means data ok.
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AData buf;
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};
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class AtomicReqRep
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{
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public:
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typedef int64_t Data;
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typedef std::function<Data(const Data)> Handler;
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bool ClientRequest(const Data request, Data &reply)
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{
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auto end_time = now() + 3s;
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do {
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Data cur = data_.load();
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if (GetState(cur) == eStateFree &&
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DataCas(cur, Encode(request, eStateRequest))) {
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do {
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yield();
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cur = data_.load();
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if (GetState(cur) == eStateReply) {
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DataCas(cur, Encode(0, eStateFree));
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reply = Decode(cur);
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return true;
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}
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} while (now() < end_time);
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}
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yield();
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} while (now() < end_time);
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return false;
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}
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bool ServerProcess(Handler onReq)
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{
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Data cur = data_.load();
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switch (GetState(cur)) {
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case eStateRequest:
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if (DataCas(cur, Encode(onReq(Decode(cur)), eStateReply))) {
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timestamp_ = now();
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return true;
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}
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break;
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case eStateReply:
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if (timestamp_.load() + 3s < now()) {
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DataCas(cur, Encode(0, eStateFree));
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}
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break;
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case eStateFree:
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default: break;
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}
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return false;
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}
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private:
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enum State {
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eStateFree,
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eStateRequest,
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eStateReply
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};
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static int GetState(Data d) { return d & MaskBits(3); }
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static Data Encode(Data d, State st) { return (d << 3) | st; }
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static Data Decode(Data d) { return d >> 3; }
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static void yield() { QuickSleep(); }
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typedef steady_clock::duration Duration;
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Duration now() { return steady_clock::now().time_since_epoch(); }
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bool DataCas(Data expected, Data val) { return data_.compare_exchange_strong(expected, val); }
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std::atomic<Data> data_;
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std::atomic<Duration> timestamp_;
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};
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} // namespace robust
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#endif // end of include guard: ROBUST_Q31RCWYU
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