| #pragma once |
| /* |
| * (C) 2022 by sysmocom s.f.m.c. GmbH <info@sysmocom.de> |
| * All Rights Reserved |
| * |
| * Author: Eric Wild <ewild@sysmocom.de> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU Affero General Public License as published by |
| * the Free Software Foundation; either version 3 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU Affero General Public License for more details. |
| * |
| * You should have received a copy of the GNU Affero General Public License |
| * along with this program. If not, see <http://www.gnu.org/licenses/>. |
| * |
| */ |
| |
| #include <atomic> |
| |
| #include <condition_variable> |
| #include <mutex> |
| #include <sys/eventfd.h> |
| #include <unistd.h> |
| |
| namespace spsc_detail |
| { |
| template <bool block_read, bool block_write> |
| class spsc_cond_timeout_detail { |
| std::condition_variable cond_r, cond_w; |
| std::mutex lr, lw; |
| std::atomic_int r_flag, w_flag; |
| const int timeout_ms = 200; |
| |
| public: |
| explicit spsc_cond_timeout_detail() : r_flag(0), w_flag(0) |
| { |
| } |
| |
| ~spsc_cond_timeout_detail() |
| { |
| } |
| |
| ssize_t spsc_check_r() |
| { |
| std::unique_lock<std::mutex> lk(lr); |
| if (cond_r.wait_for(lk, std::chrono::milliseconds(timeout_ms), [&] { return r_flag != 0; })) { |
| r_flag--; |
| return 1; |
| } else { |
| return 0; |
| } |
| } |
| ssize_t spsc_check_w() |
| { |
| std::unique_lock<std::mutex> lk(lw); |
| if (cond_w.wait_for(lk, std::chrono::milliseconds(timeout_ms), [&] { return w_flag != 0; })) { |
| w_flag--; |
| return 1; |
| } else { |
| return 0; |
| } |
| } |
| void spsc_notify_r() |
| { |
| std::unique_lock<std::mutex> lk(lr); |
| r_flag++; |
| cond_r.notify_one(); |
| } |
| void spsc_notify_w() |
| { |
| std::unique_lock<std::mutex> lk(lw); |
| w_flag++; |
| cond_w.notify_one(); |
| } |
| }; |
| |
| template <bool block_read, bool block_write> |
| class spsc_cond_detail { |
| std::condition_variable cond_r, cond_w; |
| std::mutex lr, lw; |
| std::atomic_int r_flag, w_flag; |
| |
| public: |
| explicit spsc_cond_detail() : r_flag(0), w_flag(0) |
| { |
| } |
| |
| ~spsc_cond_detail() |
| { |
| } |
| |
| ssize_t spsc_check_r() |
| { |
| std::unique_lock<std::mutex> lk(lr); |
| while (r_flag == 0) |
| cond_r.wait(lk); |
| r_flag--; |
| return 1; |
| } |
| ssize_t spsc_check_w() |
| { |
| std::unique_lock<std::mutex> lk(lw); |
| while (w_flag == 0) |
| cond_w.wait(lk); |
| w_flag--; |
| return 1; |
| } |
| void spsc_notify_r() |
| { |
| std::unique_lock<std::mutex> lk(lr); |
| r_flag++; |
| cond_r.notify_one(); |
| } |
| void spsc_notify_w() |
| { |
| std::unique_lock<std::mutex> lk(lw); |
| w_flag++; |
| cond_w.notify_one(); |
| } |
| }; |
| |
| // originally designed for select loop integration |
| template <bool block_read, bool block_write> |
| class spsc_efd_detail { |
| int efd_r, efd_w; /* eventfds used to block/notify readers/writers */ |
| |
| public: |
| explicit spsc_efd_detail() |
| : efd_r(eventfd(0, block_read ? 0 : EFD_NONBLOCK)), efd_w(eventfd(1, block_write ? 0 : EFD_NONBLOCK)) |
| { |
| } |
| |
| ~spsc_efd_detail() |
| { |
| close(efd_r); |
| close(efd_w); |
| } |
| |
| ssize_t spsc_check_r() |
| { |
| uint64_t efdr; |
| return read(efd_r, &efdr, sizeof(uint64_t)); |
| } |
| ssize_t spsc_check_w() |
| { |
| uint64_t efdr; |
| return read(efd_w, &efdr, sizeof(uint64_t)); |
| } |
| void spsc_notify_r() |
| { |
| uint64_t efdu = 1; |
| write(efd_r, &efdu, sizeof(uint64_t)); |
| } |
| void spsc_notify_w() |
| { |
| uint64_t efdu = 1; |
| write(efd_w, &efdu, sizeof(uint64_t)); |
| } |
| int get_r_efd() |
| { |
| return efd_r; |
| } |
| int get_w_efd() |
| { |
| return efd_w; |
| } |
| }; |
| |
| template <unsigned int SZ, typename ELEM, bool block_read, bool block_write, template <bool, bool> class T> |
| class spsc : public T<block_read, block_write> { |
| static_assert(SZ > 0, "queues need a size..."); |
| std::atomic<unsigned int> readptr; |
| std::atomic<unsigned int> writeptr; |
| |
| ELEM buf[SZ]; |
| |
| public: |
| using base_t = T<block_read, block_write>; |
| using elem_t = ELEM; |
| explicit spsc() : readptr(0), writeptr(0) |
| { |
| } |
| |
| ~spsc() |
| { |
| } |
| |
| /*! Adds element to the queue by copying the data. |
| * \param[in] elem input buffer, must match the originally configured queue buffer size!. |
| * \returns true if queue was not full and element was successfully pushed */ |
| bool spsc_push(const ELEM *elem) |
| { |
| size_t cur_wp, cur_rp; |
| cur_wp = writeptr.load(std::memory_order_relaxed); |
| cur_rp = readptr.load(std::memory_order_acquire); |
| if ((cur_wp + 1) % SZ == cur_rp) { |
| if (block_write) |
| base_t::spsc_check_w(); /* blocks, ensures next (!) call succeeds */ |
| return false; |
| } |
| buf[cur_wp] = *elem; |
| writeptr.store((cur_wp + 1) % SZ, std::memory_order_release); |
| if (block_read) |
| base_t::spsc_notify_r(); /* fine after release */ |
| return true; |
| } |
| |
| /*! Removes element from the queue by copying the data. |
| * \param[in] elem output buffer, must match the originally configured queue buffer size!. |
| * \returns true if queue was not empty and element was successfully removed */ |
| bool spsc_pop(ELEM *elem) |
| { |
| size_t cur_wp, cur_rp; |
| cur_wp = writeptr.load(std::memory_order_acquire); |
| cur_rp = readptr.load(std::memory_order_relaxed); |
| |
| if (cur_wp == cur_rp) /* blocks via prep_pop */ |
| return false; |
| |
| *elem = buf[cur_rp]; |
| readptr.store((cur_rp + 1) % SZ, std::memory_order_release); |
| if (block_write) |
| base_t::spsc_notify_w(); |
| return true; |
| } |
| |
| /*! Reads the read-fd of the queue, which, depending on settings passed on queue creation, blocks. |
| * This function can be used to deliberately wait for a non-empty queue on the read side. |
| * \returns result of reading the fd. */ |
| ssize_t spsc_prep_pop() |
| { |
| return base_t::spsc_check_r(); |
| } |
| }; |
| |
| } // namespace spsc_detail |
| |
| template <unsigned int SZ, typename ELEM, bool block_read, bool block_write> |
| class spsc_evfd : public spsc_detail::spsc<SZ, ELEM, block_read, block_write, spsc_detail::spsc_efd_detail> {}; |
| template <unsigned int SZ, typename ELEM, bool block_read, bool block_write> |
| class spsc_cond : public spsc_detail::spsc<SZ, ELEM, block_read, block_write, spsc_detail::spsc_cond_detail> {}; |
| template <unsigned int SZ, typename ELEM, bool block_read, bool block_write> |
| class spsc_cond_timeout |
| : public spsc_detail::spsc<SZ, ELEM, block_read, block_write, spsc_detail::spsc_cond_timeout_detail> {}; |