Christopher Faulet | 1a2b56e | 2017-10-12 16:09:09 +0200 | [diff] [blame] | 1 | /* |
| 2 | * functions about threads. |
| 3 | * |
| 4 | * Copyright (C) 2017 Christopher Fauet - cfaulet@haproxy.com |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or |
| 7 | * modify it under the terms of the GNU General Public License |
| 8 | * as published by the Free Software Foundation; either version |
| 9 | * 2 of the License, or (at your option) any later version. |
| 10 | * |
| 11 | */ |
| 12 | |
Christopher Faulet | 339fff8 | 2017-10-19 11:59:15 +0200 | [diff] [blame] | 13 | #include <unistd.h> |
| 14 | #include <fcntl.h> |
| 15 | |
Willy Tarreau | 0493149 | 2017-11-03 23:39:25 +0100 | [diff] [blame] | 16 | #include <common/cfgparse.h> |
Christopher Faulet | 1a2b56e | 2017-10-12 16:09:09 +0200 | [diff] [blame] | 17 | #include <common/hathreads.h> |
Christopher Faulet | 339fff8 | 2017-10-19 11:59:15 +0200 | [diff] [blame] | 18 | #include <common/standard.h> |
| 19 | #include <proto/fd.h> |
Christopher Faulet | 1a2b56e | 2017-10-12 16:09:09 +0200 | [diff] [blame] | 20 | |
Christopher Faulet | e9a896e | 2017-11-14 10:16:04 +0100 | [diff] [blame] | 21 | THREAD_LOCAL unsigned int tid = 0; |
| 22 | THREAD_LOCAL unsigned long tid_bit = (1UL << 0); |
Christopher Faulet | 1a2b56e | 2017-10-12 16:09:09 +0200 | [diff] [blame] | 23 | |
Willy Tarreau | e96e61c | 2018-03-29 18:54:33 +0200 | [diff] [blame] | 24 | /* Dummy I/O handler used by the sync pipe.*/ |
| 25 | void thread_sync_io_handler(int fd) |
| 26 | { |
| 27 | } |
| 28 | |
Christopher Faulet | 1a2b56e | 2017-10-12 16:09:09 +0200 | [diff] [blame] | 29 | #ifdef USE_THREAD |
| 30 | |
Christopher Faulet | 339fff8 | 2017-10-19 11:59:15 +0200 | [diff] [blame] | 31 | static HA_SPINLOCK_T sync_lock; |
| 32 | static int threads_sync_pipe[2]; |
| 33 | static unsigned long threads_want_sync = 0; |
Christopher Faulet | ddb6c16 | 2018-07-20 09:31:53 +0200 | [diff] [blame] | 34 | volatile unsigned long all_threads_mask = 0; |
Christopher Faulet | 339fff8 | 2017-10-19 11:59:15 +0200 | [diff] [blame] | 35 | |
Christopher Faulet | 1a2b56e | 2017-10-12 16:09:09 +0200 | [diff] [blame] | 36 | #if defined(DEBUG_THREAD) || defined(DEBUG_FULL) |
| 37 | struct lock_stat lock_stats[LOCK_LABELS]; |
| 38 | #endif |
| 39 | |
Christopher Faulet | 339fff8 | 2017-10-19 11:59:15 +0200 | [diff] [blame] | 40 | /* Initializes the sync point. It creates a pipe used by threads to wakup all |
| 41 | * others when a sync is requested. It also initialize the mask of all create |
| 42 | * threads. It returns 0 on success and -1 if an error occurred. |
| 43 | */ |
| 44 | int thread_sync_init(unsigned long mask) |
| 45 | { |
| 46 | int rfd; |
| 47 | |
| 48 | if (pipe(threads_sync_pipe) < 0) |
| 49 | return -1; |
| 50 | |
| 51 | rfd = threads_sync_pipe[0]; |
| 52 | fcntl(rfd, F_SETFL, O_NONBLOCK); |
Willy Tarreau | a9786b6 | 2018-01-25 07:22:13 +0100 | [diff] [blame] | 53 | fd_insert(rfd, thread_sync_io_handler, thread_sync_io_handler, MAX_THREADS_MASK); |
Christopher Faulet | 339fff8 | 2017-10-19 11:59:15 +0200 | [diff] [blame] | 54 | |
| 55 | all_threads_mask = mask; |
| 56 | return 0; |
| 57 | } |
| 58 | |
| 59 | /* Enables the sync point. */ |
| 60 | void thread_sync_enable(void) |
| 61 | { |
| 62 | fd_want_recv(threads_sync_pipe[0]); |
| 63 | } |
| 64 | |
| 65 | /* Called when a thread want to pass into the sync point. It subscribes the |
| 66 | * current thread in threads waiting for sync by update a bit-field. It this is |
| 67 | * the first one, it wakeup all other threads by writing on the sync pipe. |
| 68 | */ |
| 69 | void thread_want_sync() |
| 70 | { |
| 71 | if (all_threads_mask) { |
Christopher Faulet | 81991d3 | 2017-12-02 09:53:24 +0100 | [diff] [blame] | 72 | if (threads_want_sync & tid_bit) |
| 73 | return; |
Christopher Faulet | 339fff8 | 2017-10-19 11:59:15 +0200 | [diff] [blame] | 74 | if (HA_ATOMIC_OR(&threads_want_sync, tid_bit) == tid_bit) |
| 75 | shut_your_big_mouth_gcc(write(threads_sync_pipe[1], "S", 1)); |
| 76 | } |
| 77 | else { |
| 78 | threads_want_sync = 1; |
| 79 | } |
| 80 | } |
| 81 | |
| 82 | /* Returns 1 if no thread has requested a sync. Otherwise, it returns 0. */ |
| 83 | int thread_no_sync() |
| 84 | { |
Christopher Faulet | 148b16e | 2018-05-02 16:58:40 +0200 | [diff] [blame] | 85 | return (threads_want_sync == 0UL); |
Christopher Faulet | 339fff8 | 2017-10-19 11:59:15 +0200 | [diff] [blame] | 86 | } |
| 87 | |
| 88 | /* Returns 1 if the current thread has requested a sync. Otherwise, it returns |
| 89 | * 0. |
| 90 | */ |
| 91 | int thread_need_sync() |
| 92 | { |
Christopher Faulet | 148b16e | 2018-05-02 16:58:40 +0200 | [diff] [blame] | 93 | return ((threads_want_sync & tid_bit) != 0UL); |
Christopher Faulet | 339fff8 | 2017-10-19 11:59:15 +0200 | [diff] [blame] | 94 | } |
| 95 | |
| 96 | /* Thread barrier. Synchronizes all threads at the barrier referenced by |
| 97 | * <barrier>. The calling thread shall block until all other threads have called |
| 98 | * thread_sync_barrier specifying the same barrier. |
| 99 | * |
| 100 | * If you need to use several barriers at differnt points, you need to use a |
| 101 | * different <barrier> for each point. |
| 102 | */ |
| 103 | static inline void thread_sync_barrier(volatile unsigned long *barrier) |
| 104 | { |
| 105 | unsigned long old = all_threads_mask; |
| 106 | |
| 107 | HA_ATOMIC_CAS(barrier, &old, 0); |
Christopher Faulet | 209d02a | 2017-10-27 23:01:38 +0200 | [diff] [blame] | 108 | HA_ATOMIC_OR(barrier, tid_bit); |
Willy Tarreau | 3ea2490 | 2018-07-27 07:47:24 +0200 | [diff] [blame^] | 109 | |
| 110 | /* Note below: we need to wait for all threads to join here, but in |
| 111 | * case several threads are scheduled on the same CPU, busy polling |
| 112 | * will instead degrade the performance, forcing other threads to |
| 113 | * wait longer (typically in epoll_wait()). Let's use sched_yield() |
| 114 | * when available instead. |
| 115 | */ |
| 116 | while ((*barrier & all_threads_mask) != all_threads_mask) { |
| 117 | #if _POSIX_PRIORITY_SCHEDULING |
| 118 | sched_yield(); |
| 119 | #else |
Christopher Faulet | 339fff8 | 2017-10-19 11:59:15 +0200 | [diff] [blame] | 120 | pl_cpu_relax(); |
Willy Tarreau | 3ea2490 | 2018-07-27 07:47:24 +0200 | [diff] [blame^] | 121 | #endif |
| 122 | } |
Christopher Faulet | 339fff8 | 2017-10-19 11:59:15 +0200 | [diff] [blame] | 123 | } |
| 124 | |
| 125 | /* Enter into the sync point and lock it if the current thread has requested a |
| 126 | * sync. */ |
| 127 | void thread_enter_sync() |
| 128 | { |
| 129 | static volatile unsigned long barrier = 0; |
| 130 | |
| 131 | if (!all_threads_mask) |
| 132 | return; |
| 133 | |
| 134 | thread_sync_barrier(&barrier); |
| 135 | if (threads_want_sync & tid_bit) |
Christopher Faulet | 2a944ee | 2017-11-07 10:42:54 +0100 | [diff] [blame] | 136 | HA_SPIN_LOCK(THREAD_SYNC_LOCK, &sync_lock); |
Christopher Faulet | 339fff8 | 2017-10-19 11:59:15 +0200 | [diff] [blame] | 137 | } |
| 138 | |
| 139 | /* Exit from the sync point and unlock it if it was previously locked. If the |
| 140 | * current thread is the last one to have requested a sync, the sync pipe is |
| 141 | * flushed. |
| 142 | */ |
| 143 | void thread_exit_sync() |
| 144 | { |
| 145 | static volatile unsigned long barrier = 0; |
| 146 | |
| 147 | if (!all_threads_mask) |
| 148 | return; |
| 149 | |
| 150 | if (threads_want_sync & tid_bit) |
Christopher Faulet | 2a944ee | 2017-11-07 10:42:54 +0100 | [diff] [blame] | 151 | HA_SPIN_UNLOCK(THREAD_SYNC_LOCK, &sync_lock); |
Christopher Faulet | 339fff8 | 2017-10-19 11:59:15 +0200 | [diff] [blame] | 152 | |
| 153 | if (HA_ATOMIC_AND(&threads_want_sync, ~tid_bit) == 0) { |
| 154 | char c; |
| 155 | |
| 156 | shut_your_big_mouth_gcc(read(threads_sync_pipe[0], &c, 1)); |
| 157 | fd_done_recv(threads_sync_pipe[0]); |
| 158 | } |
| 159 | |
| 160 | thread_sync_barrier(&barrier); |
| 161 | } |
| 162 | |
| 163 | |
Christopher Faulet | 1a2b56e | 2017-10-12 16:09:09 +0200 | [diff] [blame] | 164 | __attribute__((constructor)) |
| 165 | static void __hathreads_init(void) |
| 166 | { |
Christopher Faulet | 2a944ee | 2017-11-07 10:42:54 +0100 | [diff] [blame] | 167 | HA_SPIN_INIT(&sync_lock); |
Christopher Faulet | 1a2b56e | 2017-10-12 16:09:09 +0200 | [diff] [blame] | 168 | #if defined(DEBUG_THREAD) || defined(DEBUG_FULL) |
| 169 | memset(lock_stats, 0, sizeof(lock_stats)); |
| 170 | #endif |
Willy Tarreau | 6dbd3e9 | 2017-11-05 11:50:18 +0100 | [diff] [blame] | 171 | hap_register_build_opts("Built with multi-threading support.", 0); |
Christopher Faulet | 1a2b56e | 2017-10-12 16:09:09 +0200 | [diff] [blame] | 172 | } |
| 173 | |
| 174 | #endif |