Mercurial > hg > nginx-quic
view src/core/ngx_rwlock.c @ 8394:e2e9e0fae747
Configure: fixed --test-build-epoll on FreeBSD 13.
In FreeBSD 13, eventfd(2) was added, and this breaks build
with --test-build-epoll and without --with-file-aio. Fix is
to move eventfd(2) detection to auto/os/linux, as it is used
only on Linux as a notification mechanism for epoll().
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Mon, 05 Apr 2021 20:14:16 +0300 |
parents | d1816a2696de |
children | 7752d8523066 |
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/* * Copyright (C) Ruslan Ermilov * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #if (NGX_HAVE_ATOMIC_OPS) #define NGX_RWLOCK_SPIN 2048 #define NGX_RWLOCK_WLOCK ((ngx_atomic_uint_t) -1) void ngx_rwlock_wlock(ngx_atomic_t *lock) { ngx_uint_t i, n; for ( ;; ) { if (*lock == 0 && ngx_atomic_cmp_set(lock, 0, NGX_RWLOCK_WLOCK)) { return; } if (ngx_ncpu > 1) { for (n = 1; n < NGX_RWLOCK_SPIN; n <<= 1) { for (i = 0; i < n; i++) { ngx_cpu_pause(); } if (*lock == 0 && ngx_atomic_cmp_set(lock, 0, NGX_RWLOCK_WLOCK)) { return; } } } ngx_sched_yield(); } } void ngx_rwlock_rlock(ngx_atomic_t *lock) { ngx_uint_t i, n; ngx_atomic_uint_t readers; for ( ;; ) { readers = *lock; if (readers != NGX_RWLOCK_WLOCK && ngx_atomic_cmp_set(lock, readers, readers + 1)) { return; } if (ngx_ncpu > 1) { for (n = 1; n < NGX_RWLOCK_SPIN; n <<= 1) { for (i = 0; i < n; i++) { ngx_cpu_pause(); } readers = *lock; if (readers != NGX_RWLOCK_WLOCK && ngx_atomic_cmp_set(lock, readers, readers + 1)) { return; } } } ngx_sched_yield(); } } void ngx_rwlock_unlock(ngx_atomic_t *lock) { ngx_atomic_uint_t readers; readers = *lock; if (readers == NGX_RWLOCK_WLOCK) { (void) ngx_atomic_cmp_set(lock, NGX_RWLOCK_WLOCK, 0); return; } for ( ;; ) { if (ngx_atomic_cmp_set(lock, readers, readers - 1)) { return; } readers = *lock; } } void ngx_rwlock_downgrade(ngx_atomic_t *lock) { if (*lock == NGX_RWLOCK_WLOCK) { *lock = 1; } } #else #if (NGX_HTTP_UPSTREAM_ZONE || NGX_STREAM_UPSTREAM_ZONE) #error ngx_atomic_cmp_set() is not defined! #endif #endif