Mercurial > hg > nginx
view src/core/ngx_murmurhash.c @ 6080:4296627f385a stable-1.6
Core: fixed a race resulting in extra sem_post()'s.
The mtx->wait counter was not decremented if we were able to obtain the lock
right after incrementing it. This resulted in unneeded sem_post() calls,
eventually leading to EOVERFLOW errors being logged, "sem_post() failed
while wake shmtx (75: Value too large for defined data type)".
To close the race, mtx->wait is now decremented if we obtain the lock right
after incrementing it in ngx_shmtx_lock(). The result can become -1 if a
concurrent ngx_shmtx_unlock() decrements mtx->wait before the added code does.
However, that only leads to one extra iteration in the next call of
ngx_shmtx_lock().
author | Roman Arutyunyan <arut@nginx.com> |
---|---|
date | Wed, 04 Feb 2015 16:22:43 +0300 |
parents | 203eb026ec07 |
children | f38647c651a8 |
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/* * Copyright (C) Austin Appleby */ #include <ngx_config.h> #include <ngx_core.h> uint32_t ngx_murmur_hash2(u_char *data, size_t len) { uint32_t h, k; h = 0 ^ len; while (len >= 4) { k = data[0]; k |= data[1] << 8; k |= data[2] << 16; k |= data[3] << 24; k *= 0x5bd1e995; k ^= k >> 24; k *= 0x5bd1e995; h *= 0x5bd1e995; h ^= k; data += 4; len -= 4; } switch (len) { case 3: h ^= data[2] << 16; case 2: h ^= data[1] << 8; case 1: h ^= data[0]; h *= 0x5bd1e995; } h ^= h >> 13; h *= 0x5bd1e995; h ^= h >> 15; return h; }