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| author | Ivan Zhakov <ivan@apache.org> | 2019-10-16 10:10:59 +0000 |
|---|---|---|
| committer | Ivan Zhakov <ivan@apache.org> | 2019-10-16 10:10:59 +0000 |
| commit | 6e4f7ae03f61ef72066e573c6449d649dc32c4fd (patch) | |
| tree | a4dfb1adf5d08684a0b7058835dae8895f0fd690 /atomic | |
| parent | 90eb72a36774f501c0f7349d41bb8ca41d546e7e (diff) | |
| download | apr-6e4f7ae03f61ef72066e573c6449d649dc32c4fd.tar.gz | |
* atomic/win32/apr_atomic64.c
(apr_atomic_read64): Use direct memory read when compiled for x86_x64, since
64-bit reads are atomic in 64-bit Windows [1].
Suggested by: Yann Ylavic
[1] https://docs.microsoft.com/en-us/windows/win32/sync/interlocked-variable-access
git-svn-id: https://svn.apache.org/repos/asf/apr/apr/trunk@1868502 13f79535-47bb-0310-9956-ffa450edef68
Diffstat (limited to 'atomic')
| -rw-r--r-- | atomic/win32/apr_atomic64.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/atomic/win32/apr_atomic64.c b/atomic/win32/apr_atomic64.c index ca1f5e0ec..372003aaa 100644 --- a/atomic/win32/apr_atomic64.c +++ b/atomic/win32/apr_atomic64.c @@ -51,9 +51,16 @@ APR_DECLARE(void) apr_atomic_set64(volatile apr_uint64_t *mem, apr_uint64_t val) APR_DECLARE(apr_uint64_t) apr_atomic_read64(volatile apr_uint64_t *mem) { +#if defined(_M_X64) + /* https://docs.microsoft.com/en-us/windows/win32/sync/interlocked-variable-access + * "Simple reads and writes to properly aligned 64-bit variables are atomic + * on 64-bit Windows."*/ + return *mem; +#else /* 64-bit read is not atomic on 32-bit platform: use InterlockedCompareExchange to perform atomic read. */ return InterlockedCompareExchange64((volatile LONG64 *)mem, 0, 0); +#endif } APR_DECLARE(apr_uint64_t) apr_atomic_cas64(volatile apr_uint64_t *mem, apr_uint64_t with, |