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view src/os/unix/ngx_atomic.h @ 5992:174512857ccf

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Cache: do not inherit last_modified and etag from stale response. When replacing a stale cache entry, its last_modified and etag could be inherited from the old entry if the response code is not 200 or 206. Moreover, etag could be inherited with any response code if it's missing in the new response. As a result, the cache entry is left with invalid last_modified or etag which could lead to broken revalidation. For example, when a file is deleted from backend, its last_modified is copied to the new 404 cache entry and is used later for revalidation. Once the old file appears again with its original timestamp, revalidation succeeds and the cached 404 response is sent to client instead of the file. The problem appeared with etags in 44b9ab7752e3 (1.7.3) and affected last_modified in 1573fc7875fa (1.7.9).
author Roman Arutyunyan <arut@nginx.com>
date Mon, 02 Mar 2015 19:47:13 +0300
parents 4c36e15651f7
children 2cd019520210
line wrap: on
line source


/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#ifndef _NGX_ATOMIC_H_INCLUDED_
#define _NGX_ATOMIC_H_INCLUDED_


#include <ngx_config.h>
#include <ngx_core.h>


#if (NGX_HAVE_LIBATOMIC)

#define AO_REQUIRE_CAS
#include <atomic_ops.h>

#define NGX_HAVE_ATOMIC_OPS  1

typedef long                        ngx_atomic_int_t;
typedef AO_t                        ngx_atomic_uint_t;
typedef volatile ngx_atomic_uint_t  ngx_atomic_t;

#if (NGX_PTR_SIZE == 8)
#define NGX_ATOMIC_T_LEN            (sizeof("-9223372036854775808") - 1)
#else
#define NGX_ATOMIC_T_LEN            (sizeof("-2147483648") - 1)
#endif

#define ngx_atomic_cmp_set(lock, old, new)                                    \
    AO_compare_and_swap(lock, old, new)
#define ngx_atomic_fetch_add(value, add)                                      \
    AO_fetch_and_add(value, add)
#define ngx_memory_barrier()        AO_nop()
#define ngx_cpu_pause()


#elif (NGX_DARWIN_ATOMIC)

/*
 * use Darwin 8 atomic(3) and barrier(3) operations
 * optimized at run-time for UP and SMP
 */

#include <libkern/OSAtomic.h>

/* "bool" conflicts with perl's CORE/handy.h */
#if 0
#undef bool
#endif


#define NGX_HAVE_ATOMIC_OPS  1

#if (NGX_PTR_SIZE == 8)

typedef int64_t                     ngx_atomic_int_t;
typedef uint64_t                    ngx_atomic_uint_t;
#define NGX_ATOMIC_T_LEN            (sizeof("-9223372036854775808") - 1)

#define ngx_atomic_cmp_set(lock, old, new)                                    \
    OSAtomicCompareAndSwap64Barrier(old, new, (int64_t *) lock)

#define ngx_atomic_fetch_add(value, add)                                      \
    (OSAtomicAdd64(add, (int64_t *) value) - add)

#else

typedef int32_t                     ngx_atomic_int_t;
typedef uint32_t                    ngx_atomic_uint_t;
#define NGX_ATOMIC_T_LEN            (sizeof("-2147483648") - 1)

#define ngx_atomic_cmp_set(lock, old, new)                                    \
    OSAtomicCompareAndSwap32Barrier(old, new, (int32_t *) lock)

#define ngx_atomic_fetch_add(value, add)                                      \
    (OSAtomicAdd32(add, (int32_t *) value) - add)

#endif

#define ngx_memory_barrier()        OSMemoryBarrier()

#define ngx_cpu_pause()

typedef volatile ngx_atomic_uint_t  ngx_atomic_t;


#elif (NGX_HAVE_GCC_ATOMIC)

/* GCC 4.1 builtin atomic operations */

#define NGX_HAVE_ATOMIC_OPS  1

typedef long                        ngx_atomic_int_t;
typedef unsigned long               ngx_atomic_uint_t;

#if (NGX_PTR_SIZE == 8)
#define NGX_ATOMIC_T_LEN            (sizeof("-9223372036854775808") - 1)
#else
#define NGX_ATOMIC_T_LEN            (sizeof("-2147483648") - 1)
#endif

typedef volatile ngx_atomic_uint_t  ngx_atomic_t;


#define ngx_atomic_cmp_set(lock, old, set)                                    \
    __sync_bool_compare_and_swap(lock, old, set)

#define ngx_atomic_fetch_add(value, add)                                      \
    __sync_fetch_and_add(value, add)

#define ngx_memory_barrier()        __sync_synchronize()

#if ( __i386__ || __i386 || __amd64__ || __amd64 )
#define ngx_cpu_pause()             __asm__ ("pause")
#else
#define ngx_cpu_pause()
#endif


#elif ( __i386__ || __i386 )

typedef int32_t                     ngx_atomic_int_t;
typedef uint32_t                    ngx_atomic_uint_t;
typedef volatile ngx_atomic_uint_t  ngx_atomic_t;
#define NGX_ATOMIC_T_LEN            (sizeof("-2147483648") - 1)


#if ( __SUNPRO_C )

#define NGX_HAVE_ATOMIC_OPS  1

ngx_atomic_uint_t
ngx_atomic_cmp_set(ngx_atomic_t *lock, ngx_atomic_uint_t old,
    ngx_atomic_uint_t set);

ngx_atomic_int_t
ngx_atomic_fetch_add(ngx_atomic_t *value, ngx_atomic_int_t add);

/*
 * Sun Studio 12 exits with segmentation fault on '__asm ("pause")',
 * so ngx_cpu_pause is declared in src/os/unix/ngx_sunpro_x86.il
 */

void
ngx_cpu_pause(void);

/* the code in src/os/unix/ngx_sunpro_x86.il */

#define ngx_memory_barrier()        __asm (".volatile"); __asm (".nonvolatile")


#else /* ( __GNUC__ || __INTEL_COMPILER ) */

#define NGX_HAVE_ATOMIC_OPS  1

#include "ngx_gcc_atomic_x86.h"

#endif


#elif ( __amd64__ || __amd64 )

typedef int64_t                     ngx_atomic_int_t;
typedef uint64_t                    ngx_atomic_uint_t;
typedef volatile ngx_atomic_uint_t  ngx_atomic_t;
#define NGX_ATOMIC_T_LEN            (sizeof("-9223372036854775808") - 1)


#if ( __SUNPRO_C )

#define NGX_HAVE_ATOMIC_OPS  1

ngx_atomic_uint_t
ngx_atomic_cmp_set(ngx_atomic_t *lock, ngx_atomic_uint_t old,
    ngx_atomic_uint_t set);

ngx_atomic_int_t
ngx_atomic_fetch_add(ngx_atomic_t *value, ngx_atomic_int_t add);

/*
 * Sun Studio 12 exits with segmentation fault on '__asm ("pause")',
 * so ngx_cpu_pause is declared in src/os/unix/ngx_sunpro_amd64.il
 */

void
ngx_cpu_pause(void);

/* the code in src/os/unix/ngx_sunpro_amd64.il */

#define ngx_memory_barrier()        __asm (".volatile"); __asm (".nonvolatile")


#else /* ( __GNUC__ || __INTEL_COMPILER ) */

#define NGX_HAVE_ATOMIC_OPS  1

#include "ngx_gcc_atomic_amd64.h"

#endif


#elif ( __sparc__ || __sparc || __sparcv9 )

#if (NGX_PTR_SIZE == 8)

typedef int64_t                     ngx_atomic_int_t;
typedef uint64_t                    ngx_atomic_uint_t;
#define NGX_ATOMIC_T_LEN            (sizeof("-9223372036854775808") - 1)

#else

typedef int32_t                     ngx_atomic_int_t;
typedef uint32_t                    ngx_atomic_uint_t;
#define NGX_ATOMIC_T_LEN            (sizeof("-2147483648") - 1)

#endif

typedef volatile ngx_atomic_uint_t  ngx_atomic_t;


#if ( __SUNPRO_C )

#define NGX_HAVE_ATOMIC_OPS  1

#include "ngx_sunpro_atomic_sparc64.h"


#else /* ( __GNUC__ || __INTEL_COMPILER ) */

#define NGX_HAVE_ATOMIC_OPS  1

#include "ngx_gcc_atomic_sparc64.h"

#endif


#elif ( __powerpc__ || __POWERPC__ )

#define NGX_HAVE_ATOMIC_OPS  1

#if (NGX_PTR_SIZE == 8)

typedef int64_t                     ngx_atomic_int_t;
typedef uint64_t                    ngx_atomic_uint_t;
#define NGX_ATOMIC_T_LEN            (sizeof("-9223372036854775808") - 1)

#else

typedef int32_t                     ngx_atomic_int_t;
typedef uint32_t                    ngx_atomic_uint_t;
#define NGX_ATOMIC_T_LEN            (sizeof("-2147483648") - 1)

#endif

typedef volatile ngx_atomic_uint_t  ngx_atomic_t;


#include "ngx_gcc_atomic_ppc.h"

#endif


#if !(NGX_HAVE_ATOMIC_OPS)

#define NGX_HAVE_ATOMIC_OPS  0

typedef int32_t                     ngx_atomic_int_t;
typedef uint32_t                    ngx_atomic_uint_t;
typedef volatile ngx_atomic_uint_t  ngx_atomic_t;
#define NGX_ATOMIC_T_LEN            (sizeof("-2147483648") - 1)


static ngx_inline ngx_atomic_uint_t
ngx_atomic_cmp_set(ngx_atomic_t *lock, ngx_atomic_uint_t old,
     ngx_atomic_uint_t set)
{
     if (*lock == old) {
         *lock = set;
         return 1;
     }

     return 0;
}


static ngx_inline ngx_atomic_int_t
ngx_atomic_fetch_add(ngx_atomic_t *value, ngx_atomic_int_t add)
{
     ngx_atomic_int_t  old;

     old = *value;
     *value += add;

     return old;
}

#define ngx_memory_barrier()
#define ngx_cpu_pause()

#endif


void ngx_spinlock(ngx_atomic_t *lock, ngx_atomic_int_t value, ngx_uint_t spin);

#define ngx_trylock(lock)  (*(lock) == 0 && ngx_atomic_cmp_set(lock, 0, 1))
#define ngx_unlock(lock)    *(lock) = 0


#endif /* _NGX_ATOMIC_H_INCLUDED_ */