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view src/os/unix/ngx_atomic.h @ 6536:f7849bfb6d21

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Improved EPOLLRDHUP handling. When it's known that the kernel supports EPOLLRDHUP, there is no need in additional recv() call to get EOF or error when the flag is absent in the event generated by the kernel. A special runtime test is done at startup to detect if EPOLLRDHUP is actually supported by the kernel because epoll_ctl() silently ignores unknown flags. With this knowledge it's now possible to drop the "ready" flag for partial read. Previously, the "ready" flag was kept until the recv() returned EOF or error. In particular, this change allows the lingering close heuristics (which relies on the "ready" flag state) to actually work on Linux, and not wait for more data in most cases. The "available" flag is now used in the read event with the semantics similar to the corresponding counter in kqueue.
author Valentin Bartenev <vbart@nginx.com>
date Fri, 13 May 2016 17:19:23 +0300
parents 2cd019520210
children 09d15a2dbc6b
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_ */