Merging r4130, r4131, r4135: Linux AIO related fixes: *) Fixing Linux AIO syscalls return value handling: syscall(2) uses usual libc convention, it returns -1 on error and sets errno. Obsolete _syscall(2) returns negative value of error. *) Fixing Linux AIO initiatialization: AIO operations are disabled if kernel does not support them. Previously worker just exited. *) The "worker_aio_requests" directive. The default value is 32 AIO simultaneous requests per worker. Previously they were hardcoded to 1024, and it was too large, since Linux allocated them early on io_setup(), but not on request itself. So with default value of /proc/sys/fs/aio-max-nr equal to 65536 only 64 worker processes could be run simultaneously. 32 AIO requests are enough for modern disks even if server runs only 1 worker.

/*
 * Copyright (C) Igor Sysoev
 */


#ifndef _NGX_SHMEM_H_INCLUDED_
#define _NGX_SHMEM_H_INCLUDED_


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


typedef struct {
    u_char      *addr;
    size_t       size;
    ngx_str_t    name;
    HANDLE       handle;
    ngx_log_t   *log;
    ngx_uint_t   exists;   /* unsigned  exists:1;  */
} ngx_shm_t;


ngx_int_t ngx_shm_alloc(ngx_shm_t *shm);
void ngx_shm_free(ngx_shm_t *shm);


#endif /* _NGX_SHMEM_H_INCLUDED_ */