lock.h

开源备份软件源码 AMANDA, the Advanced Maryland Automatic Network Disk Archiver, is a backup system that a

    if (thread_in_use () && rw_rdlock (&NAME) != 0) abort ()
# define gl_rwlock_wrlock(NAME) \
    if (thread_in_use () && rw_wrlock (&NAME) != 0) abort ()
# define gl_rwlock_unlock(NAME) \
    if (thread_in_use () && rw_unlock (&NAME) != 0) abort ()
# define gl_rwlock_destroy(NAME) \
    if (thread_in_use () && rwlock_destroy (&NAME) != 0) abort ()

/* --------------------- gl_recursive_lock_t datatype --------------------- */

/* Old Solaris threads did not have recursive locks.
   We have to implement them ourselves.  */

typedef struct
        {
          mutex_t mutex;
          thread_t owner;
          unsigned long depth;
        }
        gl_recursive_lock_t;
# define gl_recursive_lock_define(STORAGECLASS, NAME) \
    STORAGECLASS gl_recursive_lock_t NAME;
# define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
    STORAGECLASS gl_recursive_lock_t NAME = gl_recursive_lock_initializer;
# define gl_recursive_lock_initializer \
    { DEFAULTMUTEX, (thread_t) 0, 0 }
# define gl_recursive_lock_init(NAME) \
    if (thread_in_use ()) glthread_recursive_lock_init (&NAME)
# define gl_recursive_lock_lock(NAME) \
    if (thread_in_use ()) glthread_recursive_lock_lock (&NAME)
# define gl_recursive_lock_unlock(NAME) \
    if (thread_in_use ()) glthread_recursive_lock_unlock (&NAME)
# define gl_recursive_lock_destroy(NAME) \
    if (thread_in_use ()) glthread_recursive_lock_destroy (&NAME)
extern void glthread_recursive_lock_init (gl_recursive_lock_t *lock);
extern void glthread_recursive_lock_lock (gl_recursive_lock_t *lock);
extern void glthread_recursive_lock_unlock (gl_recursive_lock_t *lock);
extern void glthread_recursive_lock_destroy (gl_recursive_lock_t *lock);

/* -------------------------- gl_once_t datatype -------------------------- */

typedef struct
        {
          volatile int inited;
          mutex_t mutex;
        }
        gl_once_t;
# define gl_once_define(STORAGECLASS, NAME) \
    STORAGECLASS gl_once_t NAME = { 0, DEFAULTMUTEX };
# define gl_once(NAME, INITFUNCTION) \
    do                                                \
      {                                               \
        if (thread_in_use ())                         \
          {                                           \
            glthread_once (&NAME, INITFUNCTION);      \
          }                                           \
        else                                          \
          {                                           \
            if (glthread_once_singlethreaded (&NAME)) \
              INITFUNCTION ();                        \
          }                                           \
      }                                               \
    while (0)
extern void glthread_once (gl_once_t *once_control, void (*initfunction) (void));
extern int glthread_once_singlethreaded (gl_once_t *once_control);

# ifdef __cplusplus
}
# endif

#endif

/* ========================================================================= */

#if USE_WIN32_THREADS

# include <windows.h>

# ifdef __cplusplus
extern "C" {
# endif

/* We can use CRITICAL_SECTION directly, rather than the Win32 Event, Mutex,
   Semaphore types, because
     - we need only to synchronize inside a single process (address space),
       not inter-process locking,
     - we don't need to support trylock operations.  (TryEnterCriticalSection
       does not work on Windows 95/98/ME.  Packages that need trylock usually
       define their own mutex type.)  */

/* There is no way to statically initialize a CRITICAL_SECTION.  It needs
   to be done lazily, once only.  For this we need spinlocks.  */

typedef struct { volatile int done; volatile long started; } gl_spinlock_t;

/* -------------------------- gl_lock_t datatype -------------------------- */

typedef struct
        {
          gl_spinlock_t guard; /* protects the initialization */
          CRITICAL_SECTION lock;
        }
        gl_lock_t;
# define gl_lock_define(STORAGECLASS, NAME) \
    STORAGECLASS gl_lock_t NAME;
# define gl_lock_define_initialized(STORAGECLASS, NAME) \
    STORAGECLASS gl_lock_t NAME = gl_lock_initializer;
# define gl_lock_initializer \
    { { 0, -1 } }
# define gl_lock_init(NAME) \
    glthread_lock_init (&NAME)
# define gl_lock_lock(NAME) \
    glthread_lock_lock (&NAME)
# define gl_lock_unlock(NAME) \
    glthread_lock_unlock (&NAME)
# define gl_lock_destroy(NAME) \
    glthread_lock_destroy (&NAME)
extern void glthread_lock_init (gl_lock_t *lock);
extern void glthread_lock_lock (gl_lock_t *lock);
extern void glthread_lock_unlock (gl_lock_t *lock);
extern void glthread_lock_destroy (gl_lock_t *lock);

/* ------------------------- gl_rwlock_t datatype ------------------------- */

/* It is impossible to implement read-write locks using plain locks, without
   introducing an extra thread dedicated to managing read-write locks.
   Therefore here we need to use the low-level Event type.  */

typedef struct
        {
          HANDLE *array; /* array of waiting threads, each represented by an event */
          unsigned int count; /* number of waiting threads */
          unsigned int alloc; /* length of allocated array */
          unsigned int offset; /* index of first waiting thread in array */
        }
        gl_waitqueue_t;
typedef struct
        {
          gl_spinlock_t guard; /* protects the initialization */
          CRITICAL_SECTION lock; /* protects the remaining fields */
          gl_waitqueue_t waiting_readers; /* waiting readers */
          gl_waitqueue_t waiting_writers; /* waiting writers */
          int runcount; /* number of readers running, or -1 when a writer runs */
        }
        gl_rwlock_t;
# define gl_rwlock_define(STORAGECLASS, NAME) \
    STORAGECLASS gl_rwlock_t NAME;
# define gl_rwlock_define_initialized(STORAGECLASS, NAME) \
    STORAGECLASS gl_rwlock_t NAME = gl_rwlock_initializer;
# define gl_rwlock_initializer \
    { { 0, -1 } }
# define gl_rwlock_init(NAME) \
    glthread_rwlock_init (&NAME)
# define gl_rwlock_rdlock(NAME) \
    glthread_rwlock_rdlock (&NAME)
# define gl_rwlock_wrlock(NAME) \
    glthread_rwlock_wrlock (&NAME)
# define gl_rwlock_unlock(NAME) \
    glthread_rwlock_unlock (&NAME)
# define gl_rwlock_destroy(NAME) \
    glthread_rwlock_destroy (&NAME)
extern void glthread_rwlock_init (gl_rwlock_t *lock);
extern void glthread_rwlock_rdlock (gl_rwlock_t *lock);
extern void glthread_rwlock_wrlock (gl_rwlock_t *lock);
extern void glthread_rwlock_unlock (gl_rwlock_t *lock);
extern void glthread_rwlock_destroy (gl_rwlock_t *lock);

/* --------------------- gl_recursive_lock_t datatype --------------------- */

/* The Win32 documentation says that CRITICAL_SECTION already implements a
   recursive lock.  But we need not rely on it: It's easy to implement a
   recursive lock without this assumption.  */

typedef struct
        {
          gl_spinlock_t guard; /* protects the initialization */
          DWORD owner;
          unsigned long depth;
          CRITICAL_SECTION lock;
        }
        gl_recursive_lock_t;
# define gl_recursive_lock_define(STORAGECLASS, NAME) \
    STORAGECLASS gl_recursive_lock_t NAME;
# define gl_recursive_lock_define_initialized(STORAGECLASS, NAME) \
    STORAGECLASS gl_recursive_lock_t NAME = gl_recursive_lock_initializer;
# define gl_recursive_lock_initializer \
    { { 0, -1 }, 0, 0 }
# define gl_recursive_lock_init(NAME) \
    glthread_recursive_lock_init (&NAME)
# define gl_recursive_lock_lock(NAME) \
    glthread_recursive_lock_lock (&NAME)
# define gl_recursive_lock_unlock(NAME) \
    glthread_recursive_lock_unlock (&NAME)
# define gl_recursive_lock_destroy(NAME) \
    glthread_recursive_lock_destroy (&NAME)
extern void glthread_recursive_lock_init (gl_recursive_lock_t *lock);
extern void glthread_recursive_lock_lock (gl_recursive_lock_t *lock);
extern void glthread_recursive_lock_unlock (gl_recursive_lock_t *lock);
extern void glthread_recursive_lock_destroy (gl_recursive_lock_t *lock);

/* -------------------------- gl_once_t datatype -------------------------- */

typedef struct
        {
          volatile int inited;
          volatile long started;
          CRITICAL_SECTION lock;
        }
        gl_once_t;
# define gl_once_define(STORAGECLASS, NAME) \
    STORAGECLASS gl_once_t NAME = { -1, -1 };
# define gl_once(NAME, INITFUNCTION) \
    glthread_once (&NAME, INITFUNCTION)
extern void glthread_once (gl_once_t *once_control, void (*initfunction) (void));

# ifdef __cplusplus
}
# endif

#endif

/* ========================================================================= */

#if !(USE_POSIX_THREADS || USE_PTH_THREADS || USE_SOLARIS_THREADS || USE_WIN32_THREADS)

/* Provide dummy implementation if threads are not supported.  */

/* -------------------------- gl_lock_t datatype -------------------------- */

typedef int gl_lock_t;
# define gl_lock_define(STORAGECLASS, NAME)
# define gl_lock_define_initialized(STORAGECLASS, NAME)
# define gl_lock_init(NAME)
# define gl_lock_lock(NAME)
# define gl_lock_unlock(NAME)

/* ------------------------- gl_rwlock_t datatype ------------------------- */

typedef int gl_rwlock_t;
# define gl_rwlock_define(STORAGECLASS, NAME)
# define gl_rwlock_define_initialized(STORAGECLASS, NAME)
# define gl_rwlock_init(NAME)
# define gl_rwlock_rdlock(NAME)
# define gl_rwlock_wrlock(NAME)
# define gl_rwlock_unlock(NAME)

/* --------------------- gl_recursive_lock_t datatype --------------------- */

typedef int gl_recursive_lock_t;
# define gl_recursive_lock_define(STORAGECLASS, NAME)
# define gl_recursive_lock_define_initialized(STORAGECLASS, NAME)
# define gl_recursive_lock_init(NAME)
# define gl_recursive_lock_lock(NAME)
# define gl_recursive_lock_unlock(NAME)

/* -------------------------- gl_once_t datatype -------------------------- */

typedef int gl_once_t;
# define gl_once_define(STORAGECLASS, NAME) \
    STORAGECLASS gl_once_t NAME = 0;
# define gl_once(NAME, INITFUNCTION) \
    do                       \
      {                      \
        if (NAME == 0)       \
          {                  \
            NAME = ~ 0;      \
            INITFUNCTION (); \
          }                  \
      }                      \
    while (0)

#endif

/* ========================================================================= */

#endif /* _LOCK_H */