Compatibility Macros

Collaboration diagram for Compatibility Macros:

Macros
#define	MDB_DEVEL   0
#define	mdb_func_   "<mdb_unknown>"
#define	MDB_NO_ROOT   (MDB_LAST_ERRCODE + 10)
#define	MDB_USE_ROBUST   1
#define	THREAD_RET   void *
#define	THREAD_CREATE(thr, start, arg)
#define	THREAD_FINISH(thr)
#define	MDB_PIDLOCK   1
#define	LOCK_MUTEX0(mutex)
#define	UNLOCK_MUTEX(mutex)
#define	mdb_mutex_consistent(mutex)
#define	ErrCode()
#define	HANDLE   int
#define	INVALID_HANDLE_VALUE   (-1)
#define	GET_PAGESIZE(x)
#define	Z   MDB_FMT_Z
#define	Yu   MDB_PRIy(u)
#define	Yd   MDB_PRIy(d)
#define	MNAME_LEN   (sizeof(pthread_mutex_t))

Typedefs
typedef pthread_mutex_t	mdb_mutex_t[1]
typedef pthread_mutex_t *	mdb_mutexref_t

Detailed Description

A bunch of macros to minimize the amount of platform-specific ifdefs needed throughout the rest of the code. When the features this library needs are similar enough to POSIX to be hidden in a one-or-two line replacement, this macro approach is used.

Macro Definition Documentation

ErrCode

#define ErrCode

(

)

Value:

errno

Get the error code for the last failed system function.

GET_PAGESIZE

#define GET_PAGESIZE

(

x

)

Value:

((x) = sysconf(_SC_PAGE_SIZE))

Get the size of a memory page for the system. This is the basic size that the platform's memory manager uses, and is fundamental to the use of memory-mapped files.

HANDLE

#define HANDLE   int

An abstraction for a file handle. On POSIX systems file handles are small integers. On Windows they're opaque pointers.

INVALID_HANDLE_VALUE

#define INVALID_HANDLE_VALUE   (-1)

A value for an invalid file handle. Mainly used to initialize file variables and signify that they are unused.

LOCK_MUTEX0

#define LOCK_MUTEX0

(

mutex

)

Value:

pthread_mutex_lock(mutex)

Lock the reader or writer mutex. Returns 0 or a code to give mdb_mutex_failed(), as in LOCK_MUTEX().

MDB_DEVEL

#define MDB_DEVEL   0

Features under development

mdb_func_

#define mdb_func_   "<mdb_unknown>"

Wrapper around func, which is a C99 feature

mdb_mutex_consistent

#define mdb_mutex_consistent

(

mutex

)

Value:

pthread_mutex_consistent(mutex)

Mark mutex-protected data as repaired, after death of previous owner.

MDB_NO_ROOT

#define MDB_NO_ROOT   (MDB_LAST_ERRCODE + 10)

MDB_PIDLOCK

#define MDB_PIDLOCK   1

For MDB_LOCK_FORMAT: True if readers take a pid lock in the lockfile

MDB_USE_ROBUST

#define MDB_USE_ROBUST   1

Some platforms define the EOWNERDEAD error code even though they don't support Robust Mutexes. Compile with -DMDB_USE_ROBUST=0, or use some other mechanism like -DMDB_USE_SYSV_SEM instead of -DMDB_USE_POSIX_MUTEX. (SysV semaphores are also Robust, but some systems don't support them either.)

MNAME_LEN

#define MNAME_LEN   (sizeof(pthread_mutex_t))

THREAD_CREATE

#define THREAD_CREATE	(		thr,
			start,
			arg )

Value:

pthread_create(&thr,NULL,start,arg)

THREAD_FINISH

#define THREAD_FINISH

(

thr

)

Value:

pthread_join(thr,NULL)

THREAD_RET

#define THREAD_RET   void *

UNLOCK_MUTEX

#define UNLOCK_MUTEX

(

mutex

)

Value:

pthread_mutex_unlock(mutex)

Unlock the reader or writer mutex.

Yd

#define Yd   MDB_PRIy(d)

printf format for 'signed mdb_size_t'

Yu

#define Yu   MDB_PRIy(u)

printf format for mdb_size_t

Z

#define Z   MDB_FMT_Z

printf/scanf format modifier for size_t

Typedef Documentation

mdb_mutex_t

typedef pthread_mutex_t mdb_mutex_t[1]

Shared mutex/semaphore as the original is stored.

Not for copies. Instead it can be assigned to an mdb_mutexref_t. When mdb_mutexref_t is a pointer and mdb_mutex_t is not, then it is array[size 1] so it can be assigned to the pointer.

mdb_mutexref_t

typedef pthread_mutex_t* mdb_mutexref_t

Reference to an mdb_mutex_t