ACE_File_Lock Class Reference

A wrapper around the UNIX file locking mechanism. More...

#include <File_Lock.h>

Collaboration diagram for ACE_File_Lock:

List of all members.

Public Member Functions
	ACE_File_Lock (ACE_HANDLE handle=ACE_INVALID_HANDLE, bool unlink_in_destructor=true)
	ACE_File_Lock (const ACE_TCHAR *filename, int flags, mode_t mode=0, bool unlink_in_destructor=true)
int	open (const ACE_TCHAR *filename, int flags, mode_t mode=0)
	~ACE_File_Lock (void)
	Remove a File lock by releasing it and closing down the <handle_>.
int	remove (bool unlink_file=true)
int	acquire (short whence=0, ACE_OFF_T start=0, ACE_OFF_T len=1)
int	tryacquire (short whence=0, ACE_OFF_T start=0, ACE_OFF_T len=1)
int	release (short whence=0, ACE_OFF_T start=0, ACE_OFF_T len=1)
	Unlock a readers/writer lock.
int	acquire_write (short whence=0, ACE_OFF_T start=0, ACE_OFF_T len=1)
int	tryacquire_write (short whence=0, ACE_OFF_T start=0, ACE_OFF_T len=1)
int	tryacquire_write_upgrade (short whence=0, ACE_OFF_T start=0, ACE_OFF_T len=1)
int	acquire_read (short whence=0, ACE_OFF_T start=0, ACE_OFF_T len=1)
int	tryacquire_read (short whence=0, ACE_OFF_T start=0, ACE_OFF_T len=1)
ACE_HANDLE	get_handle (void) const
	Get underlying ACE_HANDLE for the file.
void	set_handle (ACE_HANDLE)
void	dump (void) const
	Dump state of the object.
Public Attributes
	ACE_ALLOC_HOOK_DECLARE
	Declare the dynamic allocation hooks.
Protected Attributes
ACE_OS::ace_flock_t	lock_
	Locking structure for OS record locks.
bool	removed_
bool const	unlink_in_destructor_
Private Member Functions
void	operator= (const ACE_File_Lock &)
	ACE_File_Lock (const ACE_File_Lock &)

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Detailed Description

A wrapper around the UNIX file locking mechanism.

Allows us to "adapt" the UNIX file locking mechanisms to work with all of our Guard stuff...

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Constructor & Destructor Documentation

ACE_File_Lock::ACE_File_Lock	(	ACE_HANDLE	handle = ACE_INVALID_HANDLE,
		bool	unlink_in_destructor = true
	)

Set the <handle_> of the File_Lock to handle. Note that this constructor assumes ownership of the handle and will close it down in <remove>. If you want the handle to stay open when <remove> is called make sure to call <dup> on the handle. If you don't want the file unlinked in the destructor pass a zero value for <unlink_in_destructor>.

ACE_File_Lock::ACE_File_Lock	(	const ACE_TCHAR *	filename,
		int	flags,
		mode_t	mode = 0,
		bool	unlink_in_destructor = true
	)

Open the filename with flags and mode and set the result to <handle_>. If you don't want the file unlinked in the destructor pass a false value for unlink_in_destructor.

ACE_File_Lock::~ACE_File_Lock

(

void

)

Remove a File lock by releasing it and closing down the <handle_>.

ACE_File_Lock::ACE_File_Lock

(

const ACE_File_Lock &

)

[private]

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Member Function Documentation

int ACE_File_Lock::acquire	(	short	whence = 0,
		ACE_OFF_T	start = 0,
		ACE_OFF_T	len = 1
	)		[inline]

Note, for interface uniformity with other synchronization wrappers we include the acquire() method. This is implemented as a write-lock to be on the safe-side...

int ACE_File_Lock::acquire_read	(	short	whence = 0,
		ACE_OFF_T	start = 0,
		ACE_OFF_T	len = 1
	)		[inline]

Acquire a read lock, but block if a writer hold the lock. Returns -1 on failure. If we "failed" because someone else already had the lock, errno is set to EBUSY.

int ACE_File_Lock::acquire_write	(	short	whence = 0,
		ACE_OFF_T	start = 0,
		ACE_OFF_T	len = 1
	)		[inline]

Acquire a write lock, but block if any readers or a writer hold the lock.

void ACE_File_Lock::dump

(

void

)

const

Dump state of the object.

ACE_HANDLE ACE_File_Lock::get_handle

(

void

)

const [inline]

Get underlying ACE_HANDLE for the file.

int ACE_File_Lock::open	(	const ACE_TCHAR *	filename,
		int	flags,
		mode_t	mode = 0
	)

Open the filename with flags and mode and set the result to <handle_>.

void ACE_File_Lock::operator=

(

const ACE_File_Lock &

)

[private]

int ACE_File_Lock::release	(	short	whence = 0,
		ACE_OFF_T	start = 0,
		ACE_OFF_T	len = 1
	)		[inline]

Unlock a readers/writer lock.

int ACE_File_Lock::remove

(

bool

unlink_file = true

)

[inline]

Remove a File lock by releasing it and closing down the <handle_>. If unlink_file is true then we unlink the file.

void ACE_File_Lock::set_handle

(

ACE_HANDLE

h

)

[inline]

Set underlying ACE_HANDLE. Note that this method assumes ownership of the handle and will close it down in <remove>. If you want the handle to stay open when <remove> is called make sure to call <dup> on the handle before closing it. You are responsible for the closing the existing handle before overwriting it.

int ACE_File_Lock::tryacquire	(	short	whence = 0,
		ACE_OFF_T	start = 0,
		ACE_OFF_T	len = 1
	)		[inline]

Note, for interface uniformity with other synchronization wrappers we include the <tryacquire> method. This is implemented as a write-lock to be on the safe-side... Returns -1 on failure. If we "failed" because someone else already had the lock, errno is set to EBUSY.

int ACE_File_Lock::tryacquire_read	(	short	whence = 0,
		ACE_OFF_T	start = 0,
		ACE_OFF_T	len = 1
	)		[inline]

Conditionally acquire a read lock (i.e., won't block). Returns -1 on failure. If we "failed" because someone else already had the lock, errno is set to EBUSY.

int ACE_File_Lock::tryacquire_write	(	short	whence = 0,
		ACE_OFF_T	start = 0,
		ACE_OFF_T	len = 1
	)		[inline]

Conditionally acquire a write lock (i.e., won't block). Returns -1 on failure. If we "failed" because someone else already had the lock, errno is set to EBUSY.

int ACE_File_Lock::tryacquire_write_upgrade	(	short	whence = 0,
		ACE_OFF_T	start = 0,
		ACE_OFF_T	len = 1
	)		[inline]

Conditionally upgrade to a write lock (i.e., won't block). Returns -1 on failure. If we "failed" because someone else already had the lock, errno is set to EBUSY.

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Member Data Documentation

ACE_File_Lock::ACE_ALLOC_HOOK_DECLARE

Declare the dynamic allocation hooks.

ACE_OS::ace_flock_t ACE_File_Lock::lock_ [protected]

Locking structure for OS record locks.

bool ACE_File_Lock::removed_ [protected]

Keeps track of whether <remove> has been called yet to avoid multiple <remove> calls, e.g., explicitly and implicitly in the destructor. This flag isn't protected by a lock, so make sure that you don't have multiple threads simultaneously calling <remove> on the same object, which is a bad idea anyway...

bool const ACE_File_Lock::unlink_in_destructor_ [protected]

Keeps track of whether to unlink the underlying file in the destructor.

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The documentation for this class was generated from the following files:

• File_Lock.h
• File_Lock.cpp
• File_Lock.inl