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ACE_File_Lock Class Reference

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

#include <File_Lock.h>

Collaboration diagram for ACE_File_Lock:

[legend]List of all members.

Public Methods
	ACE_File_Lock (ACE_HANDLE handle=ACE_INVALID_HANDLE, int unlink_in_destructor=1)
	ACE_File_Lock (const ACE_TCHAR *filename, int flags, mode_t mode=0, int unlink_in_destructor=1)
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 (int unlink_file=1)
int	acquire (short whence=0, off_t start=0, off_t len=1)
int	tryacquire (short whence=0, off_t start=0, off_t len=1)
int	release (short whence=0, off_t start=0, off_t len=1)
	Unlock a readers/writer lock.
int	acquire_write (short whence=0, off_t start=0, off_t len=1)
int	tryacquire_write (short whence=0, off_t start=0, off_t len=1)
int	tryacquire_write_upgrade (short whence=0, off_t start=0, off_t len=1)
int	acquire_read (short whence=0, off_t start=0, off_t len=1)
int	tryacquire_read (short whence=0, off_t start=0, 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.
int	removed_
int	unlink_in_destructor_
Private Methods
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, int    unlink_in_destructor = 1 )

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, int    unlink_in_destructor = 1 )

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 zero 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

ACE_INLINE int ACE_File_Lock::acquire (  short    whence = 0, off_t    start = 0, off_t    len = 1 )

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...

ACE_INLINE int ACE_File_Lock::acquire_read (  short    whence = 0, off_t    start = 0, off_t    len = 1 )

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>.

ACE_INLINE int ACE_File_Lock::acquire_write (  short    whence = 0, off_t    start = 0, off_t    len = 1 )

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_INLINE ACE_HANDLE ACE_File_Lock::get_handle (  void    )  const

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]

ACE_INLINE int ACE_File_Lock::release (  short    whence = 0, off_t    start = 0, off_t    len = 1 )

Unlock a readers/writer lock.

ACE_INLINE int ACE_File_Lock::remove (  int    unlink_file = 1 )

Remove a File lock by releasing it and closing down the <handle_>. If <unlink_file> is non-0 then we unlink the file.

ACE_INLINE void ACE_File_Lock::set_handle (  ACE_HANDLE    )

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.

ACE_INLINE int ACE_File_Lock::tryacquire (  short    whence = 0, off_t    start = 0, off_t    len = 1 )

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>.

ACE_INLINE int ACE_File_Lock::tryacquire_read (  short    whence = 0, off_t    start = 0, off_t    len = 1 )

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>.

ACE_INLINE int ACE_File_Lock::tryacquire_write (  short    whence = 0, off_t    start = 0, off_t    len = 1 )

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>.

ACE_INLINE int ACE_File_Lock::tryacquire_write_upgrade (  short    whence = 0, off_t    start = 0, off_t    len = 1 )

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.

int 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...

int 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

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