ACE  6.1.0
Public Member Functions | Public Attributes | Protected Attributes | Private Member Functions
ACE_File_Lock Class Reference

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

#include <File_Lock.h>

Collaboration diagram for ACE_File_Lock:
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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 &)

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...


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]

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.


Member Data Documentation

Declare the dynamic allocation hooks.

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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