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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:

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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)
 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>.

int open (const ACE_TCHAR *filename, int flags, mode_t mode = 0)
 Open the <filename> with <flags> and <mode> and set the result to <handle_>.

 ~ACE_File_Lock (void)
 Remove a File lock by releasing it and closing down the <handle_>.

int 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.

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

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


Private Methods

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,
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]
 


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 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 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 h )
 

Set underlying . 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>.


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.


The documentation for this class was generated from the following files:
Generated at Fri Oct 5 07:02:04 2001 for ACE by doxygen1.2.3 written by Dimitri van Heesch, © 1997-2000