sbuild::lock Class Reference

Advisory locking. More...

#include <sbuild-lock.h>

Inheritance diagram for sbuild::lock:

Public Types
enum	type { LOCK_SHARED = F_RDLCK, LOCK_EXCLUSIVE = F_WRLCK, LOCK_NONE = F_UNLCK }
	Lock type. More...
enum	error_code {   TIMEOUT_HANDLER, TIMEOUT_SET, TIMEOUT_CANCEL, LOCK,   UNLOCK, LOCK_TIMEOUT, UNLOCK_TIMEOUT, DEVICE_LOCK,   DEVICE_LOCK_TIMEOUT, DEVICE_TEST, DEVICE_UNLOCK, DEVICE_UNLOCK_TIMEOUT }
	Error codes. More...
typedef custom_error< error_code >	error
	Exception type.

Public Member Functions
virtual void	set_lock (type lock_type, unsigned int timeout)=0
	Acquire a lock. More...
virtual void	unset_lock ()=0
	Release a lock. More...

Protected Member Functions
	lock ()
	The constructor.
virtual	~lock ()
	The destructor.
void	set_alarm ()
	Set the SIGALARM handler. More...
void	clear_alarm ()
	Restore the state of SIGALRM prior to starting lock acquisition.
void	set_timer (struct itimerval const &timer)
	Set up an itimer for future expiry. More...
void	unset_timer ()
	Remove any itimer currently set up. More...

Private Attributes
struct sigaction	saved_signals
	Signals saved during timeout.

Detailed Description

Advisory locking.

This class defines a simple interface for shared and exclusive locks.

Member Enumeration Documentation

enum sbuild::lock::error_code

Error codes.

Enumerator
TIMEOUT_HANDLER	Failed to set timeout handler.
TIMEOUT_SET	Failed to set timeout.
TIMEOUT_CANCEL	Failed to cancel timeout.
LOCK	Failed to lock file.
UNLOCK	Failed to unlock file.
LOCK_TIMEOUT	Failed to lock file (timed out).
UNLOCK_TIMEOUT	Failed to unlock file (timed out).
DEVICE_LOCK	Failed to lock device.
DEVICE_LOCK_TIMEOUT	Failed to lock device (timed out).
DEVICE_TEST	Failed to test device lock.
DEVICE_UNLOCK	Failed to unlock device.
DEVICE_UNLOCK_TIMEOUT	Failed to unlock device (timed out)

enum sbuild::lock::type

Lock type.

Enumerator
LOCK_SHARED	A shared (read) lock.
LOCK_EXCLUSIVE	An exclusive (write) lock.
LOCK_NONE	No lock.

Member Function Documentation

void lock::set_alarm ( )

protected

Set the SIGALARM handler.

An error will be thrown on failure.

References saved_signals, and TIMEOUT_HANDLER.

Referenced by set_timer().

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virtual void sbuild::lock::set_lock ( type  lock_type, unsigned int  timeout  )

pure virtual

Acquire a lock.

Parameters

lock_type	the type of lock to acquire.
timeout	the time in seconds to wait on the lock.

Implemented in sbuild::file_lock.

void lock::set_timer ( struct itimerval const &  timer )

protected

Set up an itimer for future expiry.

This is used to interrupt system calls. This will set a handler for SIGALRM as a side effect (using set_alarm).

An error will be thrown on failure.

Parameters

timer

the timeout to set.

References clear_alarm(), set_alarm(), and TIMEOUT_SET.

Referenced by sbuild::file_lock::set_lock().

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virtual void sbuild::lock::unset_lock ( )

pure virtual

Release a lock.

This is equivalent to set_lock with a lock_type of LOCK_NONE and a timeout of 0.

Implemented in sbuild::file_lock.

void lock::unset_timer ( )

protected

Remove any itimer currently set up.

This will clear any SIGALRM handler (using clear_alarm).

An error will be thrown on failure.

References clear_alarm(), and TIMEOUT_CANCEL.

Referenced by sbuild::file_lock::set_lock().

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

• sbuild/sbuild-lock.h
• sbuild/sbuild-lock.cc