L4Re::Inhibitor Class Reference

Set of inhibitor locks, which inhibit specific actions when held. More...

#include <inhibitor>

Inheritance diagram for L4Re::Inhibitor:

Collaboration diagram for L4Re::Inhibitor:

Public Types
enum	{ Name_max = 20 }

Public Member Functions
long	acquire (l4_umword_t id, L4::Ipc::String<> reason)
	Acquire a specific inhibitor lock.
long	release (l4_umword_t id)
	Release a specific inhibitor lock.
long	next_lock_info (char *name, unsigned len, l4_mword_t current_id=-1, l4_utcb_t *utcb=l4_utcb())
	Get information for the next available inhibitor lock.
Public Member Functions inherited from L4::Kobject
l4_msgtag_t	dec_refcnt (l4_mword_t diff, l4_utcb_t *utcb=l4_utcb())
	Decrement the in kernel reference counter for the object.

Additional Inherited Members
Protected Types inherited from L4::Kobject_t< Inhibitor, L4::Kobject, L4RE_PROTO_INHIBITOR >
typedef Inhibitor	Class
	The target interface type (inheriting from Kobject_t)
typedef Typeid::Iface< PROTO, Inhibitor >	__Iface
	The interface description for the derived class.
typedef Typeid::Merge_list< Typeid::Iface_list< __Iface >, typename Base::__Iface_list >	__Iface_list
	The list of all RPC interfaces provided directly or through inheritance.
Protected Member Functions inherited from L4::Kobject_t< Inhibitor, L4::Kobject, L4RE_PROTO_INHIBITOR >
L4::Cap< Class >	c () const noexcept
	Get the capability to ourselves.
Protected Member Functions inherited from L4::Kobject
l4_cap_idx_t	cap () const noexcept
	Return capability selector.
Static Protected Member Functions inherited from L4::Kobject_t< Inhibitor, L4::Kobject, L4RE_PROTO_INHIBITOR >
static void	__check_protocols__ () noexcept
	Helper to check for protocol conflicts.

Detailed Description

Set of inhibitor locks, which inhibit specific actions when held.

This interface provides access to a set of inhibitor locks, each determined by an ID that is specific to the Inhibitor object. Each individual lock shall prevent, a specific (implementation defined) action to be executed, as long as the lock is held.

For example there can be an inhibitor lock to prevent a transition to suspend-to-RAM state and a different one to prevent shutdown.

A client shall take an inhibitor lock if it needs to execute code before the action is taken. For example a lock-screen application shall grab an inhibitor lock for the suspend action to be able to lock the screen before the system goes to sleep.

Inhibitor locks are usually closely related to specific events. Usually a server automatically subscribes a client holding a lock to the corresponding event. The server shall send the event to inform the client that an action is pending. Upon reception of the event, the client is supposed to release the corresponding inhibitor lock.

Definition at line 40 of file inhibitor.

Member Enumeration Documentation

anonymous enum

anonymous enum

Enumerator
Name_max	The maximum length of a lock's name.

Definition at line 44 of file inhibitor.

Member Function Documentation

acquire()

long L4Re::Inhibitor::acquire	(	l4_umword_t	id,
		L4::Ipc::String<>	reason
	)

Acquire a specific inhibitor lock.

Parameters

id	ID of the inhibitor lock that the client intends to acquire
reason	The reason why you need the lock. Used for informing the user or debugging.

Return values

0	Success
-L4_ENODEV	The specified id does not exist.

next_lock_info()

long L4Re::Inhibitor::next_lock_info ( char *  name, unsigned  len, l4_mword_t  current_id = -1, l4_utcb_t *  utcb = l4_utcb()  )

inline

Get information for the next available inhibitor lock.

Parameters

name	A pointer to a buffer for the name of the lock.
len	The length of the available buffer (usually Name_max is used).
current_id	The ID of the last available lock, use -1 to get the first lock.
utcb	The UTCB to use for the message.

Return values

>0	The ID of the next available lock if there is one (in this case name shall contain the name of the inhibitor lock).
-L4_ENODEV	There are no more locks.

Definition at line 86 of file inhibitor.

References L4::Kobject_t< Inhibitor, L4::Kobject, L4RE_PROTO_INHIBITOR >::c().

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release()

long L4Re::Inhibitor::release

(

l4_umword_t

id

)

Release a specific inhibitor lock.

Parameters

id	The ID of the inhibitor lock to release.

Return values

0	Success
-L4_ENODEV	Lock with the given id does not exist.

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

• l4/re/inhibitor