semaphore

func (*Registry) FindByID ¶

func (r *Registry) FindByID(id ipc.ID) *Set

FindByID looks up a set given an ID.

func (*Registry) FindByIndex ¶

func (r *Registry) FindByIndex(index int32) *Set

FindByIndex looks up a set given an index.

func (*Registry) FindOrCreate ¶

func (r *Registry) FindOrCreate(ctx context.Context, key ipc.Key, nsems int32, mode linux.FileMode, private, create, exclusive bool) (*Set, error)

FindOrCreate searches for a semaphore set that matches 'key'. If not found, it may create a new one if requested. If private is true, key is ignored and a new set is always created. If create is false, it fails if a set cannot be found. If exclusive is true, it fails if a set with the same key already exists.

func (*Registry) HighestIndex ¶

func (r *Registry) HighestIndex() int32

HighestIndex returns the index of the highest used entry in the kernel's array.

func (*Registry) IPCInfo ¶

func (r *Registry) IPCInfo() *linux.SemInfo

IPCInfo returns information about system-wide semaphore limits and parameters.

func (*Registry) Remove ¶

func (r *Registry) Remove(id ipc.ID, creds *auth.Credentials) error

Remove removes set with give 'id' from the registry and marks the set as dead. All waiters will be awakened and fail.

func (*Registry) SemInfo ¶

func (r *Registry) SemInfo() *linux.SemInfo

SemInfo returns a seminfo structure containing the same information as for IPC_INFO, except that SemUsz field returns the number of existing semaphore sets, and SemAem field returns the number of existing semaphores.

func (*Set) AbortWait ¶

func (s *Set) AbortWait(num int32, ch chan struct{})

AbortWait notifies that a waiter is giving up and will not wait on the channel anymore.

func (*Set) CountNegativeWaiters ¶

func (s *Set) CountNegativeWaiters(num int32, creds *auth.Credentials) (uint16, error)

CountNegativeWaiters returns number of waiters waiting for the sem to go to zero.

func (*Set) CountZeroWaiters ¶

func (s *Set) CountZeroWaiters(num int32, creds *auth.Credentials) (uint16, error)

CountZeroWaiters returns number of waiters waiting for the sem's value to increase.

func (*Set) Destroy ¶

func (s *Set) Destroy()

Destroy implements ipc.Mechanism.Destroy.

Preconditions: Caller must hold 's.mu'.

func (*Set) ExecuteOps ¶

func (s *Set) ExecuteOps(ctx context.Context, ops []linux.Sembuf, creds *auth.Credentials, pid int32) (chan struct{}, int32, error)

ExecuteOps attempts to execute a list of operations to the set. It only succeeds when all operations can be applied. No changes are made if it fails.

On failure, it may return an error (retries are hopeless) or it may return a channel that can be waited on before attempting again.

func (*Set) GetPID ¶

func (s *Set) GetPID(num int32, creds *auth.Credentials) (int32, error)

GetPID returns the PID set when performing operations in the semaphore.

func (*Set) GetStat ¶

func (s *Set) GetStat(creds *auth.Credentials) (*linux.SemidDS, error)

GetStat extracts semid_ds information from the set.

func (*Set) GetStatAny ¶

func (s *Set) GetStatAny(creds *auth.Credentials) (*linux.SemidDS, error)

GetStatAny extracts semid_ds information from the set without requiring read access.

func (*Set) GetVal ¶

func (s *Set) GetVal(num int32, creds *auth.Credentials) (int16, error)

GetVal returns a semaphore value.

func (*Set) GetValAll ¶

func (s *Set) GetValAll(creds *auth.Credentials) ([]uint16, error)

GetValAll returns value for all semaphores.

func (*Set) ID ¶

func (s *Set) ID() ipc.ID

ID returns semaphore's ID.

func (*Set) Lock ¶

func (s *Set) Lock()

Lock implements ipc.Mechanism.Lock.

func (*Set) Object ¶

func (s *Set) Object() *ipc.Object

Object implements ipc.Mechanism.Object.

func (*Set) Set ¶

func (s *Set) Set(ctx context.Context, ds *linux.SemidDS) error

Set modifies attributes for a semaphore set. See semctl(IPC_SET).

func (*Set) SetVal ¶

func (s *Set) SetVal(ctx context.Context, num int32, val int16, creds *auth.Credentials, pid int32) error

SetVal overrides a semaphore value, waking up waiters as needed.

func (*Set) SetValAll ¶

func (s *Set) SetValAll(ctx context.Context, vals []uint16, creds *auth.Credentials, pid int32) error

SetValAll overrides all semaphores values, waking up waiters as needed. It also sets semaphore's PID which was fixed in Linux 4.6.

'len(vals)' must be equal to 's.Size()'.

func (*Set) Size ¶

func (s *Set) Size() int

Size returns the number of semaphores in the set. Size is immutable.

func (*Set) Unlock ¶

func (s *Set) Unlock()

Unlock implements ipc.mechanism.Unlock.

+checklocksignore