method lock
Documentation for method lock
assembled from the following types:
class Lock
From Lock
(Lock) method lock
Defined as:
method lock(Lock:)
Acquires the lock. If it is currently not available, waits for it.
my = Lock.new;.lock;
Since a Lock
is implemented using OS-provided facilities, a thread waiting for the lock will not be scheduled until the lock is available for it. Since Lock
is re-entrant, if the current thread already holds the lock, calling lock
will simply bump a recursion count.
While it's easy enough to use the lock
method, it's more difficult to correctly use unlock
. Instead, prefer to use the protect
method instead, which takes care of making sure the lock
/unlock
calls always both occur.
class IO::CatHandle
From IO::CatHandle
(IO::CatHandle) method lock
Defined as:
method lock(IO::CatHandle: Bool : = False, Bool : = False --> True)
Same as IO::Handle.lock
. Returns Nil if the source handle queue has been exhausted.
Locks only the currently active source handle. The .on-switch
Callable can be used to conveniently lock/unlock the handles as they're being processed by the CatHandle.
class IO::Handle
From IO::Handle
(IO::Handle) method lock
Defined as:
method lock(IO::Handle: Bool : = False, Bool : = False --> True)
Places an advisory lock on the filehandle. If :$non-blocking
is True
will fail
with X::IO::Lock
if lock could not be obtained, otherwise will block until the lock can be placed. If :$shared
is True
will place a shared (read) lock, otherwise will place an exclusive (write) lock. On success, returns True
; fails with X::IO::Lock
if lock cannot be placed (e.g. when trying to place a shared lock on a filehandle opened in write mode or trying to place an exclusive lock on a filehandle opened in read mode).
You can use lock
again to replace an existing lock with another one. To remove a lock, close
the filehandle or use unlock
.
# One program writes, the other reads, and thanks to locks either# will wait for the other to finish before proceeding to read/write# Writergiven "foo".IO.open(:w)# Readergiven "foo".IO.open
class Lock::Async
From Lock::Async
(Lock::Async) method lock
Defined as:
method lock(Lock::Async: --> Promise)
Returns a Promise that will be kept when the lock is available. In the case that the lock is already available, an already kept Promise
will be returned. Use await
to wait for the lock to be available in a non-blocking manner.
my = Lock::Async.new;await .lock;
Prefer to use protect instead of explicit calls to lock
and unlock
.