Run Goal, synchronized with LockId in ModeSpec. ModeSpec
is one of
read, write, read(Priority) or write(Priority).
The default
read priority is 100 and the default write
priority is 200. These values prioritize writers over readers. Goal
may start if
- If there is no goal waiting with higher priority and
- It is a read goal and no write goal is running or
- It is a write goal and no other goal is running.
If Goal may not start immediately the thread waits using
thread_wait/2.
The Options timeout and deadline
are passed to
thread_wait/2.
If the time limit is exceeded an exception is raised.
Read/write locks are widely critized for their poor behaviour
on several workloads. They perform well in scenarios where read
operations take long, and write operations are relatively fast and occur
only occasionally. Transactions, as implemented by
transaction/1,2 are
often a better alternative.
This predicate uses a normal mutex and a flag with the same name. See
with_mutex/2 and flag/3.
Neither the mutex nor the flag should be used directly.
- throws
time_limit_exceeded(rwlock) if a timeout or deadline is
specified and this is exceeded.- bug
- The current implementation is written in Prolog and comes with
significant overhead. It is intended to synchronize slow operations.
