7:59 a.m.
Pedro Zapata created ISPN-8284:
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Summary: Clustered Locks Embedded Mode
Key: ISPN-8284
URL: https://issues.jboss.org/browse/ISPN-8284
Project: Infinispan
Issue Type: Feature Request
Reporter: Pedro Zapata
Assignee: Katia Aresti
h2. ClusteredLockManager and configuration
{code:java}
package org.infinispan.lock.api;
public class ClusteredLockManager {
boolean defineLock(String name, LockConfiguration configuration);
InfinispanLock get(String name);
LockConfiguration getConfiguration(String name);
boolean isDefined(String name);
CompletableFuture<Boolean> remove(String name);
CompletableFuture<Void> reset(String name);
}
public class LockConfiguration {
private final RentrancyLevel lentrancyLevel; // default NOT_REENTRANT
private final boolean silentFailover; // default true
// The maximum length of time for which a client can hold and renew a lock aquisition
private final long maxLeaseTime;
// Maximum length of time a lock may be held without updating the lease,
// after that time any attempt to lock it will succeed
private final long renewalLeaseTime;
}
public enum RentrancyLevel {
NODE, // Node can lock if it owns the lock without blocking, only the owner node can
unlock
INSTANCE, // Instance can lock multiple times if it owns the lock without blocking,
only the owner instance can unlock
NOT_REENTRANT // Nobody can take the lock if already taken, but everybody can release
it
}
{code}
h4. InfinispanLock defineLock(String name, LockConfiguration configuration)
Defines a lock with the specific name and LockConfiguration. It does not overwrite
existing configurations.
Returns true if successfully defined or false if the lock is already defined or any other
failure. If silentFailover is false, then InfinispanLockException will be raised.
h4. InfinispanLock get(String name)
Get’s a InfinipanLock by it’s name and throws InfinispanLockException if the lock is not
not defined. User must call defineLock before this method.
h4. Optional<LockConfiguration> getConfiguration(String name);
Get’s the configuration for a Lock. If the Lock does not exist, Optional.empty() will be
returned.
h4. boolean isDefined(String name)
True if the lock exists, false if it doesn’t
h4. CompletableFuture<Boolean> remove(String name)
Removes a Lock from the system. Returns true when it was removed, false when the lock does
not exist. If any other Runtime problems appear, InfinispanLockException will be raised
withe the reason. As Locks are not removed automatically, so this has to be done
programatically when the Lock is no longer needed. Otherwise, OutOfMemoryException could
happen.
Remove must be executed when the lock is locked, because running that without exclusive
access should result in an exception. Internally, the implementation should contain
generation number so that attempts to acquire a lock of a removed generation will result
it exceptions in the other callers, too.
h4. CompletableFuture<Void> reset(String name)
Resets the lock to its initial state. If any parties are currently waiting at the lock,
they will return with failure on the CompletableFuture
h2. InfinispanLock
When a cluster node holding a Lock dies, this lock is released and available for the
others.
{code:java}
public interface InfinispanLock {
CompletableFuture<Void> lock();
CompletableFuture<Boolean> tryLock();
CompletableFuture<Boolean> tryLock(long time, TimeUnit unit);
CompletableFuture<Void> unlock();
}
{code}
h4. CompletableFuture<Void> lock();
CompletableFuture is completed successfully when the lock is acquired When a lock is
aquired by a client, it will be automatically released after the maxLeaseTime specified.
RenewalLeaseTime is the interval time is the time a client can aquire a lock consecutively
User should set the timeouts to non-positive value The initial embedded implementation
does not have to support positive values
h4. CompletableFuture<Boolean> tryLock();
Acquires the lock only if it is free at the time of invocation. Acquires the lock if it is
available and returns with the value true. If the lock is not available then this method
with the value false.
h4. CompletableFuture<Boolean> tryLock(long time, TimeUnit unit);
Acquires the lock if it is free within the given waiting time. If the lock is available
this method returns with the value true.
Parameters: time - the maximum time to wait for the lock unit - the time unit of the time
argument Returns: true if the lock was acquired and false if the waiting time elapsed
before the lock was acquired
CompletableFuture fails with InfinispanLockException in case of error
(InterruptedException, or any other non checked exceptions)
h4. CompletableFuture<Boolean> unlock();
If the lock is rentrant (Node or Instance), only the instance or node holding the lock
will be able to unlock, otherwise, anybody can unlock and it will behave as a Semaphore
with one permit. True answer will say that the operation was succesul and the lock has
been released, false the lock has not been relased
h2. Demo
{code:java}
public static void main(String[] args) throws Exception {
EmbeddedCacheManager cm = Infinispan.createClustered();
CounterManager counterManager =
EmbeddedCounterManagerFactory.asCounterManager(cm);
counterManager.defineCounter("counter", ...);
WeakCounter counter = counterManager.weakCounter("counter");
ClusteredLockManager lockManager =
EmbeddedLockManagerFactory.asClusteredLockManager(cm);
lockManager.defineLock("lock", ...);
InfinispanLock lock = lockManager.get("lock");
for (int i = 0; i < 100; i++) {
System.out.println("Counter on " + i + " is => " +
counter.getValue());
lock.lock()
.thenRun(new CounterExample(counter))
.whenComplete((nil, t) -> lock.unlock());
}
cm.stop();
}
static class CounterExample implements Runnable {
private WeakCounter counter;
public CounterExample(WeakCounter counter) {
this.counter = counter;
}
@Override
public void run() {
counter.increment();
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
counter.decrement();
}
}
{code}
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