Package org.eclipse.aether.named.support
Class FileLockNamedLock
- java.lang.Object
-
- org.eclipse.aether.named.support.NamedLockSupport
-
- org.eclipse.aether.named.support.FileLockNamedLock
-
- All Implemented Interfaces:
java.lang.AutoCloseable
,NamedLock
public final class FileLockNamedLock extends NamedLockSupport
Named lock that usesFileLock
. An instance of this class is about ONE LOCK (one file) and is possibly used by multiple threads. Each thread (if properly coded re boxing) will try to obtain either shared or exclusive lock. As file locks are JVM-scoped (so one JVM can obtain same file lock only once), the threads share file lock and synchronize according to it. Still, as file lock obtain operation does not block (or in other words, the method that does block cannot be controlled for how long it blocks), we are "simulating" thread blocking usingRetry
utility. This implementation performs coordination not only on thread (JVM-local) level, but also on process level, as long as other parties are using this same "advisory" locking mechanism.- Since:
- 1.7.3
-
-
Field Summary
Fields Modifier and Type Field Description private java.util.concurrent.locks.ReentrantLock
criticalRegion
Lock protecting "critical region": this is where threads are allowed to perform locking but should leave this region as quick as possible.private java.nio.channels.FileChannel
fileChannel
TheFileChannel
this instance is about.private java.util.concurrent.atomic.AtomicReference<java.nio.channels.FileLock>
fileLockRef
The reference ofFileLock
, if obtained.private static long
LOCK_POSITION
private static long
LOCK_SIZE
private static long
RETRY_SLEEP_MILLIS
private java.util.Map<java.lang.Thread,java.util.Deque<java.lang.Boolean>>
threadSteps
Thread -> steps stack (true = shared, false = exclusive)-
Fields inherited from class org.eclipse.aether.named.support.NamedLockSupport
logger
-
-
Constructor Summary
Constructors Constructor Description FileLockNamedLock(java.lang.String name, java.nio.channels.FileChannel fileChannel, NamedLockFactorySupport factory)
-
Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description private boolean
anyOtherThreadHasSteps()
Returnstrue
if any other than this thread using this instance has any step recorded.private java.lang.Boolean
doLockExclusively()
private java.lang.Boolean
doLockShared()
boolean
lockExclusively(long time, java.util.concurrent.TimeUnit unit)
Tries to lock exclusively, may block for given time.boolean
lockShared(long time, java.util.concurrent.TimeUnit unit)
Tries to lock shared, may block for given time.private java.nio.channels.FileLock
obtainFileLock(boolean shared)
Attempts to obtain realFileLock
, returns non-null value is succeeds, ornull
if cannot.void
unlock()
Unlocks the lock, must be invoked by caller after one of theNamedLock.lockShared(long, TimeUnit)
orNamedLock.lockExclusively(long, TimeUnit)
.-
Methods inherited from class org.eclipse.aether.named.support.NamedLockSupport
close, name
-
-
-
-
Field Detail
-
RETRY_SLEEP_MILLIS
private static final long RETRY_SLEEP_MILLIS
- See Also:
- Constant Field Values
-
LOCK_POSITION
private static final long LOCK_POSITION
- See Also:
- Constant Field Values
-
LOCK_SIZE
private static final long LOCK_SIZE
- See Also:
- Constant Field Values
-
threadSteps
private final java.util.Map<java.lang.Thread,java.util.Deque<java.lang.Boolean>> threadSteps
Thread -> steps stack (true = shared, false = exclusive)
-
fileChannel
private final java.nio.channels.FileChannel fileChannel
TheFileChannel
this instance is about.
-
fileLockRef
private final java.util.concurrent.atomic.AtomicReference<java.nio.channels.FileLock> fileLockRef
The reference ofFileLock
, if obtained.
-
criticalRegion
private final java.util.concurrent.locks.ReentrantLock criticalRegion
Lock protecting "critical region": this is where threads are allowed to perform locking but should leave this region as quick as possible.
-
-
Constructor Detail
-
FileLockNamedLock
public FileLockNamedLock(java.lang.String name, java.nio.channels.FileChannel fileChannel, NamedLockFactorySupport factory)
-
-
Method Detail
-
lockShared
public boolean lockShared(long time, java.util.concurrent.TimeUnit unit) throws java.lang.InterruptedException
Description copied from interface:NamedLock
Tries to lock shared, may block for given time. If successful, returnstrue
.- Throws:
java.lang.InterruptedException
-
lockExclusively
public boolean lockExclusively(long time, java.util.concurrent.TimeUnit unit) throws java.lang.InterruptedException
Description copied from interface:NamedLock
Tries to lock exclusively, may block for given time. If successful, returnstrue
.- Throws:
java.lang.InterruptedException
-
doLockShared
private java.lang.Boolean doLockShared()
-
doLockExclusively
private java.lang.Boolean doLockExclusively()
-
unlock
public void unlock()
Description copied from interface:NamedLock
Unlocks the lock, must be invoked by caller after one of theNamedLock.lockShared(long, TimeUnit)
orNamedLock.lockExclusively(long, TimeUnit)
.
-
anyOtherThreadHasSteps
private boolean anyOtherThreadHasSteps()
Returnstrue
if any other than this thread using this instance has any step recorded.
-
obtainFileLock
private java.nio.channels.FileLock obtainFileLock(boolean shared)
Attempts to obtain realFileLock
, returns non-null value is succeeds, ornull
if cannot.
-
-