Examples of RWLock

com.lightcrafts.media.jai.util.RWLock
A class that provides a classic reader/writer lock functionality. This implementation is based on the JavaWorld article by Tark Modi titled "Lock on to an alternate synchronized mechanism" with some minor modifications.
This lock provides the following functionality :
- Allows multiple threads read access while only a single thread can have a write access.
- Allows a thread owning a read lock to "upgrade" to a write lock.
- Allows a thread owning a write lock to "downgrade" to a read lock.
- Allows the option to either block or specify a waitTime on certain requests.
com.pcmsolutions.util.RWLock
@author pmeehan
com.sun.media.jai.util.RWLock
A class that provides a classic reader/writer lock functionality. This implementation is based on the JavaWorld article by Tark Modi titled "Lock on to an alternate synchronized mechanism" with some minor modifications.
This lock provides the following functionality :
- Allows multiple threads read access while only a single thread can have a write access.
- Allows a thread owning a read lock to "upgrade" to a write lock.
- Allows a thread owning a write lock to "downgrade" to a read lock.
- Allows the option to either block or specify a waitTime on certain requests.
marauroa.server.RWLock
This class is a Reader/Writters lock A Reader Writer Lock is a synchronization mechanism allowing access to data.
It allows multiple threads to read the data simultaneously, but only one thread at a time to update it.
Controlling concurrent access to a shared, mutable resource is a classic problem. Clients request, and later release, either read-only or read-write access to the resource. To preserve consistency but minimize waiting, one usually wishes to allow either any number of readers or a single writer, but not both, to have access at any one time.
While a thread is updating, no other thread can read the data. The name is misleading. It may cause you to think there are two locks; in reality there is a single lock that restricts both reading and writing.
one.nio.lock.RWLock
org.jacorb.trading.util.RWLock
RWLock is a read-write lock; it allows multiple readers or a single writer; priority is given to writers
sil.spatialindex.RWLock

Examples of one.nio.lock.RWLock


    public void touch(K key) {
        long hashCode = hashCode(key);
        long currentPtr = bucketFor(hashCode);


        RWLock lock = lockFor(hashCode).lockRead();
        try {
            for (long entry; (entry = unsafe.getAddress(currentPtr)) != 0; currentPtr = entry + NEXT_OFFSET) {
                if (unsafe.getLong(entry + HASH_OFFSET) == hashCode && equalsAt(entry, key)) {
                    setTimeAt(entry);
                    return;
                }
            }
        } finally {
            lock.unlockRead();
        }
    }

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Examples of one.nio.lock.RWLock


    public Record<K, V> lockRecordForRead(K key) {
        long hashCode = hashCode(key);
        long currentPtr = bucketFor(hashCode);


        RWLock lock = lockFor(hashCode).lockRead();


        for (long entry; (entry = unsafe.getAddress(currentPtr)) != 0; currentPtr = entry + NEXT_OFFSET) {
            if (unsafe.getLong(entry + HASH_OFFSET) == hashCode && equalsAt(entry, key)) {
                if (isExpired(entry)) break;
                return new Record<K, V>(this, lock, entry);
            }
        }


        lock.unlockRead();
        return null;
    }

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Examples of one.nio.lock.RWLock


    public WritableRecord<K, V> lockRecordForWrite(K key, boolean create) {
        long hashCode = hashCode(key);
        long currentPtr = bucketFor(hashCode);


        RWLock lock = lockFor(hashCode).lockWrite();


        for (long entry; (entry = unsafe.getAddress(currentPtr)) != 0; currentPtr = entry + NEXT_OFFSET) {
            if (unsafe.getLong(entry + HASH_OFFSET) == hashCode && equalsAt(entry, key)) {
                return new WritableRecord<K, V>(this, lock, entry, key, currentPtr);
            }
        }


        if (create) {
            return new WritableRecord<K, V>(this, lock, 0, key, currentPtr);
        }


        lock.unlockWrite();
        return null;
    }

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Examples of one.nio.lock.RWLock

    public int removeExpired(long expirationAge) {
        int expired = 0;
        long expirationTime = System.currentTimeMillis() - expirationAge;


        for (int i = 0; i < CONCURRENCY_LEVEL; i++) {
            RWLock lock = locks[i];
            if (!lock.lockWrite(lockWaitTime)) {
                log.debug("Could not lock segment " + i + " for cleanup");
                continue;
            }


            try {
                for (int j = i; j < capacity; j += CONCURRENCY_LEVEL) {
                    long currentPtr = mapBase + (long) j * 8;
                    long nextEntry;
                    for (long entry = unsafe.getAddress(currentPtr); entry != 0; entry = nextEntry) {
                        nextEntry = unsafe.getAddress(entry + NEXT_OFFSET);
                        if (unsafe.getLong(entry + TIME_OFFSET) <= expirationTime) {
                            unsafe.putAddress(currentPtr, nextEntry);
                            evicted(entry);
                            destroyEntry(entry);
                            expired++;
                        } else {
                            currentPtr = entry + NEXT_OFFSET;
                        }
                    }
                }
            } finally {
                lock.unlockWrite();
            }
        }


        count.addAndGet(-expired);
        expirations.addAndGet(expired);

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Examples of one.nio.lock.RWLock


    public void clear() {
        int cleared = 0;


        for (int i = 0; i < CONCURRENCY_LEVEL; i++) {
            RWLock lock = locks[i].lockWrite();
            try {
                for (int j = i; j < capacity; j += CONCURRENCY_LEVEL) {
                    long currentPtr = mapBase + (long) j * 8;
                    long nextEntry;
                    for (long entry = unsafe.getAddress(currentPtr); entry != 0; entry = nextEntry) {
                        nextEntry = unsafe.getAddress(entry + NEXT_OFFSET);
                        destroyEntry(entry);
                        cleared++;
                    }
                    unsafe.putAddress(currentPtr, 0);
                }
            } finally {
                lock.unlockWrite();
            }
        }


        count.addAndGet(-cleared);
    }

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Examples of one.nio.lock.RWLock

    }


    private void iterate(Visitor<K, V> visitor, int taskNum, int taskCount) {
        for (int i = taskNum; i < capacity; i += taskCount) {
            long currentPtr = mapBase + (long) i * 8;
            RWLock lock = locks[i & (CONCURRENCY_LEVEL - 1)].lockRead();
            try {
                for (long entry; (entry = unsafe.getAddress(currentPtr)) != 0; currentPtr = entry + NEXT_OFFSET) {
                    visitor.visit(new Record<K, V>(this, lock, entry));
                }
            } finally {
                lock.unlockRead();
            }
        }
    }

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Examples of one.nio.lock.RWLock

    }


    private void iterate(WritableVisitor<K, V> visitor, int taskNum, int taskCount) {
        for (int i = taskNum; i < capacity; i += taskCount) {
            long currentPtr = mapBase + (long) i * 8;
            RWLock lock = locks[i & (CONCURRENCY_LEVEL - 1)].lockWrite();
            try {
                for (long entry; (entry = unsafe.getAddress(currentPtr)) != 0; ) {
                    WritableRecord<K, V> record = new WritableRecord<K, V>(this, lock, entry, keyAt(entry), currentPtr);
                    visitor.visit(record);
                    if (record.entry != 0) {
                        currentPtr = record.entry + NEXT_OFFSET;
                    }
                }
            } finally {
                lock.unlockWrite();
            }
        }
    }

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Examples of one.nio.lock.RWLock

            int samples = 0;
            int startBucket = random.nextInt(CONCURRENCY_LEVEL);
            int bucket = startBucket;


            do {
                RWLock lock = locks[bucket].lockRead();
                try {
                    for (int i = bucket; i < capacity; i += CONCURRENCY_LEVEL) {
                        long currentPtr = mapBase + (long) i * 8;
                        for (long entry; (entry = unsafe.getAddress(currentPtr)) != 0; currentPtr = entry + NEXT_OFFSET) {
                            timestamps[samples++] = unsafe.getLong(entry + TIME_OFFSET);
                            if (samples == timestamps.length) return samples;
                        }
                    }
                } finally {
                    lock.unlockRead();
                }
                bucket = (bucket + 1) & (CONCURRENCY_LEVEL - 1);
            } while (bucket != startBucket);


            return samples;

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Examples of one.nio.lock.RWLock

    }


    private static RWLock[] createLocks() {
        RWLock[] locks = new RWLock[CONCURRENCY_LEVEL];
        for (int i = 0; i < CONCURRENCY_LEVEL; i++) {
            locks[i] = new RWLock();
        }
        return locks;
    }

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Examples of one.nio.lock.RWLock


    public V get(K key) {
        long hashCode = hashCode(key);
        long currentPtr = bucketFor(hashCode);


        RWLock lock = lockFor(hashCode).lockRead();
        try {
            for (long entry; (entry = unsafe.getAddress(currentPtr)) != 0; currentPtr = entry + NEXT_OFFSET) {
                if (unsafe.getLong(entry + HASH_OFFSET) == hashCode && equalsAt(entry, key)) {
                    return isExpired(entry) ? null : valueAt(entry);
                }
            }
        } finally {
            lock.unlockRead();
        }


        return null;
    }

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