net.openhft.chronicle.queue.impl

Interface TableStore<T extends Metadata>

All Superinterfaces:

AutoCloseable, Closeable, net.openhft.chronicle.bytes.CommonMarshallable, CommonStore, net.openhft.chronicle.wire.Demarshallable, net.openhft.chronicle.core.io.QueryCloseable, net.openhft.chronicle.wire.WriteMarshallable, net.openhft.chronicle.wire.WriteValue

All Known Implementing Classes:

ReadonlyTableStore, SingleTableStore

public interface TableStore<T extends Metadata>
extends CommonStore, net.openhft.chronicle.core.io.Closeable

Field Summary

Fields inherited from interface net.openhft.chronicle.wire.Demarshallable

DEMARSHALLABLES

Fields inherited from interface net.openhft.chronicle.wire.WriteMarshallable

EMPTY

Method Summary

Modifier and Type	Method and Description
default net.openhft.chronicle.core.values.LongValue	acquireValueFor(CharSequence key) Acquire LongValue mapped to underlying file, providing atomic operations on the value that is shared across threads and/or JVMs.
net.openhft.chronicle.core.values.LongValue	acquireValueFor(CharSequence key, long defaultValue)
<R> R	doWithExclusiveLock(Function<TableStore<T>,? extends R> code) Acquires file-system level lock on the underlying file, to prevent concurrent access from multiple processes.
<A> void	forEachKey(A accumulator, TableStoreIterator<A> tsIterator)
T	metadata()
default boolean	readOnly()

Methods inherited from interface net.openhft.chronicle.queue.impl.CommonStore

bytes, dump, file, shortDump

Methods inherited from interface net.openhft.chronicle.wire.Demarshallable

newInstance

Methods inherited from interface net.openhft.chronicle.wire.WriteMarshallable

usesSelfDescribingMessage, writeMarshallable, writeValue

Methods inherited from interface net.openhft.chronicle.core.io.Closeable

close, closeQuietly, closeQuietly, notifyClosing

Methods inherited from interface net.openhft.chronicle.core.io.QueryCloseable

isClosed, isClosing, throwExceptionIfClosed

Method Detail

acquireValueFor

default net.openhft.chronicle.core.values.LongValue acquireValueFor(CharSequence key)

Acquire LongValue mapped to underlying file, providing atomic operations on the value that is shared across threads and/or JVMs. Note: The implementation of this method is not required to guarantee that if the value does not exist in the file, it will create one and only one value in the file in case of concurrent access. On the contrary, it's possible that different threads or processes acquire LongValues pointing to different fields in the underlying file. To prevent this, it is advised to use doWithExclusiveLock(Function) to wrap calls to this method, which will ensure exclusive access to file while initially acquiring values. Additionally, if this call is not guarded with doWithExclusiveLock(Function) it may potentially overwrite incomplete records done by other instances leading to data corruption.

If the value isn't found, it is created with Long.MIN_VALUE value by default. To specify other default value, use acquireValueFor(CharSequence, long)

Parameters:

key - the key of the value

Returns:

LongValue object pointing to particular location in mapped underlying file

acquireValueFor

net.openhft.chronicle.core.values.LongValue acquireValueFor(CharSequence key,
                                                            long defaultValue)

forEachKey

<A> void forEachKey(A accumulator,
                    TableStoreIterator<A> tsIterator)

doWithExclusiveLock

<R> R doWithExclusiveLock(Function<TableStore<T>,? extends R> code)

Acquires file-system level lock on the underlying file, to prevent concurrent access from multiple processes. It is recommended to use this when acquiring your values for the first time, otherwise it is possible to get unpredictable results in case of multiple processes/threads trying to acquire values for the same key. In addition, it allows to batch multiple acquireValueFor(CharSequence) calls, to atomically acquire multiple values.

Type Parameters:

R - result type

Parameters:

code - code block to execute using locked table store

Returns:

result of code block execution

metadata

T metadata()

readOnly

default boolean readOnly()