public abstract class MappedBytes extends AbstractBytes<Void> implements net.openhft.chronicle.core.io.Closeable, net.openhft.chronicle.core.io.ManagedCloseable, net.openhft.chronicle.core.io.Syncable
AbstractBytes that wraps memory-mapped data for efficient random file access.
Memory is grouped in chunks of 64 MB by default. The chunk size can be significantly increased if the
OS supports sparse files via the OS.isSparseFileSupported() method, e.g. blockSize(512 << 30).
Only the most recently accessed memory chunk is reserved, and the previous chunk is released. For random access, a chunk can be manually reserved by obtaining the bytesStore() and using reserve(owner) on it. However, it is crucial to call release(owner) on the same BytesStore before closing the file to avoid memory leaks.
Several factory methods are provided to create different types of MappedBytes, including single mapped bytes and chunked mapped bytes, with optional settings for read-only mode and chunk overlap size.
Note: MappedBytes, like all Bytes, are single-threaded. Also, it is recommended to ensure the mapped file is reserved before using MappedBytes.
BytesStore,
MappedFile,
AbstractBytes| Modifier and Type | Field and Description |
|---|---|
protected static boolean |
TRACE |
bytesStore, DISABLE_THREAD_SAFETY, isPresent, readPosition, writeLimitreferenceCounted, WARN_COUNT, WARN_NSDEFAULT_BYTE_BUFFER_CAPACITY, MAX_CAPACITY, MAX_HEAP_CAPACITYcharToStringJAVA9_STRING_CODER_LATIN, JAVA9_STRING_CODER_UTF16| Modifier | Constructor and Description |
|---|---|
protected |
MappedBytes() |
protected |
MappedBytes(String name) |
| Modifier and Type | Method and Description |
|---|---|
@NotNull Bytes<Void> |
bytesForRead()
Provides a bytes object for read operations.
|
@NotNull Bytes<Void> |
bytesForWrite()
Provides a bytes object for write operations.
|
abstract void |
chunkCount(long[] chunkCount)
Updates the number of chunks in the mapped file.
|
abstract MappedBytes |
disableThreadSafetyCheck(boolean disableThreadSafetyCheck)
Deprecated.
|
abstract boolean |
isBackingFileReadOnly()
Checks if the backing file is read-only.
|
static @NotNull MappedBytes |
mappedBytes(@NotNull File file,
long chunkSize)
Creates a MappedBytes instance that wraps a memory-mapped file divided into chunks of a specified size.
|
static @NotNull MappedBytes |
mappedBytes(@NotNull File file,
long chunkSize,
long overlapSize)
Creates a MappedBytes instance that wraps a memory-mapped file divided into chunks of a specified size.
|
static @NotNull MappedBytes |
mappedBytes(@NotNull File file,
long chunkSize,
long overlapSize,
boolean readOnly)
Creates a MappedBytes instance that wraps a memory-mapped file divided into chunks of a specified size.
|
static @NotNull MappedBytes |
mappedBytes(@NotNull MappedFile rw)
Create a MappedBytes for a MappedFile
|
static @NotNull MappedBytes |
mappedBytes(@NotNull String filename,
long chunkSize)
Creates a MappedBytes instance that wraps a memory-mapped file divided into chunks of a specified size.
|
abstract MappedFile |
mappedFile()
Retrieves the mapped file.
|
static @NotNull MappedBytes |
readOnly(@NotNull File file)
Creates a MappedBytes instance that wraps a read-only memory-mapped file.
|
boolean |
sharedMemory()
Checks if the bytes are stored in shared memory.
|
static @NotNull MappedBytes |
singleMappedBytes(@NotNull File file,
long capacity)
Creates a MappedBytes instance that wraps a single memory-mapped file.
|
static @NotNull MappedBytes |
singleMappedBytes(@NotNull File file,
long capacity,
boolean readOnly)
Creates a MappedBytes instance that wraps a single memory-mapped file.
|
static @NotNull MappedBytes |
singleMappedBytes(@NotNull String filename,
long capacity)
Creates a MappedBytes instance that wraps a single memory-mapped file.
|
void |
sync()
Ensures that any modifications to this MappedBytes instance are written to the storage device containing the mapped file.
|
acquireUncheckedInput, addressForRead, addressForWrite, addressForWritePosition, append, append, append, append, append, append, appendAndReturnLength, byteCheckSum, byteCheckSum, byteCheckSum, bytesStore, bytesStore, canReadDirect, canWriteDirect, capacity, clear, clearAndPad, compact, compareAndSwapInt, compareAndSwapLong, copy, copyTo, decimaliser, decimaliser, equals, fpAppend0, fpAppend0, hashCode, internalNumberBuffer, isDirectMemory, isElastic, isImmutableEmptyByteStore, lastDecimalPlaces, lastDecimalPlaces, lastNumberHadDigits, lastNumberHadDigits, length, lenient, lenient, move, nativeRead, nativeWrite, peekUnsignedByte, peekUnsignedByte, performRelease, prewrite, prewrite, prewriteByte, prewriteInt, prewriteLong, prewriteOffsetPositionMoved, prewriteShort, read, read, readByte, readByte, readCheckOffset, readDouble, readDouble, readFloat, readFloat, readInt, readInt, readLimit, readLimit, readLong, readLong, readOffsetPositionMoved, readPosition, readPosition, readPositionForHeader, readShort, readShort, readSkip, readUnsignedByte, readUnsignedByte, readVolatileByte, readVolatileInt, readVolatileInt, readVolatileLong, readVolatileLong, readVolatileShort, realCapacity, safeCopySize, start, startsWith, testAndSetInt, toString, uncheckedReadSkipBackOne, uncheckedReadSkipOne, uncheckedReadUnsignedByte, uncheckedWritePosition, underlyingObject, write, write, write, write, write, write, write8bit, write8bit, write8bit, write8bit, writeBoolean, writeByte, writeByte, writeCheckOffset, writeDouble, writeDouble, writeDoubleAndInt, writeFloat, writeFloat, writeInt, writeInt, writeIntAdv, writeLimit, writeLimit, writeLong, writeLong, writeLongAdv, writeOffsetPositionMoved, writeOffsetPositionMoved, writeOrderedInt, writeOrderedInt, writeOrderedLong, writeOrderedLong, writePosition, writePosition, writeShort, writeShort, writeSkip, writeSome, writeVolatileByte, writeVolatileInt, writeVolatileLong, writeVolatileShortaddReferenceChangeListener, assertReferencesReleased, backgroundPerformRelease, canReleaseInBackground, clearUsedByThread, createdHere, disableReferenceTracing, enableReferenceTracing, refCount, referenceCountedUnmonitored, referenceId, release, releaseLast, removeReferenceChangeListener, reserve, reservedBy, reserveTransfer, singleThreadedCheckDisabled, singleThreadedCheckReset, threadSafetyCheck, throwExceptionIfNotReleased, throwExceptionIfReleased, tryReserve, unmonitor, warnAndReleaseIfNotReleasedclone, finalize, getClass, notify, notifyAll, wait, wait, waitcreatedHere, throwExceptionIfClosed, warnAndCloseIfNotClosedclose, closeQuietly, closeQuietlyallocateDirect, allocateDirect, allocateElasticDirect, allocateElasticDirect, allocateElasticOnHeap, allocateElasticOnHeap, copyTo, copyTo, directFrom, elasticByteBuffer, elasticByteBuffer, elasticByteBuffer, elasticHeapByteBuffer, elasticHeapByteBuffer, empty, ensureCapacity, forFieldGroup, from, from, fromDirect, fromHexString, indexOf, indexOf, isClear, isEqual, readMarshallableLength16, readWithLength, readWrite, safeLimit, toHexString, toHexString, toHexString, toString, toString, toString, unchecked, unchecked, unwrite, valueOf, wrapForRead, wrapForRead, wrapForWrite, wrapForWrite, write, writeMarshallableLength16addAndGetDouble, addAndGetDoubleNotAtomic, addAndGetFloat, addAndGetFloatNotAtomic, addAndGetInt, addAndGetIntNotAtomic, addAndGetLong, addAndGetShortNotAtomic, addAndGetUnsignedByteNotAtomic, charAt, cipher, cipher, compareAndSwapDouble, compareAndSwapFloat, contentEquals, elasticByteBuffer, endsWith, equalBytes, follow, forFields, from, hash, inside, inside, isEmpty, isEqual, lazyNativeBytesStoreWithFixedCapacity, nativePointer, nativeStore, nativeStoreFrom, nativeStoreWithFixedCapacity, startsWith, subSequence, to8bitString, toDebugString, toDebugString, wrap, wrap, wrap, writeMaxInt, writeMaxLong, zeroOutappend, append, write, write, writeBoolean, writeByte, writeInt24, writeOrderedDouble, writeOrderedFloat, writeUnsignedByte, writeUnsignedInt, writeUnsignedShort, writeUtf8, writeUtf8Limited, writeVolatileDouble, writeVolatileFloatchars, codePointsbytesMethodReader, bytesMethodReaderBuilder, readObjectcanReadDirect, compareUtf8, copyTo, createCharToString, fastHash, findByte, parseLong, peekVolatileInt, printable, readBoolean, readIncompleteLong, readUnsignedInt, readUnsignedInt24, readUnsignedShort, readUtf8, readUtf8Limited, readUtf8Limited, readVolatileDouble, readVolatileFloat, subBytes, toByteArray, toTemporaryDirectByteBufferparse8bit, parse8bit, parse8bit, parse8bit, parse8bit, parseBigDecimal, parseBoolean, parseBoolean, parseDouble, parseFlexibleLong, parseFloat, parseInt, parseLong, parseLongDecimal, parseUtf8, parseUtf8, parseUtf8, reader, skipToinputStream, parseHexLong, parseUtf8, parseUtf8, rawReadByte, rawReadInt, rawReadLong, read, read, read, read, read, read8bit, read8bit, read8bit, readBigDecimal, readBigInteger, readBoolean, readChar, readEnum, readHistogram, readIncompleteLong, readInt24, readLimitToCapacity, readPositionRemaining, readPositionUnlimited, readStopBit, readStopBitChar, readStopBitDecimal, readStopBitDouble, readUnsignedInt, readUnsignedInt24, readUnsignedShort, readUtf8, readUtf8, readUtf8, readUtf8, readWithLength, readWithLength, readWithLength0, unsafeRead, unsafeReadObject, unsafeReadObjectbytesMethodWriter, writeObjectappend, append, append, append, append, append8bit, append8bit, append8bit, append8bit, append8bit, appendBase, appendBase16, appendBase16, appendDateMillis, appendDecimal, appendTimeMillis, writerappendUtf8, appendUtf8, appendUtf8, appendUtf8, appendUtf8, appendUtf8, copyFrom, outputStream, rawWriteByte, rawWriteInt, rawWriteLong, unsafeWrite, unsafeWriteObject, unsafeWriteObject, write, write, write, write, write, write8bit, write8bit, write8bit, writeBigDecimal, writeBigInteger, writeChar, writeEnum, writeHistogram, writeInt24, writePositionForHeader, writePositionRemaining, writeSome, writeStopBit, writeStopBit, writeStopBit, writeStopBitDecimal, writeUnsignedByte, writeUnsignedInt, writeUnsignedInt24, writeUnsignedShort, writeUtf8, writeUtf8, writeWithLengthprependadjustHexDumpIndentation, retainedHexDumpDescription, writeHexDumpDescriptionprotected MappedBytes()
throws IllegalStateException
IllegalStateExceptionprotected MappedBytes(String name) throws IllegalStateException
IllegalStateException@NotNull public static @NotNull MappedBytes singleMappedBytes(@NotNull @NotNull String filename, long capacity) throws FileNotFoundException, IllegalStateException
filename - The name of the file to be memory-mapped.capacity - The maximum number of bytes that can be read from or written to the mapped file.FileNotFoundException - if the file does not exist.IllegalStateException - if there is an error while mapping the file.@NotNull public static @NotNull MappedBytes singleMappedBytes(@NotNull @NotNull File file, long capacity) throws FileNotFoundException, IllegalStateException
file - The name of the file to be memory-mapped.capacity - The maximum number of bytes that can be read from or written to the mapped file.FileNotFoundException - if the file does not exist.IllegalStateException - if there is an error while mapping the file.@NotNull public static @NotNull MappedBytes singleMappedBytes(@NotNull @NotNull File file, long capacity, boolean readOnly) throws FileNotFoundException, IllegalStateException
file - The name of the file to be memory-mapped.capacity - The maximum number of bytes that can be read from or written to the mapped file.readOnly - read only is true, read-write if falseFileNotFoundException - if the file does not exist.IllegalStateException - if there is an error while mapping the file.@NotNull public static @NotNull MappedBytes mappedBytes(@NotNull @NotNull String filename, long chunkSize) throws FileNotFoundException, IllegalStateException
filename - The name of the file to be memory-mapped.chunkSize - The size of each chunk in bytes.FileNotFoundException - if the file does not exist.IllegalStateException - if there is an error while mapping the file.@NotNull public static @NotNull MappedBytes mappedBytes(@NotNull @NotNull File file, long chunkSize) throws FileNotFoundException, IllegalStateException
file - The name of the file to be memory-mapped.chunkSize - The size of each chunk in bytes.FileNotFoundException - if the file does not exist.IllegalStateException - if there is an error while mapping the file.@NotNull public static @NotNull MappedBytes mappedBytes(@NotNull @NotNull File file, long chunkSize, long overlapSize) throws FileNotFoundException, IllegalStateException
file - The name of the file to be memory-mapped.chunkSize - The size of each chunk in bytes.overlapSize - The size of overlap of chunks in bytes.FileNotFoundException - if the file does not exist.IllegalStateException - if there is an error while mapping the file.@NotNull public static @NotNull MappedBytes mappedBytes(@NotNull @NotNull File file, long chunkSize, long overlapSize, boolean readOnly) throws FileNotFoundException, IllegalStateException
file - The name of the file to be memory-mapped.chunkSize - The size of each chunk in bytes.overlapSize - The size of overlap of chunks in bytes.readOnly - read only is true, read-write if falseFileNotFoundException - if the file does not exist.IllegalStateException - if there is an error while mapping the file.@NotNull public static @NotNull MappedBytes mappedBytes(@NotNull @NotNull MappedFile rw) throws IllegalStateException
rw - MappedFile to useIllegalStateException - if the MappedFile is closed or unusable.@NotNull public static @NotNull MappedBytes readOnly(@NotNull @NotNull File file) throws FileNotFoundException
file - The file to be memory-mapped in read-only mode.FileNotFoundException - if the file does not exist.public abstract boolean isBackingFileReadOnly()
public boolean sharedMemory()
sharedMemory in interface Bytes<Void>@Deprecated public abstract MappedBytes disableThreadSafetyCheck(boolean disableThreadSafetyCheck)
disableThreadSafetyCheck - true to disable the thread safety check, false to enable it.public abstract void chunkCount(long[] chunkCount)
chunkCount - The new number of chunks.public abstract MappedFile mappedFile()
public void sync()
sync in interface net.openhft.chronicle.core.io.Syncable@NotNull public @NotNull Bytes<Void> bytesForRead() throws IllegalStateException
bytesForRead in interface Bytes<Void>bytesForRead in interface BytesStore<Bytes<Void>,Void>IllegalStateException - if the MappedBytes instance has been released.@NotNull public @NotNull Bytes<Void> bytesForWrite() throws IllegalStateException
bytesForWrite in interface Bytes<Void>bytesForWrite in interface BytesStore<Bytes<Void>,Void>IllegalStateException - if the MappedBytes instance has been released.Copyright © 2023. All rights reserved.