com.bigdata.io.writecache

Class WriteCache.ReadCache

java.lang.Object

com.bigdata.io.writecache.WriteCache

com.bigdata.io.writecache.WriteCache.ReadCache

All Implemented Interfaces:

IWriteCache

Enclosing class:

WriteCache

public static class WriteCache.ReadCache
extends WriteCache

Nested Class Summary

Nested classes/interfaces inherited from class com.bigdata.io.writecache.WriteCache

WriteCache.FileChannelScatteredWriteCache, WriteCache.FileChannelWriteCache, WriteCache.HAPackage, WriteCache.ReadCache, WriteCache.RecordMetadata

Field Summary

Fields inherited from class com.bigdata.io.writecache.WriteCache

counters, log, recordMap

Constructor Summary

Constructors

Constructor and Description
WriteCache.ReadCache(IBufferAccess buf)

Method Summary

Methods

Modifier and Type	Method and Description
void	closeForWrites() Called from WriteCacheService to lock buffer content immediately prior to flushing and HA pipline replication.
boolean	isClosedForWrites() ReadCache is always closedForWrites
protected boolean	writeOnChannel(ByteBuffer buf, long firstOffset, Map<Long,WriteCache.RecordMetadata> recordMap, long nanos) Write the data from the buffer onto the channel.

Methods inherited from class com.bigdata.io.writecache.WriteCache

allocate, bytesWritten, capacity, close, contains, decrementReferenceCount, flush, flush, getCompressorKey, getCounters, getFileExtent, getLastOffset, getReferenceCount, incrementReferenceCount, read, registerWriteStatus, reset, resetRecordMapFromBuffer, resetRecordMapFromBuffer, setFileExtent, setFirstOffset, setRecordMap, toString, write

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

WriteCache.ReadCache

public WriteCache.ReadCache(IBufferAccess buf)
                     throws InterruptedException

Throws:

InterruptedException

Method Detail

writeOnChannel

protected boolean writeOnChannel(ByteBuffer buf,
                     long firstOffset,
                     Map<Long,WriteCache.RecordMetadata> recordMap,
                     long nanos)
                          throws InterruptedException,
                                 TimeoutException,
                                 IOException

Description copied from class: WriteCache

Write the data from the buffer onto the channel. This method provides a uniform means to request that the buffer write itself onto the backing channel, regardless of whether the channel is backed by a file, a socket, etc.

Implementations of this method MAY support gathered writes, depending on the channel. The necessary information to perform a gathered write is present in the recordMap. On the other hand, the implementation MAY require that the records in the cache are laid out for a WORM, in which case WriteCache.getFirstOffset() provides the starting offset for the data to be written. The application MUST coordinate the requirements for a R/W or WORM store with the use of the WriteCache and the means to write on the backing channel.

Specified by:

writeOnChannel in class WriteCache

Parameters:

buf - The data to be written. Only the dirty bytes are visible in this view. The implementation should write all bytes from the current position to the limit.

firstOffset - The offset of the first record in the recordMap into the file (may be relative to a base offset within the file). This is provided as an optimization for the WORM which writes its records contiguously on the backing store.

recordMap - The mapping of record offsets onto metadata about those records.

nanos - The timeout for the operation in nanoseconds.

Returns:

true if the operation was completed successfully within the time alloted.

Throws:

InterruptedException - if the thread was interrupted.

IOException - if there was an IO problem.

TimeoutException

isClosedForWrites

public boolean isClosedForWrites()

ReadCache is always closedForWrites

Overrides:

isClosedForWrites in class WriteCache

closeForWrites

public void closeForWrites()

Description copied from class: WriteCache

Called from WriteCacheService to lock buffer content immediately prior to flushing and HA pipline replication. Neither the internal buffer state nor the WriteCache.recordMap may be changed once the WriteCache has been closed for writes. This is necessary to provide 100% binary replication. Otherwise the stores can differ in the data in freed allocation slots.

Overrides:

closeForWrites in class WriteCache