com.github.ambry.store

Interface MessageReadSet

public interface MessageReadSet

This represents a list of messages from a given store.

Method Summary

Modifier and Type	Method and Description
int	count()
void	doPrefetch(int index, long relativeOffset, long size) Do data prefetch from store.
StoreKey	getKeyAt(int index) Returns the key of the ith message
long	sizeInBytes(int index) Returns the size of the ith message
void	writeTo(AsyncWritableChannel channel, Callback<java.lang.Long> callback) This method is intend to write prefetched data from MessageReadSet to AsyncWritableChannel.
long	writeTo(int index, java.nio.channels.WritableByteChannel channel, long relativeOffset, long maxSize) Write the message referred by the index in this set to the given channel from the given relative offset up to maxSize.

Method Detail

writeTo

long writeTo(int index,
             java.nio.channels.WritableByteChannel channel,
             long relativeOffset,
             long maxSize)
      throws java.io.IOException

Write the message referred by the index in this set to the given channel from the given relative offset up to maxSize. Less than the complete amount may be written, but no more than maxSize can be. The number of bytes written is returned

Parameters:

index - the index of the message in the set that needs to be written

channel - the channel into which the data needs to be written to

relativeOffset - The relative offset into the message from which the write needs to start

maxSize - The max size that needs to be written from the given message

Returns:

The total bytes that was written into the channel

Throws:

java.io.IOException

writeTo

void writeTo(AsyncWritableChannel channel,
             Callback<java.lang.Long> callback)

This method is intend to write prefetched data from MessageReadSet to AsyncWritableChannel. Data should be ready in memory(no blocking call) before write to AsyncWritableChannel asynchronously. Callback is called when the entire batch of writes succeeds or fails.

Parameters:

channel - the channel into which the data needs to be written to

callback - The callback when data is fully wrote to the channel.

count

int count()

Returns:

The total number of messages in this set

sizeInBytes

long sizeInBytes(int index)

Returns the size of the ith message

Parameters:

index - The index into the message set

Returns:

The size in bytes of the message represented by the index

getKeyAt

StoreKey getKeyAt(int index)

Returns the key of the ith message

Parameters:

index - The index into the message set

Returns:

The key of the message represented by the index

doPrefetch

void doPrefetch(int index,
                long relativeOffset,
                long size)
         throws java.io.IOException

Do data prefetch from store.

Parameters:

index - The index into the message set

relativeOffset - The relativeOffset to start with

size - The size requested to doPrefetch.

Throws:

java.io.IOException