com.crankuptheamps.client

Class PublishStore

java.lang.Object

com.crankuptheamps.client.BlockPublishStore

com.crankuptheamps.client.PublishStore

All Implemented Interfaces:

Store, java.lang.AutoCloseable

public class PublishStore
extends BlockPublishStore

PublishStore is a memory-mapped file-backed store for storing outgoing messages. As messages are stored, space is allocated from a pre-created flat buffer on disk. As messages are discarded, space in that buffer is marked "free" for future store operations. If messages are stored faster than they are published, the buffer is re-sized to create more capacity. PublishStore helps in keeping track of unacknowledged messages. If messages are published at a rate exceeding the storage capacity, the buffer is resized to accommodate more messages.

The PublishStore class provides a robust foundation for implementing features such as tracking unacknowledged messages and ensuring message persistence.

Nested Class Summary

Nested classes/interfaces inherited from class com.crankuptheamps.client.BlockPublishStore

BlockPublishStore.Buffer, BlockPublishStore.ByteSequence

Nested classes/interfaces inherited from interface com.crankuptheamps.client.Store

Store.StoreReplayer

Field Summary

Fields inherited from class com.crankuptheamps.client.BlockPublishStore

_buffer, _errorOnPublishGap, _resizeHandler, AMPS_MIN_PUB_STORE_DISCARDED_VERSION, METADATA_LAST_DISCARDED_LOCATION, METADATA_VERSION_LOCATION

Fields inherited from interface com.crankuptheamps.client.Store

SOWDeleteByBookmark, SOWDeleteByBookmarkCancel, SOWDeleteByData, SOWDeleteByFilter, SOWDeleteByKeys

Constructor Summary

Constructors

Constructor and Description
PublishStore(java.lang.String path) Creates a new PublishStore with the given path.
PublishStore(java.lang.String path, int initialCapacity) Creates a new PublishStore with the given path.

Method Summary

Modifier and Type	Method and Description
void	close() Closes the memory mapped file.
protected void	finalize() Overridden to call close() upon garbage collection.
void	sync() Forces any in memory changes to be written to persistent storage.
void	truncateOnClose(boolean truncate) Tells the PublishStore to truncate the file to its original size if there are no saved Messages when it is closed.

Methods inherited from class com.crankuptheamps.client.BlockPublishStore

discardUpTo, flush, flush, getErrorOnPublishGap, getHighestUnpersisted, getLastPersisted, getLowestUnpersisted, growFreeListIfEmpty, recover, replay, replaySingle, setErrorOnPublishGap, setMessage, setResizeHandler, store, store, unpersistedCount

Methods inherited from class java.lang.Object

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

Constructor Detail

PublishStore

public PublishStore(java.lang.String path)
             throws StoreException

Creates a new PublishStore with the given path. Immediately proceeds to recovery if the file exists.

Parameters:

path - The path (absolute or relative) of the publish store

Throws:

StoreException - Thrown when an operation on the store fails.

PublishStore

public PublishStore(java.lang.String path,
                    int initialCapacity)
             throws StoreException

Creates a new PublishStore with the given path. Immediately proceeds to recovery if the file exists.

Parameters:

path - The path (absolute or relative) of the publish store

initialCapacity - The initial capacity (in 2k blocks) of the store. This size is also used when resizing the store: the store is resized by this value each time the store grows. A general guideline for initial capacity is to set the capacity to messages_published_per_second * int(average_message_size / block_size) + 1.

Throws:

StoreException - Thrown when an operation on the store fails.

Method Detail

truncateOnClose

public void truncateOnClose(boolean truncate)

Tells the PublishStore to truncate the file to its original size if there are no saved Messages when it is closed. This feature is not supported on Windows.

Parameters:

truncate - If true, file will be truncated when the PublishStore is closed.

close

public void close()
           throws java.lang.Exception

Closes the memory mapped file.

Specified by:

close in interface java.lang.AutoCloseable

Overrides:

close in class BlockPublishStore

Throws:

java.io.IOException - Thrown when an operation on the file produces an IOException.

java.lang.Exception - If an error occurs during the closing operation.

sync

public void sync()
          throws java.io.IOException

Forces any in memory changes to be written to persistent storage. This method ensures that any unsaved modifications are committed to the underlying file.

Throws:

java.io.IOException - Thrown when an operation on the file produces an IOException.

finalize

protected void finalize()
                 throws java.lang.Throwable

Overridden to call close() upon garbage collection.

Overrides:

finalize in class java.lang.Object

Throws:

java.lang.Throwable