MckoiObjectIOManager (The MoBIoS Library: Overview)

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mobios.util
Class MckoiObjectIOManager

java.lang.Object
  mobios.util.MckoiObjectIOManager

All Implemented Interfaces:: ObjectIOManager

public class MckoiObjectIOManager
extends Object
implements ObjectIOManager
extends Object
implements ObjectIOManager

An implementation of ObjectIOManager based on the Mckoi(http://www.mckoi.com/database) I/O mechanism. It is backed by a Store (defined in Mckoi), and is able to perform cached page-based I/O on a file on disk or in memory. The serialized form of an object is read from/written to the stream. In Mckoi, a Store manages a collection of Areas. In this class, each Area saves the serialized format of an Object. Therefore, an Object that can be read/written by this class should be serializable. For example, the following code creates a MckoiObjectIOManager that works on multiple disk files, using the new java.nio package, with cache and page-based access mechanism.

//Create a buffer manager, using java.nio mechanism, max page number:65536, page size:4096 bytes, you can also use java IO mechsnism, by providing "java IO", which is recommended:

BufferManager myBM = new BufferManager("Java NIO", 65536, 4096);

//Create a ScatteringFileStore, the disk files are on current directory, file names start with "test" if one file grows too big, it will be split, all files have extension names start from "0", max file size is 1G. The buffer manager is the one just created, and the files are in read/write mode If the last argument is true, then the file is read only:

Store myStore = new ScatteringFileStore("", "test", "0", 1024*1024*1024, myBM, false);

// create a MckoiObjectIOManager with the store instance just created

ObjectIOManager myManager = new MckoiObjectIOManager( mystore); if (myManger.open() == false) System.out.println("Error opening ObjectIOManager: myManager!");

Version:: 2005.11.01
Author:: Rui Mao

Constructor Summary
`MckoiObjectIOManager(Store store)` Constructor.
`MckoiObjectIOManager(String fileHeader, String fileExt, long fileSize, String bufferType, int cacheSize, int pageSize, boolean readOnly)` Constructor.

Method Summary
`void`	`close()` Closes the backing stream.
`void`	`flush()` Flushes the backing stream.
`Iterator`	`iterator()`
`boolean`	`open()` Opens the backing stream.
`Object`	`readObject(long pointer)` Reads a previously written object at a given position.
`Object`	`readPersistObject(long pointer)` Reads a previously written object at a given position, and holds this object in memory for the duration of the program.
`Object`	`removeObject(long pointer)` Deletes an object from the underlying stream.
`long`	`size()`
`long`	`writeObject(Object object)` Writes a new object to the underlying stream.
`Object`	`writeObject(Object object, long pointer)` Writes an object to a given position in the underlying stream.

Methods inherited from class java.lang.Object
`equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

MckoiObjectIOManager

public MckoiObjectIOManager(Store store)

Constructor.

Parameters:: store - the mckoi store to use as the backing store.

MckoiObjectIOManager

public MckoiObjectIOManager(String fileHeader,
                            String fileExt,
                            long fileSize,
                            String bufferType,
                            int cacheSize,
                            int pageSize,
                            boolean readOnly)

Constructor.

Parameters:: fileHeader - header of backing file names, may include the path; fileExt - extension name of backing files, normally use "000"; fileSize - max size of a backing file, if a file is not enough, more files will be used; bufferType - type of buffer, should be one of "Java NIO" or "Java IO"; cacheSize - max number of pages in the buffer, could be 2 if only iterate over the data once.; pageSize - size of a page, in number of bytes. normally use "4096", could be larger for sequential read / write, for example: 4M (4*1024*1024); readOnly - if true, the backing files are read only

Method Detail