java.lang.Object
- edu.caltech.nanodb.storage.StorageManager

```
public class StorageManager
extends java.lang.Object
```
The Storage Manager provides facilities for managing files of tuples, including in-memory buffering of data pages and support for transactions.

To Do:

This class requires synchronization, once we support multiple clients.

Field Summary

Fields
Modifier and Type	Field	Description
`private java.io.File`	`baseDir`	The base directory, in which all database files are stored.
`private BufferManager`	`bufferManager`	The buffer manager stores data pages in memory, to avoid disk IOs.
`private FileManager`	`fileManager`	The file manager performs basic operations against the filesystem, without performing any buffering whatsoever.
`private IndexManager`	`indexManager`
`private boolean`	`initialized`	A flag recording whether the Storage Manager instance has been initialized.
`private static org.apache.logging.log4j.Logger`	`logger`	A logging object for reporting anything interesting that happens.
`private NanoDBServer`	`server`	The database server that this storage manager is a part of.
`private TableManager`	`tableManager`
`private TransactionManager`	`transactionManager`	If transactions are enabled, this will be the transaction manager instance; otherwise, it will be `null`.
`private java.util.HashMap<DBFileType,TupleFileManager>`	`tupleFileManagers`	This mapping is used to keep track of the tuple-file managers for all the kinds of tuple-files we support.

Constructor Summary

Constructors
Constructor Description

StorageManager()

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`private void`	`closeDBFile(DBFile dbFile)`
`DBFile`	`createDBFile(java.lang.String filename, DBFileType type)`
`void`	`flushAllData()`	This method allows all data to be flushed from the Buffer Manager.
`java.io.File`	`getBaseDir()`	Returns the base directory where all database files are stored.
`BufferManager`	`getBufferManager()`
`FileManager`	`getFileManager()`
`IndexManager`	`getIndexManager()`
`NanoDBServer`	`getServer()`
`TableManager`	`getTableManager()`
`TransactionManager`	`getTransactionManager()`
`TupleFileManager`	`getTupleFileManager(DBFileType type)`	Returns the tuple-file manager for the specified file type.
`void`	`initialize(NanoDBServer server)`	This method initializes the storage manager.
`DBPage`	`loadDBPage(DBFile dbFile, int pageNo)`	This method returns a database page to use, retrieving it from the buffer manager if it is already loaded, or reading it from the specified data file if it is not already loaded.
`DBPage`	`loadDBPage(DBFile dbFile, int pageNo, boolean create)`	This method returns a database page to use, retrieving it from the buffer manager if it is already loaded, or reading it from the specified data file if it is not already loaded.
`void`	`logDBPageWrite(DBPage dbPage)`	This method causes any changes to the specified page to be logged by the transaction manager's write-ahead log, so that the changes can be redone or undone as may be appropriate.
`DBFile`	`openDBFile(java.lang.String filename)`
`TupleFile`	`openTupleFile(java.lang.String filename)`
`void`	`shutdown()`	This method shuts down the storage manager.

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

- Field Detail
  - logger
```
private static org.apache.logging.log4j.Logger logger
```
    A logging object for reporting anything interesting that happens.
  - server
```
private NanoDBServer server
```
    The database server that this storage manager is a part of. It provides a number of the components that the storage manager depends on, such as the event dispatcher and property registry.
  - baseDir
```
private java.io.File baseDir
```
    The base directory, in which all database files are stored.
  - initialized
```
private boolean initialized
```
    A flag recording whether the Storage Manager instance has been initialized.
  - bufferManager
```
private BufferManager bufferManager
```
    The buffer manager stores data pages in memory, to avoid disk IOs.
  - fileManager
```
private FileManager fileManager
```
    The file manager performs basic operations against the filesystem, without performing any buffering whatsoever.
  - transactionManager
```
private TransactionManager transactionManager
```
    If transactions are enabled, this will be the transaction manager instance; otherwise, it will be null.
  - tableManager
```
private TableManager tableManager
```
  - indexManager
```
private IndexManager indexManager
```
  - tupleFileManagers
```
private java.util.HashMap<DBFileType,TupleFileManager> tupleFileManagers
```
    This mapping is used to keep track of the tuple-file managers for all the kinds of tuple-files we support.
- Constructor Detail
  - StorageManager
```
public StorageManager()
```
- Method Detail
  - initialize
```
public void initialize(NanoDBServer server)
```
    This method initializes the storage manager. It should only be called once.
    
    Throws:
    
    StorageException - if
    
    java.lang.IllegalStateException - if init() has already been called
  - shutdown
```
public void shutdown()
```
    This method shuts down the storage manager. It should only be called once.
    
    Throws:
    
    java.lang.IllegalStateException - if init() has not been called
    
    StorageException - if the storage manager cannot save all data for some reason
  - getServer
```
public NanoDBServer getServer()
```
  - getBaseDir
```
public java.io.File getBaseDir()
```
    Returns the base directory where all database files are stored.
    
    Returns:
    
    the base directory where all database files are stored
  - getFileManager
```
public FileManager getFileManager()
```
  - getBufferManager
```
public BufferManager getBufferManager()
```
  - getTransactionManager
```
public TransactionManager getTransactionManager()
```
  - createDBFile
```
public DBFile createDBFile(java.lang.String filename,
                           DBFileType type)
```
  - openDBFile
```
public DBFile openDBFile(java.lang.String filename)
```
  - openTupleFile
```
public TupleFile openTupleFile(java.lang.String filename)
```
  - closeDBFile
```
private void closeDBFile(DBFile dbFile)
```
  - getTableManager
```
public TableManager getTableManager()
```
  - getIndexManager
```
public IndexManager getIndexManager()
```
  - getTupleFileManager
```
public TupleFileManager getTupleFileManager(DBFileType type)
```
    Returns the tuple-file manager for the specified file type.
    
    Parameters:
    
    type - the database file type to get the tuple-file manager for.
    
    Returns:
    
    the tuple-file manager instance for the specified file type
    
    Throws:
    
    java.lang.IllegalArgumentException - if the file-type is null, or if the file-type is currently unsupported.
  - loadDBPage
```
public DBPage loadDBPage(DBFile dbFile,
                         int pageNo,
                         boolean create)
```
    This method returns a database page to use, retrieving it from the buffer manager if it is already loaded, or reading it from the specified data file if it is not already loaded. If the page must be loaded from the file, it will be added to the buffer manager. This operation may cause other database pages to be evicted from the buffer manager, and written back to disk if the evicted pages are dirty.
    The create flag controls whether an error is propagated, if the requested page is past the current end of the data file. (Note that if a new page is created, the file's size will not reflect the new page until it is actually written to the file.)
    
    Parameters:
    
    dbFile - the database file to load the page from
    
    pageNo - the number of the page to load
    
    create - a flag specifying whether the page should be created if it doesn't already exist
    
    Returns:
    
    the database page (either from cache or from the data file), or null if the requested page is not in the data file and create is false.
    
    Throws:
    
    java.lang.IllegalArgumentException - if the page number is negative
  - loadDBPage
```
public DBPage loadDBPage(DBFile dbFile,
                         int pageNo)
```
    This method returns a database page to use, retrieving it from the buffer manager if it is already loaded, or reading it from the specified data file if it is not already loaded. If the page must be loaded from the file, it will be added to the buffer manager. This operation may cause other database pages to be evicted from the buffer manager, and written back to disk if the evicted pages are dirty.
    (This method is simply a wrapper of loadDBPage(DBFile, int, boolean), passing false for create.)
    
    Parameters:
    
    dbFile - the database file to load the page from
    
    pageNo - the number of the page to load
    
    Returns:
    
    the database page (either from cache or from the data file), or null if the requested page is not in the data file
    
    Throws:
    
    java.lang.IllegalArgumentException - if the page number is negative
  - logDBPageWrite
```
public void logDBPageWrite(DBPage dbPage)
```
    This method causes any changes to the specified page to be logged by the transaction manager's write-ahead log, so that the changes can be redone or undone as may be appropriate. Once the page's changes have been logged, the DBPage.syncOldPageData() method is called on the page, since the page's changes have been recorded in the WAL.
    
    Parameters:
    
    dbPage - the page to record changes for
  - flushAllData
```
public void flushAllData()
```
    This method allows all data to be flushed from the Buffer Manager. It should not be used in practice, but it is useful to remove buffering to expose performance issues in the storage layer.
    
    See Also:
    
    BufferManager.flushAll()

Class StorageManager

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

logger

server

baseDir

initialized

bufferManager

fileManager

transactionManager

tableManager

indexManager

tupleFileManagers

Constructor Detail

StorageManager

Method Detail

initialize

shutdown

getServer

getBaseDir

getFileManager

getBufferManager

getTransactionManager

createDBFile

openDBFile

openTupleFile

closeDBFile

getTableManager

getIndexManager

getTupleFileManager

loadDBPage

loadDBPage

logDBPageWrite

flushAllData