Storage.StorageDirectory (Hadoop 1.2.2-SNAPSHOT API)

java.lang.Object
- org.apache.hadoop.hdfs.server.common.Storage.StorageDirectory

封闭类:: Storage

public class Storage.StorageDirectory
extends Object

One of the storage directories.

构造器概要

构造器
构造器和说明

Storage.StorageDirectory(File dir)

Storage.StorageDirectory(File dir, Storage.StorageDirType dirType)

构造器
构造器和说明
`Storage.StorageDirectory(File dir)`
`Storage.StorageDirectory(File dir, Storage.StorageDirType dirType)`

方法概要

方法
限定符和类型	方法和说明
`Storage.StorageState`	`analyzeStorage(HdfsConstants.StartupOption startOpt)` Check consistency of the storage directory
`void`	`clearDirectory()` Clear and re-create storage directory.
`void`	`doRecover(Storage.StorageState curState)` Complete or recover storage state from previously failed transition.
`File`	`getCurrentDir()` Directory `current` contains latest files defining the file system meta-data.
`File`	`getFinalizedTmp()` `finalized.tmp` is a transient directory, which holds the `previous` file system state while it is being removed in response to the finalize request.
`File`	`getLastCheckpointTmp()` `lastcheckpoint.tmp` is a transient directory, which holds current file system state while the new state is saved into the new `current` during regular namespace updates.
`File`	`getPreviousCheckpoint()` `previous.checkpoint` is a directory, which holds the previous (before the last save) state of the storage directory.
`File`	`getPreviousDir()` Directory `previous` contains the previous file system state, which the system can be rolled back to.
`File`	`getPreviousTmp()` `previous.tmp` is a transient directory, which holds current file system state while the new state is saved into the new `current` during upgrade.
`File`	`getPreviousVersionFile()` File `VERSION` from the `previous` directory.
`File`	`getRemovedTmp()` `removed.tmp` is a transient directory, which holds current file system state while the previous state is moved into `current` during rollback.
`File`	`getRoot()` Get root directory of this storage
`Storage.StorageDirType`	`getStorageDirType()` Get storage directory type
`File`	`getVersionFile()` File `VERSION` contains the following fields: node type layout version namespaceID fs state creation time other fields specific for this node type The version file is always written last during storage directory updates.
`void`	`lock()` Lock storage to provide exclusive access.
`void`	`read()` Read version file.
`void`	`read(File from)`
`void`	`unlock()` Unlock storage.
`void`	`write()` Write version file.
`void`	`write(File to)`

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- 构造器详细资料
  - Storage.StorageDirectory
```
public Storage.StorageDirectory(File dir)
```
  - Storage.StorageDirectory
```
public Storage.StorageDirectory(File dir,
                        Storage.StorageDirType dirType)
```
- 方法详细资料
  - getRoot
```
public File getRoot()
```
    Get root directory of this storage
  - getStorageDirType
```
public Storage.StorageDirType getStorageDirType()
```
    Get storage directory type
  - read
```
public void read()
          throws IOException
```
    Read version file.
    
    抛出:
    
    IOException - if file cannot be read or contains inconsistent data
  - read
```
public void read(File from)
          throws IOException
```
    抛出:
    
    IOException
  - write
```
public void write()
           throws IOException
```
    Write version file.
    
    抛出:
    
    IOException
  - write
```
public void write(File to)
           throws IOException
```
    抛出:
    
    IOException
  - clearDirectory
```
public void clearDirectory()
                    throws IOException
```
    Clear and re-create storage directory.
    Removes contents of the current directory and creates an empty directory. This does not fully format storage directory. It cannot write the version file since it should be written last after all other storage type dependent files are written. Derived storage is responsible for setting specific storage values and writing the version file to disk.
    
    抛出:
    
    IOException
  - getCurrentDir
```
public File getCurrentDir()
```
    Directory current contains latest files defining the file system meta-data.
    
    返回:
    the directory path
  - getVersionFile
```
public File getVersionFile()
```
    File VERSION contains the following fields:
    1. node type
    2. layout version
    3. namespaceID
    4. fs state creation time
    5. other fields specific for this node type
    The version file is always written last during storage directory updates. The existence of the version file indicates that all other files have been successfully written in the storage directory, the storage is valid and does not need to be recovered.
    返回:
    the version file path
  - getPreviousVersionFile
```
public File getPreviousVersionFile()
```
    File VERSION from the previous directory.
    
    返回:
    the previous version file path
  - getPreviousDir
```
public File getPreviousDir()
```
    Directory previous contains the previous file system state, which the system can be rolled back to.
    
    返回:
    the directory path
  - getPreviousTmp
```
public File getPreviousTmp()
```
    previous.tmp is a transient directory, which holds current file system state while the new state is saved into the new current during upgrade. If the saving succeeds previous.tmp will be moved to previous, otherwise it will be renamed back to current by the recovery procedure during startup.
    
    返回:
    the directory path
  - getRemovedTmp
```
public File getRemovedTmp()
```
    removed.tmp is a transient directory, which holds current file system state while the previous state is moved into current during rollback. If the moving succeeds removed.tmp will be removed, otherwise it will be renamed back to current by the recovery procedure during startup.
    
    返回:
    the directory path
  - getFinalizedTmp
```
public File getFinalizedTmp()
```
    finalized.tmp is a transient directory, which holds the previous file system state while it is being removed in response to the finalize request. Finalize operation will remove finalized.tmp when completed, otherwise the removal will resume upon the system startup.
    
    返回:
    the directory path
  - getLastCheckpointTmp
```
public File getLastCheckpointTmp()
```
    lastcheckpoint.tmp is a transient directory, which holds current file system state while the new state is saved into the new current during regular namespace updates. If the saving succeeds lastcheckpoint.tmp will be moved to previous.checkpoint, otherwise it will be renamed back to current by the recovery procedure during startup.
    
    返回:
    the directory path
  - getPreviousCheckpoint
```
public File getPreviousCheckpoint()
```
    previous.checkpoint is a directory, which holds the previous (before the last save) state of the storage directory. The directory is created as a reference only, it does not play role in state recovery procedures, and is recycled automatically, but it may be useful for manual recovery of a stale state of the system.
    
    返回:
    the directory path
  - analyzeStorage
```
public Storage.StorageState analyzeStorage(HdfsConstants.StartupOption startOpt)
                                    throws IOException
```
    Check consistency of the storage directory
    
    参数:
    startOpt - a startup option.
    
    返回:
    state Storage.StorageState of the storage directory
    
    抛出:
    
    InconsistentFSStateException - if directory state is not consistent and cannot be recovered.
    
    IOException
  - doRecover
```
public void doRecover(Storage.StorageState curState)
               throws IOException
```
    Complete or recover storage state from previously failed transition.
    
    参数:
    curState - specifies what/how the state should be recovered
    
    抛出:
    
    IOException
  - lock
```
public void lock()
          throws IOException
```
    Lock storage to provide exclusive access.
    Locking is not supported by all file systems. E.g., NFS does not consistently support exclusive locks.
    If locking is supported we guarantee exculsive access to the storage directory. Otherwise, no guarantee is given.
    
    抛出:
    
    IOException - if locking fails
  - unlock
```
public void unlock()
            throws IOException
```
    Unlock storage.
    
    抛出:
    
    IOException

类 Storage.StorageDirectory

构造器概要

方法概要

从类继承的方法 java.lang.Object

构造器详细资料

Storage.StorageDirectory

Storage.StorageDirectory

方法详细资料

getRoot

getStorageDirType

read

read

write

write

clearDirectory

getCurrentDir

getVersionFile

getPreviousVersionFile

getPreviousDir

getPreviousTmp

getRemovedTmp

getFinalizedTmp

getLastCheckpointTmp

getPreviousCheckpoint

analyzeStorage

doRecover

lock

unlock