org.iq80.leveldb.fileenv

Class EnvImpl

java.lang.Object

org.iq80.leveldb.fileenv.EnvImpl

All Implemented Interfaces:

Env

public class EnvImpl
extends Object
implements Env

Method Summary

Modifier and Type	Method and Description
static Env	createEnv()
static Env	createEnv(MmapLimiter mmapLimiter)
File	createTempDir(String prefix) Create a temporary directory in filesystem
WritableFile	newAppendableFile(File file) Create an WritableFile that either appends to an existing file, or writes to a new file (if the file does not exist to begin with).
Logger	newLogger(File loggerFile) Create and return a log file for storing informational messages.
RandomInputFile	newRandomAccessFile(File file) Create a brand new random access read-only file with the specified file name.
SequentialFile	newSequentialFile(File file) Create a brand new sequentially-readable file with the specified file name.
WritableFile	newWritableFile(File file) Create an object that writes to a new file with the specified name.
long	nowMicros()
String	readFileToString(File file) Read full file content to string
File	toFile(String filename) Transform a file name into a File instance scoped to this Env instance
DbLock	tryLock(File file) Attempts to acquire an exclusive lock on this file
void	writeStringToFileSync(File file, String content) Write content to file.

Methods inherited from class java.lang.Object

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

Method Detail

createEnv

public static Env createEnv()

createEnv

public static Env createEnv(MmapLimiter mmapLimiter)

nowMicros

public long nowMicros()

Specified by:

nowMicros in interface Env

toFile

public File toFile(String filename)

Description copied from interface: Env

Transform a file name into a File instance scoped to this Env instance

Specified by:

toFile in interface Env

Parameters:

filename - full file name

Returns:

File instance

createTempDir

public File createTempDir(String prefix)

Description copied from interface: Env

Create a temporary directory in filesystem

Specified by:

createTempDir in interface Env

Parameters:

prefix - prefix to use as name

Returns:

newly created directory

newSequentialFile

public SequentialFile newSequentialFile(File file)
                                 throws IOException

Description copied from interface: Env

Create a brand new sequentially-readable file with the specified file name.

Specified by:

newSequentialFile in interface Env

Returns:

new file that can only be accessed by one thread at a time.

Throws:

IOException - If the file does not exist or inaccessible.

newRandomAccessFile

public RandomInputFile newRandomAccessFile(File file)
                                    throws IOException

Description copied from interface: Env

Create a brand new random access read-only file with the specified file name.

Specified by:

newRandomAccessFile in interface Env

Returns:

new file that may be concurrently accessed by multiple threads.

Throws:

IOException - If the file does not exist or inaccessible.

newWritableFile

public WritableFile newWritableFile(File file)
                             throws IOException

Description copied from interface: Env

Create an object that writes to a new file with the specified name. Deletes any existing file with the same name and creates a new file.

Specified by:

newWritableFile in interface Env

Returns:

new file that can be accessed by one thread at a time.

Throws:

IOException - If the file not writable.

newAppendableFile

public WritableFile newAppendableFile(File file)
                               throws IOException

Description copied from interface: Env

Create an WritableFile that either appends to an existing file, or writes to a new file (if the file does not exist to begin with).

May return an IsNotSupportedError error if this Env does not allow appending to an existing file. Users of Env (including the leveldb implementation) must be prepared to deal with an Env that does not support appending. TODO

Specified by:

newAppendableFile in interface Env

Returns:

new or existing writable file only accessible by one thread at a time.

Throws:

IOException - If the file is inaccessible.

writeStringToFileSync

public void writeStringToFileSync(File file,
                                  String content)
                           throws IOException

Description copied from interface: Env

Write content to file. Replace existing content.

Specified by:

writeStringToFileSync in interface Env

Parameters:

file - file location

content - new content

Throws:

IOException - If the file not writable.

readFileToString

public String readFileToString(File file)
                        throws IOException

Description copied from interface: Env

Read full file content to string

Specified by:

readFileToString in interface Env

Parameters:

file - file location

Throws:

IOException - If the file not readable.

newLogger

public Logger newLogger(File loggerFile)
                 throws IOException

Description copied from interface: Env

Create and return a log file for storing informational messages.

Specified by:

newLogger in interface Env

Parameters:

loggerFile - logger file

Returns:

logger instance if file is writable, null otherwise

Throws:

IOException

tryLock

public DbLock tryLock(File file)
               throws IOException

Attempts to acquire an exclusive lock on this file

Specified by:

tryLock in interface Env

Parameters:

file - lock file

Returns:

releasable db lock

Throws:

IOException - If lock is already held or some other I/O error occurs