WriterPool (webarchive-commons 1.1.9 API)

java.lang.Object
- org.archive.io.WriterPool

Direct Known Subclasses:

ARCWriterPool, WARCWriterPool
```
public abstract class WriterPool
extends java.lang.Object
```
Pool of Writers. Abstract. Override and pass in the Constructor a factory that creates WriterPoolMember implementations.

Author:

stack

Field Summary

Fields
Modifier and Type	Field and Description
`protected java.util.concurrent.BlockingQueue<WriterPoolMember>`	`availableWriters` round-robin queue of available writers
`protected int`	`currentActive` current count of active writers; only read/mutated in synchronized blocks
`static int`	`DEFAULT_MAX_ACTIVE` Default maximum active number of files in the pool.
`static int`	`DEFAULT_MAX_WAIT_FOR_IDLE` Maximum time to wait on a free file before considering making a new one (if not already at max)
`protected static int`	`LARGEST_MAX_ACTIVE` Assumed largest possible value of maxActive; pool will have this maximum capacity, so dynamic changes beyond this number won't work.
`protected long`	`lastWriterNeededTime` system time when writer was last wanted (because one was not ready in time)
`protected long`	`lastWriterRolloverTime` system time when writer was last 'rolled over' (imminent creation of new file)
`protected int`	`maxActive` maximum number of writers to create at a time
`protected int`	`maxWait` maximum ms to wait before considering creation of a writer
`protected java.util.concurrent.atomic.AtomicInteger`	`serialNo` Used to generate unique filename sequences.
`protected WriterPoolSettings`	`settings` File settings.

Constructor Summary

Constructors
Constructor and Description
`WriterPool(java.util.concurrent.atomic.AtomicInteger serial, WriterPoolSettings settings, int poolMaximumActive, int poolMaximumWait)` Constructor

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`WriterPoolMember`	`borrowFile()` Check out a `WriterPoolMember`.
`void`	`close()` Close all `WriterPoolMember`s in pool.
`void`	`destroyWriter(WriterPoolMember writer)` Discard a previously-used writer, cleanly closing it and leaving it out of the pool.
`protected java.util.Collection<WriterPoolMember>`	`drainAllWriters()` Drains all the active writers from `availableWriters`, blocking to wait for any writers currently in use to become available.
`void`	`flush()`
`int`	`getNumActive()`
`int`	`getNumIdle()`
`protected java.lang.String`	`getPoolState()`
`java.util.concurrent.atomic.AtomicInteger`	`getSerialNo()` Returns the atomic integer used to generate serial numbers for files.
`WriterPoolSettings`	`getSettings()`
`void`	`invalidateFile(WriterPoolMember f)` Close and discard a writer that experienced a potentially-corrupting error.
`org.json.JSONArray`	`jsonStatus()`
`protected WriterPoolMember`	`makeNewWriterIfAppropriate()` Create a new writer instance, if still below maxActive count.
`protected abstract WriterPoolMember`	`makeWriter()`
`void`	`returnFile(WriterPoolMember writer)` Return a writer, for likely reuse unless (1) writer's current file has reached its target size; and (2) there's been no demand for additional writers since the last time a new writer-file was rolled-over.

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

- Field Detail
  - serialNo
```
protected final java.util.concurrent.atomic.AtomicInteger serialNo
```
    Used to generate unique filename sequences.
  - DEFAULT_MAX_ACTIVE
```
public static final int DEFAULT_MAX_ACTIVE
```
    Default maximum active number of files in the pool.
    
    See Also:
    
    Constant Field Values
  - LARGEST_MAX_ACTIVE
```
protected static final int LARGEST_MAX_ACTIVE
```
    Assumed largest possible value of maxActive; pool will have this maximum capacity, so dynamic changes beyond this number won't work.
    
    See Also:
    
    Constant Field Values
  - DEFAULT_MAX_WAIT_FOR_IDLE
```
public static final int DEFAULT_MAX_WAIT_FOR_IDLE
```
    Maximum time to wait on a free file before considering making a new one (if not already at max)
    
    See Also:
    
    Constant Field Values
  - settings
```
protected final WriterPoolSettings settings
```
    File settings. Keep in data structure rather than as individual values.
  - maxActive
```
protected int maxActive
```
    maximum number of writers to create at a time
  - maxWait
```
protected int maxWait
```
    maximum ms to wait before considering creation of a writer
  - currentActive
```
protected int currentActive
```
    current count of active writers; only read/mutated in synchronized blocks
  - availableWriters
```
protected java.util.concurrent.BlockingQueue<WriterPoolMember> availableWriters
```
    round-robin queue of available writers
  - lastWriterNeededTime
```
protected long lastWriterNeededTime
```
    system time when writer was last wanted (because one was not ready in time)
  - lastWriterRolloverTime
```
protected long lastWriterRolloverTime
```
    system time when writer was last 'rolled over' (imminent creation of new file)
- Constructor Detail
  - WriterPool
```
public WriterPool(java.util.concurrent.atomic.AtomicInteger serial,
                  WriterPoolSettings settings,
                  int poolMaximumActive,
                  int poolMaximumWait)
```
    Constructor
    
    Parameters:
    
    serial - Used to generate unique filename sequences
    
    factory - Factory that knows how to make a WriterPoolMember.
    
    settings - Settings for this pool.
    
    poolMaximumActive -
    
    poolMaximumWait -
- Method Detail
  - borrowFile
```
public WriterPoolMember borrowFile()
                            throws java.io.IOException
```
    Check out a WriterPoolMember. This method should be followed by a call to returnFile(WriterPoolMember) or invalidateFile(WriterPoolMember) else pool starts leaking.
    
    Returns:
    
    Writer checked out of a pool of files or created
    
    Throws:
    
    java.io.IOException - Problem getting Writer from pool (Converted from Exception to IOException so this pool can live as a good citizen down in depths of ARCSocketFactory).
  - makeNewWriterIfAppropriate
```
protected WriterPoolMember makeNewWriterIfAppropriate()
```
    Create a new writer instance, if still below maxActive count. Remember times to help make later decision when writer should be discarded.
    
    Returns:
    
    WriterPoolMember or null if already at max
  - makeWriter
```
protected abstract WriterPoolMember makeWriter()
```
    Returns:
    
    new WriterPoolMember of appropriate type
  - destroyWriter
```
public void destroyWriter(WriterPoolMember writer)
                   throws java.io.IOException
```
    Discard a previously-used writer, cleanly closing it and leaving it out of the pool.
    
    Parameters:
    
    writer -
    
    Throws:
    
    java.io.IOException
  - returnFile
```
public void returnFile(WriterPoolMember writer)
                throws java.io.IOException
```
    Return a writer, for likely reuse unless (1) writer's current file has reached its target size; and (2) there's been no demand for additional writers since the last time a new writer-file was rolled-over. In that case, the possibly-superfluous writer instance is discarded.
    
    Parameters:
    
    writer - Writer to return to the pool.
    
    Throws:
    
    java.io.IOException - Problem returning File to pool.
  - invalidateFile
```
public void invalidateFile(WriterPoolMember f)
                    throws java.io.IOException
```
    Close and discard a writer that experienced a potentially-corrupting error.
    
    Parameters:
    
    f - writer with problem
    
    Throws:
    
    java.io.IOException
  - getNumActive
```
public int getNumActive()
                 throws java.lang.UnsupportedOperationException
```
    Returns:
    
    Number of WriterPoolMembers checked out of pool.
    
    Throws:
    
    java.lang.UnsupportedOperationException
  - getNumIdle
```
public int getNumIdle()
               throws java.lang.UnsupportedOperationException
```
    Returns:
    
    Number of WriterPoolMember instances still in the pool.
    
    Throws:
    
    java.lang.UnsupportedOperationException
  - close
```
public void close()
```
    Close all WriterPoolMembers in pool.
  - getSettings
```
public WriterPoolSettings getSettings()
```
    Returns:
    
    Returns settings.
  - getPoolState
```
protected java.lang.String getPoolState()
```
    Returns:
    
    State of the pool string
  - getSerialNo
```
public java.util.concurrent.atomic.AtomicInteger getSerialNo()
```
    Returns the atomic integer used to generate serial numbers for files.
    
    Returns:
    
    the serial number generator
  - drainAllWriters
```
protected java.util.Collection<WriterPoolMember> drainAllWriters()
```
    Drains all the active writers from availableWriters, blocking to wait for any writers currently in use to become available.
    When finished with writers, call availableWriters.addAll(...) to put them back into the rotation.
    
    Returns:
    
    all the active writers
  - flush
```
public void flush()
```
  - jsonStatus
```
public org.json.JSONArray jsonStatus()
                              throws org.json.JSONException
```
    Throws:
    
    org.json.JSONException

Class WriterPool

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

serialNo

DEFAULT_MAX_ACTIVE

LARGEST_MAX_ACTIVE

DEFAULT_MAX_WAIT_FOR_IDLE

settings

maxActive

maxWait

currentActive

availableWriters

lastWriterNeededTime

lastWriterRolloverTime

Constructor Detail

WriterPool

Method Detail

borrowFile

makeNewWriterIfAppropriate

makeWriter

destroyWriter

returnFile

invalidateFile

getNumActive

getNumIdle

close

getSettings

getPoolState

getSerialNo

drainAllWriters

flush

jsonStatus