AtomicCounter (Agrona)

java.lang.Object
- org.agrona.concurrent.status.AtomicCounter

All Implemented Interfaces:

AutoCloseable
```
public class AtomicCounter
extends Object
implements AutoCloseable
```
Atomic counter that is backed by an AtomicBuffer that can be read across threads and processes.

Constructor Summary

Constructors
Constructor and Description
`AtomicCounter(AtomicBuffer buffer, int counterId)` Map a counter over a buffer.
`AtomicCounter(AtomicBuffer buffer, int counterId, CountersManager countersManager)` Map a counter over a buffer.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`AtomicCounter`	`appendToLabel(String suffix)` Append to the label for a counter constructed with a `CountersManager`.
`void`	`close()` Close counter and free the counter slot for reuse of connected to `CountersManager`.
`boolean`	`compareAndSet(long expectedValue, long updateValue)` Compare the current value to expected and if true then set to the update value atomically.
`long`	`decrement()` Perform an atomic decrement that will not lose updates across threads.
`long`	`decrementOrdered()` Perform an atomic decrement that is not safe across threads.
`void`	`disconnectCountersManager()` Disconnect from `CountersManager` if allocated so it can be closed without freeing the slot.
`long`	`get()` Get the latest value for the counter with volatile semantics.
`long`	`getAndAdd(long increment)` Add an increment to the counter that will not lose updates across threads.
`long`	`getAndAddOrdered(long increment)` Add an increment to the counter with ordered store semantics.
`long`	`getAndSet(long value)` Get the current value of a counter and atomically set it to a new value.
`long`	`getWeak()` Get the value of the counter using weak ordering semantics.
`int`	`id()` Identity for the counter within the `CountersManager`.
`long`	`increment()` Perform an atomic increment that will not lose updates across threads.
`long`	`incrementOrdered()` Perform an atomic increment that is not safe across threads.
`boolean`	`isClosed()` Has this counter been closed?
`String`	`label()` Return the label for the counter within the `CountersManager`.
`boolean`	`proposeMax(long proposedValue)` Set the value to a new proposedValue if greater than the current value with memory ordering semantics.
`boolean`	`proposeMaxOrdered(long proposedValue)` Set the value to a new proposedValue if greater than the current value with memory ordering semantics.
`void`	`set(long value)` Set the counter with volatile semantics.
`void`	`setOrdered(long value)` Set the counter with ordered semantics.
`void`	`setWeak(long value)` Set the counter with normal semantics.
`String`	`toString()`
`void`	`updateKey(Consumer<MutableDirectBuffer> keyFunc)` Update the key for a counter constructed with a `CountersManager`.
`void`	`updateKey(DirectBuffer keyBuffer, int offset, int length)` Update the key for a counter constructed with a `CountersManager`.
`void`	`updateLabel(String newLabel)` Update the label for the counter constructed with a `CountersManager`.

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

- Constructor Detail
  - AtomicCounter
```
public AtomicCounter(AtomicBuffer buffer,
                     int counterId)
```
    Map a counter over a buffer. This version will NOT free the counter on close.
    
    Parameters:
    
    buffer - containing the counter.
    
    counterId - identifier of the counter.
  - AtomicCounter
```
public AtomicCounter(AtomicBuffer buffer,
                     int counterId,
                     CountersManager countersManager)
```
    Map a counter over a buffer. This version will free the counter on close.
    
    Parameters:
    
    buffer - containing the counter.
    
    counterId - identifier for the counter.
    
    countersManager - to be called to free the counter on close.
- Method Detail
  - id
```
public int id()
```
    Identity for the counter within the CountersManager.
    
    Returns:
    
    identity for the counter within the CountersManager.
  - disconnectCountersManager
```
public void disconnectCountersManager()
```
    Disconnect from CountersManager if allocated so it can be closed without freeing the slot.
  - close
```
public void close()
```
    Close counter and free the counter slot for reuse of connected to CountersManager.
    
    Specified by:
    
    close in interface AutoCloseable
  - isClosed
```
public boolean isClosed()
```
    Has this counter been closed?
    
    Returns:
    
    true if this counter has already been closed.
  - label
```
public String label()
```
    Return the label for the counter within the CountersManager.
    
    Returns:
    
    the label for the counter within the CountersManager.
  - updateLabel
```
public void updateLabel(String newLabel)
```
    Update the label for the counter constructed with a CountersManager.
    
    Parameters:
    
    newLabel - for the counter with a CountersManager.
    
    Throws:
    
    IllegalStateException - is not constructed CountersManager.
  - appendToLabel
```
public AtomicCounter appendToLabel(String suffix)
```
    Append to the label for a counter constructed with a CountersManager.
    
    Parameters:
    
    suffix - for the counter within a CountersManager.
    
    Returns:
    
    this for a fluent API.
    
    Throws:
    
    IllegalStateException - is not constructed CountersManager.
  - updateKey
```
public void updateKey(Consumer<MutableDirectBuffer> keyFunc)
```
    Update the key for a counter constructed with a CountersManager.
    
    Parameters:
    
    keyFunc - callback to use to update the counter's key
    
    Throws:
    
    IllegalStateException - is not constructed CountersManager.
  - updateKey
```
public void updateKey(DirectBuffer keyBuffer,
                      int offset,
                      int length)
```
    Update the key for a counter constructed with a CountersManager.
    
    Parameters:
    
    keyBuffer - contains key data to be copied into the counter.
    
    offset - start of the key data within the keyBuffer
    
    length - length of the data within the keyBuffer (must be <= CountersReader.MAX_KEY_LENGTH)
    
    Throws:
    
    IllegalStateException - is not constructed CountersManager.
  - increment
```
public long increment()
```
    Perform an atomic increment that will not lose updates across threads.
    
    Returns:
    
    the previous value of the counter
  - incrementOrdered
```
public long incrementOrdered()
```
    Perform an atomic increment that is not safe across threads.
    
    Returns:
    
    the previous value of the counter
  - decrement
```
public long decrement()
```
    Perform an atomic decrement that will not lose updates across threads.
    
    Returns:
    
    the previous value of the counter
  - decrementOrdered
```
public long decrementOrdered()
```
    Perform an atomic decrement that is not safe across threads.
    
    Returns:
    
    the previous value of the counter
  - set
```
public void set(long value)
```
    Set the counter with volatile semantics.
    
    Parameters:
    
    value - to be set with volatile semantics.
  - setOrdered
```
public void setOrdered(long value)
```
    Set the counter with ordered semantics.
    
    Parameters:
    
    value - to be set with ordered semantics.
  - setWeak
```
public void setWeak(long value)
```
    Set the counter with normal semantics.
    
    Parameters:
    
    value - to be set with normal semantics.
  - getAndAdd
```
public long getAndAdd(long increment)
```
    Add an increment to the counter that will not lose updates across threads.
    
    Parameters:
    
    increment - to be added.
    
    Returns:
    
    the previous value of the counter
  - getAndAddOrdered
```
public long getAndAddOrdered(long increment)
```
    Add an increment to the counter with ordered store semantics.
    
    Parameters:
    
    increment - to be added with ordered store semantics.
    
    Returns:
    
    the previous value of the counter
  - getAndSet
```
public long getAndSet(long value)
```
    Get the current value of a counter and atomically set it to a new value.
    
    Parameters:
    
    value - to be set.
    
    Returns:
    
    the previous value of the counter
  - compareAndSet
```
public boolean compareAndSet(long expectedValue,
                             long updateValue)
```
    Compare the current value to expected and if true then set to the update value atomically.
    
    Parameters:
    
    expectedValue - for the counter.
    
    updateValue - for the counter.
    
    Returns:
    
    true if successful otherwise false.
  - get
```
public long get()
```
    Get the latest value for the counter with volatile semantics.
    
    Returns:
    
    the latest value for the counter.
  - getWeak
```
public long getWeak()
```
    Get the value of the counter using weak ordering semantics. This is the same a standard read of a field.
    
    Returns:
    
    the value for the counter.
  - proposeMax
```
public boolean proposeMax(long proposedValue)
```
    Set the value to a new proposedValue if greater than the current value with memory ordering semantics.
    
    Parameters:
    
    proposedValue - for the new max.
    
    Returns:
    
    true if a new max as been set otherwise false.
  - proposeMaxOrdered
```
public boolean proposeMaxOrdered(long proposedValue)
```
    Set the value to a new proposedValue if greater than the current value with memory ordering semantics.
    
    Parameters:
    
    proposedValue - for the new max.
    
    Returns:
    
    true if a new max as been set otherwise false.
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object

Class AtomicCounter

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

AtomicCounter

AtomicCounter

Method Detail

id

disconnectCountersManager

close

isClosed

label

updateLabel

appendToLabel

updateKey

updateKey

increment

incrementOrdered

decrement

decrementOrdered

set

setOrdered

setWeak

getAndAdd

getAndAddOrdered

getAndSet

compareAndSet

get

getWeak

proposeMax

proposeMaxOrdered

toString