Guava: Google Core Libraries for Java 32.1.2-jre · com.google.common.hash.LongAdder

One or more variables that together maintain an initially zero long sum. When updates (method add) are contended across threads, the set of variables may grow dynamically to reduce contention. Method sum (or, equivalently, longValue) returns the current total combined across the variables maintaining the sum.

This class is usually preferable to AtomicLong when multiple threads update a common sum that is used for purposes such as collecting statistics, not for fine-grained synchronization control. Under low update contention, the two classes have similar characteristics. But under high contention, expected throughput of this class is significantly higher, at the expense of higher space consumption.

This class extends Number, but does not define methods such as equals, hashCode and compareTo because instances are expected to be mutated, and so are not useful as collection keys.

JSR 166e Note

This class is targeted to be placed in java.util.concurrent.atomic.

Field Summary

Modifier and Type	Field and Description
private static final long	serialVersionUID Hides java.lang.Number.serialVersionUID.

Inherited from com.google.common.hash.Striped64:: base busy cells NCPU rng threadHashCode

Constructor Summary

Access	Constructor and Description
public	LongAdder() Creates a new adder with initial sum of zero.

Method Summary

Modifier and Type	Method and Description
public void	add(long the value to add x) Implements com.google.common.hash.LongAddable.add. Adds the given value.
public void	decrement() Equivalent to `add(-1)`.
public double	doubleValue() Implements abstract java.lang.Number.doubleValue. Returns the `sum` as a `double` after a widening primitive conversion.
public float	floatValue() Implements abstract java.lang.Number.floatValue. Returns the `sum` as a `float` after a widening primitive conversion.
pack-priv final long	fn(long the current value (of either base or a cell) v, long the argument from a user update call x) Implements abstract com.google.common.hash.Striped64.fn. Version of plus for use in retryUpdate
public void	increment() Implements com.google.common.hash.LongAddable.increment. Equivalent to `add(1)`.
public int	intValue() Implements abstract java.lang.Number.intValue. Returns the `sum` as an `int` after a narrowing primitive conversion.
public long	Returns: the sum longValue() Implements abstract java.lang.Number.longValue. Equivalent to `sum`.
private void	readObject(ObjectInputStream s)
public void	reset() Resets variables maintaining the sum to zero.
public long	Returns: the sum sum() Implements com.google.common.hash.LongAddable.sum. Returns the current sum.
public long	Returns: the sum sumThenReset() Equivalent in effect to `sum` followed by `reset`.
public String	Returns: the String representation of the `sum` toString() Overrides java.lang.Object.toString. Returns the String representation of the `sum`.
private void	writeObject(ObjectOutputStream s)

Inherited from com.google.common.hash.Striped64:: casBase casBusy internalReset retryUpdate

Field Detail

serialVersionUID	back to summary
private static final long serialVersionUID Hides java.lang.Number.serialVersionUID.

Constructor Detail

LongAdder	back to summary
public LongAdder() Creates a new adder with initial sum of zero.

Method Detail

add	back to summary
public void add(long x) Implements com.google.common.hash.LongAddable.add. Adds the given value. Parameters x:long the value to add Annotations @Override

add

back to summary

public void add(long x)

Implements com.google.common.hash.LongAddable.add.

Adds the given value.

Parameters

x:long: the value to add

Annotations

@Override

decrement	back to summary
public void decrement() Equivalent to `add(-1)`.

doubleValue back to summary

doubleValue	back to summary
public double doubleValue() Implements abstract java.lang.Number.doubleValue. Returns the `sum` as a `double` after a widening primitive conversion. Returns:double Doc from java.lang.Number.doubleValue. the numeric value represented by this object after conversion to type `double`. Annotations @Override

public double doubleValue()

Implements abstract java.lang.Number.doubleValue.

Returns the sum as a double after a widening primitive conversion.

Returns:double

Doc from java.lang.Number.doubleValue.

the numeric value represented by this object after conversion to type double.

Annotations

@Override

floatValue back to summary

floatValue	back to summary
public float floatValue() Implements abstract java.lang.Number.floatValue. Returns the `sum` as a `float` after a widening primitive conversion. Returns:float Doc from java.lang.Number.floatValue. the numeric value represented by this object after conversion to type `float`. Annotations @Override

public float floatValue()

Implements abstract java.lang.Number.floatValue.

Returns the sum as a float after a widening primitive conversion.

Returns:float

Doc from java.lang.Number.floatValue.

the numeric value represented by this object after conversion to type float.

Annotations

@Override

fn	back to summary
pack-priv final long fn(long v, long x) Implements abstract com.google.common.hash.Striped64.fn. Version of plus for use in retryUpdate Parameters v:long Doc from com.google.common.hash.Striped64.fn. the current value (of either base or a cell) x:long Doc from com.google.common.hash.Striped64.fn. the argument from a user update call Returns:long Doc from com.google.common.hash.Striped64.fn. result of the update function Annotations @Override

back to summary

pack-priv final long fn(long v, long x)

Implements abstract com.google.common.hash.Striped64.fn.

Version of plus for use in retryUpdate

Parameters

v:long

Doc from com.google.common.hash.Striped64.fn.

the current value (of either base or a cell)

x:long

Doc from com.google.common.hash.Striped64.fn.

the argument from a user update call

Returns:long

Doc from com.google.common.hash.Striped64.fn.

result of the update function

Annotations

@Override

increment back to summary

increment	back to summary
public void increment() Implements com.google.common.hash.LongAddable.increment. Equivalent to `add(1)`. Annotations @Override

public void increment()

Implements com.google.common.hash.LongAddable.increment.

Equivalent to add(1).

Annotations

@Override

intValue back to summary

intValue	back to summary
public int intValue() Implements abstract java.lang.Number.intValue. Returns the `sum` as an `int` after a narrowing primitive conversion. Returns:int Doc from java.lang.Number.intValue. the numeric value represented by this object after conversion to type `int`. Annotations @Override

public int intValue()

Implements abstract java.lang.Number.intValue.

Returns the sum as an int after a narrowing primitive conversion.

Returns:int

Doc from java.lang.Number.intValue.

the numeric value represented by this object after conversion to type int.

Annotations

@Override

longValue back to summary

longValue	back to summary
public long longValue() Implements abstract java.lang.Number.longValue. Equivalent to `sum`. Returns:long the sum Annotations @Override

public long longValue()

Implements abstract java.lang.Number.longValue.

Equivalent to sum.

Returns:long

the sum

Annotations

@Override

readObject	back to summary
private void readObject(ObjectInputStream s) throws IOException, ClassNotFoundException

reset	back to summary
public void reset() Resets variables maintaining the sum to zero. This method may be a useful alternative to creating a new adder, but is only effective if there are no concurrent updates. Because this method is intrinsically racy, it should only be used when it is known that no threads are concurrently updating.

sum	back to summary
public long sum() Implements com.google.common.hash.LongAddable.sum. Returns the current sum. The returned value is NOT an atomic snapshot; invocation in the absence of concurrent updates returns an accurate result, but concurrent updates that occur while the sum is being calculated might not be incorporated. Returns:long the sum Annotations @Override

sum

back to summary

public long sum()

Implements com.google.common.hash.LongAddable.sum.

Returns the current sum. The returned value is NOT an atomic snapshot; invocation in the absence of concurrent updates returns an accurate result, but concurrent updates that occur while the sum is being calculated might not be incorporated.

Returns:long

the sum

Annotations

@Override

sumThenReset back to summary

sumThenReset	back to summary
public long sumThenReset() Equivalent in effect to `sum` followed by `reset`. This method may apply for example during quiescent points between multithreaded computations. If there are updates concurrent with this method, the returned value is not guaranteed to be the final value occurring before the reset. Returns:long the sum

public long sumThenReset()

Equivalent in effect to sum followed by reset. This method may apply for example during quiescent points between multithreaded computations. If there are updates concurrent with this method, the returned value is not guaranteed to be the final value occurring before the reset.

Returns:long: the sum

toString back to summary

toString	back to summary
public String toString() Overrides java.lang.Object.toString. Returns the String representation of the `sum`. Returns:String the String representation of the `sum` Annotations @Override

public String toString()

Overrides java.lang.Object.toString.

Returns the String representation of the sum.

Returns:String

the String representation of the sum

Annotations

@Override

writeObject	back to summary
private void writeObject(ObjectOutputStream s) throws IOException

pack-priv final Class LongAdder

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail