final class LongAdder extends Striped64 implements java.io.Serializable, LongAddable
long
sum. When updates
(method add(long)
) 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.
jsr166e note: This class is targeted to be placed in java.util.concurrent.atomic.
Striped64.Cell
Modifier and Type | Field and Description |
---|---|
private static long |
serialVersionUID |
Constructor and Description |
---|
LongAdder()
Creates a new adder with initial sum of zero.
|
Modifier and Type | Method and Description |
---|---|
void |
add(long x)
Adds the given value.
|
void |
decrement()
Equivalent to
add(-1) . |
double |
doubleValue()
Returns the
sum() as a double after a widening primitive conversion. |
float |
floatValue()
Returns the
sum() as a float after a widening primitive conversion. |
(package private) long |
fn(long v,
long x)
Version of plus for use in retryUpdate
|
void |
increment()
Equivalent to
add(1) . |
int |
intValue()
Returns the
sum() as an int after a narrowing primitive conversion. |
long |
longValue()
Equivalent to
sum() . |
private void |
readObject(java.io.ObjectInputStream s) |
void |
reset()
Resets variables maintaining the sum to zero.
|
long |
sum()
Returns the current sum.
|
long |
sumThenReset()
|
java.lang.String |
toString()
Returns the String representation of the
sum() . |
private void |
writeObject(java.io.ObjectOutputStream s) |
casBase, casBusy, internalReset, retryUpdate
private static final long serialVersionUID
final long fn(long v, long x)
public void add(long x)
add
in interface LongAddable
x
- the value to addpublic void increment()
add(1)
.increment
in interface LongAddable
public void decrement()
add(-1)
.public long sum()
sum
in interface LongAddable
public void reset()
public long sumThenReset()
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.public java.lang.String toString()
sum()
.toString
in class java.lang.Object
sum()
public long longValue()
sum()
.longValue
in class java.lang.Number
public int intValue()
sum()
as an int
after a narrowing primitive conversion.intValue
in class java.lang.Number
public float floatValue()
sum()
as a float
after a widening primitive conversion.floatValue
in class java.lang.Number
public double doubleValue()
sum()
as a double
after a widening primitive conversion.doubleValue
in class java.lang.Number
private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException
java.io.IOException
private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, java.lang.ClassNotFoundException
java.io.IOException
java.lang.ClassNotFoundException