jsr166e
Class LongMaxUpdater
java.lang.Object
java.lang.Number
jsr166e.LongMaxUpdater
- All Implemented Interfaces:
- Serializable
public class LongMaxUpdater
- extends Number
- implements Serializable
One or more variables that together maintain a running long
maximum with initial value Long.MIN_VALUE
. When updates
(method update(long)
) are contended across threads, the set of
variables may grow dynamically to reduce contention. Method max()
(or, equivalently, longValue()
) returns the current
maximum across the variables maintaining updates.
This class extends Number
, but does not define
methods such as 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
- Since:
- 1.8
- Author:
- Doug Lea
- See Also:
- Serialized Form
Constructor Summary |
LongMaxUpdater()
Creates a new instance with initial maximum of Long.MIN_VALUE . |
Method Summary |
double |
doubleValue()
Returns the max() as a double after a widening
primitive conversion. |
float |
floatValue()
Returns the max() as a float
after a widening primitive conversion. |
int |
intValue()
Returns the max() as an int after a narrowing
primitive conversion. |
long |
longValue()
Equivalent to max() . |
long |
max()
Returns the current maximum. |
long |
maxThenReset()
Equivalent in effect to max() followed by reset() . |
void |
reset()
Resets variables maintaining updates to Long.MIN_VALUE . |
String |
toString()
Returns the String representation of the max() . |
void |
update(long x)
Updates the maximum to be at least the given value. |
LongMaxUpdater
public LongMaxUpdater()
- Creates a new instance with initial maximum of
Long.MIN_VALUE
.
update
public void update(long x)
- Updates the maximum to be at least the given value.
- Parameters:
x
- the value to update
max
public long max()
- Returns the current maximum. 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 value is being calculated might
not be incorporated.
- Returns:
- the maximum
reset
public void reset()
- Resets variables maintaining updates to
Long.MIN_VALUE
.
This method may be a useful alternative to creating a new
updater, 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.
maxThenReset
public long maxThenReset()
- Equivalent in effect to
max()
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:
- the maximum
toString
public String toString()
- Returns the String representation of the
max()
.
- Overrides:
toString
in class Object
- Returns:
- the String representation of the
max()
longValue
public long longValue()
- Equivalent to
max()
.
- Specified by:
longValue
in class Number
- Returns:
- the maximum
intValue
public int intValue()
- Returns the
max()
as an int
after a narrowing
primitive conversion.
- Specified by:
intValue
in class Number
floatValue
public float floatValue()
- Returns the
max()
as a float
after a widening primitive conversion.
- Specified by:
floatValue
in class Number
doubleValue
public double doubleValue()
- Returns the
max()
as a double
after a widening
primitive conversion.
- Specified by:
doubleValue
in class Number
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