Added in [API level 31](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels) Summary: [Methods](https://developer.android.com/reference/android/os/PerformanceHintManager.Session#pubmethods) \| [Protected Methods](https://developer.android.com/reference/android/os/PerformanceHintManager.Session#promethods) \| [Inherited Methods](https://developer.android.com/reference/android/os/PerformanceHintManager.Session#inhmethods)
# PerformanceHintManager.Session
*** ** * ** ***
`
public
static
class
PerformanceHintManager.Session
`
`
extends https://developer.android.com/reference/java/lang/Object
`
`
implements
https://developer.android.com/reference/java/io/Closeable
`
|---|---|
| [java.lang.Object](https://developer.android.com/reference/java/lang/Object) ||
| ↳ | android.os.PerformanceHintManager.Session |
*** ** * ** ***
A Session represents a group of threads with an inter-related workload such that hints for
their performance should be considered as a unit. The threads in a given session should be
long-lived and not created or destroyed dynamically.
The work duration API can be used with periodic workloads to dynamically adjust thread
performance and keep the work on schedule while optimizing the available power budget.
When using the work duration API, the starting target duration should be specified
while creating the session, but can later be adjusted with
`https://developer.android.com/reference/android/os/PerformanceHintManager.Session#updateTargetWorkDuration(long)`. While using the work duration API, the client is be
expected to call `https://developer.android.com/reference/android/os/PerformanceHintManager.Session#reportActualWorkDuration(long)` each cycle to report the actual
time taken to complete to the system.
Any call in this class will change its internal data, so you must do your own thread
safety to protect from racing.
All timings should be in `https://developer.android.com/reference/android/os/SystemClock#uptimeNanos()`.
## Summary
| ### Public methods ||
|---|---|
| ` void` | ` https://developer.android.com/reference/android/os/PerformanceHintManager.Session#close()() ` Ends the current hint session. |
| ` void` | ` https://developer.android.com/reference/android/os/PerformanceHintManager.Session#reportActualWorkDuration(android.os.WorkDuration)(https://developer.android.com/reference/android/os/WorkDuration workDuration) ` Reports the work duration for the last cycle of work. |
| ` void` | ` https://developer.android.com/reference/android/os/PerformanceHintManager.Session#reportActualWorkDuration(long)(long actualDurationNanos) ` Reports the actual duration for the last cycle of work. |
| ` void` | ` https://developer.android.com/reference/android/os/PerformanceHintManager.Session#setPreferPowerEfficiency(boolean)(boolean enabled) ` This tells the session that these threads can be safely scheduled to prefer power efficiency over performance. |
| ` void` | ` https://developer.android.com/reference/android/os/PerformanceHintManager.Session#setThreads(int[])(int[] tids) ` Set a list of threads to the performance hint session. |
| ` void` | ` https://developer.android.com/reference/android/os/PerformanceHintManager.Session#updateTargetWorkDuration(long)(long targetDurationNanos) ` Updates this session's target total duration for each cycle of work. |
| ### Protected methods ||
|---|---|
| ` void` | ` https://developer.android.com/reference/android/os/PerformanceHintManager.Session#finalize()() ` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. |
### Inherited methods
From class `
https://developer.android.com/reference/java/lang/Object
` `
https://developer.android.com/reference/java/lang/Object` `
https://developer.android.com/reference/java/lang/Object#clone()()
`
Creates and returns a copy of this object.
`
boolean` `
https://developer.android.com/reference/java/lang/Object#equals(java.lang.Object)(https://developer.android.com/reference/java/lang/Object obj)
`
Indicates whether some other object is "equal to" this one.
`
void` `
https://developer.android.com/reference/java/lang/Object#finalize()()
`
Called by the garbage collector on an object when garbage collection
determines that there are no more references to the object.
`
final
https://developer.android.com/reference/java/lang/Class` `
https://developer.android.com/reference/java/lang/Object#getClass()()
`
Returns the runtime class of this `Object`.
`
int` `
https://developer.android.com/reference/java/lang/Object#hashCode()()
`
Returns a hash code value for the object.
`
final
void` `
https://developer.android.com/reference/java/lang/Object#notify()()
`
Wakes up a single thread that is waiting on this object's
monitor.
`
final
void` `
https://developer.android.com/reference/java/lang/Object#notifyAll()()
`
Wakes up all threads that are waiting on this object's monitor.
`
https://developer.android.com/reference/java/lang/String` `
https://developer.android.com/reference/java/lang/Object#toString()()
`
Returns a string representation of the object.
`
final
void` `
https://developer.android.com/reference/java/lang/Object#wait(long,%20int)(long timeoutMillis, int nanos)
`
Causes the current thread to wait until it is awakened, typically
by being *notified* or *interrupted*, or until a
certain amount of real time has elapsed.
`
final
void` `
https://developer.android.com/reference/java/lang/Object#wait(long)(long timeoutMillis)
`
Causes the current thread to wait until it is awakened, typically
by being *notified* or *interrupted*, or until a
certain amount of real time has elapsed.
`
final
void` `
https://developer.android.com/reference/java/lang/Object#wait()()
`
Causes the current thread to wait until it is awakened, typically
by being *notified* or *interrupted*.
From interface `
https://developer.android.com/reference/java/io/Closeable
` `
abstract
void` `
https://developer.android.com/reference/java/io/Closeable#close()()
`
Closes this stream and releases any system resources associated
with it.
From interface `
https://developer.android.com/reference/java/lang/AutoCloseable
` `
abstract
void` `
https://developer.android.com/reference/java/lang/AutoCloseable#close()()
`
Closes this resource, relinquishing any underlying resources.
## Public methods
### close
Added in [API level 31](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void close ()
```
Ends the current hint session.
Once called, you should not call anything else on this object.
### reportActualWorkDuration
Added in [API level 35](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void reportActualWorkDuration (WorkDuration workDuration)
```
Reports the work duration for the last cycle of work.
The system will attempt to adjust the core placement of the threads within the thread
group and/or the frequency of the core on which they are run to bring the actual duration
close to the target duration.
| Parameters ||
|---|---|
| `workDuration` | `WorkDuration`: the work duration of each component. This value cannot be `null`.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/IllegalArgumentException` | if the work period start timestamp or the total duration are less than or equal to zero, if either the actual CPU duration or actual GPU duration is less than zero, or if both the CPU and GPU durations are zero. |
### reportActualWorkDuration
Added in [API level 31](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void reportActualWorkDuration (long actualDurationNanos)
```
Reports the actual duration for the last cycle of work.
The system will attempt to adjust the core placement of the threads within the thread
group and/or the frequency of the core on which they are run to bring the actual duration
close to the target duration.
| Parameters ||
|---|---|
| `actualDurationNanos` | `long`: how long the thread group took to complete its last task in nanoseconds
|
### setPreferPowerEfficiency
Added in [API level 35](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void setPreferPowerEfficiency (boolean enabled)
```
This tells the session that these threads can be
safely scheduled to prefer power efficiency over performance.
| Parameters ||
|---|---|
| `enabled` | `boolean`: The flag that sets whether this session uses power-efficient scheduling.
|
### setThreads
Added in [API level 34](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void setThreads (int[] tids)
```
Set a list of threads to the performance hint session. This operation will replace
the current list of threads with the given list of threads.
Note that this is not an oneway method.
| Parameters ||
|---|---|
| `tids` | `int`: The list of threads to be associated with this session. They must be part of this app's thread group. This value cannot be `null`.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/IllegalArgumentException` | if the thread id list is empty |
| `https://developer.android.com/reference/java/lang/IllegalStateException` | if the hint session is not in the foreground |
| `https://developer.android.com/reference/java/lang/SecurityException` | if any thread id doesn't belong to the application |
### updateTargetWorkDuration
Added in [API level 31](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void updateTargetWorkDuration (long targetDurationNanos)
```
Updates this session's target total duration for each cycle of work.
| Parameters ||
|---|---|
| `targetDurationNanos` | `long`: the new desired duration in nanoseconds
|
## Protected methods
### finalize
Added in [API level 31](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
protected void finalize ()
```
Called by the garbage collector on an object when garbage collection
determines that there are no more references to the object.
A subclass overrides the `finalize` method to dispose of
system resources or to perform other cleanup.
The general contract of `finalize` is that it is invoked
if and when the Java virtual
machine has determined that there is no longer any
means by which this object can be accessed by any thread that has
not yet died, except as a result of an action taken by the
finalization of some other object or class which is ready to be
finalized. The `finalize` method may take any action, including
making this object available again to other threads; the usual purpose
of `finalize`, however, is to perform cleanup actions before
the object is irrevocably discarded. For example, the finalize method
for an object that represents an input/output connection might perform
explicit I/O transactions to break the connection before the object is
permanently discarded.
The `finalize` method of class `Object` performs no
special action; it simply returns normally. Subclasses of
`Object` may override this definition.
The Java programming language does not guarantee which thread will
invoke the `finalize` method for any given object. It is
guaranteed, however, that the thread that invokes finalize will not
be holding any user-visible synchronization locks when finalize is
invoked. If an uncaught exception is thrown by the finalize method,
the exception is ignored and finalization of that object terminates.
After the `finalize` method has been invoked for an object, no
further action is taken until the Java virtual machine has again
determined that there is no longer any means by which this object can
be accessed by any thread that has not yet died, including possible
actions by other objects or classes which are ready to be finalized,
at which point the object may be discarded.
The `finalize` method is never invoked more than once by a Java
virtual machine for any given object.
Any exception thrown by the `finalize` method causes
the finalization of this object to be halted, but is otherwise
ignored.
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/Throwable` | |