Session
class Session : Closeable
| kotlin.Any | |
| ↳ | 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 updateTargetWorkDuration(long). While using the work duration API, the client is be expected to call 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 SystemClock.uptimeNanos().
Summary
| Public methods | |
|---|---|
| open Unit |
close()Ends the current hint session. |
| open Unit |
reportActualWorkDuration(workDuration: WorkDuration)Reports the work duration for the last cycle of work. |
| open Unit |
reportActualWorkDuration(actualDurationNanos: Long)Reports the actual duration for the last cycle of work. |
| open Unit |
setPreferPowerEfficiency(enabled: Boolean)This tells the session that these threads can be safely scheduled to prefer power efficiency over performance. |
| open Unit |
setThreads(tids: IntArray)Set a list of threads to the performance hint session. |
| open Unit |
updateTargetWorkDuration(targetDurationNanos: Long)Updates this session's target total duration for each cycle of work. |
Public methods
close
open fun close(): Unit
Ends the current hint session. Once called, you should not call anything else on this object.
| Exceptions | |
|---|---|
java.lang.Exception |
if this resource cannot be closed |
java.io.IOException |
if an I/O error occurs |
reportActualWorkDuration
open fun reportActualWorkDuration(workDuration: WorkDuration): Unit
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. |
| Exceptions | |
|---|---|
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
open fun reportActualWorkDuration(actualDurationNanos: Long): Unit
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
open fun setPreferPowerEfficiency(enabled: Boolean): Unit
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
open fun setThreads(tids: IntArray): Unit
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 |
IntArray: 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. |
| Exceptions | |
|---|---|
java.lang.IllegalStateException |
if the hint session is not in the foreground |
java.lang.IllegalArgumentException |
if the thread id list is empty |
java.lang.SecurityException |
if any thread id doesn't belong to the application |
updateTargetWorkDuration
open fun updateTargetWorkDuration(targetDurationNanos: Long): Unit
Updates this session's target total duration for each cycle of work.
| Parameters | |
|---|---|
targetDurationNanos |
Long: the new desired duration in nanoseconds |