set_thread_execution_state() state parameter¶
The state parameter specifies the thread’s execution requirements. This parameter can be one or more of the following values defined in sculptor.h.
ES_AWAYMODE_REQUIRED |
Enables away mode. This value must be specified with ES_CONTINUOUS. Away mode should be used only by media-recording and media-distribution applications that must perform critical background processing on desktop computers while the computer appears to be sleeping. See below. |
ES_CONTINUOUS |
Informs the system that the state being set should remain in effect until the next call that uses ES_CONTINUOUS and one of the other state flags is cleared. |
ES_DISPLAY_REQUIRED |
Forces the display to be on by resetting the display idle timer. |
ES_SYSTEM_REQUIRED |
Forces the system to be in the working state by resetting the system idle timer. |
Calling set_thread_execution_state without ES_CONTINUOUS simply resets the idle timer; to keep the display or system in the working state, the thread must call set_thread_execution_state periodically.
To run properly on a power-managed computer, applications such as fax servers, answering machines, backup agents, and network management applications must use both ES_SYSTEM_REQUIRED and ES_CONTINUOUS when they process events. Multimedia applications, such as video players and presentation applications, must use ES_DISPLAY_REQUIRED when they display video for long periods of time without user input. Applications such as word processors, spreadsheets, browsers, and games do not need to call set_thread_execution_state.
The ES_AWAYMODE_REQUIRED value should be used only when absolutely necessary by media applications that require the system to perform background tasks such as recording television content or streaming media to other devices while the system appears to be sleeping. Applications that do not require critical background processing or that run on portable computers should not enable away mode because it prevents the system from conserving power by entering true sleep.
To enable away mode, an application uses both ES_AWAYMODE_REQUIRED and ES_CONTINUOUS; to disable away mode, an application calls set_thread_execution_state with ES_CONTINUOUS and clears ES_AWAYMODE_REQUIRED. When away mode is enabled, any operation that would put the computer to sleep puts it in away mode instead. The computer appears to be sleeping while the system continues to perform tasks that do not require user input. Away mode does not affect the sleep idle timer; to prevent the system from entering sleep when the timer expires, an application must also set the ES_SYSTEM_REQUIRED value.
The set_thread_execution_state function cannot be used to prevent the user from putting the computer to sleep. Applications should respect that the user expects a certain behavior when they close the lid on their laptop or press the power button.
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