@ohos.resourceschedule.backgroundTaskManager (Background Task Management)

The BackgroundTaskManager module provides APIs to manage background tasks.

If a service needs to be continued when the application or service module is running in the background (not visible to users), the application or service module can request a transient task to delay the suspension or a continuous task to prevent the suspension.

If an application has a task that needs to be continued when the application is switched to the background and can be completed within a short period of time, the application can request a transient task. For example, if a user chooses to clear junk files in the Files application and exits the application, the application can request a transient task to complete the cleanup.

If an application has a service that can be intuitively perceived by users and needs to run in the background for a long period of time (for example, music playback in the background), the application can request a continuous task.

If a privileged system application needs to use certain system resources (for example, it wants to receive common events when suspended), it can request efficiency resources.

NOTE

The initial APIs of this module are supported since API version 9. Newly added APIs will be marked with a superscript to indicate their earliest API version.

Modules to Import

import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  

backgroundTaskManager.requestSuspendDelay

requestSuspendDelay(reason: string, callback: Callback<void>): DelaySuspendInfo

Requests delayed suspension after the application switches to the background.

The default duration of delayed suspension is 3 minutes when the battery level is higher than or equal to the broadcast low battery level and 1 minute when the battery level is lower than the broadcast low battery level.

System capability: SystemCapability.ResourceSchedule.BackgroundTaskManager.TransientTask

Parameters

Return value

Error codes

For details about the error codes, see backgroundTaskManager Error Codes.

Example

import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  

let myReason = 'test requestSuspendDelay';
try {
  let delayInfo = backgroundTaskManager.requestSuspendDelay(myReason, () => {
      console.info("Request suspension delay will time out.");
  })
  var id = delayInfo.requestId;
  var time = delayInfo.actualDelayTime;
  console.info("The requestId is: " + id);
  console.info("The actualDelayTime is: " + time);
} catch (error) {
  console.error(`requestSuspendDelay failed. code is ${error.code} message is ${error.message}`);
}

backgroundTaskManager.getRemainingDelayTime:callback

getRemainingDelayTime(requestId: number, callback: AsyncCallback<number>): void

Obtains the remaining duration before the application is suspended. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.ResourceSchedule.BackgroundTaskManager.TransientTask

Parameters

Error codes

For details about the error codes, see backgroundTaskManager Error Codes.

Example

import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  

let id = 1;
try {
  backgroundTaskManager.getRemainingDelayTime(id, (error, res) => {
      if(error) {
          console.error(`callback => Operation getRemainingDelayTime failed. code is ${error.code} message is ${error.message}`);
      } else {
          console.log('callback => Operation getRemainingDelayTime succeeded. Data: ' + JSON.stringify(res));
      }
  })
} catch (error) {
  console.error(`callback => Operation getRemainingDelayTime failed. code is ${error.code} message is ${error.message}`);
}

backgroundTaskManager.getRemainingDelayTime:promise

getRemainingDelayTime(requestId: number): Promise<number>

Obtains the remaining duration before the application is suspended. This API uses a promise to return the result.

System capability: SystemCapability.ResourceSchedule.BackgroundTaskManager.TransientTask

Parameters

Return value

Error codes

For details about the error codes, see backgroundTaskManager Error Codes.

Example

import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  

let id = 1;
try {
  backgroundTaskManager.getRemainingDelayTime(id).then( res => {
      console.log('promise => Operation getRemainingDelayTime succeeded. Data: ' + JSON.stringify(res));
  }).catch( error => {
      console.error(`promise => Operation getRemainingDelayTime failed. code is ${error.code} message is ${error.message}`);
  })
} catch (error) {
  console.error(`promise => Operation getRemainingDelayTime failed. code is ${error.code} message is ${error.message}`);
}

backgroundTaskManager.cancelSuspendDelay

cancelSuspendDelay(requestId: number): void

Cancels the suspension delay.

System capability: SystemCapability.ResourceSchedule.BackgroundTaskManager.TransientTask

Parameters

Error codes

For details about the error codes, see backgroundTaskManager Error Codes.

Example

import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  

let id = 1;
try {
  backgroundTaskManager.cancelSuspendDelay(id);
} catch (error) {
  console.error(`cancelSuspendDelay failed. code is ${error.code} message is ${error.message}`);
}

backgroundTaskManager.startBackgroundRunning:callback

startBackgroundRunning(context: Context, bgMode: BackgroundMode, wantAgent: WantAgent, callback: AsyncCallback<void>): void

Requests a continuous task from the system. This API uses an asynchronous callback to return the result.

Required permissions: ohos.permission.KEEP_BACKGROUND_RUNNING

System capability: SystemCapability.ResourceSchedule.BackgroundTaskManager.ContinuousTask

Parameters

Error codes

For details about the error codes, see backgroundTaskManager Error Codes.

Example

import UIAbility from '@ohos.app.ability.UIAbility';
import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  
import wantAgent from '@ohos.app.ability.wantAgent';

function callback(error, data) {
    if (error) {
        console.error(`Operation startBackgroundRunning failed. code is ${error.code} message is ${error.message}`);
    } else {
        console.info("Operation startBackgroundRunning succeeded");
    }
}

export default class EntryAbility extends UIAbility {
    onCreate(want, launchParam) {
        let wantAgentInfo = {
            wants: [
                {
                    bundleName: "com.example.myapplication",
                    abilityName: "EntryAbility"
                }
            ],
            operationType: wantAgent.OperationType.START_ABILITY,
            requestCode: 0,
            wantAgentFlags: [wantAgent.WantAgentFlags.UPDATE_PRESENT_FLAG]
        };

        try {
            wantAgent.getWantAgent(wantAgentInfo).then((wantAgentObj) => {
                try {
                    backgroundTaskManager.startBackgroundRunning(this.context,
                        backgroundTaskManager.BackgroundMode.LOCATION, wantAgentObj, callback)
                } catch (error) {
                    console.error(`Operation startBackgroundRunning failed. code is ${error.code} message is ${error.message}`);
                }
            });
        } catch (error) {
            console.error(`Operation getWantAgent failed. code is ${error.code} message is ${error.message}`);
        }
    }
};

backgroundTaskManager.startBackgroundRunning:promise

startBackgroundRunning(context: Context, bgMode: BackgroundMode, wantAgent: WantAgent): Promise<void>

Requests a continuous task from the system. This API uses a promise to return the result.

Required permissions: ohos.permission.KEEP_BACKGROUND_RUNNING

System capability: SystemCapability.ResourceSchedule.BackgroundTaskManager.ContinuousTask

Parameters

Return value

Error codes

For details about the error codes, see backgroundTaskManager Error Codes.

Example

import UIAbility from '@ohos.app.ability.UIAbility';
import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager'; 
import wantAgent from '@ohos.app.ability.wantAgent';

export default class EntryAbility extends UIAbility {
    onCreate(want, launchParam) {
        let wantAgentInfo = {
            wants: [
                {
                    bundleName: "com.example.myapplication",
                    abilityName: "EntryAbility"
                }
            ],
            operationType: wantAgent.OperationType.START_ABILITY,
            requestCode: 0,
            wantAgentFlags: [wantAgent.WantAgentFlags.UPDATE_PRESENT_FLAG]
        };

        try {
            wantAgent.getWantAgent(wantAgentInfo).then((wantAgentObj) => {
                try {
                    backgroundTaskManager.startBackgroundRunning(this.context,
                        backgroundTaskManager.BackgroundMode.LOCATION, wantAgentObj).then(() => {
                        console.info("Operation startBackgroundRunning succeeded");
                    }).catch((error) => {
                        console.error(`Operation startBackgroundRunning failed. code is ${error.code} message is ${error.message}`);
                    });
                } catch (error) {
                    console.error(`Operation startBackgroundRunning failed. code is ${error.code} message is ${error.message}`);
                }
            });
        } catch (error) {
            console.error(`Operation getWantAgent failed. code is ${error.code} message is ${error.message}`);
        }
    }
};

backgroundTaskManager.stopBackgroundRunning:callback

stopBackgroundRunning(context: Context, callback: AsyncCallback<void>): void

Requests to cancel a continuous task. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.ResourceSchedule.BackgroundTaskManager.ContinuousTask

Parameters

Error codes

For details about the error codes, see backgroundTaskManager Error Codes.

Example

import UIAbility from '@ohos.app.ability.UIAbility';
import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  

function callback(error, data) {
    if (error) {
        console.error(`Operation stopBackgroundRunning failed. code is ${error.code} message is ${error.message}`);
    } else {
        console.info("Operation stopBackgroundRunning succeeded");
    }
}

export default class EntryAbility extends UIAbility {
    onCreate(want, launchParam) {
        try {
            backgroundTaskManager.stopBackgroundRunning(this.context, callback);
        } catch (error) {
            console.error(`Operation stopBackgroundRunning failed. code is ${error.code} message is ${error.message}`);
        }
    }
};

backgroundTaskManager.stopBackgroundRunning:promise

stopBackgroundRunning(context: Context): Promise<void>

Requests to cancel a continuous task. This API uses a promise to return the result.

System capability: SystemCapability.ResourceSchedule.BackgroundTaskManager.ContinuousTask

Parameters

Return value

Error codes

For details about the error codes, see backgroundTaskManager Error Codes.

Example

import UIAbility from '@ohos.app.ability.UIAbility';
import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  

export default class EntryAbility extends UIAbility {
    onCreate(want, launchParam) {
        try {
            backgroundTaskManager.stopBackgroundRunning(this.context).then(() => {
                console.info("Operation stopBackgroundRunning succeeded");
            }).catch((error) => {
                console.error(`Operation stopBackgroundRunning failed. code is ${error.code} message is ${error.message}`);
            });
        } catch (error) {
            console.error(`Operation stopBackgroundRunning failed. code is ${error.code} message is ${error.message}`);
        }
    }
};

backgroundTaskManager.applyEfficiencyResources

applyEfficiencyResources(request: EfficiencyResourcesRequest): void

Requests efficiency resources from the system. A process and its application can request the same type of resources at the same time, for example, CPU resources. When the application releases the resources, the same type of resources requested by the process are also released.

System capability: SystemCapability.ResourceSchedule.BackgroundTaskManager.EfficiencyResourcesApply

System API: This is a system API.

Parameters

Error codes

For details about the error codes, see backgroundTaskManager Error Codes.

Example

import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  

let request = {
    resourceTypes: backgroundTaskManager.ResourceType.CPU,
    isApply: true,
    timeOut: 0,
    reason: "apply",
    isPersist: true,
    isProcess: false,
};
try {
    backgroundTaskManager.applyEfficiencyResources(request);
    console.info("applyEfficiencyResources success. ");
} catch (error) {
    console.error(`applyEfficiencyResources failed. code is ${error.code} message is ${error.message}`);
}

backgroundTaskManager.resetAllEfficiencyResources

resetAllEfficiencyResources(): void

Releases all resources that have been requested.

System capability: SystemCapability.ResourceSchedule.BackgroundTaskManager.EfficiencyResourcesApply

System API: This is a system API.

Error codes

For details about the error codes, see backgroundTaskManager Error Codes.

Example

import backgroundTaskManager from '@ohos.resourceschedule.backgroundTaskManager';  

try {
    backgroundTaskManager.resetAllEfficiencyResources();
} catch (error) {
    console.error(`resetAllEfficiencyResources failed. code is ${error.code} message is ${error.message}`);
}

DelaySuspendInfo

Provides the information about the suspension delay.

System capability: SystemCapability.ResourceSchedule.BackgroundTaskManager.TransientTask

BackgroundMode

System capability: SystemCapability.ResourceSchedule.BackgroundTaskManager.ContinuousTask

EfficiencyResourcesRequest

Describes the parameters for requesting efficiency resources.

System capability: SystemCapability.ResourceSchedule.BackgroundTaskManager.EfficiencyResourcesApply

System API: This is a system API.

ResourceType

Enumerates the efficiency resource types.

System capability: SystemCapability.ResourceSchedule.BackgroundTaskManager.EfficiencyResourcesApply

System API: This is a system API.