@ohos.hiviewdfx.hiAppEvent (Application Event Logging)

The hiAppEvent module provides application event-related functions, including flushing application events to a disk, querying and clearing application events, and customizing application event logging configuration.

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 hiAppEvent from '@ohos.hiviewdfx.hiAppEvent';

hiAppEvent.write

write(info: AppEventInfo, callback: AsyncCallback<void>): void

Writes events to the event file of the current day through AppEventInfo objects. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.HiviewDFX.HiAppEvent

Parameters

Name Type Mandatory Description
info AppEventInfo Yes Application event object.
callback AsyncCallback<void> Yes Callback used to return the result.

Error codes

For details about the error codes, see Application Event Logging Error Codes.

ID Error Message
11100001 Function is disabled.
11101001 Invalid event domain.
11101002 Invalid event name.
11101003 Invalid number of event parameters.
11101004 Invalid string length of the event parameter.
11101005 Invalid event parameter name.
11101006 Invalid array length of the event parameter.

Example

hiAppEvent.write({
    domain: "test_domain",
    name: "test_event",
    eventType: hiAppEvent.EventType.FAULT,
    params: {
        int_data: 100,
        str_data: "strValue"
    }
}, (err) => {
    if (err) {
        console.error(`code: ${err.code}, message: ${err.message}`);
        return;
    }
    console.log(`success to write event`);
});

hiAppEvent.write

write(info: AppEventInfo): Promise<void>

Writes events to the event file of the current day through AppEventInfo objects. This API uses a promise to return the result.

System capability: SystemCapability.HiviewDFX.HiAppEvent

Parameters

Name Type Mandatory Description
info AppEventInfo Yes Application event object.

Return value

Type Description
Promise<void> Promise used to return the result.

Error codes

For details about the error codes, see Application Event Logging Error Codes.

ID Error Message
11100001 Function is disabled.
11101001 Invalid event domain.
11101002 Invalid event name.
11101003 Invalid number of event parameters.
11101004 Invalid string length of the event parameter.
11101005 Invalid event parameter name.
11101006 Invalid array length of the event parameter.

Example

hiAppEvent.write({
    domain: "test_domain",
    name: "test_event",
    eventType: hiAppEvent.EventType.FAULT,
    params: {
        int_data: 100,
        str_data: "strValue"
    }
}).then(() => {
    console.log(`success to write event`);
}).catch((err) => {
    console.error(`code: ${err.code}, message: ${err.message}`);
});

AppEventInfo

Defines parameters for an AppEventInfo object.

System capability: SystemCapability.HiviewDFX.HiAppEvent

Name Type Mandatory Description
domain string Yes Event domain. Event domain name, which is a string of up to 32 characters, including digits (0 to 9), letters (a to z), and underscores (_). It must start with a lowercase letter and cannot end with an underscore (_).
name string Yes Event name. Event name, which is a string of up to 48 characters, including digits (0 to 9), letters (a to z), and underscores (_). It must start with a lowercase letter and cannot end with an underscore (_).
eventType EventType Yes Event type.
params object Yes Event parameter object, which consists of a parameter name and a parameter value. The specifications are as follows:
- The parameter name is a string of up to 16 characters, including digits (0 to 9), letters (a to z), and underscores (_). It must start with a lowercase letter and cannot end with an underscore (_).
- The parameter value can be a string, number, boolean, or array. If the parameter value is a string, its maximum length is 8*1024 characters. If this limit is exceeded, excess characters will be discarded. If the parameter value is a number, the value must be within the range of Number.MIN_SAFE_INTEGER to Number.MAX_SAFE_INTEGER. Otherwise, uncertain values may be generated. If the parameter value is an array, the elements in the array must be of the same type, which can only be string, number, or boolean. In addition, the number of elements must be less than 100. If this limit is exceeded, excess elements will be discarded.
- The maximum number of parameters is 32. If this limit is exceeded, excess parameters will be discarded.

hiAppEvent.configure

configure(config: ConfigOption): void

Configures the application event logging function, such as setting the event logging switch and maximum size of the directory that stores the event logging files.

System capability: SystemCapability.HiviewDFX.HiAppEvent

Parameters

Name Type Mandatory Description
config ConfigOption Yes Configuration items for application event logging.

Error codes

For details about the error codes, see Application Event Logging Error Codes.

ID Error Message
11103001 Invalid max storage quota value.

Example

// Disable the event logging function.
hiAppEvent.configure({
    disable: true
});

// Set the maximum size of the file storage directory to 100 MB.
hiAppEvent.configure({
    maxStorage: '100M'
});

ConfigOption

Configures options for application event logging.

System capability: SystemCapability.HiviewDFX.HiAppEvent

Name Type Mandatory Description
disable boolean No Whether to enable the event logging function. The default value is false. The value true means to disable the event logging function, and the value false means the opposite.
maxStorage string No Maximum size of the directory that stores event logging files. The default value is 10M.
If the directory size exceeds the specified quota when application event logging is performed, event logging files in the directory will be cleared one by one based on the generation time to ensure that directory size does not exceed the quota.

hiAppEvent.addWatcher

addWatcher(watcher: Watcher): AppEventPackageHolder

Adds a watcher to subscribe to application events.

System capability: SystemCapability.HiviewDFX.HiAppEvent

Parameters

Name Type Mandatory Description
watcher Watcher Yes Watcher for application events.

Return value

Type Description
AppEventPackageHolder Subscription data holder. If the subscription fails, null will be returned.

Error codes

For details about the error codes, see Application Event Logging Error Codes.

ID Error Message
11102001 Invalid watcher name.
11102002 Invalid filtering event domain.
11102003 Invalid row value.
11102004 Invalid size value.
11102005 Invalid timeout value.

Example

// 1. If callback parameters are passed to the watcher, you can have subscription events processed in the callback that is automatically triggered.
hiAppEvent.addWatcher({
    name: "watcher1",
    appEventFilters: [
        {
            domain: "test_domain",
            eventTypes: [hiAppEvent.EventType.FAULT, hiAppEvent.EventType.BEHAVIOR]
        }
    ],
    triggerCondition: {
        row: 10,
        size: 1000,
        timeOut: 1
    },
    onTrigger: function (curRow, curSize, holder) {
        if (holder == null) {
            console.error("holder is null");
            return;
        }
        let eventPkg = null;
        while ((eventPkg = holder.takeNext()) != null) {
            console.info(`eventPkg.packageId=${eventPkg.packageId}`);
            console.info(`eventPkg.row=${eventPkg.row}`);
            console.info(`eventPkg.size=${eventPkg.size}`);
            for (const eventInfo of eventPkg.data) {
                console.info(`eventPkg.data=${eventInfo}`);
            }
        }
    }
});

// 2. If no callback parameters are passed to the watcher, you can have subscription events processed manually through the subscription data holder.
let holder = hiAppEvent.addWatcher({
    name: "watcher2",
});
if (holder != null) {
    let eventPkg = null;
    while ((eventPkg = holder.takeNext()) != null) {
        console.info(`eventPkg.packageId=${eventPkg.packageId}`);
        console.info(`eventPkg.row=${eventPkg.row}`);
        console.info(`eventPkg.size=${eventPkg.size}`);
        for (const eventInfo of eventPkg.data) {
            console.info(`eventPkg.data=${eventInfo}`);
        }
    }
}

hiAppEvent.removeWatcher

removeWatcher(watcher: Watcher): void

Removes a watcher to unsubscribe from application events.

System capability: SystemCapability.HiviewDFX.HiAppEvent

Parameters

Name Type Mandatory Description
watcher Watcher Yes Watcher for application events.

Error codes

For details about the error codes, see Application Event Logging Error Codes.

ID Error Message
11102001 Invalid watcher name.

Example

// 1. Define a watcher for application events.
let watcher = {
    name: "watcher1",
}

// 2. Add the watcher to subscribe to application events.
hiAppEvent.addWatcher(watcher);

// 3. Remove the watcher to unsubscribe from application events.
hiAppEvent.removeWatcher(watcher);

Watcher

Defines parameters for a Watcher object.

System capability: SystemCapability.HiviewDFX.HiAppEvent

Name Type Mandatory Description
name string Yes Unique name of the watcher.
triggerCondition TriggerCondition No Subscription callback triggering condition. This parameter takes effect only when it is passed together with the callback.
appEventFilters AppEventFilter[] No Subscription filtering condition. This parameter is passed only when subscription events need to be filtered.
onTrigger (curRow: number, curSize: number, holder: AppEventPackageHolder) => void No Subscription callback, which takes effect only when it is passed together with the callback triggering condition. The input arguments are described as follows:
curRow: total number of subscription events when the callback is triggered.
curSize: total size of subscribed events when the callback is triggered, in bytes.
holder: subscription data holder, which can be used to process subscribed events.

TriggerCondition

Defines callback triggering conditions. Subscription callback is triggered when any condition is met.

System capability: SystemCapability.HiviewDFX.HiAppEvent

Name Type Mandatory Description
row number No Number of events.
size number No Event data size, in bytes.
timeOut number No Timeout interval, in unit of 30s.

AppEventFilter

Defines parameters for an AppEventFilter object.

System capability: SystemCapability.HiviewDFX.HiAppEvent

Name Type Mandatory Description
domain string Yes Event domain.
eventTypes EventType[] No Event types.

AppEventPackageHolder

Defines a subscription data holder for processing subscription events.

System capability: SystemCapability.HiviewDFX.HiAppEvent

constructor

constructor(watcherName: string)

Constructor of the Watcher class. When a watcher is added, the system automatically calls this API to create a subscription data holder object for the watcher and returns the holder object to the application.

System capability: SystemCapability.HiviewDFX.HiAppEvent

Parameters

Name Type Mandatory Description
watcherName string Yes Watcher name.

Example

let holder = hiAppEvent.addWatcher({
    name: "watcher",
});

setSize

setSize(size: number): void

Sets the threshold for the data size of the application event package obtained each time.

System capability: SystemCapability.HiviewDFX.HiAppEvent

Parameters

Name Type Mandatory Description
size number Yes Data size threshold, in bytes. The default value is 512*1024.

Error codes

For details about the error codes, see Application Event Logging Error Codes.

ID Error Message
11104001 Invalid size value.

Example

let holder = hiAppEvent.addWatcher({
    name: "watcher",
});
holder.setSize(1000);

takeNext

takeNext(): AppEventPackage

Extracts subscription event data based on the configured data size threshold. If all subscription event data has been extracted, null will be returned.

System capability: SystemCapability.HiviewDFX.HiAppEvent

Example

let holder = hiAppEvent.addWatcher({
    name: "watcher",
});
let eventPkg = holder.takeNext();

AppEventPackage

Defines parameters for an AppEventPackage object.

System capability: SystemCapability.HiviewDFX.HiAppEvent

Name Type Mandatory Description
packageId number Yes Event package ID, which is named from 0 in ascending order.
row number Yes Number of events in the event package.
size number Yes Event size of the event package, in bytes.
data string[] Yes Event data in the event package.

hiAppEvent.clearData

clearData(): void

Clears local application event logging data.

System capability: SystemCapability.HiviewDFX.HiAppEvent

Example

hiAppEvent.clearData();

EventType

Enumerates event types.

System capability: SystemCapability.HiviewDFX.HiAppEvent

Name Value Description
FAULT 1 Fault event.
STATISTIC 2 Statistical event.
SECURITY 3 Security event.
BEHAVIOR 4 Behavior event.

event

Provides constants that define the names of all predefined events.

System capability: SystemCapability.HiviewDFX.HiAppEvent

Name Type Description
USER_LOGIN string User login event.
USER_LOGOUT string User logout event.
DISTRIBUTED_SERVICE_START string Distributed service startup event.

param

Provides constants that define the names of all predefined event parameters.

System capability: SystemCapability.HiviewDFX.HiAppEvent

Name Type Description
USER_ID string Custom user ID.
DISTRIBUTED_SERVICE_NAME string Distributed service name.
DISTRIBUTED_SERVICE_INSTANCE_ID string Distributed service instance ID.