@ohos.hiSysEvent (System Event Logging)

The hiSysEvent module provides the system event logging functions, such as configuring trace points, subscribing to system events, and querying system events written to the event file.

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.
• The APIs provided by this module are system APIs.

Modules to Import

import hiSysEvent from '@ohos.hiSysEvent';

EventType

Enumerates event types.

System capability: SystemCapability.HiviewDFX.HiSysEvent

SysEventInfo

Defines a system event.

System capability: SystemCapability.HiviewDFX.HiSysEvent

hiSysEvent.write

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

Writes event information to the event file. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.HiviewDFX.HiSysEvent

Parameters

Error codes

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

Example

import hiSysEvent from '@ohos.hiSysEvent';
import { BusinessError } from '@ohos.base';

try {
  let customizedParams: Record<string, string|number> = {
    'PID': 487,
    'UID': 103,
    'PACKAGE_NAME': "com.ohos.hisysevent.test",
    'PROCESS_NAME': "syseventservice",
    'MSG': "no msg."
  };
  let eventInfo: hiSysEvent.SysEventInfo = {
    domain: "RELIABILITY",
    name: "STACK",
    eventType: hiSysEvent.EventType.FAULT,
    params: customizedParams
  };
  hiSysEvent.write(eventInfo, (err: BusinessError, val: number) => {
    // do something here.
  });
} catch (err) {
  console.error(`error code: ${(err as BusinessError).code}, error msg: ${(err as BusinessError).message}`);
}

hiSysEvent.write

write(info: SysEventInfo): Promise<void>

Writes event information to the event file. This API uses a promise to return the result.

System capability: SystemCapability.HiviewDFX.HiSysEvent

Parameters

Return value

Error codes

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

Example

import hiSysEvent from '@ohos.hiSysEvent';
import { BusinessError } from '@ohos.base';

try {
  let customizedParams: Record<string, string|number> = {
    'PID': 487,
    'UID': 103,
    'PACKAGE_NAME': "com.ohos.hisysevent.test",
    'PROCESS_NAME': "syseventservice",
    'MSG': "no msg."
  };
  let eventInfo: hiSysEvent.SysEventInfo = {
    domain: "RELIABILITY",
    name: "STACK",
    eventType: hiSysEvent.EventType.FAULT,
    params: customizedParams
  };
  hiSysEvent.write(eventInfo).then(
    () => {
      // do something here.
    }
  ).catch(
    (err: BusinessError) => {
      console.error(`error code: ${err.code}, error msg: ${err.message}`);
    }
  );
} catch (err) {
  console.error(`error code: ${(err as BusinessError).code}, error msg: ${(err as BusinessError).message}`);
}

RuleType

Enumerates matching rule types.

System capability: SystemCapability.HiviewDFX.HiSysEvent

WatchRule

Defines event subscription rules.

System capability: SystemCapability.HiviewDFX.HiSysEvent

Watcher

Defines a watcher for event subscription.

System capability: SystemCapability.HiviewDFX.HiSysEvent

hiSysEvent.addWatcher

addWatcher(watcher: Watcher): void

Adds a watcher for event subscription.

Required permission: ohos.permission.READ_DFX_SYSEVENT

System capability: SystemCapability.HiviewDFX.HiSysEvent

Parameters

Error codes

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

Example

import hiSysEvent from '@ohos.hiSysEvent';
import { BusinessError } from '@ohos.base';

let watchRules: hiSysEvent.WatchRule[] = [{
    domain: "RELIABILITY",
    name: "STACK",
    tag: "STABILITY",
    ruleType: hiSysEvent.RuleType.WHOLE_WORD,
  } as hiSysEvent.WatchRule];
let watcher: hiSysEvent.Watcher = {
  rules: watchRules,
  onEvent: (info: hiSysEvent.SysEventInfo) => {
    // do something here.
  },
  onServiceDied: () => {
    // do something here.
  }
};
try {
  hiSysEvent.addWatcher(watcher);
} catch (err) {
  console.error(`error code: ${(err as BusinessError).code}, error msg: ${(err as BusinessError).message}`);
}

hiSysEvent.removeWatcher

removeWatcher(watcher: Watcher): void

Removes a watcher used for event subscription.

Required permission: ohos.permission.READ_DFX_SYSEVENT

System capability: SystemCapability.HiviewDFX.HiSysEvent

Parameters

Error codes

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

Example

import hiSysEvent from '@ohos.hiSysEvent';
import { BusinessError } from '@ohos.base';

let watchRules: hiSysEvent.WatchRule[] = [{
    domain: "RELIABILITY",
    name: "STACK",
    tag: "STABILITY",
    ruleType: hiSysEvent.RuleType.WHOLE_WORD,
  } as hiSysEvent.WatchRule ];
let watcher: hiSysEvent.Watcher = {
  rules: watchRules,
  onEvent: (info: hiSysEvent.SysEventInfo) => {
    // do something here.
  },
  onServiceDied: () => {
    // do something here.
  }
};
try {
  hiSysEvent.addWatcher(watcher);
  hiSysEvent.removeWatcher(watcher);
} catch (err) {
  console.error(`error code: ${(err as BusinessError).code}, error msg: ${(err as BusinessError).message}`);
}

QueryArg

Defines arguments for an event query.

System capability: SystemCapability.HiviewDFX.HiSysEvent

QueryRule

Defines event query rules.

System capability: SystemCapability.HiviewDFX.HiSysEvent

Querier

Defines an event query instance.

System capability: SystemCapability.HiviewDFX.HiSysEvent

hiSysEvent.query

query(queryArg: QueryArg, rules: QueryRule[], querier: Querier): void

Queries system events.

Required permission: ohos.permission.READ_DFX_SYSEVENT

System capability: SystemCapability.HiviewDFX.HiSysEvent

Parameters

Error codes

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

Example

import hiSysEvent from '@ohos.hiSysEvent';
import { BusinessError } from '@ohos.base';

try {
  let customizedParams: Record<string, string|number> = {
    'PID': 487,
    'UID': 103,
    'PACKAGE_NAME': "com.ohos.hisysevent.test",
    'PROCESS_NAME': "syseventservice",
    'MSG': "no msg."
  };
  let eventInfo: hiSysEvent.SysEventInfo = {
    domain: "RELIABILITY",
    name: "STACK",
    eventType: hiSysEvent.EventType.FAULT,
    params: customizedParams
  };
  hiSysEvent.write(eventInfo, (err: BusinessError, val: number) => {
    // do something here.
  });

  let queryArg: hiSysEvent.QueryArg = {
    beginTime: -1,
    endTime: -1,
    maxEvents: 5,
  };
  let queryRules: hiSysEvent.QueryRule[] = [{
    domain: "RELIABILITY",
    names: ["STACK"],
  } as hiSysEvent.QueryRule];
  let querier: hiSysEvent.Querier = {
    onQuery: (infos: hiSysEvent.SysEventInfo[]) => {
      // do something here.
    },
    onComplete: (reason: number, total: number) => {
      // do something here.
    }
  };
  hiSysEvent.query(queryArg, queryRules, querier);
} catch (err) {
  console.error(`error code: ${(err as BusinessError).code}, error msg: ${(err as BusinessError).message}`);
}

hiSysEvent.exportSysEvents¹⁰⁺

exportSysEvents(queryArg: QueryArg, rules: QueryRule[]): number

Exports system events in batches and writes them as a file to the fixed directory of the application sandbox (that is, /data/storage/el2/base/cache/hiview/event/).

Required permission: ohos.permission.READ_DFX_SYSEVENT

System capability: SystemCapability.HiviewDFX.HiSysEvent

Parameters

Return value

Error codes

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

Example

import hiSysEvent from '@ohos.hiSysEvent';
import fs from '@ohos.file.fs';
import { BusinessError } from '@ohos.base';

try {
  let customizedParams: Record<string, string|number> = {
    'PID': 487,
    'UID': 103,
    'PACKAGE_NAME': "com.ohos.hisysevent.test",
    'PROCESS_NAME': "syseventservice",
    'MSG': "no msg."
  };
  let eventInfo: hiSysEvent.SysEventInfo = {
    domain: "RELIABILITY",
    name: "STACK",
    eventType: hiSysEvent.EventType.FAULT,
    params: customizedParams
  };
  hiSysEvent.write(eventInfo, (err: BusinessError, val: number) => {
    // do something here.
  });

  let queryArg: hiSysEvent.QueryArg = {
    beginTime: -1,
    endTime: -1,
    maxEvents: 1,
  };
  let queryRules: hiSysEvent.QueryRule[] = [{
    domain: "RELIABILITY",
    names: ["STACK"],
  } as hiSysEvent.QueryRule];
  let time = hiSysEvent.exportSysEvents(queryArg, queryRules);
  console.log(`receive export task time is : ${time}`);

  // Postpone reading of exported events.
  setTimeout(() => {
    let eventDir = '/data/storage/el2/base/cache/hiview/event';
    let filenames = fs.listFileSync(eventDir);
    for (let i = 0; i < filenames.length; i++) {
      if (filenames[i].indexOf(time.toString()) != -1) {
        let res = fs.readTextSync(eventDir + '/' + filenames[i]);
        let events: string = JSON.parse('[' + res.slice(0, res.length - 1) + ']');
        console.log("read file end, events is :" + JSON.stringify(events));
      }
    }
  }, 10000);
} catch catch (err) {
  console.error(`error code: ${(err as BusinessError).code}, error msg: ${(err as BusinessError).message}`);
}

hiSysEvent.subscribe¹⁰⁺

subscribe(rules: QueryRule[]): number

Subscribes to real-time system events that occur occasionally or occur in a low frequency. These events are written as a file to the fixed directory of the application sandbox (that is, /data/storage/el2/base/cache/hiview/event/).

Required permission: ohos.permission.READ_DFX_SYSEVENT

System capability: SystemCapability.HiviewDFX.HiSysEvent

Parameters

Return value

Error codes

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

Example

import hiSysEvent from '@ohos.hiSysEvent';
import fs from '@ohos.file.fs';
import { BusinessError } from '@ohos.base';

try {
  let rules: hiSysEvent.QueryRule[] = [{
    domain: "RELIABILITY",
    names: ["STACK"],
  } as hiSysEvent.QueryRule,
  {
    domain: "BUNDLE_MANAGER",
    names: ["BUNDLE_UNINSTALL"],
  } as hiSysEvent.QueryRule];
  hiSysEvent.subscribe(rules);

  let customizedParams: Record<string, string|number> = {
    'PID': 487,
    'UID': 103,
    'PACKAGE_NAME': "com.ohos.hisysevent.test",
    'PROCESS_NAME': "syseventservice",
    'MSG': "no msg."
  };
  let eventInfo: hiSysEvent.SysEventInfo = {
    domain: "RELIABILITY",
    name: "STACK",
    eventType: hiSysEvent.EventType.FAULT,
    params: customizedParams
  };
  hiSysEvent.write(eventInfo, (err: BusinessError, val: number) => {
    // do something here.
  });

  // Postpone reading of subscribed events.
  setTimeout(() => {
    let eventDir = '/data/storage/el2/base/cache/hiview/event';
    let filenames = fs.listFileSync(eventDir);
    for (let i = 0; i < filenames.length; i++) {
      let res = fs.readTextSync(eventDir + '/' + filenames[i]);
      let events: string = JSON.parse('[' + res.slice(0, res.length - 1) + ']');
      console.log("read file end, events is :" + JSON.stringify(events));
    }
  }, 10000);
} catch catch (err) {
  console.error(`error code: ${(err as BusinessError).code}, error msg: ${(err as BusinessError).message}`);
}

hiSysEvent.unsubscribe¹⁰⁺

unsubscribe(): void

Unsubscribes from system events.

Required permission: ohos.permission.READ_DFX_SYSEVENT

System capability: SystemCapability.HiviewDFX.HiSysEvent

Error codes

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

Example

import hiSysEvent from '@ohos.hiSysEvent';
import { BusinessError } from '@ohos.base';

try {
  let rules: hiSysEvent.QueryRule[] = [{
    domain: "RELIABILITY",
    names: ["STACK"],
  } as hiSysEvent.QueryRule,
  {
    domain: "BUNDLE_MANAGER",
    names: ["BUNDLE_UNINSTALL"],
  } as hiSysEvent.QueryRule];
  hiSysEvent.subscribe(rules);
  hiSysEvent.unsubscribe();
} catch (err) {
  console.error(`error code: ${(err as BusinessError).code}, error msg: ${(err as BusinessError).message}`);
}

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