HiSysEvent Logging

Overview

Function Introduction

HiSysEvent provides event logging APIs for OpenHarmony to record important information of key processes during system running. Besides, it supports shielding of event logging by event domain, helping you to evaluate the impact of event logging.

Working Principles

Before logging system events, you need to configure HiSysEvent logging. For details, see HiSysEvent Logging Configuration.

How to Develop

Use Cases

Use HiSysEvent logging to flush logged event data to the event file.

Available APIs

C++ Event Logging API

HiSysEvent logging is implemented using the API provided by the HiSysEvent class. For details, see the API Header Files.

NOTE

In OpenHarmony-3.2-Beta3, HiSysEvent logging is open for restricted use to avoid event storms. The HiSysEvent::Write API in Table 1 is replaced by the HiSysEventWrite API in Table 2. The HiSysEvent::Write API has been deprecated. Use the HiSysEventWrite API instead for HiSysEvent logging.

Table 1 Description of the C++ event logging API (deprecated)

Table 2 Description of the C++ event logging API (in use)

Table 3 Description of EventType enums

C Event Logging API

HiSysEvent logging is implemented using the API provided in the following table. For details, see the API Header Files.

Table 4 Description of the C event logging API

Table 5 Description of HiSysEventEventType enums

Table 6 Description of the HiSysEventParam structure

Table 7 Description of HiSysEventParamType enums

Table 8 Description of the HiSysEventParamValue union

Kernel Event Logging APIs

Kernel event logging is implemented using the APIs provided in the following table. For details, see the API Header File.

Table 9 Description of kernel event logging APIs

Table 10 Description of hisysevent_type enums

How to Develop

C++ Event Logging

Call the event logging API wherever needed, with required event parameters passed to the API.

HiSysEventWrite(HiSysEvent::Domain::AAFWK, "START_APP", HiSysEvent::EventType::BEHAVIOR, "APP_NAME", "com.ohos.demo");

C Event Logging

1. If you want to pass custom event parameters to the event logging API, create an event parameter object based on the event parameter type and add the object to the event parameter array.

   // Create an event parameter of the int32_t type.
   HiSysEventParam param1 = {
       .name = "KEY_INT32",
       .t = HISYSEVENT_INT32,
       .v = { .i32 = 1 },
       .arraySize = 0,
   };
   
   // Create an event parameter of the int32_t array type.
   int32_t int32Arr[] = { 1, 2, 3 };
   HiSysEventParam param2 = {
       .name = "KEY_INT32_ARR",
       .t = HISYSEVENT_INT32_ARRAY,
       .v = { .array = int32Arr },
       .arraySize = sizeof(int32Arr) / sizeof(int32Arr[0]),
   };
   
   // Add the event parameter object to the created event parameter array.
   HiSysEventParam params[] = { param1, param2 };
   

2. Call the event logging API wherever needed, with required event parameters passed to the API.

   OH_HiSysEvent_Write("TEST_DOMAIN", "TEST_NAME", HISYSEVENT_BEHAVIOR, params, sizeof(params) / sizeof(params[0]));
   

Kernel Event Logging

1. Create a hisysevent object based on the specified event domain, event name, and event type.

   struct hiview_hisysevent *event = hisysevent_create("KERNEL", "BOOT", BEHAVIOR);
   

2. Pass the customized event parameters to the hisysevent object.

   // Add a parameter of the integer type.
   hisysevent_put_integer(event, "BOOT_TIME", 100);
   
   // Add a parameter of the string type.
   hisysevent_put_string(event, "MSG", "This is a test message");
   

3. Trigger reporting of the hisysevent event.

   hisysevent_write(event);
   

4. Manually destroy the hisysevent object.

   hisysevent_destroy(&event);
   

Shielding of Event Logging by Event Domain

1. In the corresponding file, define the DOMAIN_MASKS macro with content similar to DOMAIN_NAME_1|DOMAIN_NAME_2|...|DOMAIN_NAME_n. There are three scenarios:

• Shielding only event logging for the event domains configured in the current source code file: Define the DOMAIN_MASKS macro before importing the .cpp file to the hisysevent.h file.

  #define DOMAIN_MASKS "DOMAIN_NAME_1|DOMAIN_NAME_2|...|DOMAIN_NAME_n"
  #include "hisysevent.h"
  

• Shielding event logging for event domains of the entire module: Define the DOMAIN_MASKS macro in the BUILD.gn file of the module.

  config("module_a"){
    cflags_cc += ["-DDOMAIN_MASKS=\"DOMAIN_NAME_1|DOMAIN_NAME_2|...|DOMAIN_NAME_n\""]
  }
  

• Shielding event logging for event domains globally: Define the DOMAIN_MASKS macro in /build/config/compiler/BUILD.gn.

    cflags_cc += ["-DDOMAIN_MASKS=\"DOMAIN_NAME_1|DOMAIN_NAME_2|...|DOMAIN_NAME_n\""]
  

2. Perform event logging by using the HiSysEventWrite API.

   constexpr char DOMAIN[] = "DOMAIN_NAME_1";
   const std::string eventName = "EVENT_NAME1";
   OHOS:HiviewDFX::HiSysEvent::EventType eventType = OHOS:HiviewDFX::HiSysEvent::EventType::FAULT;
   HiSysEventWrite(domain, eventName, eventType); // Event logging is shielded for DOMAIN_NAME_1 because it has been defined in the DOMAIN_MASKS macro.
   

Development Example

C++ Event Logging

Assume that a service module needs to trigger event logging during application startup to record the application startup event and application bundle name. The following is the complete sample code:

1. Add the HiSysEvent component dependency to the BUILD.gn file of the service module.

   external_deps = [ "hisysevent:libhisysevent" ]
   

2. In the application startup function StartAbility() of the service module, call the event logging API with event parameters passed in.

   #include "hisysevent.h"
   
   int StartAbility()
   {
       ... // Other service logic
       int ret = HiSysEventWrite(HiSysEvent::Domain::AAFWK, "START_APP", HiSysEvent::EventType::BEHAVIOR, "APP_NAME", "com.ohos.demo");
       ... // Other service logic
   }
   

C Event Logging

Assume that a service module needs to trigger event logging during application startup to record the application startup event and application bundle name. The following is the complete sample code:

1. Add the HiSysEvent component dependency to the BUILD.gn file of the service module.

   external_deps = [ "hisysevent:libhisysevent" ]
   

2. In the application startup function StartAbility() of the service module, call the event logging API with event parameters passed in.

   #include "hisysevent_c.h"
   
   int StartAbility()
   {
       ... // Other service logic
       char packageName[] = "com.ohos.demo";
       HiSysEventParam param = {
           .name = "APP_NAME",
           .t = HISYSEVENT_STRING,
           .v = { .s = packageName },
           .arraySize = 0,
       };
       HiSysEventParam params[] = { param };
       int ret = OH_HiSysEvent_Write("AAFWK", "START_APP", HISYSEVENT_BEHAVIOR, params, sizeof(params) / sizeof(params[0]));
       ... // Other service logic
   }
   

Kernel Event Logging

Assume that the kernel service module needs to trigger event logging during device startup to record the device startup event. The following is the complete sample code:

1. In the device startup function device_boot(), construct a hisysevent object. After that, trigger event reporting, and then destroy the hisysevent object.

   #include <dfx/hiview_hisysevent.h>
   
   #include <linux/errno.h>
   #include <linux/printk.h>
   
   int device_boot()
   {
       ... // Other service logic
       struct hiview_hisysevent *event = NULL;
       int ret = 0;
   
       event = hisysevent_create("KERNEL", "BOOT", BEHAVIOR);
       if (!event) {
           pr_err("failed to create event");
           return -EINVAL;
       }
       ret = hisysevent_put_string(event, "MSG", "This is a test message");
       if (ret != 0) {
           pr_err("failed to put sting to event, ret=%d", ret);
           goto hisysevent_end;
       }
       ret = hisysevent_write(event);
   
   hisysevent_end:
       hisysevent_destroy(&event);
       ... // Other service logic
   }
   

Shielding of Event Logging by Event Domain

• If you want to shield event logging for the AAFWK and POWER domains in a .cpp file, define the DOMAIN_MASKS macro before including the hisysevent.h header file to the .cpp file.

  #define DOMAIN_MASKS "AAFWK|POWER"
  
  #include "hisysevent.h"
  ... // Other service logic
  HiSysEventWrite(OHOS:HiviewDFX::HiSysEvent::Domain::AAFWK, "JS_ERROR", OHOS:HiviewDFX::HiSysEvent::EventType::FAULT, "MODULE", "com.ohos.module"); // HiSysEvent logging is not performed.
  ... // Other service logic
  HiSysEventWrite(OHOS:HiviewDFX::HiSysEvent::Domain::POWER, "POWER_RUNNINGLOCK", OHOS:HiviewDFX::HiSysEvent::EventType::FAULT, "NAME", "com.ohos.module"); // HiSysEvent logging is not performed.
  

• If you want to shield event logging for the AAFWK and POWER domains of the entire service module, define the DOMAIN_MASKS macro as follows in the BUILG.gn file of the service module.

  config("module_a") {
      ... // Other configuration items
      cflags_cc += ["-DDOMAIN_MASKS=\"AAFWK|POWER\""]
  }
  

• If you want to shield event logging for the AAFWK and POWER domains globally, define the DOMAIN_MASKS macro as follows in /build/config/compiler/BUILD.gn.

  ... // Other configuration items
  cflags_cc += ["-DDOMAIN_MASKS=\"AAFWK|POWER\""]
  

Reference

The HiSysEvent module writes the logged event data to the node file, and the Hiview module parses and processes the event data in a unified manner. For details, see the Hiview Development Guide.