harmony 鸿蒙HiLog

2023-06-24
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HiLog

Provides logging functions.

For example, you can use logging functions to output logs of the specified log type, service domain, log tag, and log level.

@syscap SystemCapability.HiviewDFX.HiLog

Since

Summary

File

Name	Description
log.h	Defines the logging functions of the HiLog module. File to include: Library: libhilog_ndk.z.so

Macros

Name	Description
LOG_DOMAIN 0	Defines the service domain for a log file.
LOG_TAG NULL	Defines a string constant used to identify the class, file, or service.
OH_LOG_DEBUG(type, …) ((void)OH_LOG_Print((type), LOG_DEBUG, LOG_DOMAIN, LOG_TAG, __VA_ARGS__))	Outputs DEBUG logs. This is a function-like macro.
OH_LOG_INFO(type, …) ((void)OH_LOG_Print((type), LOG_INFO, LOG_DOMAIN, LOG_TAG, __VA_ARGS__))	Outputs INFO logs. This is a function-like macro.
OH_LOG_WARN(type, …) ((void)OH_LOG_Print((type), LOG_WARN, LOG_DOMAIN, LOG_TAG, __VA_ARGS__))	Outputs WARN logs. This is a function-like macro.
OH_LOG_ERROR(type, …) ((void)OH_LOG_Print((type), LOG_ERROR, LOG_DOMAIN, LOG_TAG, __VA_ARGS__))	Outputs ERROR logs. This is a function-like macro.
OH_LOG_FATAL(type, …) ((void)HiLogPrint((type), LOG_FATAL, LOG_DOMAIN, LOG_TAG, __VA_ARGS__))	Outputs FATAL logs. This is a function-like macro.

Enum

Name	Description
LogType { LOG_APP= 0 }	Log Type
LogLevel { LOG_DEBUG = 3, LOG_INFO = 4, LOG_WARN = 5, LOG_ERROR = 6, LOG_FATAL =7 }	Log level.

Functions

Name	Description
OH_LOG_Print (LogType type, LogLevel level, unsigned int domain, const char tag, const char fmt,…) __attribute__((__format__(os_log, 5,6)))	Outputs logs.
OH_LOG_IsLoggable (unsigned int domain, const char *tag, LogLevel level)	Checks whether logs of the specified service domain, tag, and level can be printed.

Description

Macro Description

LOG_DOMAIN

#define LOG_DOMAIN   0

Description

Defines the service domain for a log file.

The service domain is used to identify the subsystem and module of a service. Its value is a hexadecimal integer ranging from 0x0 to 0xFFFF. If the value is beyond the range, its significant bits are automatically truncated.

Since

LOG_TAG

#define LOG_TAG   NULL

Description

Defines a string constant used to identify the class, file, or service.

Since

OH_LOG_DEBUG

#define OH_LOG_DEBUG( type,  ... )   ((void)OH_LOG_Print((type), LOG_DEBUG, LOG_DOMAIN, LOG_TAG, __VA_ARGS__))

Description

Outputs DEBUG logs. This is a function-like macro.

Before calling this function, define the log service domain and log tag. Generally, you need to define them at the beginning of the source file.

Parameters

Name	Description
type	Log type. The type for third-party applications is defined by LOG_APP.
fmt	Format string, which is an enhancement of a printf format string and supports the privacy identifier. Specifically, {public} or {private} is added between the % character and the format specifier in each parameter.
…	Parameter list corresponding to the parameter type in the format string. The number and type of parameters must be mapped onto the identifier in the format string.

See

OH_LOG_Print

Since

OH_LOG_ERROR

#define OH_LOG_ERROR( type,  ... )   ((void)OH_LOG_Print((type), LOG_ERROR, LOG_DOMAIN, LOG_TAG, __VA_ARGS__))

Description

Outputs ERROR logs. This is a function-like macro.

Before calling this function, define the log service domain and log tag. Generally, you need to define them at the beginning of the source file.

Parameters

Name	Description
type	Log type. The type for third-party applications is defined by LOG_APP.
fmt	Format string, which is an enhancement of a printf format string and supports the privacy identifier. Specifically, {public} or {private} is added between the % character and the format specifier in each parameter.
…	Parameter list corresponding to the parameter type in the format string. The number and type of parameters must be mapped onto the identifier in the format string.

See

OH_LOG_Print

Since

OH_LOG_FATAL

#define OH_LOG_FATAL( type,  ... )   ((void)HiLogPrint((type), LOG_FATAL, LOG_DOMAIN, LOG_TAG, __VA_ARGS__))

Description

Outputs FATAL logs. This is a function-like macro.

Before calling this function, define the log service domain and log tag. Generally, you need to define them at the beginning of the source file.

Parameters

Name	Description
type	Log type. The type for third-party applications is defined by LOG_APP.
fmt	Format string, which is an enhancement of a printf format string and supports the privacy identifier. Specifically, {public} or {private} is added between the % character and the format specifier in each parameter.
…	Parameter list corresponding to the parameter type in the format string. The number and type of parameters must be mapped onto the identifier in the format string.

See

OH_LOG_Print

Since

OH_LOG_INFO

#define OH_LOG_INFO( type,  ... )   ((void)OH_LOG_Print((type), LOG_INFO, LOG_DOMAIN, LOG_TAG, __VA_ARGS__))

Description

Outputs INFO logs. This is a function-like macro.

Before calling this function, define the log service domain and log tag. Generally, you need to define them at the beginning of the source file.

Parameters

Name	Description
type	Log type. The type for third-party applications is defined by LOG_APP.
fmt	Format string, which is an enhancement of a printf format string and supports the privacy identifier. Specifically, {public} or {private} is added between the % character and the format specifier in each parameter.
…	Parameter list corresponding to the parameter type in the format string. The number and type of parameters must be mapped onto the identifier in the format string.

See

OH_LOG_Print

Since

OH_LOG_WARN

#define OH_LOG_WARN( type,  ... )   ((void)OH_LOG_Print((type), LOG_WARN, LOG_DOMAIN, LOG_TAG, __VA_ARGS__))

Description

Outputs WARN logs. This is a function-like macro.

Before calling this function, define the log service domain and log tag. Generally, you need to define them at the beginning of the source file.

Parameters

Name	Description
type	Log type. The type for third-party applications is defined by LOG_APP.
fmt	Format string, which is an enhancement of a printf format string and supports the privacy identifier. Specifically, {public} or {private} is added between the % character and the format specifier in each parameter.
…	Parameter list corresponding to the parameter type in the format string. The number and type of parameters must be mapped onto the identifier in the format string.

See

OH_LOG_Print

Since

Enum Description

LogLevel

enum LogLevel

Description

Enumerates log levels.

You are advised to select log levels based on their respective use cases.

Log levels:

DEBUG: provides more detailed process information than INFO logs to help developers analyze service processes and locate faults. DEBUG logs are not recorded in official versions by default. They are available in debug versions or in official versions with the debug function enabled.

INFO: indicates the key service process nodes and exceptions (for example, no network signal or login failure) that occur during service running. These logs should be recorded by the dominant module in the service to avoid repeated logging conducted by multiple invoked modules or low-level functions.

WARN: indicates a severe, unexpected fault that has little impact on users and can be rectified by the programs themselves or through simple operations.

ERROR: indicates a program or functional error that affects the normal running or use of the functionality and can be fixed at a high cost, for example, by resetting data.

FATAL: indicates that a program or functionality is about to crash and the fault cannot be rectified.

Value	Description
LOG_DEBUG	DEBUG level to be used by OH_LOG_DEBUG.
LOG_INFO	INFO level to be used by OH_LOG_INFO.
LOG_WARN	WARN level to be used by OH_LOG_WARN.
LOG_ERROR	ERROR level to be used by OH_LOG_ERROR.
LOG_FATAL	FATAL level to be used by OH_LOG_FATAL.

Since

LogType

enum LogType

Description

Enumerates log types.

You can use this function to specify the type of output logs. Currently, only LOG_APP is available.

Value	Description
LOG_APP	Application log.

Since

Function Description

OH_LOG_IsLoggable()

bool OH_LOG_IsLoggable (unsigned int domain, const char * tag, LogLevel level )

Description

Checks whether logs of the specified service domain, tag, and level can be printed.

Parameters

Name	Description
domain	Service domain.
tag	Log tag.
level	Log level.

Returns

true if the specified logs can be output; false otherwise.

Since

OH_LOG_Print()

int OH_LOG_Print (LogType type, LogLevel level, unsigned int domain, const char * tag, const char * fmt,  ... )

Description

Outputs logs.

You can use this function to output logs based on the specified log type, log level, service domain, log tag, and variable parameters determined by the format specifier and privacy identifier in the printf format.

Parameters

Name	Description
type	Log type. The type for third-party applications is defined by LOG_APP.
level	Log level. The value can be LOG_DEBUG, LOG_INFO, LOG_WARN, LOG_ERROR, and LOG_FATAL.
domain	Service domain. Its value is a hexadecimal integer ranging from 0x0 to 0xFFFF.
tag	Log tag, which is a string used to identify the class, file, or service.
fmt	Format string, which is an enhancement of a printf format string and supports the privacy identifier. Specifically, {public} or {private} is added between the % character and the format specifier in each parameter.
…	Parameter list corresponding to the parameter type in the format string. The number and type of parameters must be mapped onto the identifier in the format string.