Documentation
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Overview ¶
Package sglog provides a logging handler for the log/slog package that writes log messages to multiple files based on their severity, similar to Google's glog package.
This package is inspired by Google's glog package for Go but introduces several differences and new features, such as log file reuse. Most of the code is adapted from glog, with modifications to support the slog ecosystem and additional functionality.
Differences from Google's glog ¶
- Log messages are not buffered inline with the application control flow.
- The standard log/slog package does not define a Fatal level, so FATAL messages and log files are not supported.
- Global flags from glog are replaced with an Options struct for configuration.
- Unlike glog, this package does not add a footer message when rotating log files.
- When log file reuse is enabled, log file names may not precisely reflect the log file creation time, though timestamps in file names remain in chronological order.
Log File Reuse ¶
Google's glog creates a new log file each time a process restarts, which can exhaust filesystem inodes if the process crashes repeatedly. The sglog package mitigates this by enabling log file reuse with a configurable timeout (e.g., one log file per hour).
Log files are still rotated when they reach the configured maximum size limit.
VModule Usage ¶
In addition to log levels, logging can be selectively enabled or disabled using vmodule attributes, similar to glog's vmodule feature. Users must define a reusable attribute for each module (typically at global scope) and use it with the slog.With function to log module-specific messages.
Example:
var network = sglog.VModule("network", slog.LevelDebug)
...
slog.With(network).Info("Network event", ...)
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func SetVModuleLevel ¶
SetVModuleLevel changes a vmodule attribute's level dynamically. Returns false if input attribute is not a vmodule attribute.
Types ¶
type Backend ¶
type Backend struct {
// contains filtered or unexported fields
}
func (*Backend) Close ¶
func (v *Backend) Close()
Close flushes the logs and waits for the background goroutine to finish.
type Options ¶
type Options struct {
// Name holds the program name to use with the log files.
Name string
// LogDirs if non-empty create/write log files in one of these directories.
LogDirs []string
// LogLinkDir if non-empty, adds symbolic links in this directory to the log
// files.
LogLinkDir string
// LogFileMaxSize is the maximum size of a log file in bytes. Header and
// footer messages are not accounted in this so final log file size can be
// larger than this limit by a few hundred bytes.
LogFileMaxSize uint64
// LogFileMode is the log file mode/permissions.
LogFileMode os.FileMode
// LogFileHeader when true writes the file header at the start of each log
// file.
LogFileHeader bool
// LogFileReuseDuration is the maximum duration to reuse/reopen an existing
// log file as long as it doesn't cross the maximum log file size.
LogFileReuseDuration time.Duration
// LogMessageMaxLen is the limit on length of a formatted log message,
// including the standard line prefix and trailing newline. Messages longer
// than this value are truncated.
LogMessageMaxLen int
}
Source Files