build: separate sublogger and rotator pipe management

These are two separate concerns. So this commit splits them up and just
passes a LogWriter from the one to the other. This will become cleaner
in an upcoming commit where the Rotator will implement io.Writer and
there will no longer be a need for LogWriter.

build/logrotator.go

@@ -6,9 +6,7 @@ import (
 	"io"
 	"os"
 	"path/filepath"
-	"sort"
 
-	"github.com/btcsuite/btclog"
 	"github.com/jrick/logrotate/rotator"
 	"github.com/klauspost/compress/zstd"
 )
@@ -18,43 +16,15 @@ import (
 type RotatingLogWriter struct {
 	logWriter *LogWriter
 
-	backendLog *btclog.Backend
-
-	logRotator *rotator.Rotator
-
-	subsystemLoggers SubLoggers
+	rotator *rotator.Rotator
 }
 
-// A compile time check to ensure RotatingLogWriter implements the
-// LeveledSubLogger interface.
-var _ LeveledSubLogger = (*RotatingLogWriter)(nil)
-
 // NewRotatingLogWriter creates a new file rotating log writer.
 //
 // NOTE: `InitLogRotator` must be called to set up log rotation after creating
 // the writer.
-func NewRotatingLogWriter() *RotatingLogWriter {
-	logWriter := &LogWriter{}
-	backendLog := btclog.NewBackend(logWriter)
-	return &RotatingLogWriter{
-		logWriter:        logWriter,
-		backendLog:       backendLog,
-		subsystemLoggers: SubLoggers{},
-	}
-}
-
-// GenSubLogger creates a new sublogger. A shutdown callback function
-// is provided to be able to shutdown in case of a critical error.
-func (r *RotatingLogWriter) GenSubLogger(tag string, shutdown func()) btclog.Logger {
-	logger := r.backendLog.Logger(tag)
-	return NewShutdownLogger(logger, shutdown)
-}
-
-// RegisterSubLogger registers a new subsystem logger.
-func (r *RotatingLogWriter) RegisterSubLogger(subsystem string,
-	logger btclog.Logger) {
-
-	r.subsystemLoggers[subsystem] = logger
+func NewRotatingLogWriter(w *LogWriter) *RotatingLogWriter {
+	return &RotatingLogWriter{logWriter: w}
 }
 
 // InitLogRotator initializes the log file rotator to write logs to logFile and
@@ -68,7 +38,8 @@ func (r *RotatingLogWriter) InitLogRotator(logFile, logCompressor string,
 	if err != nil {
 		return fmt.Errorf("failed to create log directory: %w", err)
 	}
-	r.logRotator, err = rotator.New(
+
+	r.rotator, err = rotator.New(
 		logFile, int64(maxLogFileSize*1024), false, maxLogFiles,
 	)
 	if err != nil {
@@ -94,7 +65,7 @@ func (r *RotatingLogWriter) InitLogRotator(logFile, logCompressor string,
 	}
 
 	// Apply the compressor and its file suffix to the log rotator.
-	r.logRotator.SetCompressor(c, logCompressors[logCompressor])
+	r.rotator.SetCompressor(c, logCompressors[logCompressor])
 
 	// Run rotator as a goroutine now but make sure we catch any errors
 	// that happen in case something with the rotation goes wrong during
@@ -102,7 +73,7 @@ func (r *RotatingLogWriter) InitLogRotator(logFile, logCompressor string,
 	// create a new logfile for whatever reason).
 	pr, pw := io.Pipe()
 	go func() {
-		err := r.logRotator.Run(pr)
+		err := r.rotator.Run(pr)
 		if err != nil {
 			_, _ = fmt.Fprintf(os.Stderr,
 				"failed to run file rotator: %v\n", err)
@@ -110,67 +81,15 @@ func (r *RotatingLogWriter) InitLogRotator(logFile, logCompressor string,
 	}()
 
 	r.logWriter.RotatorPipe = pw
+
 	return nil
 }
 
 // Close closes the underlying log rotator if it has already been created.
 func (r *RotatingLogWriter) Close() error {
-	if r.logRotator != nil {
-		return r.logRotator.Close()
+	if r.rotator != nil {
+		return r.rotator.Close()
 	}
+
 	return nil
 }
-
-// SubLoggers returns all currently registered subsystem loggers for this log
-// writer.
-//
-// NOTE: This is part of the LeveledSubLogger interface.
-func (r *RotatingLogWriter) SubLoggers() SubLoggers {
-	return r.subsystemLoggers
-}
-
-// SupportedSubsystems returns a sorted string slice of all keys in the
-// subsystems map, corresponding to the names of the subsystems.
-//
-// NOTE: This is part of the LeveledSubLogger interface.
-func (r *RotatingLogWriter) SupportedSubsystems() []string {
-	// Convert the subsystemLoggers map keys to a string slice.
-	subsystems := make([]string, 0, len(r.subsystemLoggers))
-	for subsysID := range r.subsystemLoggers {
-		subsystems = append(subsystems, subsysID)
-	}
-
-	// Sort the subsystems for stable display.
-	sort.Strings(subsystems)
-	return subsystems
-}
-
-// SetLogLevel sets the logging level for provided subsystem. Invalid
-// subsystems are ignored. Uninitialized subsystems are dynamically created as
-// needed.
-//
-// NOTE: This is part of the LeveledSubLogger interface.
-func (r *RotatingLogWriter) SetLogLevel(subsystemID string, logLevel string) {
-	// Ignore invalid subsystems.
-	logger, ok := r.subsystemLoggers[subsystemID]
-	if !ok {
-		return
-	}
-
-	// Defaults to info if the log level is invalid.
-	level, _ := btclog.LevelFromString(logLevel)
-	logger.SetLevel(level)
-}
-
-// SetLogLevels sets the log level for all subsystem loggers to the passed
-// level. It also dynamically creates the subsystem loggers as needed, so it
-// can be used to initialize the logging system.
-//
-// NOTE: This is part of the LeveledSubLogger interface.
-func (r *RotatingLogWriter) SetLogLevels(logLevel string) {
-	// Configure all sub-systems with the new logging level. Dynamically
-	// create loggers as needed.
-	for subsystemID := range r.subsystemLoggers {
-		r.SetLogLevel(subsystemID, logLevel)
-	}
-}