/
datalogger.go
99 lines (85 loc) · 2.12 KB
/
datalogger.go
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package modules
import (
"fmt"
"io"
"sync"
"google.golang.org/protobuf/encoding/protojson"
"google.golang.org/protobuf/proto"
"google.golang.org/protobuf/types/known/anypb"
)
// MetricsLogger logs data in protobuf message format.
type MetricsLogger interface {
Log(proto.Message)
io.Closer
}
type jsonLogger struct {
mut sync.Mutex
mods *Modules
wr io.Writer
first bool
}
// NewJSONLogger returns a new metrics logger that logs to the specified writer.
func NewJSONLogger(wr io.Writer) (MetricsLogger, error) {
_, err := io.WriteString(wr, "[\n")
if err != nil {
return nil, fmt.Errorf("failed to write start of JSON array: %v", err)
}
return &jsonLogger{wr: wr, first: true}, nil
}
// InitModule initializes the metrics logger module.
func (dl *jsonLogger) InitModule(mods *Modules) {
dl.mods = mods
}
func (dl *jsonLogger) Log(msg proto.Message) {
var (
any *anypb.Any
err error
ok bool
)
if any, ok = msg.(*anypb.Any); !ok {
any, err = anypb.New(msg)
if err != nil {
dl.mods.Logger().Errorf("failed to create Any message: %v", err)
return
}
}
err = dl.write(any)
if err != nil {
dl.mods.Logger().Errorf("failed to write message to log: %v", err)
}
}
func (dl *jsonLogger) write(msg proto.Message) (err error) {
dl.mut.Lock()
defer dl.mut.Unlock()
if dl.first {
dl.first = false
} else {
// write a comma and newline to separate the messages
_, err := io.WriteString(dl.wr, ",\n")
if err != nil {
return err
}
}
b, err := protojson.MarshalOptions{
Indent: "\t",
EmitUnpopulated: true,
}.Marshal(msg)
if err != nil {
return fmt.Errorf("failed to marshal message to JSON: %w", err)
}
_, err = dl.wr.Write(b)
return err
}
// Close closes the metrics logger
func (dl *jsonLogger) Close() error {
_, err := io.WriteString(dl.wr, "\n]")
return err
}
type nopLogger struct{}
func (nopLogger) Log(proto.Message) {}
func (nopLogger) Close() error { return nil }
// NopLogger returns a metrics logger that discards any messages.
// This is useful for testing and other situations where metrics logging is disabled.
func NopLogger() MetricsLogger {
return nopLogger{}
}