github.com/nikandfor/tlog@v0.21.5-0.20231108111739-3ef89426a96d/examples/dumper/main.go (about)

     1  package main
     2  
     3  import (
     4  	"context"
     5  	"io"
     6  	"strings"
     7  
     8  	"github.com/nikandfor/loc"
     9  	"github.com/nikandfor/tlog"
    10  	"github.com/nikandfor/tlog/tlio"
    11  )
    12  
    13  func main() {
    14  	cw := tlog.NewConsoleWriter(tlog.Stderr, tlog.LdetFlags)
    15  	tlog.DefaultLogger = tlog.New(cw)
    16  
    17  	cw.StringOnNewLineMinLen = 10
    18  
    19  	q := "some file content or socket...\nor some other data you want to dump to logs"
    20  
    21  	w := io.Discard // just for example
    22  
    23  	_ = copyStream(context.Background(), w, strings.NewReader(q))
    24  
    25  	//	tlog.Printw("msg", "obj", map[string]string{"key": q, "key2": q})
    26  }
    27  
    28  func copyStream(ctx context.Context, w io.Writer, r io.Reader) (err error) {
    29  	tr := tlog.SpawnFromContextOrStart(ctx, "copy_stream")
    30  	defer func() { tr.Finish("err", err, tlog.KeyCaller, loc.Caller(1)) }()
    31  
    32  	// Here is the trick
    33  	lw := tlio.WriterFunc(func(p []byte) (int, error) {
    34  		tr.Printw("copied block", "len", tlog.NextAsHex, len(p), "block", p)
    35  
    36  		return len(p), nil
    37  	})
    38  
    39  	w = io.MultiWriter(w, lw)
    40  
    41  	r = tlio.NopCloser{Reader: r} // preserve 20 bytes buffer, prevent WriteTo fastpath
    42  
    43  	_, err = io.CopyBuffer(w, r, make([]byte, 20))
    44  
    45  	return err
    46  }