log: remove lazy, remove unused interfaces, unexport methods (#28622)

This change

- Removes interface `log.Format`,
- Removes method `log.FormatFunc`,
- unexports `TerminalHandler.TerminalFormat` formatting methods (renamed to `TerminalHandler.format`)
- removes the notion of `log.Lazy` values

The lazy handler was useful in the old log package, since it
could defer the evaluation of costly attributes until later in the
log pipeline: thus, if the logging was done at 'Trace', we could
skip evaluation if logging only was set to 'Info'.

With the move to slog, this way of deferring evaluation is no longer
needed, since slog introduced 'Enabled': the caller can thus do
the evaluate-or-not decision at the callsite, which is much more
straight-forward than dealing with lazy reflect-based evaluation.

Also, lazy evaluation would not work with 'native' slog, as in, these
two statements would be evaluated differently:

```golang
  log.Info("foo", "my lazy", lazyObj)
  slog.Info("foo", "my lazy", lazyObj)
```

internal/testlog/testlog.go

@@ -100,6 +100,10 @@ func LoggerWithHandler(t *testing.T, handler slog.Handler) log.Logger {
 
 func (l *logger) Write(level slog.Level, msg string, ctx ...interface{}) {}
 
+func (l *logger) Enabled(ctx context.Context, level slog.Level) bool {
+	return l.l.Enabled(ctx, level)
+}
+
 func (l *logger) Trace(msg string, ctx ...interface{}) {
 	l.t.Helper()
 	l.mu.Lock()
@@ -183,7 +187,7 @@ func (h *bufHandler) terminalFormat(r slog.Record) string {
 	}
 
 	for _, attr := range attrs {
-		fmt.Fprintf(buf, " %s=%s", attr.Key, string(log.FormatSlogValue(attr.Value, true, nil)))
+		fmt.Fprintf(buf, " %s=%s", attr.Key, string(log.FormatSlogValue(attr.Value, nil)))
 	}
 	buf.WriteByte('\n')
 	return buf.String()

light/txpool.go

@@ -450,7 +450,10 @@ func (p *TxPool) add(ctx context.Context, tx *types.Transaction) error {
 	}
 
 	// Print a log message if low enough level is set
-	log.Debug("Pooled new transaction", "hash", hash, "from", log.Lazy{Fn: func() common.Address { from, _ := types.Sender(p.signer, tx); return from }}, "to", tx.To())
+	if log.Enabled(log.LevelDebug) {
+		from, _ := types.Sender(p.signer, tx)
+		log.Debug("Pooled new transaction", "hash", hash, "from", from, "to", tx.To())
+	}
 	return nil
 }
 

log/format.go

@@ -23,22 +23,6 @@ const (
 // 40 spaces
 var spaces = []byte("                                        ")
 
-type Format interface {
-	Format(r slog.Record) []byte
-}
-
-// FormatFunc returns a new Format object which uses
-// the given function to perform record formatting.
-func FormatFunc(f func(slog.Record) []byte) Format {
-	return formatFunc(f)
-}
-
-type formatFunc func(slog.Record) []byte
-
-func (f formatFunc) Format(r slog.Record) []byte {
-	return f(r)
-}
-
 // TerminalStringer is an analogous interface to the stdlib stringer, allowing
 // own types to have custom shortened serialization formats when printed to the
 // screen.
@@ -46,7 +30,7 @@ type TerminalStringer interface {
 	TerminalString() string
 }
 
-func (h *TerminalHandler) TerminalFormat(buf []byte, r slog.Record, usecolor bool) []byte {
+func (h *TerminalHandler) format(buf []byte, r slog.Record, usecolor bool) []byte {
 	msg := escapeMessage(r.Message)
 	var color = ""
 	if usecolor {
@@ -88,13 +72,13 @@ func (h *TerminalHandler) TerminalFormat(buf []byte, r slog.Record, usecolor boo
 	if (r.NumAttrs()+len(h.attrs)) > 0 && length < termMsgJust {
 		b.Write(spaces[:termMsgJust-length])
 	}
-	// print the keys logfmt style
+	// print the attributes
-	h.logfmt(b, r, color)
+	h.formatAttributes(b, r, color)
 
 	return b.Bytes()
 }
 
-func (h *TerminalHandler) logfmt(buf *bytes.Buffer, r slog.Record, color string) {
+func (h *TerminalHandler) formatAttributes(buf *bytes.Buffer, r slog.Record, color string) {
 	// tmp is a temporary buffer we use, until bytes.Buffer.AvailableBuffer() (1.21)
 	// can be used.
 	var tmp = make([]byte, 40)
@@ -112,7 +96,7 @@ func (h *TerminalHandler) logfmt(buf *bytes.Buffer, r slog.Record, color string)
 			buf.WriteByte('=')
 		}
 		//val := FormatSlogValue(attr.Value, true, buf.AvailableBuffer())
-		val := FormatSlogValue(attr.Value, true, tmp[:0])
+		val := FormatSlogValue(attr.Value, tmp[:0])
 
 		padding := h.fieldPadding[attr.Key]
 
@@ -140,8 +124,8 @@ func (h *TerminalHandler) logfmt(buf *bytes.Buffer, r slog.Record, color string)
 	buf.WriteByte('\n')
 }
 
-// FormatSlogValue formats a slog.Value for serialization
+// FormatSlogValue formats a slog.Value for serialization to terminal.
-func FormatSlogValue(v slog.Value, term bool, tmp []byte) (result []byte) {
+func FormatSlogValue(v slog.Value, tmp []byte) (result []byte) {
 	var value any
 	defer func() {
 		if err := recover(); err != nil {
@@ -156,11 +140,9 @@ func FormatSlogValue(v slog.Value, term bool, tmp []byte) (result []byte) {
 	switch v.Kind() {
 	case slog.KindString:
 		return appendEscapeString(tmp, v.String())
-	case slog.KindAny:
+	case slog.KindInt64: // All int-types (int8, int16 etc) wind up here
-		value = v.Any()
-	case slog.KindInt64: // All int-types (int8 ,int16 etc) wind up here
 		return appendInt64(tmp, v.Int64())
-	case slog.KindUint64: // All uint-types (int8 ,int16 etc) wind up here
+	case slog.KindUint64: // All uint-types (uint8, uint16 etc) wind up here
 		return appendUint64(tmp, v.Uint64(), false)
 	case slog.KindFloat64:
 		return strconv.AppendFloat(tmp, v.Float64(), floatFormat, 3, 64)
@@ -180,27 +162,14 @@ func FormatSlogValue(v slog.Value, term bool, tmp []byte) (result []byte) {
 		return []byte("<nil>")
 	}
 	switch v := value.(type) {
-	case *big.Int:
+	case *big.Int: // Need to be before fmt.Stringer-clause
-		// Big ints get consumed by the Stringer clause, so we need to handle
-		// them earlier on.
-		if v == nil {
-			return append(tmp, []byte("<nil>")...)
-		}
 		return appendBigInt(tmp, v)
-
+	case *uint256.Int: // Need to be before fmt.Stringer-clause
-	case *uint256.Int:
-		// Uint256s get consumed by the Stringer clause, so we need to handle
-		// them earlier on.
-		if v == nil {
-			return append(tmp, []byte("<nil>")...)
-		}
 		return appendU256(tmp, v)
 	case error:
 		return appendEscapeString(tmp, v.Error())
 	case TerminalStringer:
-		if term {
+		return appendEscapeString(tmp, v.TerminalString())
-			return appendEscapeString(tmp, v.TerminalString()) // Custom terminal stringer provided, use that
-		}
 	case fmt.Stringer:
 		return appendEscapeString(tmp, v.String())
 	}

log/handler.go

@@ -13,42 +13,6 @@ import (
 	"golang.org/x/exp/slog"
 )
 
-// Lazy allows you to defer calculation of a logged value that is expensive
-// to compute until it is certain that it must be evaluated with the given filters.
-//
-// You may wrap any function which takes no arguments to Lazy. It may return any
-// number of values of any type.
-type Lazy struct {
-	Fn interface{}
-}
-
-func evaluateLazy(lz Lazy) (interface{}, error) {
-	t := reflect.TypeOf(lz.Fn)
-
-	if t.Kind() != reflect.Func {
-		return nil, fmt.Errorf("INVALID_LAZY, not func: %+v", lz.Fn)
-	}
-
-	if t.NumIn() > 0 {
-		return nil, fmt.Errorf("INVALID_LAZY, func takes args: %+v", lz.Fn)
-	}
-
-	if t.NumOut() == 0 {
-		return nil, fmt.Errorf("INVALID_LAZY, no func return val: %+v", lz.Fn)
-	}
-
-	value := reflect.ValueOf(lz.Fn)
-	results := value.Call([]reflect.Value{})
-	if len(results) == 1 {
-		return results[0].Interface(), nil
-	}
-	values := make([]interface{}, len(results))
-	for i, v := range results {
-		values[i] = v.Interface()
-	}
-	return values, nil
-}
-
 type discardHandler struct{}
 
 // DiscardHandler returns a no-op handler
@@ -112,7 +76,7 @@ func NewTerminalHandlerWithLevel(wr io.Writer, lvl slog.Level, useColor bool) *T
 func (h *TerminalHandler) Handle(_ context.Context, r slog.Record) error {
 	h.mu.Lock()
 	defer h.mu.Unlock()
-	buf := h.TerminalFormat(h.buf, r, h.useColor)
+	buf := h.format(h.buf, r, h.useColor)
 	h.wr.Write(buf)
 	h.buf = buf[:0]
 	return nil
@@ -149,6 +113,7 @@ func (l *leveler) Level() slog.Level {
 	return l.minLevel
 }
 
+// JSONHandler returns a handler which prints records in JSON format.
 func JSONHandler(wr io.Writer) slog.Handler {
 	return slog.NewJSONHandler(wr, &slog.HandlerOptions{
 		ReplaceAttr: builtinReplaceJSON,

log/logger.go

@@ -134,6 +134,9 @@ type Logger interface {
 
 	// Write logs a message at the specified level
 	Write(level slog.Level, msg string, attrs ...any)
+
+	// Enabled reports whether l emits log records at the given context and level.
+	Enabled(ctx context.Context, level slog.Level) bool
 }
 
 type logger struct {
@@ -159,26 +162,6 @@ func (l *logger) Write(level slog.Level, msg string, attrs ...any) {
 	if len(attrs)%2 != 0 {
 		attrs = append(attrs, nil, errorKey, "Normalized odd number of arguments by adding nil")
 	}
-
-	// evaluate lazy values
-	var hadErr bool
-	for i := 1; i < len(attrs); i += 2 {
-		lz, ok := attrs[i].(Lazy)
-		if ok {
-			v, err := evaluateLazy(lz)
-			if err != nil {
-				hadErr = true
-				attrs[i] = err
-			} else {
-				attrs[i] = v
-			}
-		}
-	}
-
-	if hadErr {
-		attrs = append(attrs, errorKey, "bad lazy")
-	}
-
 	r := slog.NewRecord(time.Now(), level, msg, pcs[0])
 	r.Add(attrs...)
 	l.inner.Handler().Handle(context.Background(), r)
@@ -196,6 +179,11 @@ func (l *logger) New(ctx ...interface{}) Logger {
 	return l.With(ctx...)
 }
 
+// Enabled reports whether l emits log records at the given context and level.
+func (l *logger) Enabled(ctx context.Context, level slog.Level) bool {
+	return l.inner.Enabled(ctx, level)
+}
+
 func (l *logger) Trace(msg string, ctx ...interface{}) {
 	l.Write(LevelTrace, msg, ctx...)
 }

log/logger_test.go

@@ -107,7 +107,6 @@ func TestLoggerOutput(t *testing.T) {
 		bigint    = big.NewInt(100)
 		nilbig    *big.Int
 		err       = fmt.Errorf("Oh nooes it's crap")
-		lazy      = Lazy{Fn: func() interface{} { return "lazy value" }}
 		smallUint = uint256.NewInt(500_000)
 		bigUint   = &uint256.Int{0xff, 0xff, 0xff, 0xff}
 	)
@@ -126,13 +125,12 @@ func TestLoggerOutput(t *testing.T) {
 		"struct", customA,
 		"struct", customB,
 		"ptrstruct", &customA,
-		"lazy", lazy,
 		"smalluint", smallUint,
 		"bigUint", bigUint)
 
 	have := out.String()
 	t.Logf("output %v", out.String())
-	want := `INFO [11-07|19:14:33.821] This is a message                        foo=123 bytes="[0 0 0 0 0 0 0 0 0 0]" bonk="a string with text" time=0001-01-01T00:00:00+0000 bigint=100 nilbig=<nil> err="Oh nooes it's crap" struct="{A:Foo B:12}" struct="{A:Foo\nLinebreak B:122}" ptrstruct="&{A:Foo B:12}" lazy="lazy value" smalluint=500,000 bigUint=1,600,660,942,523,603,594,864,898,306,482,794,244,293,965,082,972,225,630,372,095
+	want := `INFO [11-07|19:14:33.821] This is a message                        foo=123 bytes="[0 0 0 0 0 0 0 0 0 0]" bonk="a string with text" time=0001-01-01T00:00:00+0000 bigint=100 nilbig=<nil> err="Oh nooes it's crap" struct="{A:Foo B:12}" struct="{A:Foo\nLinebreak B:122}" ptrstruct="&{A:Foo B:12}" smalluint=500,000 bigUint=1,600,660,942,523,603,594,864,898,306,482,794,244,293,965,082,972,225,630,372,095
 `
 	if !bytes.Equal([]byte(have)[25:], []byte(want)[25:]) {
 		t.Errorf("Error\nhave: %q\nwant: %q", have, want)

log/root.go

@@ -1,6 +1,7 @@
 package log
 
 import (
+	"context"
 	"os"
 	"sync/atomic"
 
@@ -115,3 +116,7 @@ func Crit(msg string, ctx ...interface{}) {
 func New(ctx ...interface{}) Logger {
 	return Root().With(ctx...)
 }
+
+func Enabled(level slog.Level) bool {
+	return Root().Enabled(context.Background(), level)
+}

p2p/discover/table.go

@@ -23,6 +23,7 @@
 package discover
 
 import (
+	"context"
 	crand "crypto/rand"
 	"encoding/binary"
 	"errors"
@@ -72,7 +73,10 @@ type Table struct {
 	rand    *mrand.Rand       // source of randomness, periodically reseeded
 	ips     netutil.DistinctNetSet
 
-	db         *nodeDB // database of known nodes
+	db  *nodeDB // database of known nodes
+	log log.Logger
+
+	// loop channels
 	refreshReq chan chan struct{}
 	initDone   chan struct{}
 	closeReq   chan struct{}
@@ -118,9 +122,11 @@ func newTable(t transport, ourID NodeID, ourAddr *net.UDPAddr, nodeDBPath string
 	if err != nil {
 		return nil, err
 	}
+
 	tab := &Table{
 		net:        t,
 		db:         db,
+		log:        log.Root(),
 		self:       NewNode(ourID, ourAddr.IP, uint16(ourAddr.Port), uint16(ourAddr.Port)),
 		bonding:    make(map[NodeID]*bondproc),
 		bondslots:  make(chan struct{}, maxBondingPingPongs),
@@ -322,10 +328,10 @@ func (tab *Table) lookup(targetID NodeID, refreshIfEmpty bool) []*Node {
 						// Bump the failure counter to detect and evacuate non-bonded entries
 						fails := tab.db.findFails(n.ID) + 1
 						tab.db.updateFindFails(n.ID, fails)
-						log.Trace("Bumping findnode failure counter", "id", n.ID, "failcount", fails)
+						tab.log.Trace("Bumping findnode failure counter", "id", n.ID, "failcount", fails)
 
 						if fails >= maxFindnodeFailures {
-							log.Trace("Too many findnode failures, dropping", "id", n.ID, "failcount", fails)
+							tab.log.Trace("Too many findnode failures, dropping", "id", n.ID, "failcount", fails)
 							tab.delete(n)
 						}
 					}
@@ -455,8 +461,10 @@ func (tab *Table) loadSeedNodes(bond bool) {
 	}
 	for i := range seeds {
 		seed := seeds[i]
-		age := log.Lazy{Fn: func() interface{} { return time.Since(tab.db.bondTime(seed.ID)) }}
+		if tab.log.Enabled(context.Background(), log.LevelTrace) {
-		log.Debug("Found seed node in database", "id", seed.ID, "addr", seed.addr(), "age", age)
+			age := time.Since(tab.db.bondTime(seed.ID))
+			tab.log.Debug("Found seed node in database", "id", seed.ID, "addr", seed.addr(), "age", age)
+		}
 		tab.add(seed)
 	}
 }
@@ -480,16 +488,16 @@ func (tab *Table) doRevalidate(done chan<- struct{}) {
 	b := tab.buckets[bi]
 	if err == nil {
 		// The node responded, move it to the front.
-		log.Debug("Revalidated node", "b", bi, "id", last.ID)
+		tab.log.Debug("Revalidated node", "b", bi, "id", last.ID)
 		b.bump(last)
 		return
 	}
 	// No reply received, pick a replacement or delete the node if there aren't
 	// any replacements.
 	if r := tab.replace(b, last); r != nil {
-		log.Debug("Replaced dead node", "b", bi, "id", last.ID, "ip", last.IP, "r", r.ID, "rip", r.IP)
+		tab.log.Debug("Replaced dead node", "b", bi, "id", last.ID, "ip", last.IP, "r", r.ID, "rip", r.IP)
 	} else {
-		log.Debug("Removed dead node", "b", bi, "id", last.ID, "ip", last.IP)
+		tab.log.Debug("Removed dead node", "b", bi, "id", last.ID, "ip", last.IP)
 	}
 }
 
@@ -599,7 +607,7 @@ func (tab *Table) bond(pinged bool, id NodeID, addr *net.UDPAddr, tcpPort uint16
 	age := time.Since(tab.db.bondTime(id))
 	var result error
 	if fails > 0 || age > nodeDBNodeExpiration {
-		log.Trace("Starting bonding ping/pong", "id", id, "known", node != nil, "failcount", fails, "age", age)
+		tab.log.Trace("Starting bonding ping/pong", "id", id, "known", node != nil, "failcount", fails, "age", age)
 
 		tab.bondmu.Lock()
 		w := tab.bonding[id]
@@ -724,11 +732,11 @@ func (tab *Table) addIP(b *bucket, ip net.IP) bool {
 		return true
 	}
 	if !tab.ips.Add(ip) {
-		log.Debug("IP exceeds table limit", "ip", ip)
+		tab.log.Debug("IP exceeds table limit", "ip", ip)
 		return false
 	}
 	if !b.ips.Add(ip) {
-		log.Debug("IP exceeds bucket limit", "ip", ip)
+		tab.log.Debug("IP exceeds bucket limit", "ip", ip)
 		tab.ips.Remove(ip)
 		return false
 	}

p2p/discover/udp.go

@@ -228,6 +228,9 @@ type Config struct {
 	NetRestrict  *netutil.Netlist  // network whitelist
 	Bootnodes    []*Node           // list of bootstrap nodes
 	Unhandled    chan<- ReadPacket // unhandled packets are sent on this channel
+
+	// The options below are useful in very specific cases, like in unit tests.
+	Log log.Logger // if set, log messages go here
 }
 
 // ListenUDP returns a new table that listens for UDP packets on laddr.

p2p/discv5/net.go

@@ -420,7 +420,6 @@ loop:
 
 		// Ingress packet handling.
 		case pkt := <-net.read:
-			//fmt.Println("read", pkt.ev)
 			log.Trace("<-net.read")
 			n := net.internNode(&pkt)
 			prestate := n.state
@@ -428,10 +427,10 @@ loop:
 			if err := net.handle(n, pkt.ev, &pkt); err != nil {
 				status = err.Error()
 			}
-			log.Trace("", "msg", log.Lazy{Fn: func() string {
+			if log.Enabled(log.LevelTrace) {
-				return fmt.Sprintf("<<< (%d) %v from %x@%v: %v -> %v (%v)",
+				msg := fmt.Sprintf("<<< (%d) %v from %x@%v: %v -> %v (%v)", net.tab.count, pkt.ev, pkt.remoteID[:8], pkt.remoteAddr, prestate, n.state, status)
-					net.tab.count, pkt.ev, pkt.remoteID[:8], pkt.remoteAddr, prestate, n.state, status)
+				log.Trace("", "msg", msg)
-			}})
+			}
 			// TODO: persist state if n.state goes >= known, delete if it goes <= known
 
 		// State transition timeouts.
@@ -447,10 +446,10 @@ loop:
 			if err := net.handle(timeout.node, timeout.ev, nil); err != nil {
 				status = err.Error()
 			}
-			log.Trace("", "msg", log.Lazy{Fn: func() string {
+			if log.Enabled(log.LevelTrace) {
-				return fmt.Sprintf("--- (%d) %v for %x@%v: %v -> %v (%v)",
+				msg := fmt.Sprintf("--- (%d) %v for %x@%v: %v -> %v (%v)", net.tab.count, timeout.ev, timeout.node.ID[:8], timeout.node.addr(), prestate, timeout.node.state, status)
-					net.tab.count, timeout.ev, timeout.node.ID[:8], timeout.node.addr(), prestate, timeout.node.state, status)
+				log.Trace("", "msg", msg)
-			}})
+			}
 
 		// Querying.
 		case q := <-net.queryReq:
@@ -683,15 +682,15 @@ func (net *Network) refresh(done chan<- struct{}) {
 		return
 	}
 	for _, n := range seeds {
-		log.Debug("", "msg", log.Lazy{Fn: func() string {
+		if log.Enabled(log.LevelDebug) {
 			var age string
 			if net.db != nil {
 				age = time.Since(net.db.lastPong(n.ID)).String()
 			} else {
 				age = "unknown"
 			}
-			return fmt.Sprintf("seed node (age %s): %v", age, n)
+			log.Debug("", "msg", fmt.Sprintf("seed node (age %s): %v", age, n))
-		}})
+		}
 		n = net.internNodeFromDB(n)
 		if n.state == unknown {
 			net.transition(n, verifyinit)