*: replace IteratorDebug with treesteps.Node

Switch to using the treesteps infrastructure for debug printing of
iterator trees.

Author: RaduBerinde

batch.go

@@ -29,7 +29,7 @@ import (
 	"github.com/cockroachdb/pebble/internal/rangedel"
 	"github.com/cockroachdb/pebble/internal/rangekey"
 	"github.com/cockroachdb/pebble/internal/rawalloc"
-	"github.com/cockroachdb/pebble/internal/treeprinter"
+	"github.com/cockroachdb/pebble/internal/treesteps"
 )
 
 const (
@@ -1867,9 +1867,9 @@ func (i *batchIter) SetBounds(lower, upper []byte) {
 
 func (i *batchIter) SetContext(_ context.Context) {}
 
-// DebugTree is part of the InternalIterator interface.
-func (i *batchIter) DebugTree(tp treeprinter.Node) {
-	tp.Childf("%T(%p)", i, i)
+// TreeStepsNode is part of the InternalIterator interface.
+func (i *batchIter) TreeStepsNode() treesteps.NodeInfo {
+	return treesteps.NodeInfof(i, "%T(%p)", i, i)
 }
 
 type flushableBatchEntry struct {
@@ -2378,9 +2378,9 @@ func (i *flushableBatchIter) SetBounds(lower, upper []byte) {
 
 func (i *flushableBatchIter) SetContext(_ context.Context) {}
 
-// DebugTree is part of the InternalIterator interface.
-func (i *flushableBatchIter) DebugTree(tp treeprinter.Node) {
-	tp.Childf("%T(%p)", i, i)
+// TreeStepsNode is part of the InternalIterator interface.
+func (i *flushableBatchIter) TreeStepsNode() treesteps.NodeInfo {
+	return treesteps.NodeInfof(i, "%T(%p)", i, i)
 }
 
 // flushFlushableBatchIter is similar to flushableBatchIter but it keeps track

error_iter.go

@@ -9,7 +9,7 @@ import (
 
 	"github.com/cockroachdb/pebble/internal/base"
 	"github.com/cockroachdb/pebble/internal/keyspan"
-	"github.com/cockroachdb/pebble/internal/treeprinter"
+	"github.com/cockroachdb/pebble/internal/treesteps"
 )
 
 type errorIter struct {
@@ -73,8 +73,8 @@ func (c *errorIter) SetBounds(lower, upper []byte) {}
 
 func (c *errorIter) SetContext(_ context.Context) {}
 
-func (c *errorIter) DebugTree(tp treeprinter.Node) {
-	tp.Childf("%T(%p)", c, c)
+func (c *errorIter) TreeStepsNode() treesteps.NodeInfo {
+	return treesteps.NodeInfof(c, "%T(%p)", c, c)
 }
 
 type errorKeyspanIter struct {
@@ -94,4 +94,6 @@ func (i *errorKeyspanIter) SetContext(ctx context.Context)           {}
 func (i *errorKeyspanIter) Close()                                   {}
 func (*errorKeyspanIter) String() string                             { return "error" }
 func (*errorKeyspanIter) WrapChildren(wrap keyspan.WrapFn)           {}
-func (i *errorKeyspanIter) DebugTree(tp treeprinter.Node)            { tp.Childf("%T(%p)", i, i) }
+func (i *errorKeyspanIter) TreeStepsNode() treesteps.NodeInfo {
+	return treesteps.NodeInfof(i, "%T(%p)", i, i)
+}

get.go

@@ -14,7 +14,7 @@ import (
 	"github.com/cockroachdb/pebble/internal/base"
 	"github.com/cockroachdb/pebble/internal/keyspan"
 	"github.com/cockroachdb/pebble/internal/manifest"
-	"github.com/cockroachdb/pebble/internal/treeprinter"
+	"github.com/cockroachdb/pebble/internal/treesteps"
 	"github.com/cockroachdb/pebble/sstable/blob"
 	"github.com/cockroachdb/pebble/sstable/block"
 )
@@ -288,12 +288,11 @@ func (g *getIter) SetBounds(lower, upper []byte) {
 
 func (g *getIter) SetContext(_ context.Context) {}
 
-// DebugTree is part of the InternalIterator interface.
-func (g *getIter) DebugTree(tp treeprinter.Node) {
-	n := tp.Childf("%T(%p)", g, g)
-	if g.iter != nil {
-		g.iter.DebugTree(n)
-	}
+// TreeStepsNode is part of the InternalIterator interface.
+func (g *getIter) TreeStepsNode() treesteps.NodeInfo {
+	info := treesteps.NodeInfof(g, "%T(%p)", g, g)
+	info.AddChildren(g.iter)
+	return info
 }
 
 func (g *getIter) initializeNextIterator() (ok bool) {

internal/arenaskl/iterator.go

@@ -22,7 +22,7 @@ import (
 	"sync"
 
 	"github.com/cockroachdb/pebble/internal/base"
-	"github.com/cockroachdb/pebble/internal/treeprinter"
+	"github.com/cockroachdb/pebble/internal/treesteps"
 )
 
 type splice struct {
@@ -249,9 +249,9 @@ func (it *Iterator) SetBounds(lower, upper []byte) {
 // SetContext implements base.InternalIterator.
 func (it *Iterator) SetContext(_ context.Context) {}
 
-// DebugTree is part of the InternalIterator interface.
-func (it *Iterator) DebugTree(tp treeprinter.Node) {
-	tp.Childf("%T(%p)", it, it)
+// TreeStepsNode is part of the InternalIterator interface.
+func (it *Iterator) TreeStepsNode() treesteps.NodeInfo {
+	return treesteps.NodeInfof(it, "%T(%p)", it, it)
 }
 
 func (it *Iterator) decodeKey() {

internal/base/internal.go

@@ -664,6 +664,13 @@ func (kv *InternalKV) IsExclusiveSentinel() bool {
 	return kv.K.IsExclusiveSentinel()
 }
 
+func (kv *InternalKV) String() string {
+	if kv == nil {
+		return "<nil>"
+	}
+	return kv.K.String()
+}
+
 // AtomicSeqNum is an atomic SeqNum.
 type AtomicSeqNum struct {
 	value atomic.Uint64

internal/base/iterator.go

@@ -10,7 +10,7 @@ import (
 	"time"
 
 	"github.com/cockroachdb/pebble/internal/humanize"
-	"github.com/cockroachdb/pebble/internal/treeprinter"
+	"github.com/cockroachdb/pebble/internal/treesteps"
 	"github.com/cockroachdb/pebble/sstable/block/blockkind"
 	"github.com/cockroachdb/redact"
 )
@@ -220,7 +220,7 @@ type InternalIterator interface {
 
 	fmt.Stringer
 
-	IteratorDebug
+	treesteps.Node
 }
 
 // TopLevelIterator extends InternalIterator to include an additional absolute
@@ -516,19 +516,3 @@ func (s *InternalIteratorStats) SafeFormat(p redact.SafePrinter, verb rune) {
 			humanize.Bytes.Uint64(s.SeparatedPointValue.ValueBytesFetched))
 	}
 }
-
-// IteratorDebug is an interface implemented by all internal iterators and
-// fragment iterators.
-type IteratorDebug interface {
-	// DebugTree prints the entire iterator stack, used for debugging.
-	//
-	// Each implementation should perform a single Child/Childf call on tp.
-	DebugTree(tp treeprinter.Node)
-}
-
-// DebugTree returns the iterator tree as a multi-line string.
-func DebugTree(iter IteratorDebug) string {
-	tp := treeprinter.New()
-	iter.DebugTree(tp)
-	return tp.String()
-}

internal/base/test_utils.go

@@ -11,7 +11,7 @@ import (
 	"strconv"
 	"strings"
 
-	"github.com/cockroachdb/pebble/internal/treeprinter"
+	"github.com/cockroachdb/pebble/internal/treesteps"
 )
 
 // NewDeletableSumValueMerger return a ValueMerger which computes the sum of its
@@ -253,9 +253,9 @@ func (f *FakeIter) SetBounds(lower, upper []byte) {
 // SetContext is part of the InternalIterator interface.
 func (f *FakeIter) SetContext(_ context.Context) {}
 
-// DebugTree is part of the InternalIterator interface.
-func (f *FakeIter) DebugTree(tp treeprinter.Node) {
-	tp.Childf("%T(%p)", f, f)
+// TreeStepsNode is part of the InternalIterator interface.
+func (f *FakeIter) TreeStepsNode() treesteps.NodeInfo {
+	return treesteps.NodeInfof(f, "%T(%p)", f, f)
 }
 
 // ParseUserKeyBounds parses UserKeyBounds from a string representation of the

internal/invalidating/iter.go

@@ -10,7 +10,7 @@ import (
 
 	"github.com/cockroachdb/pebble/internal/base"
 	"github.com/cockroachdb/pebble/internal/invariants"
-	"github.com/cockroachdb/pebble/internal/treeprinter"
+	"github.com/cockroachdb/pebble/internal/treesteps"
 )
 
 // MaybeWrapIfInvariants wraps some iterators with an invalidating iterator.
@@ -164,12 +164,11 @@ func (i *iter) SetContext(ctx context.Context) {
 	i.iter.SetContext(ctx)
 }
 
-// DebugTree is part of the InternalIterator interface.
-func (i *iter) DebugTree(tp treeprinter.Node) {
-	n := tp.Childf("%T(%p)", i, i)
-	if i.iter != nil {
-		i.iter.DebugTree(n)
-	}
+// TreeStepsNode is part of the InternalIterator interface.
+func (i *iter) TreeStepsNode() treesteps.NodeInfo {
+	info := treesteps.NodeInfof(i, "%T(%p)", i, i)
+	info.AddChildren(i.iter)
+	return info
 }
 
 func (i *iter) String() string {

internal/itertest/probe.go

@@ -11,7 +11,7 @@ import (
 
 	"github.com/cockroachdb/pebble/internal/base"
 	"github.com/cockroachdb/pebble/internal/dsl"
-	"github.com/cockroachdb/pebble/internal/treeprinter"
+	"github.com/cockroachdb/pebble/internal/treesteps"
 )
 
 // OpKind indicates the type of iterator operation being performed.
@@ -249,12 +249,11 @@ func (p *probeIterator) SetContext(ctx context.Context) {
 	}
 }
 
-// DebugTree is part of the InternalIterator interface.
-func (p *probeIterator) DebugTree(tp treeprinter.Node) {
-	n := tp.Childf("%T(%p)", p, p)
-	if p.iter != nil {
-		p.iter.DebugTree(n)
-	}
+// TreeStepsNode is part of the InternalIterator interface.
+func (p *probeIterator) TreeStepsNode() treesteps.NodeInfo {
+	info := treesteps.NodeInfof(p, "%T(%p)", p, p)
+	info.AddChildren(p.iter)
+	return info
 }
 
 func (p *probeIterator) String() string {

internal/keyspan/assert_iter.go

@@ -11,7 +11,7 @@ import (
 	"github.com/cockroachdb/errors"
 	"github.com/cockroachdb/pebble/internal/base"
 	"github.com/cockroachdb/pebble/internal/invariants"
-	"github.com/cockroachdb/pebble/internal/treeprinter"
+	"github.com/cockroachdb/pebble/internal/treesteps"
 )
 
 // Assert wraps an iterator which asserts that operations return sane results.
@@ -181,10 +181,9 @@ func (i *assertIter) WrapChildren(wrap WrapFn) {
 	i.iter = wrap(i.iter)
 }
 
-// DebugTree is part of the FragmentIterator interface.
-func (i *assertIter) DebugTree(tp treeprinter.Node) {
-	n := tp.Childf("%T(%p)", i, i)
-	if i.iter != nil {
-		i.iter.DebugTree(n)
-	}
+// TreeStepsNode is part of the FragmentIterator interface.
+func (i *assertIter) TreeStepsNode() treesteps.NodeInfo {
+	info := treesteps.NodeInfof(i, "%T(%p)", i, i)
+	info.AddChildren(i.iter)
+	return info
 }