btrfstree: Change the NodeSource API so that it can do caching

1 files changed, 13 insertions, 21 deletions

diff --git a/lib/btrfsutil/rebuilt_readitem.go b/lib/btrfsutil/rebuilt_readitem.go
index 2520593..73dc01e 100644
--- a/lib/btrfsutil/rebuilt_readitem.go
+++ b/lib/btrfsutil/rebuilt_readitem.go
@@ -8,8 +8,6 @@ import (
 	"context"
 	"fmt"
 
-	"github.com/datawire/dlib/dlog"
-
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsitem"
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsprim"
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfstree"
@@ -26,16 +24,20 @@ func (ptr ItemPtr) String() string {
 	return fmt.Sprintf("node@%v[%v]", ptr.Node, ptr.Slot)
 }
 
-func (ts *RebuiltForrest) readNode(ctx context.Context, laddr btrfsvol.LogicalAddr, out *btrfstree.Node) {
-	dlog.Debugf(ctx, "cache-miss node@%v, reading...", laddr)
-
-	graphInfo, ok := ts.graph.Nodes[laddr]
+func (ts *RebuiltForrest) readItem(ctx context.Context, ptr ItemPtr) btrfsitem.Item {
+	graphInfo, ok := ts.graph.Nodes[ptr.Node]
 	if !ok {
-		panic(fmt.Errorf("should not happen: node@%v is not mentioned in the in-memory graph", laddr))
+		panic(fmt.Errorf("should not happen: btrfsutil.RebuiltForrest.readItem called for node@%v not mentioned in the in-memory graph", ptr.Node))
+	}
+	if graphInfo.Level != 0 {
+		panic(fmt.Errorf("should not happen: btrfsutil.RebuiltForrest.readItem called for non-leaf node@%v", ptr.Node))
+	}
+	if ptr.Slot < 0 {
+		panic(fmt.Errorf("should not happen: btrfsutil.RebuiltForrest.readItem called for negative item slot: %v", ptr.Slot))
 	}
 
-	node, err := ts.file.ReadNode(ctx, laddr, btrfstree.NodeExpectations{
-		LAddr:      containers.OptionalValue(laddr),
+	node, err := ts.file.AcquireNode(ctx, ptr.Node, btrfstree.NodeExpectations{
+		LAddr:      containers.OptionalValue(ptr.Node),
 		Level:      containers.OptionalValue(graphInfo.Level),
 		Generation: containers.OptionalValue(graphInfo.Generation),
 		Owner: func(treeID btrfsprim.ObjID, gen btrfsprim.Generation) error {
@@ -49,22 +51,12 @@ func (ts *RebuiltForrest) readNode(ctx context.Context, laddr btrfsvol.LogicalAd
 		MinItem: containers.OptionalValue(graphInfo.MinItem()),
 		MaxItem: containers.OptionalValue(graphInfo.MaxItem()),
 	})
+	defer ts.file.ReleaseNode(node)
 	if err != nil {
 		panic(fmt.Errorf("should not happen: i/o error: %w", err))
 	}
-	*out = *node
-}
-
-func (ts *RebuiltForrest) readItem(ctx context.Context, ptr ItemPtr) btrfsitem.Item {
-	if ts.graph.Nodes[ptr.Node].Level != 0 {
-		panic(fmt.Errorf("should not happen: btrfsutil.RebuiltForrest.readItem called for non-leaf node@%v", ptr.Node))
-	}
-	if ptr.Slot < 0 {
-		panic(fmt.Errorf("should not happen: btrfsutil.RebuiltForrest.readItem called for negative item slot: %v", ptr.Slot))
-	}
 
-	items := ts.nodes.Acquire(ctx, ptr.Node).BodyLeaf
-	defer ts.nodes.Release(ptr.Node)
+	items := node.BodyLeaf
 
 	if ptr.Slot >= len(items) {
 		panic(fmt.Errorf("should not happen: btrfsutil.RebuiltForrest.readItem called for out-of-bounds item slot: slot=%v len=%v",