add asserts for detecting pgid high watermark overflow

bucket.go

@@ -476,6 +476,7 @@ func (b *Bucket) spill() error {
 	b.rootNode = b.rootNode.root()
 
 	// Update the root node for this bucket.
+	_assert(b.rootNode.pgid < b.tx.meta.pgid, "pgid (%d) above high water mark (%d)", b.rootNode.pgid, b.tx.meta.pgid)
 	b.root = b.rootNode.pgid
 
 	return nil

cmd/bolt/stats.go

@@ -0,0 +1,54 @@
+package main
+
+import (
+	"os"
+
+	"github.com/boltdb/bolt"
+)
+
+// Keys retrieves a list of keys for a given bucket.
+func Stats(path, name string) {
+	if _, err := os.Stat(path); os.IsNotExist(err) {
+		fatal(err)
+		return
+	}
+
+	db, err := bolt.Open(path, 0600)
+	if err != nil {
+		fatal(err)
+		return
+	}
+	defer db.Close()
+
+	err = db.View(func(tx *bolt.Tx) error {
+		// Find bucket.
+		b := tx.Bucket([]byte(name))
+		if b == nil {
+			fatalf("bucket not found: %s", name)
+			return nil
+		}
+
+		// Iterate over each key.
+		s := b.Stats()
+		println("Page count statistics")
+		printf("\tNumber of logical branch pages: %d\n", s.BranchPageN)
+		printf("\tNumber of physical branch overflow pages: %d\n", s.BranchOverflowN)
+		printf("\tNumber of logical leaf pages: %d\n", s.LeafPageN)
+		printf("\tNumber of physical leaf overflow pages: %d\n", s.LeafOverflowN)
+
+		println("Tree statistics")
+		printf("\tNumber of keys/value pairs: %d\n", s.KeyN)
+		printf("\tNumber of levels in B+tree: %d\n", s.Depth)
+
+		println("Page size utilization")
+		printf("\tBytes allocated for physical branch pages: %d\n", s.BranchAlloc)
+		printf("\tBytes actually used for branch data: %d\n", s.BranchInuse)
+		printf("\tBytes allocated for physical leaf pages: %d\n", s.LeafAlloc)
+		printf("\tBytes actually used for leaf data: %d\n", s.LeafInuse)
+		return nil
+	})
+	if err != nil {
+		fatal(err)
+		return
+	}
+}

db.go

@@ -705,6 +705,10 @@ func (m *meta) copy(dest *meta) {
 
 // write writes the meta onto a page.
 func (m *meta) write(p *page) {
+
+	_assert(m.root.root < m.pgid, "root bucket pgid (%d) above high water mark (%d)", m.root.root, m.pgid)
+	_assert(m.freelist < m.pgid, "freelist pgid (%d) above high water mark (%d)", m.freelist, m.pgid)
+
 	// Page id is either going to be 0 or 1 which we can determine by the transaction ID.
 	p.id = pgid(m.txid % 2)
 	p.flags |= metaPageFlag

node.go

@@ -98,6 +98,8 @@ func (n *node) prevSibling() *node {
 
 // put inserts a key/value.
 func (n *node) put(oldKey, newKey, value []byte, pgid pgid, flags uint32) {
+	_assert(pgid < n.bucket.tx.meta.pgid, "pgid (%d) above high water mark (%d)", pgid, n.bucket.tx.meta.pgid)
+
 	// Find insertion index.
 	index := sort.Search(len(n.inodes), func(i int) bool { return bytes.Compare(n.inodes[i].key, oldKey) != -1 })
 
@@ -278,6 +280,7 @@ func (n *node) spill() error {
 		}
 
 		// Write the node.
+		_assert(p.id < tx.meta.pgid, "pgid (%d) above high water mark (%d)", p.id, tx.meta.pgid)
 		node.pgid = p.id
 		node.write(p)
 
@@ -307,6 +310,7 @@ func (n *node) spill() error {
 		}
 
 		// Write the new root.
+		_assert(p.id < tx.meta.pgid, "pgid (%d) above high water mark (%d)", p.id, tx.meta.pgid)
 		parent.pgid = p.id
 		parent.write(p)
 	}