Merge pull request #444 from pmezard/doc-bucket-lifetime

bucket: document buckets are valid only during the transaction

bucket.go

@@ -99,6 +99,7 @@ func (b *Bucket) Cursor() *Cursor {
 
 // Bucket retrieves a nested bucket by name.
 // Returns nil if the bucket does not exist.
+// The bucket instance is only valid for the lifetime of the transaction.
 func (b *Bucket) Bucket(name []byte) *Bucket {
 	if b.buckets != nil {
 		if child := b.buckets[string(name)]; child != nil {
@@ -148,6 +149,7 @@ func (b *Bucket) openBucket(value []byte) *Bucket {
 
 // CreateBucket creates a new bucket at the given key and returns the new bucket.
 // Returns an error if the key already exists, if the bucket name is blank, or if the bucket name is too long.
+// The bucket instance is only valid for the lifetime of the transaction.
 func (b *Bucket) CreateBucket(key []byte) (*Bucket, error) {
 	if b.tx.db == nil {
 		return nil, ErrTxClosed
@@ -192,6 +194,7 @@ func (b *Bucket) CreateBucket(key []byte) (*Bucket, error) {
 
 // CreateBucketIfNotExists creates a new bucket if it doesn't already exist and returns a reference to it.
 // Returns an error if the bucket name is blank, or if the bucket name is too long.
+// The bucket instance is only valid for the lifetime of the transaction.
 func (b *Bucket) CreateBucketIfNotExists(key []byte) (*Bucket, error) {
 	child, err := b.CreateBucket(key)
 	if err == ErrBucketExists {

tx.go

@@ -87,18 +87,21 @@ func (tx *Tx) Stats() TxStats {
 
 // Bucket retrieves a bucket by name.
 // Returns nil if the bucket does not exist.
+// The bucket instance is only valid for the lifetime of the transaction.
 func (tx *Tx) Bucket(name []byte) *Bucket {
 	return tx.root.Bucket(name)
 }
 
 // CreateBucket creates a new bucket.
 // Returns an error if the bucket already exists, if the bucket name is blank, or if the bucket name is too long.
+// The bucket instance is only valid for the lifetime of the transaction.
 func (tx *Tx) CreateBucket(name []byte) (*Bucket, error) {
 	return tx.root.CreateBucket(name)
 }
 
 // CreateBucketIfNotExists creates a new bucket if it doesn't already exist.
 // Returns an error if the bucket name is blank, or if the bucket name is too long.
+// The bucket instance is only valid for the lifetime of the transaction.
 func (tx *Tx) CreateBucketIfNotExists(name []byte) (*Bucket, error) {
 	return tx.root.CreateBucketIfNotExists(name)
 }