diff options
Diffstat (limited to 'vendor/github.com/etcd-io/bbolt/cursor.go')
-rw-r--r-- | vendor/github.com/etcd-io/bbolt/cursor.go | 396 |
1 files changed, 0 insertions, 396 deletions
diff --git a/vendor/github.com/etcd-io/bbolt/cursor.go b/vendor/github.com/etcd-io/bbolt/cursor.go deleted file mode 100644 index 3000aced6..000000000 --- a/vendor/github.com/etcd-io/bbolt/cursor.go +++ /dev/null @@ -1,396 +0,0 @@ -package bbolt - -import ( - "bytes" - "fmt" - "sort" -) - -// Cursor represents an iterator that can traverse over all key/value pairs in a bucket in sorted order. -// Cursors see nested buckets with value == nil. -// Cursors can be obtained from a transaction and are valid as long as the transaction is open. -// -// Keys and values returned from the cursor are only valid for the life of the transaction. -// -// Changing data while traversing with a cursor may cause it to be invalidated -// and return unexpected keys and/or values. You must reposition your cursor -// after mutating data. -type Cursor struct { - bucket *Bucket - stack []elemRef -} - -// Bucket returns the bucket that this cursor was created from. -func (c *Cursor) Bucket() *Bucket { - return c.bucket -} - -// First moves the cursor to the first item in the bucket and returns its key and value. -// If the bucket is empty then a nil key and value are returned. -// The returned key and value are only valid for the life of the transaction. -func (c *Cursor) First() (key []byte, value []byte) { - _assert(c.bucket.tx.db != nil, "tx closed") - c.stack = c.stack[:0] - p, n := c.bucket.pageNode(c.bucket.root) - c.stack = append(c.stack, elemRef{page: p, node: n, index: 0}) - c.first() - - // If we land on an empty page then move to the next value. - // https://github.com/boltdb/bolt/issues/450 - if c.stack[len(c.stack)-1].count() == 0 { - c.next() - } - - k, v, flags := c.keyValue() - if (flags & uint32(bucketLeafFlag)) != 0 { - return k, nil - } - return k, v - -} - -// Last moves the cursor to the last item in the bucket and returns its key and value. -// If the bucket is empty then a nil key and value are returned. -// The returned key and value are only valid for the life of the transaction. -func (c *Cursor) Last() (key []byte, value []byte) { - _assert(c.bucket.tx.db != nil, "tx closed") - c.stack = c.stack[:0] - p, n := c.bucket.pageNode(c.bucket.root) - ref := elemRef{page: p, node: n} - ref.index = ref.count() - 1 - c.stack = append(c.stack, ref) - c.last() - k, v, flags := c.keyValue() - if (flags & uint32(bucketLeafFlag)) != 0 { - return k, nil - } - return k, v -} - -// Next moves the cursor to the next item in the bucket and returns its key and value. -// If the cursor is at the end of the bucket then a nil key and value are returned. -// The returned key and value are only valid for the life of the transaction. -func (c *Cursor) Next() (key []byte, value []byte) { - _assert(c.bucket.tx.db != nil, "tx closed") - k, v, flags := c.next() - if (flags & uint32(bucketLeafFlag)) != 0 { - return k, nil - } - return k, v -} - -// Prev moves the cursor to the previous item in the bucket and returns its key and value. -// If the cursor is at the beginning of the bucket then a nil key and value are returned. -// The returned key and value are only valid for the life of the transaction. -func (c *Cursor) Prev() (key []byte, value []byte) { - _assert(c.bucket.tx.db != nil, "tx closed") - - // Attempt to move back one element until we're successful. - // Move up the stack as we hit the beginning of each page in our stack. - for i := len(c.stack) - 1; i >= 0; i-- { - elem := &c.stack[i] - if elem.index > 0 { - elem.index-- - break - } - c.stack = c.stack[:i] - } - - // If we've hit the end then return nil. - if len(c.stack) == 0 { - return nil, nil - } - - // Move down the stack to find the last element of the last leaf under this branch. - c.last() - k, v, flags := c.keyValue() - if (flags & uint32(bucketLeafFlag)) != 0 { - return k, nil - } - return k, v -} - -// Seek moves the cursor to a given key and returns it. -// If the key does not exist then the next key is used. If no keys -// follow, a nil key is returned. -// The returned key and value are only valid for the life of the transaction. -func (c *Cursor) Seek(seek []byte) (key []byte, value []byte) { - k, v, flags := c.seek(seek) - - // If we ended up after the last element of a page then move to the next one. - if ref := &c.stack[len(c.stack)-1]; ref.index >= ref.count() { - k, v, flags = c.next() - } - - if k == nil { - return nil, nil - } else if (flags & uint32(bucketLeafFlag)) != 0 { - return k, nil - } - return k, v -} - -// Delete removes the current key/value under the cursor from the bucket. -// Delete fails if current key/value is a bucket or if the transaction is not writable. -func (c *Cursor) Delete() error { - if c.bucket.tx.db == nil { - return ErrTxClosed - } else if !c.bucket.Writable() { - return ErrTxNotWritable - } - - key, _, flags := c.keyValue() - // Return an error if current value is a bucket. - if (flags & bucketLeafFlag) != 0 { - return ErrIncompatibleValue - } - c.node().del(key) - - return nil -} - -// seek moves the cursor to a given key and returns it. -// If the key does not exist then the next key is used. -func (c *Cursor) seek(seek []byte) (key []byte, value []byte, flags uint32) { - _assert(c.bucket.tx.db != nil, "tx closed") - - // Start from root page/node and traverse to correct page. - c.stack = c.stack[:0] - c.search(seek, c.bucket.root) - - // If this is a bucket then return a nil value. - return c.keyValue() -} - -// first moves the cursor to the first leaf element under the last page in the stack. -func (c *Cursor) first() { - for { - // Exit when we hit a leaf page. - var ref = &c.stack[len(c.stack)-1] - if ref.isLeaf() { - break - } - - // Keep adding pages pointing to the first element to the stack. - var pgid pgid - if ref.node != nil { - pgid = ref.node.inodes[ref.index].pgid - } else { - pgid = ref.page.branchPageElement(uint16(ref.index)).pgid - } - p, n := c.bucket.pageNode(pgid) - c.stack = append(c.stack, elemRef{page: p, node: n, index: 0}) - } -} - -// last moves the cursor to the last leaf element under the last page in the stack. -func (c *Cursor) last() { - for { - // Exit when we hit a leaf page. - ref := &c.stack[len(c.stack)-1] - if ref.isLeaf() { - break - } - - // Keep adding pages pointing to the last element in the stack. - var pgid pgid - if ref.node != nil { - pgid = ref.node.inodes[ref.index].pgid - } else { - pgid = ref.page.branchPageElement(uint16(ref.index)).pgid - } - p, n := c.bucket.pageNode(pgid) - - var nextRef = elemRef{page: p, node: n} - nextRef.index = nextRef.count() - 1 - c.stack = append(c.stack, nextRef) - } -} - -// next moves to the next leaf element and returns the key and value. -// If the cursor is at the last leaf element then it stays there and returns nil. -func (c *Cursor) next() (key []byte, value []byte, flags uint32) { - for { - // Attempt to move over one element until we're successful. - // Move up the stack as we hit the end of each page in our stack. - var i int - for i = len(c.stack) - 1; i >= 0; i-- { - elem := &c.stack[i] - if elem.index < elem.count()-1 { - elem.index++ - break - } - } - - // If we've hit the root page then stop and return. This will leave the - // cursor on the last element of the last page. - if i == -1 { - return nil, nil, 0 - } - - // Otherwise start from where we left off in the stack and find the - // first element of the first leaf page. - c.stack = c.stack[:i+1] - c.first() - - // If this is an empty page then restart and move back up the stack. - // https://github.com/boltdb/bolt/issues/450 - if c.stack[len(c.stack)-1].count() == 0 { - continue - } - - return c.keyValue() - } -} - -// search recursively performs a binary search against a given page/node until it finds a given key. -func (c *Cursor) search(key []byte, pgid pgid) { - p, n := c.bucket.pageNode(pgid) - if p != nil && (p.flags&(branchPageFlag|leafPageFlag)) == 0 { - panic(fmt.Sprintf("invalid page type: %d: %x", p.id, p.flags)) - } - e := elemRef{page: p, node: n} - c.stack = append(c.stack, e) - - // If we're on a leaf page/node then find the specific node. - if e.isLeaf() { - c.nsearch(key) - return - } - - if n != nil { - c.searchNode(key, n) - return - } - c.searchPage(key, p) -} - -func (c *Cursor) searchNode(key []byte, n *node) { - var exact bool - index := sort.Search(len(n.inodes), func(i int) bool { - // TODO(benbjohnson): Optimize this range search. It's a bit hacky right now. - // sort.Search() finds the lowest index where f() != -1 but we need the highest index. - ret := bytes.Compare(n.inodes[i].key, key) - if ret == 0 { - exact = true - } - return ret != -1 - }) - if !exact && index > 0 { - index-- - } - c.stack[len(c.stack)-1].index = index - - // Recursively search to the next page. - c.search(key, n.inodes[index].pgid) -} - -func (c *Cursor) searchPage(key []byte, p *page) { - // Binary search for the correct range. - inodes := p.branchPageElements() - - var exact bool - index := sort.Search(int(p.count), func(i int) bool { - // TODO(benbjohnson): Optimize this range search. It's a bit hacky right now. - // sort.Search() finds the lowest index where f() != -1 but we need the highest index. - ret := bytes.Compare(inodes[i].key(), key) - if ret == 0 { - exact = true - } - return ret != -1 - }) - if !exact && index > 0 { - index-- - } - c.stack[len(c.stack)-1].index = index - - // Recursively search to the next page. - c.search(key, inodes[index].pgid) -} - -// nsearch searches the leaf node on the top of the stack for a key. -func (c *Cursor) nsearch(key []byte) { - e := &c.stack[len(c.stack)-1] - p, n := e.page, e.node - - // If we have a node then search its inodes. - if n != nil { - index := sort.Search(len(n.inodes), func(i int) bool { - return bytes.Compare(n.inodes[i].key, key) != -1 - }) - e.index = index - return - } - - // If we have a page then search its leaf elements. - inodes := p.leafPageElements() - index := sort.Search(int(p.count), func(i int) bool { - return bytes.Compare(inodes[i].key(), key) != -1 - }) - e.index = index -} - -// keyValue returns the key and value of the current leaf element. -func (c *Cursor) keyValue() ([]byte, []byte, uint32) { - ref := &c.stack[len(c.stack)-1] - - // If the cursor is pointing to the end of page/node then return nil. - if ref.count() == 0 || ref.index >= ref.count() { - return nil, nil, 0 - } - - // Retrieve value from node. - if ref.node != nil { - inode := &ref.node.inodes[ref.index] - return inode.key, inode.value, inode.flags - } - - // Or retrieve value from page. - elem := ref.page.leafPageElement(uint16(ref.index)) - return elem.key(), elem.value(), elem.flags -} - -// node returns the node that the cursor is currently positioned on. -func (c *Cursor) node() *node { - _assert(len(c.stack) > 0, "accessing a node with a zero-length cursor stack") - - // If the top of the stack is a leaf node then just return it. - if ref := &c.stack[len(c.stack)-1]; ref.node != nil && ref.isLeaf() { - return ref.node - } - - // Start from root and traverse down the hierarchy. - var n = c.stack[0].node - if n == nil { - n = c.bucket.node(c.stack[0].page.id, nil) - } - for _, ref := range c.stack[:len(c.stack)-1] { - _assert(!n.isLeaf, "expected branch node") - n = n.childAt(int(ref.index)) - } - _assert(n.isLeaf, "expected leaf node") - return n -} - -// elemRef represents a reference to an element on a given page/node. -type elemRef struct { - page *page - node *node - index int -} - -// isLeaf returns whether the ref is pointing at a leaf page/node. -func (r *elemRef) isLeaf() bool { - if r.node != nil { - return r.node.isLeaf - } - return (r.page.flags & leafPageFlag) != 0 -} - -// count returns the number of inodes or page elements. -func (r *elemRef) count() int { - if r.node != nil { - return len(r.node.inodes) - } - return int(r.page.count) -} |