iradix

package module
Version: v1.3.1 Latest Latest
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Published: Jun 28, 2021 License: MPL-2.0 Imports: 4 Imported by: 241

README

go-immutable-radix CircleCI

Provides the iradix package that implements an immutable radix tree. The package only provides a single Tree implementation, optimized for sparse nodes.

As a radix tree, it provides the following:

  • O(k) operations. In many cases, this can be faster than a hash table since the hash function is an O(k) operation, and hash tables have very poor cache locality.
  • Minimum / Maximum value lookups
  • Ordered iteration

A tree supports using a transaction to batch multiple updates (insert, delete) in a more efficient manner than performing each operation one at a time.

For a mutable variant, see go-radix.

Documentation

The full documentation is available on Godoc.

Example

Below is a simple example of usage

// Create a tree
r := iradix.New()
r, _, _ = r.Insert([]byte("foo"), 1)
r, _, _ = r.Insert([]byte("bar"), 2)
r, _, _ = r.Insert([]byte("foobar"), 2)

// Find the longest prefix match
m, _, _ := r.Root().LongestPrefix([]byte("foozip"))
if string(m) != "foo" {
    panic("should be foo")
}

Here is an example of performing a range scan of the keys.

// Create a tree
r := iradix.New()
r, _, _ = r.Insert([]byte("001"), 1)
r, _, _ = r.Insert([]byte("002"), 2)
r, _, _ = r.Insert([]byte("005"), 5)
r, _, _ = r.Insert([]byte("010"), 10)
r, _, _ = r.Insert([]byte("100"), 10)

// Range scan over the keys that sort lexicographically between [003, 050)
it := r.Root().Iterator()
it.SeekLowerBound([]byte("003"))
for key, _, ok := it.Next(); ok; key, _, ok = it.Next() {
  if key >= "050" {
      break
  }
  fmt.Println(key)
}
// Output:
//  005
//  010

Documentation

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

This section is empty.

Types

type Iterator

type Iterator struct {
	// contains filtered or unexported fields
}

Iterator is used to iterate over a set of nodes in pre-order

func (*Iterator) Next

func (i *Iterator) Next() ([]byte, interface{}, bool)

Next returns the next node in order

func (*Iterator) SeekLowerBound added in v1.1.0

func (i *Iterator) SeekLowerBound(key []byte)

SeekLowerBound is used to seek the iterator to the smallest key that is greater or equal to the given key. There is no watch variant as it's hard to predict based on the radix structure which node(s) changes might affect the result.

func (*Iterator) SeekPrefix

func (i *Iterator) SeekPrefix(prefix []byte)

SeekPrefix is used to seek the iterator to a given prefix

func (*Iterator) SeekPrefixWatch

func (i *Iterator) SeekPrefixWatch(prefix []byte) (watch <-chan struct{})

SeekPrefixWatch is used to seek the iterator to a given prefix and returns the watch channel of the finest granularity

type Node

type Node struct {
	// contains filtered or unexported fields
}

Node is an immutable node in the radix tree

func (*Node) Get

func (n *Node) Get(k []byte) (interface{}, bool)

func (*Node) GetWatch

func (n *Node) GetWatch(k []byte) (<-chan struct{}, interface{}, bool)

func (*Node) Iterator

func (n *Node) Iterator() *Iterator

Iterator is used to return an iterator at the given node to walk the tree

func (*Node) LongestPrefix

func (n *Node) LongestPrefix(k []byte) ([]byte, interface{}, bool)

LongestPrefix is like Get, but instead of an exact match, it will return the longest prefix match.

func (*Node) Maximum

func (n *Node) Maximum() ([]byte, interface{}, bool)

Maximum is used to return the maximum value in the tree

func (*Node) Minimum

func (n *Node) Minimum() ([]byte, interface{}, bool)

Minimum is used to return the minimum value in the tree

func (*Node) ReverseIterator added in v1.3.0

func (n *Node) ReverseIterator() *ReverseIterator

ReverseIterator is used to return an iterator at the given node to walk the tree backwards

func (*Node) Walk

func (n *Node) Walk(fn WalkFn)

Walk is used to walk the tree

func (*Node) WalkBackwards added in v1.3.0

func (n *Node) WalkBackwards(fn WalkFn)

WalkBackwards is used to walk the tree in reverse order

func (*Node) WalkPath

func (n *Node) WalkPath(path []byte, fn WalkFn)

WalkPath is used to walk the tree, but only visiting nodes from the root down to a given leaf. Where WalkPrefix walks all the entries *under* the given prefix, this walks the entries *above* the given prefix.

func (*Node) WalkPrefix

func (n *Node) WalkPrefix(prefix []byte, fn WalkFn)

WalkPrefix is used to walk the tree under a prefix

type ReverseIterator added in v1.3.0

type ReverseIterator struct {
	// contains filtered or unexported fields
}

ReverseIterator is used to iterate over a set of nodes in reverse in-order

func NewReverseIterator added in v1.3.0

func NewReverseIterator(n *Node) *ReverseIterator

NewReverseIterator returns a new ReverseIterator at a node

func (*ReverseIterator) Previous added in v1.3.0

func (ri *ReverseIterator) Previous() ([]byte, interface{}, bool)

Previous returns the previous node in reverse order

func (*ReverseIterator) SeekPrefix added in v1.3.0

func (ri *ReverseIterator) SeekPrefix(prefix []byte)

SeekPrefix is used to seek the iterator to a given prefix

func (*ReverseIterator) SeekPrefixWatch added in v1.3.0

func (ri *ReverseIterator) SeekPrefixWatch(prefix []byte) (watch <-chan struct{})

SeekPrefixWatch is used to seek the iterator to a given prefix and returns the watch channel of the finest granularity

func (*ReverseIterator) SeekReverseLowerBound added in v1.3.0

func (ri *ReverseIterator) SeekReverseLowerBound(key []byte)

SeekReverseLowerBound is used to seek the iterator to the largest key that is lower or equal to the given key. There is no watch variant as it's hard to predict based on the radix structure which node(s) changes might affect the result.

type Tree

type Tree struct {
	// contains filtered or unexported fields
}

Tree implements an immutable radix tree. This can be treated as a Dictionary abstract data type. The main advantage over a standard hash map is prefix-based lookups and ordered iteration. The immutability means that it is safe to concurrently read from a Tree without any coordination.

func New

func New() *Tree

New returns an empty Tree

func (*Tree) Delete

func (t *Tree) Delete(k []byte) (*Tree, interface{}, bool)

Delete is used to delete a given key. Returns the new tree, old value if any, and a bool indicating if the key was set.

func (*Tree) DeletePrefix

func (t *Tree) DeletePrefix(k []byte) (*Tree, bool)

DeletePrefix is used to delete all nodes starting with a given prefix. Returns the new tree, and a bool indicating if the prefix matched any nodes

func (*Tree) Get

func (t *Tree) Get(k []byte) (interface{}, bool)

Get is used to lookup a specific key, returning the value and if it was found

func (*Tree) Insert

func (t *Tree) Insert(k []byte, v interface{}) (*Tree, interface{}, bool)

Insert is used to add or update a given key. The return provides the new tree, previous value and a bool indicating if any was set.

func (*Tree) Len

func (t *Tree) Len() int

Len is used to return the number of elements in the tree

func (*Tree) Root

func (t *Tree) Root() *Node

Root returns the root node of the tree which can be used for richer query operations.

func (*Tree) Txn

func (t *Tree) Txn() *Txn

Txn starts a new transaction that can be used to mutate the tree

type Txn

type Txn struct {
	// contains filtered or unexported fields
}

Txn is a transaction on the tree. This transaction is applied atomically and returns a new tree when committed. A transaction is not thread safe, and should only be used by a single goroutine.

func (*Txn) Clone added in v1.2.0

func (t *Txn) Clone() *Txn

Clone makes an independent copy of the transaction. The new transaction does not track any nodes and has TrackMutate turned off. The cloned transaction will contain any uncommitted writes in the original transaction but further mutations to either will be independent and result in different radix trees on Commit. A cloned transaction may be passed to another goroutine and mutated there independently however each transaction may only be mutated in a single thread.

func (*Txn) Commit

func (t *Txn) Commit() *Tree

Commit is used to finalize the transaction and return a new tree. If mutation tracking is turned on then notifications will also be issued.

func (*Txn) CommitOnly

func (t *Txn) CommitOnly() *Tree

CommitOnly is used to finalize the transaction and return a new tree, but does not issue any notifications until Notify is called.

func (*Txn) Delete

func (t *Txn) Delete(k []byte) (interface{}, bool)

Delete is used to delete a given key. Returns the old value if any, and a bool indicating if the key was set.

func (*Txn) DeletePrefix

func (t *Txn) DeletePrefix(prefix []byte) bool

DeletePrefix is used to delete an entire subtree that matches the prefix This will delete all nodes under that prefix

func (*Txn) Get

func (t *Txn) Get(k []byte) (interface{}, bool)

Get is used to lookup a specific key, returning the value and if it was found

func (*Txn) GetWatch

func (t *Txn) GetWatch(k []byte) (<-chan struct{}, interface{}, bool)

GetWatch is used to lookup a specific key, returning the watch channel, value and if it was found

func (*Txn) Insert

func (t *Txn) Insert(k []byte, v interface{}) (interface{}, bool)

Insert is used to add or update a given key. The return provides the previous value and a bool indicating if any was set.

func (*Txn) Notify

func (t *Txn) Notify()

Notify is used along with TrackMutate to trigger notifications. This must only be done once a transaction is committed via CommitOnly, and it is called automatically by Commit.

func (*Txn) Root

func (t *Txn) Root() *Node

Root returns the current root of the radix tree within this transaction. The root is not safe across insert and delete operations, but can be used to read the current state during a transaction.

func (*Txn) TrackMutate

func (t *Txn) TrackMutate(track bool)

TrackMutate can be used to toggle if mutations are tracked. If this is enabled then notifications will be issued for affected internal nodes and leaves when the transaction is committed.

type WalkFn

type WalkFn func(k []byte, v interface{}) bool

WalkFn is used when walking the tree. Takes a key and value, returning if iteration should be terminated.

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