README
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chring
chring is an implementation of a consistent hash ring. It is currently a naive implementation that does not allow for virtual nodes. I plan on adding that soon.
Usage
Create a new hash ring with ring := chring.New().
You add nodes with ring.Add(NodeName). I suggest you use an IP address for a node's name.
Now, you can get a consistent node destination when you ring.Get(key), where key is any value that you want to route upon, such as a user's ID.
If a node goes down, you can ring.Remove(NodeName).
Data Visualization
You can visualize your hash ring and its node locations with chring.ServeRing(ring, ":5000"). Check it out live with cd example/ring; go run main.go and load http://localhost:5000. Neat!
Ring manager
The RingManager is a double ring implementation that allows you to manage nodes and keys separately and you can see its usage in example/ringmanager. You can run its visualization just like with the ring example. The current implementation should allow you to back the ring manager's keys with a kv store such as redis. I plan on putting an example of this together. Currently, only keys would be able to be stored outside of memory. This probably should be expanded to store nodes outside of memory too, but currently this would be an exercise for the developer when using the RingManager.
Pending Development
- on visualization and in code for node manager, be able to get weights of nodes (know x% of keys in node N)
- allow for virtal nodes
- provide example of using a kv store like redis
- allow placing of nodes at a given hash id so you can manually balance nodes
- provide a clear path for rebalancing when you add or remove a node by providing a list of nodes that require migrations of data
Inspiration
Documentation
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Index ¶
- Variables
- func DefaultHasher(id string) uint32
- func FindInGOPATH(filename string) string
- func ServeRing(r *Ring, addr string)
- func ServeRingManager(rm *RingManager, addr string)
- type Ring
- type RingManager
- func (rm *RingManager) AddKey(key string) error
- func (rm *RingManager) AddNode(nodeID string) error
- func (rm *RingManager) GetKeys(nodeID string) (nodes, error)
- func (rm *RingManager) GetNodes() []string
- func (rm *RingManager) RemoveKey(key string) error
- func (rm *RingManager) RemoveNode(nodeID string) error
- func (rm *RingManager) SetKeyFetcher(fn func(nodeRing, dataRing *Ring, id string) (nodes, error))
- func (rm *RingManager) SetKeyStorer(fn func(key string) error)
Constants ¶
This section is empty.
Variables ¶
var Debug = false
Debug if true, prints verbose logging
var ErrNotFound = errors.New("node not found")
Functions ¶
func FindInGOPATH ¶
FindInGOPATH searches through all GOPATHS and attempts to find the given file this is useful here because we want to find chring files but we can't know the relative import path as the importer could be a subpackage
func ServeRingManager ¶
func ServeRingManager(rm *RingManager, addr string)
ServeRingManager presents a web view into your consistent hash ring manager
Types ¶
type Ring ¶
Ring is a consistent hash ring. Use New() to create a ring. You may change out the hasher function to change key balancing if needed.
func NewRing ¶
func NewRing() *Ring
New creates a new consistent hash ring with a default hashing algo
type RingManager ¶
func NewRingManager ¶
func NewRingManager() *RingManager
func (*RingManager) AddKey ¶
func (rm *RingManager) AddKey(key string) error
func (*RingManager) AddNode ¶
func (rm *RingManager) AddNode(nodeID string) error
func (*RingManager) GetKeys ¶
func (rm *RingManager) GetKeys(nodeID string) (nodes, error)
func (*RingManager) GetNodes ¶
func (rm *RingManager) GetNodes() []string
func (*RingManager) RemoveKey ¶
func (rm *RingManager) RemoveKey(key string) error
func (*RingManager) RemoveNode ¶
func (rm *RingManager) RemoveNode(nodeID string) error
func (*RingManager) SetKeyFetcher ¶
func (rm *RingManager) SetKeyFetcher(fn func(nodeRing, dataRing *Ring, id string) (nodes, error))
SetKeyFetcher allows a user to override the default in memory ring store
func (*RingManager) SetKeyStorer ¶
func (rm *RingManager) SetKeyStorer(fn func(key string) error)
SetKeyStorer allows a user to override the default in memory key store
Source Files
Directories