718b2177ce
This adds snapshot and restore methods to state and uses the snapshot one to save a copy of the state when shutting down. Right now, this is not used for anything else. Some lines performing a migration, but this is only an idea of how it could work. License: MIT Signed-off-by: Hector Sanjuan <hector@protocol.ai>
111 lines
2.4 KiB
Go
111 lines
2.4 KiB
Go
package mapstate
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import (
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"encoding/json"
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"io"
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"io/ioutil"
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"sync"
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"github.com/ipfs/ipfs-cluster/api"
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cid "github.com/ipfs/go-cid"
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)
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// Version is the map state Version. States with old versions should
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// perform an upgrade before.
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const Version = 2
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// MapState is a very simple database to store the state of the system
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// using a Go map. It is thread safe. It implements the State interface.
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type MapState struct {
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pinMux sync.RWMutex
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PinMap map[string]api.PinSerial
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Version int
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}
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// NewMapState initializes the internal map and returns a new MapState object.
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func NewMapState() *MapState {
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return &MapState{
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PinMap: make(map[string]api.PinSerial),
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Version: Version,
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}
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}
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// Add adds a Pin to the internal map.
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func (st *MapState) Add(c api.Pin) error {
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st.pinMux.Lock()
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defer st.pinMux.Unlock()
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st.PinMap[c.Cid.String()] = c.ToSerial()
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return nil
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}
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// Rm removes a Cid from the internal map.
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func (st *MapState) Rm(c *cid.Cid) error {
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st.pinMux.Lock()
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defer st.pinMux.Unlock()
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delete(st.PinMap, c.String())
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return nil
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}
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// Get returns Pin information for a CID.
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func (st *MapState) Get(c *cid.Cid) api.Pin {
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st.pinMux.RLock()
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defer st.pinMux.RUnlock()
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pins, ok := st.PinMap[c.String()]
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if !ok { // make sure no panics
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return api.Pin{}
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}
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return pins.ToPin()
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}
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// Has returns true if the Cid belongs to the State.
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func (st *MapState) Has(c *cid.Cid) bool {
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st.pinMux.RLock()
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defer st.pinMux.RUnlock()
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_, ok := st.PinMap[c.String()]
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return ok
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}
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// List provides the list of tracked Pins.
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func (st *MapState) List() []api.Pin {
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st.pinMux.RLock()
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defer st.pinMux.RUnlock()
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cids := make([]api.Pin, 0, len(st.PinMap))
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for _, v := range st.PinMap {
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if v.Cid == "" {
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continue
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}
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cids = append(cids, v.ToPin())
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}
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return cids
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}
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// Snapshot dumps the MapState to the given writer, in pretty json
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// format.
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func (st *MapState) Snapshot(w io.Writer) error {
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st.pinMux.RLock()
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defer st.pinMux.RUnlock()
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enc := json.NewEncoder(w)
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enc.SetIndent("", " ")
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return enc.Encode(st)
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}
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func (st *MapState) Restore(r io.Reader) error {
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snap, err := ioutil.ReadAll(r)
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if err != nil {
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return err
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}
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var vonly struct{ Version int }
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err = json.Unmarshal(snap, &vonly)
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if err != nil {
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return err
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}
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if vonly.Version == Version {
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// we are good
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err := json.Unmarshal(snap, st)
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return err
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} else {
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return st.migrateFrom(vonly.Version, snap)
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}
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}
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