Tracking, conflict resolution, and dedupe

This commit is contained in:
Chad Retz 2019-02-25 14:09:47 -06:00
parent 5120875087
commit c79ea0e04c
8 changed files with 210 additions and 83 deletions

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@ -39,6 +39,7 @@ const (
) )
const DefaultPeerSleepOnError = 30 * time.Second const DefaultPeerSleepOnError = 30 * time.Second
const DefaultOldestAllowedStorageValue = 7 * (60 * time.Minute)
func New(ctx context.Context, config Config) (*Gun, error) { func New(ctx context.Context, config Config) (*Gun, error) {
g := &Gun{ g := &Gun{
@ -75,7 +76,7 @@ func New(ctx context.Context, config Config) (*Gun, error) {
} }
// Set defaults // Set defaults
if g.storage == nil { if g.storage == nil {
g.storage = &StorageInMem{} g.storage = NewStorageInMem(DefaultOldestAllowedStorageValue)
} }
if g.soulGen == nil { if g.soulGen == nil {
g.soulGen = DefaultSoulGen g.soulGen = DefaultSoulGen
@ -103,6 +104,9 @@ func (g *Gun) Close() error {
errs = append(errs, err) errs = append(errs, err)
} }
} }
if err := g.storage.Close(); err != nil {
errs = append(errs, err)
}
if len(errs) == 0 { if len(errs) == 0 {
return nil return nil
} else if len(errs) == 1 { } else if len(errs) == 1 {
@ -165,6 +169,17 @@ func (g *Gun) startReceiving() {
} }
func (g *Gun) onPeerMessage(ctx context.Context, msg *MessageReceived) { func (g *Gun) onPeerMessage(ctx context.Context, msg *MessageReceived) {
// If we're tracking everything, persist all puts here.
if g.tracking == TrackingEverything {
for parentSoul, node := range msg.Put {
for field, value := range node.Values {
if state, ok := node.Metadata.State[field]; ok {
// TODO: warn on error or something
g.storage.Put(ctx, parentSoul, field, value, state, false)
}
}
}
}
// If there is a listener for this message, use it // If there is a listener for this message, use it
if msg.Ack != "" { if msg.Ack != "" {
g.messageIDListenersLock.RLock() g.messageIDListenersLock.RLock()

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@ -122,9 +122,3 @@ func (ValueRelation) nodeValue() {}
func (n ValueRelation) MarshalJSON() ([]byte, error) { func (n ValueRelation) MarshalJSON() ([]byte, error) {
return json.Marshal(map[string]string{"#": string(n)}) return json.Marshal(map[string]string{"#": string(n)})
} }
// type ValueWithState struct {
// Value Value
// // This is 0 for top-level values
// State int64
// }

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@ -89,8 +89,10 @@ func (s *Scoped) fetchRemote(ctx context.Context, ch chan *FetchResult) {
s.fetchResultListenersLock.Unlock() s.fetchResultListenersLock.Unlock()
// Listen for responses to this get // Listen for responses to this get
s.gun.registerMessageIDListener(req.ID, msgCh) s.gun.registerMessageIDListener(req.ID, msgCh)
// TODO: only for children: s.gun.RegisterValueIDListener(s.id, msgCh) // TODO: Also listen for any changes to the value or just for specific requests?
// Handle received messages turning them to value fetches // Handle received messages turning them to value fetches
var lastSeenValue Value
var lastSeenState State
go func() { go func() {
for { for {
select { select {
@ -106,12 +108,28 @@ func (s *Scoped) fetchRemote(ctx context.Context, ch chan *FetchResult) {
// We asked for a single field, should only get that field or it doesn't exist // We asked for a single field, should only get that field or it doesn't exist
if msg.Err != "" { if msg.Err != "" {
r.Err = fmt.Errorf("Remote error: %v", msg.Err) r.Err = fmt.Errorf("Remote error: %v", msg.Err)
} else if n := msg.Put[parentSoul]; n != nil && n.Values[s.field] != nil { } else if n := msg.Put[parentSoul]; n != nil {
r.Value, r.State, r.ValueExists = n.Values[s.field], n.State[s.field], true if newVal, ok := n.Values[s.field]; ok {
newState := n.State[s.field]
// Dedupe the value
if lastSeenValue == newVal && lastSeenState == newState {
continue
}
// If we're storing only what we requested (we do "everything" at a higher level), do it here
// and only send result if it was an update. Otherwise only do it if we would have done one.
confRes := ConflictResolutionNeverSeenUpdate
if s.gun.tracking == TrackingRequested {
confRes, r.Err = s.gun.storage.Put(ctx, parentSoul, s.field, newVal, newState, false)
} else if lastSeenState > 0 {
confRes = ConflictResolve(lastSeenValue, lastSeenState, newVal, newState, StateNow())
}
// If there are no errors and it was an update, update the last seen and set the response vals
if r.Err == nil && confRes.IsImmediateUpdate() {
lastSeenValue, lastSeenState = newVal, newState
r.Value, r.State, r.ValueExists = newVal, newState, true
}
}
} }
// TODO: conflict resolution and defer
// TODO: dedupe
// TODO: store and cache
safeFetchResultSend(ch, r) safeFetchResultSend(ch, r)
} }
} }

View File

@ -87,14 +87,10 @@ func (s *Scoped) Put(ctx context.Context, val Value, opts ...PutOption) <-chan *
// Also store locally and set the cached soul // Also store locally and set the cached soul
// TODO: Should I not store until the very end just in case it errors halfway // TODO: Should I not store until the very end just in case it errors halfway
// though? There are no standard cases where it should fail. // though? There are no standard cases where it should fail.
if ok, err := s.gun.storage.Put(ctx, prevParentSoul, parent.field, ValueRelation(parentCachedSoul), currState); err != nil { if _, err := s.gun.storage.Put(ctx, prevParentSoul, parent.field, ValueRelation(parentCachedSoul), currState, false); err != nil {
ch <- &PutResult{Err: err} ch <- &PutResult{Err: err}
close(ch) close(ch)
return ch return ch
} else if !ok {
ch <- &PutResult{Err: fmt.Errorf("Unexpected deferred local store")}
close(ch)
return ch
} else if !parent.setCachedSoul(ValueRelation(parentCachedSoul)) { } else if !parent.setCachedSoul(ValueRelation(parentCachedSoul)) {
ch <- &PutResult{Err: fmt.Errorf("Concurrent cached soul set")} ch <- &PutResult{Err: fmt.Errorf("Concurrent cached soul set")}
close(ch) close(ch)
@ -104,14 +100,10 @@ func (s *Scoped) Put(ctx context.Context, val Value, opts ...PutOption) <-chan *
prevParentSoul = parentCachedSoul prevParentSoul = parentCachedSoul
} }
// Now that we've setup all the parents, we can do this store locally // Now that we've setup all the parents, we can do this store locally
if ok, err := s.gun.storage.Put(ctx, prevParentSoul, s.field, val, currState); err != nil { if _, err := s.gun.storage.Put(ctx, prevParentSoul, s.field, val, currState, false); err != nil {
ch <- &PutResult{Err: err} ch <- &PutResult{Err: err}
close(ch) close(ch)
return ch return ch
} else if !ok {
ch <- &PutResult{Err: fmt.Errorf("Unexpected deferred local store")}
close(ch)
return ch
} }
// We need an ack for local store and stop if local only // We need an ack for local store and stop if local only
ch <- &PutResult{} ch <- &PutResult{}

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@ -1,7 +1,8 @@
package gun package gun
import ( import (
"sync/atomic" "bytes"
"encoding/json"
"time" "time"
) )
@ -9,42 +10,40 @@ type State uint64
func StateNow() State { return State(timeNowUnixMs()) } func StateNow() State { return State(timeNowUnixMs()) }
// timeFromUnixMs returns zero'd time if ms is 0 func StateFromTime(t time.Time) State { return State(timeToUnixMs(t)) }
func timeFromUnixMs(ms int64) time.Time {
if ms == 0 { type ConflictResolution int
return time.Time{}
} const (
return time.Unix(0, ms*int64(time.Millisecond)) ConflictResolutionNeverSeenUpdate ConflictResolution = iota
ConflictResolutionTooFutureDeferred
ConflictResolutionOlderHistorical
ConflictResolutionNewerUpdate
ConflictResolutionSameKeep
ConflictResolutionSameUpdate
)
func (c ConflictResolution) IsImmediateUpdate() bool {
return c == ConflictResolutionNeverSeenUpdate || c == ConflictResolutionNewerUpdate || c == ConflictResolutionSameUpdate
} }
// timeToUnixMs returns 0 if t.IsZero func ConflictResolve(existingVal Value, existingState State, newVal Value, newState State, sysState State) ConflictResolution {
func timeToUnixMs(t time.Time) int64 { // Existing gunjs impl serializes to JSON first to do lexical comparisons, so we will too
if t.IsZero() { if sysState < newState {
return 0 return ConflictResolutionTooFutureDeferred
} } else if newState < existingState {
return t.UnixNano() / int64(time.Millisecond) return ConflictResolutionOlderHistorical
} } else if existingState < newState {
return ConflictResolutionNewerUpdate
func timeNowUnixMs() int64 { } else if existingVal == newVal {
return timeToUnixMs(time.Now()) return ConflictResolutionSameKeep
} } else if existingJSON, err := json.Marshal(existingVal); err != nil {
panic(err)
var lastNano int64 } else if newJSON, err := json.Marshal(newVal); err != nil {
panic(err)
// uniqueNano is 0 if ms is first time seen, otherwise a unique num in combination with ms } else if bytes.Compare(existingJSON, newJSON) < 0 {
func timeNowUniqueUnix() (ms int64, uniqueNum int64) { return ConflictResolutionSameUpdate
now := time.Now() } else {
newNano := now.UnixNano() return ConflictResolutionSameKeep
for {
prevLastNano := lastNano
if prevLastNano < newNano && atomic.CompareAndSwapInt64(&lastNano, prevLastNano, newNano) {
ms = newNano / int64(time.Millisecond)
// If was same ms as seen before, set uniqueNum to the nano part
if prevLastNano/int64(time.Millisecond) == ms {
uniqueNum = newNano%int64(time.Millisecond) + 1
}
return
}
newNano = prevLastNano + 1
} }
} }

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@ -4,19 +4,21 @@ import (
"context" "context"
"errors" "errors"
"sync" "sync"
"time"
) )
var ErrStorageNotFound = errors.New("Not found") var ErrStorageNotFound = errors.New("Not found")
type Storage interface { type Storage interface {
Get(ctx context.Context, parentSoul, field string) (Value, State, error) Get(ctx context.Context, parentSoul, field string) (Value, State, error)
// If bool is false, it's deferred Put(ctx context.Context, parentSoul, field string, val Value, state State, onlyIfExists bool) (ConflictResolution, error)
Put(ctx context.Context, parentSoul, field string, val Value, state State) (bool, error) Close() error
Tracking(ctx context.Context, parentSoul, field string) (bool, error)
} }
type StorageInMem struct { type storageInMem struct {
values sync.Map values map[parentSoulAndField]*valueWithState
valueLock sync.RWMutex
purgeCancelFn context.CancelFunc
} }
type parentSoulAndField struct{ parentSoul, field string } type parentSoulAndField struct{ parentSoul, field string }
@ -26,22 +28,75 @@ type valueWithState struct {
state State state State
} }
func (s *StorageInMem) Get(ctx context.Context, parentSoul, field string) (Value, State, error) { func NewStorageInMem(oldestAllowed time.Duration) Storage {
v, ok := s.values.Load(parentSoulAndField{parentSoul, field}) s := &storageInMem{values: map[parentSoulAndField]*valueWithState{}}
if !ok { // Start the purger
return nil, 0, ErrStorageNotFound if oldestAllowed > 0 {
var ctx context.Context
ctx, s.purgeCancelFn = context.WithCancel(context.Background())
go func() {
tick := time.NewTicker(5 * time.Second)
defer tick.Stop()
for {
select {
case <-ctx.Done():
return
case t := <-tick.C:
oldestStateAllowed := StateFromTime(t.Add(-oldestAllowed))
s.valueLock.Lock()
s.valueLock.Unlock()
for k, v := range s.values {
if v.state < oldestStateAllowed {
delete(s.values, k)
}
}
}
}
}()
} }
vs := v.(*valueWithState) return s
return vs.val, vs.state, nil
} }
func (s *StorageInMem) Put(ctx context.Context, parentSoul, field string, val Value, state State) (bool, error) { func (s *storageInMem) Get(ctx context.Context, parentSoul, field string) (Value, State, error) {
s.values.Store(parentSoulAndField{parentSoul, field}, &valueWithState{val, state}) s.valueLock.RLock()
// TODO: conflict resolution state check? defer s.valueLock.RUnlock()
return true, nil if vs := s.values[parentSoulAndField{parentSoul, field}]; vs == nil {
return nil, 0, ErrStorageNotFound
} else {
return vs.val, vs.state, nil
}
} }
func (s *StorageInMem) Tracking(ctx context.Context, parentSoul, field string) (bool, error) { func (s *storageInMem) Put(
_, ok := s.values.Load(parentSoulAndField{parentSoul, field}) ctx context.Context, parentSoul, field string, val Value, state State, onlyIfExists bool,
return ok, nil ) (confRes ConflictResolution, err error) {
s.valueLock.Lock()
defer s.valueLock.Unlock()
key, newVs := parentSoulAndField{parentSoul, field}, &valueWithState{val, state}
sysState := StateNow()
if existingVs := s.values[key]; existingVs == nil && onlyIfExists {
return 0, ErrStorageNotFound
} else if existingVs == nil {
confRes = ConflictResolutionNeverSeenUpdate
} else {
confRes = ConflictResolve(existingVs.val, existingVs.state, val, state, sysState)
}
if confRes == ConflictResolutionTooFutureDeferred {
// Schedule for 100ms past when it's deferred to
time.AfterFunc(time.Duration(state-sysState)*time.Millisecond+100, func() {
// TODO: should I check whether closed?
// TODO: what to do w/ error?
s.Put(ctx, parentSoul, field, val, state, onlyIfExists)
})
} else if confRes.IsImmediateUpdate() {
s.values[key] = newVs
}
return
}
func (s *storageInMem) Close() error {
if s.purgeCancelFn != nil {
s.purgeCancelFn()
}
return nil
} }

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@ -9,8 +9,10 @@ import (
func TestGunGetSimple(t *testing.T) { func TestGunGetSimple(t *testing.T) {
// Run the server, put in one call, get in another, then check // Run the server, put in one call, get in another, then check
ctx, cancelFn := newContextWithGunJServer(t) ctx, cancelFn := newContext(t)
defer cancelFn() defer cancelFn()
serverCancelFn := ctx.startGunJSServer()
defer serverCancelFn()
randStr := randString(30) randStr := randString(30)
// Write w/ JS // Write w/ JS
ctx.runJSWithGun(` ctx.runJSWithGun(`
@ -29,11 +31,12 @@ func TestGunGetSimple(t *testing.T) {
r := g.Scoped(ctx, "esgopeta-test", "TestGunGetSimple", "some-key").FetchOne(ctx) r := g.Scoped(ctx, "esgopeta-test", "TestGunGetSimple", "some-key").FetchOne(ctx)
ctx.Require.NoError(r.Err) ctx.Require.NoError(r.Err)
ctx.Require.Equal(gun.ValueString(randStr), r.Value.(gun.ValueString)) ctx.Require.Equal(gun.ValueString(randStr), r.Value.(gun.ValueString))
// // Do it again TODO: make sure there are no network calls, it's all from mem // Do it again with the JS server closed since it should fetch from memory
// ctx.debugf("Asking for key again") serverCancelFn()
// f = g.Scoped(ctx, "esgopeta-test", "TestGunGetSimple", "some-key").FetchOne(ctx) ctx.debugf("Asking for key again")
// ctx.Require.NoError(f.Err) r = g.Scoped(ctx, "esgopeta-test", "TestGunGetSimple", "some-key").FetchOne(ctx)
// ctx.Require.Equal(gun.ValueString(randStr), f.Value.(gun.ValueString)) ctx.Require.NoError(r.Err)
ctx.Require.Equal(gun.ValueString(randStr), r.Value.(gun.ValueString))
} }
func TestGunPutSimple(t *testing.T) { func TestGunPutSimple(t *testing.T) {
@ -59,3 +62,12 @@ func TestGunPutSimple(t *testing.T) {
`) `)
ctx.Require.Equal(randStr, strings.TrimSpace(string(out))) ctx.Require.Equal(randStr, strings.TrimSpace(string(out)))
} }
/*
TODO Tests to write:
* test put w/ future state happens then
* test put w/ old state is discarded
* test put w/ new state is persisted
* test put w/ same state but greater is persisted
* test put w/ same state but less is discarded
*/

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@ -2,6 +2,8 @@ package gun
import ( import (
"crypto/rand" "crypto/rand"
"sync/atomic"
"time"
) )
const randChars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" const randChars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
@ -17,3 +19,43 @@ func randString(n int) (s string) {
} }
return s return s
} }
// timeFromUnixMs returns zero'd time if ms is 0
func timeFromUnixMs(ms int64) time.Time {
if ms == 0 {
return time.Time{}
}
return time.Unix(0, ms*int64(time.Millisecond))
}
// timeToUnixMs returns 0 if t.IsZero
func timeToUnixMs(t time.Time) int64 {
if t.IsZero() {
return 0
}
return t.UnixNano() / int64(time.Millisecond)
}
func timeNowUnixMs() int64 {
return timeToUnixMs(time.Now())
}
var lastNano int64
// uniqueNano is 0 if ms is first time seen, otherwise a unique num in combination with ms
func timeNowUniqueUnix() (ms int64, uniqueNum int64) {
now := time.Now()
newNano := now.UnixNano()
for {
prevLastNano := lastNano
if prevLastNano < newNano && atomic.CompareAndSwapInt64(&lastNano, prevLastNano, newNano) {
ms = newNano / int64(time.Millisecond)
// If was same ms as seen before, set uniqueNum to the nano part
if prevLastNano/int64(time.Millisecond) == ms {
uniqueNum = newNano%int64(time.Millisecond) + 1
}
return
}
newNano = prevLastNano + 1
}
}