enforce encapsulation by breaking up replication package into packages

not perfect yet, public shouldn't be required to use 'common' package to
use replication package
This commit is contained in:
Christian Schwarz
2018-08-16 21:05:21 +02:00
parent c7d28fee8f
commit 38532abf45
22 changed files with 1057 additions and 1491 deletions
+117
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@@ -0,0 +1,117 @@
package mainfsm
import (
"sort"
. "github.com/zrepl/zrepl/cmd/replication/pdu"
)
type ConflictNoCommonAncestor struct {
SortedSenderVersions, SortedReceiverVersions []*FilesystemVersion
}
func (c *ConflictNoCommonAncestor) Error() string {
return "no common snapshot or suitable bookmark between sender and receiver"
}
type ConflictDiverged struct {
SortedSenderVersions, SortedReceiverVersions []*FilesystemVersion
CommonAncestor *FilesystemVersion
SenderOnly, ReceiverOnly []*FilesystemVersion
}
func (c *ConflictDiverged) Error() string {
return "the receiver's latest snapshot is not present on sender"
}
func SortVersionListByCreateTXGThenBookmarkLTSnapshot(fsvslice []*FilesystemVersion) []*FilesystemVersion {
lesser := func(s []*FilesystemVersion) func(i, j int) bool {
return func(i, j int) bool {
if s[i].CreateTXG < s[j].CreateTXG {
return true
}
if s[i].CreateTXG == s[j].CreateTXG {
// Bookmark < Snapshot
return s[i].Type == FilesystemVersion_Bookmark && s[j].Type == FilesystemVersion_Snapshot
}
return false
}
}
if sort.SliceIsSorted(fsvslice, lesser(fsvslice)) {
return fsvslice
}
sorted := make([]*FilesystemVersion, len(fsvslice))
copy(sorted, fsvslice)
sort.Slice(sorted, lesser(sorted))
return sorted
}
// conflict may be a *ConflictDiverged or a *ConflictNoCommonAncestor
func IncrementalPath(receiver, sender []*FilesystemVersion) (incPath []*FilesystemVersion, conflict error) {
if receiver == nil {
panic("receiver must not be nil")
}
if sender == nil {
panic("sender must not be nil")
}
receiver = SortVersionListByCreateTXGThenBookmarkLTSnapshot(receiver)
sender = SortVersionListByCreateTXGThenBookmarkLTSnapshot(sender)
if len(sender) == 0 {
return []*FilesystemVersion{}, nil
}
// Find most recent common ancestor by name, preferring snapshots over bookmarks
mrcaRcv := len(receiver) - 1
mrcaSnd := len(sender) - 1
for mrcaRcv >= 0 && mrcaSnd >= 0 {
if receiver[mrcaRcv].Guid == sender[mrcaSnd].Guid {
if mrcaSnd-1 >= 0 && sender[mrcaSnd-1].Guid == sender[mrcaSnd].Guid && sender[mrcaSnd-1].Type == FilesystemVersion_Bookmark {
// prefer bookmarks over snapshots as the snapshot might go away sooner
mrcaSnd -= 1
}
break
}
if receiver[mrcaRcv].CreateTXG < sender[mrcaSnd].CreateTXG {
mrcaSnd--
} else {
mrcaRcv--
}
}
if mrcaRcv == -1 || mrcaSnd == -1 {
return nil, &ConflictNoCommonAncestor{
SortedSenderVersions: sender,
SortedReceiverVersions: receiver,
}
}
if mrcaRcv != len(receiver)-1 {
return nil, &ConflictDiverged{
SortedSenderVersions: sender,
SortedReceiverVersions: receiver,
CommonAncestor: sender[mrcaSnd],
SenderOnly: sender[mrcaSnd+1:],
ReceiverOnly: receiver[mrcaRcv+1:],
}
}
// incPath must not contain bookmarks except initial one,
incPath = make([]*FilesystemVersion, 0, len(sender))
incPath = append(incPath, sender[mrcaSnd])
// it's ok if incPath[0] is a bookmark, but not the subsequent ones in the incPath
for i := mrcaSnd + 1; i < len(sender); i++ {
if sender[i].Type == FilesystemVersion_Snapshot && incPath[len(incPath)-1].Guid != sender[i].Guid {
incPath = append(incPath, sender[i])
}
}
if len(incPath) == 1 {
// nothing to do
incPath = incPath[1:]
}
return incPath, nil
}
+342
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@@ -0,0 +1,342 @@
package mainfsm
import (
"context"
"errors"
"fmt"
"math/bits"
"sync"
"time"
. "github.com/zrepl/zrepl/cmd/replication/common"
"github.com/zrepl/zrepl/cmd/replication/pdu"
"github.com/zrepl/zrepl/cmd/replication/internal/fsfsm"
. "github.com/zrepl/zrepl/cmd/replication/internal/mainfsm/queue"
)
//go:generate stringer -type=ReplicationState
type ReplicationState uint
const (
Planning ReplicationState = 1 << iota
PlanningError
Working
WorkingWait
Completed
ContextDone
)
func (s ReplicationState) rsf() replicationStateFunc {
idx := bits.TrailingZeros(uint(s))
if idx == bits.UintSize {
panic(s) // invalid value
}
m := []replicationStateFunc{
rsfPlanning,
rsfPlanningError,
rsfWorking,
rsfWorkingWait,
nil,
nil,
}
return m[idx]
}
type Replication struct {
// lock protects all fields of this struct (but not the fields behind pointers!)
lock sync.Mutex
state ReplicationState
// Working, WorkingWait, Completed, ContextDone
queue *ReplicationQueue
completed []*fsfsm.FSReplication
active *ReplicationQueueItemHandle
// PlanningError
planningError error
// ContextDone
contextError error
// PlanningError, WorkingWait
sleepUntil time.Time
}
type Report struct {
Status string
Problem string
Completed []*fsfsm.FilesystemReplicationReport
Pending []*fsfsm.FilesystemReplicationReport
Active *fsfsm.FilesystemReplicationReport
}
func NewReplication() *Replication {
r := Replication{
state: Planning,
}
return &r
}
type replicationUpdater func(func(*Replication)) (newState ReplicationState)
type replicationStateFunc func(context.Context, EndpointPair, replicationUpdater) replicationStateFunc
func (r *Replication) Drive(ctx context.Context, ep EndpointPair) {
var u replicationUpdater = func(f func(*Replication)) ReplicationState {
r.lock.Lock()
defer r.lock.Unlock()
if f != nil {
f(r)
}
return r.state
}
var s replicationStateFunc = rsfPlanning
var pre, post ReplicationState
for s != nil {
preTime := time.Now()
pre = u(nil)
s = s(ctx, ep, u)
delta := time.Now().Sub(preTime)
post = u(nil)
GetLogger(ctx).
WithField("transition", fmt.Sprintf("%s => %s", pre, post)).
WithField("duration", delta).
Debug("main state transition")
}
GetLogger(ctx).
WithField("final_state", post).
Debug("main final state")
}
func resolveConflict(conflict error) (path []*pdu.FilesystemVersion, msg string) {
if noCommonAncestor, ok := conflict.(*ConflictNoCommonAncestor); ok {
if len(noCommonAncestor.SortedReceiverVersions) == 0 {
// FIXME hard-coded replication policy: most recent
// snapshot as source
var mostRecentSnap *pdu.FilesystemVersion
for n := len(noCommonAncestor.SortedSenderVersions) - 1; n >= 0; n-- {
if noCommonAncestor.SortedSenderVersions[n].Type == pdu.FilesystemVersion_Snapshot {
mostRecentSnap = noCommonAncestor.SortedSenderVersions[n]
break
}
}
if mostRecentSnap == nil {
return nil, "no snapshots available on sender side"
}
return []*pdu.FilesystemVersion{mostRecentSnap}, fmt.Sprintf("start replication at most recent snapshot %s", mostRecentSnap.RelName())
}
}
return nil, "no automated way to handle conflict type"
}
func rsfPlanning(ctx context.Context, ep EndpointPair, u replicationUpdater) replicationStateFunc {
log := GetLogger(ctx)
handlePlanningError := func(err error) replicationStateFunc {
return u(func(r *Replication) {
r.planningError = err
r.state = PlanningError
}).rsf()
}
sfss, err := ep.Sender().ListFilesystems(ctx)
if err != nil {
log.WithError(err).Error("error listing sender filesystems")
return handlePlanningError(err)
}
rfss, err := ep.Receiver().ListFilesystems(ctx)
if err != nil {
log.WithError(err).Error("error listing receiver filesystems")
return handlePlanningError(err)
}
q := NewReplicationQueue()
mainlog := log
for _, fs := range sfss {
log := mainlog.WithField("filesystem", fs.Path)
log.Info("assessing filesystem")
sfsvs, err := ep.Sender().ListFilesystemVersions(ctx, fs.Path)
if err != nil {
log.WithError(err).Error("cannot get remote filesystem versions")
return handlePlanningError(err)
}
if len(sfsvs) <= 1 {
err := errors.New("sender does not have any versions")
log.Error(err.Error())
q.Add(fsfsm.NewFSReplicationWithPermanentError(fs.Path, err))
continue
}
receiverFSExists := false
for _, rfs := range rfss {
if rfs.Path == fs.Path {
receiverFSExists = true
}
}
var rfsvs []*pdu.FilesystemVersion
if receiverFSExists {
rfsvs, err = ep.Receiver().ListFilesystemVersions(ctx, fs.Path)
if err != nil {
if _, ok := err.(*FilteredError); ok {
log.Info("receiver ignores filesystem")
continue
}
log.WithError(err).Error("receiver error")
return handlePlanningError(err)
}
} else {
rfsvs = []*pdu.FilesystemVersion{}
}
path, conflict := IncrementalPath(rfsvs, sfsvs)
if conflict != nil {
var msg string
path, msg = resolveConflict(conflict) // no shadowing allowed!
if path != nil {
log.WithField("conflict", conflict).Info("conflict")
log.WithField("resolution", msg).Info("automatically resolved")
} else {
log.WithField("conflict", conflict).Error("conflict")
log.WithField("problem", msg).Error("cannot resolve conflict")
}
}
if path == nil {
q.Add(fsfsm.NewFSReplicationWithPermanentError(fs.Path, conflict))
continue
}
fsrfsm := fsfsm.BuildFSReplication(fs.Path)
if len(path) == 1 {
fsrfsm.AddStep(nil, path[0])
} else {
for i := 0; i < len(path)-1; i++ {
fsrfsm.AddStep(path[i], path[i+1])
}
}
qitem := fsrfsm.Done()
q.Add(qitem)
}
return u(func(r *Replication) {
r.completed = nil
r.queue = q
r.planningError = nil
r.state = Working
}).rsf()
}
func rsfPlanningError(ctx context.Context, ep EndpointPair, u replicationUpdater) replicationStateFunc {
sleepTime := 10 * time.Second
u(func(r *Replication) {
r.sleepUntil = time.Now().Add(sleepTime)
})
t := time.NewTimer(sleepTime) // FIXME make constant onfigurable
defer t.Stop()
select {
case <-ctx.Done():
return u(func(r *Replication) {
r.state = ContextDone
r.contextError = ctx.Err()
}).rsf()
case <-t.C:
return u(func(r *Replication) {
r.state = Planning
}).rsf()
}
}
func rsfWorking(ctx context.Context, ep EndpointPair, u replicationUpdater) replicationStateFunc {
var active *ReplicationQueueItemHandle
rsfNext := u(func(r *Replication) {
done, next := r.queue.GetNext()
r.completed = append(r.completed, done...)
if next == nil {
r.state = Completed
}
r.active = next
active = next
}).rsf()
if active == nil {
return rsfNext
}
state, nextStepDate := active.GetFSReplication().TakeStep(ctx, ep)
return u(func(r *Replication) {
active.Update(state, nextStepDate)
r.active = nil
}).rsf()
}
func rsfWorkingWait(ctx context.Context, ep EndpointPair, u replicationUpdater) replicationStateFunc {
sleepTime := 10 * time.Second
u(func(r *Replication) {
r.sleepUntil = time.Now().Add(sleepTime)
})
t := time.NewTimer(sleepTime)
defer t.Stop()
select {
case <-ctx.Done():
return u(func(r *Replication) {
r.state = ContextDone
r.contextError = ctx.Err()
}).rsf()
case <-t.C:
return u(func(r *Replication) {
r.state = Working
}).rsf()
}
}
func (r *Replication) Report() *Report {
r.lock.Lock()
defer r.lock.Unlock()
rep := Report{
Status: r.state.String(),
}
if r.state&(Planning|PlanningError|ContextDone) != 0 {
switch r.state {
case PlanningError:
rep.Problem = r.planningError.Error()
case ContextDone:
rep.Problem = r.contextError.Error()
}
return &rep
}
rep.Pending = make([]*fsfsm.FilesystemReplicationReport, 0, r.queue.Len())
rep.Completed = make([]*fsfsm.FilesystemReplicationReport, 0, len(r.completed)) // room for active (potentially)
var active *fsfsm.FSReplication
if r.active != nil {
active = r.active.GetFSReplication()
rep.Active = active.Report()
}
r.queue.Foreach(func (h *ReplicationQueueItemHandle){
fsr := h.GetFSReplication()
if active != fsr {
rep.Pending = append(rep.Pending, fsr.Report())
}
})
for _, fsr := range r.completed {
rep.Completed = append(rep.Completed, fsr.Report())
}
return &rep
}
@@ -0,0 +1,124 @@
package queue
import (
"time"
"sort"
. "github.com/zrepl/zrepl/cmd/replication/internal/fsfsm"
)
type replicationQueueItem struct {
retriesSinceLastError int
// duplicates fsr.state to avoid accessing and locking fsr
state FSReplicationState
// duplicates fsr.current.nextStepDate to avoid accessing & locking fsr
nextStepDate time.Time
fsr *FSReplication
}
type ReplicationQueue []*replicationQueueItem
func NewReplicationQueue() *ReplicationQueue {
q := make(ReplicationQueue, 0)
return &q
}
func (q ReplicationQueue) Len() int { return len(q) }
func (q ReplicationQueue) Swap(i, j int) { q[i], q[j] = q[j], q[i] }
type lessmapEntry struct{
prio int
less func(a,b *replicationQueueItem) bool
}
var lessmap = map[FSReplicationState]lessmapEntry {
FSReady: {
prio: 0,
less: func(a, b *replicationQueueItem) bool {
return a.nextStepDate.Before(b.nextStepDate)
},
},
FSRetryWait: {
prio: 1,
less: func(a, b *replicationQueueItem) bool {
return a.retriesSinceLastError < b.retriesSinceLastError
},
},
}
func (q ReplicationQueue) Less(i, j int) bool {
a, b := q[i], q[j]
al, aok := lessmap[a.state]
if !aok {
panic(a)
}
bl, bok := lessmap[b.state]
if !bok {
panic(b)
}
if al.prio != bl.prio {
return al.prio < bl.prio
}
return al.less(a, b)
}
func (q *ReplicationQueue) sort() (done []*FSReplication) {
// pre-scan for everything that is not ready
newq := make(ReplicationQueue, 0, len(*q))
done = make([]*FSReplication, 0, len(*q))
for _, qitem := range *q {
if _, ok := lessmap[qitem.state]; !ok {
done = append(done, qitem.fsr)
} else {
newq = append(newq, qitem)
}
}
sort.Stable(newq) // stable to avoid flickering in reports
*q = newq
return done
}
// next remains valid until the next call to GetNext()
func (q *ReplicationQueue) GetNext() (done []*FSReplication, next *ReplicationQueueItemHandle) {
done = q.sort()
if len(*q) == 0 {
return done, nil
}
next = &ReplicationQueueItemHandle{(*q)[0]}
return done, next
}
func (q *ReplicationQueue) Add(fsr *FSReplication) {
*q = append(*q, &replicationQueueItem{
fsr: fsr,
state: fsr.State(),
})
}
func (q *ReplicationQueue) Foreach(fu func(*ReplicationQueueItemHandle)) {
for _, qitem := range *q {
fu(&ReplicationQueueItemHandle{qitem})
}
}
type ReplicationQueueItemHandle struct {
i *replicationQueueItem
}
func (h ReplicationQueueItemHandle) GetFSReplication() *FSReplication {
return h.i.fsr
}
func (h ReplicationQueueItemHandle) Update(newState FSReplicationState, nextStepDate time.Time) {
h.i.state = newState
h.i.nextStepDate = nextStepDate
if h.i.state&FSReady != 0 {
h.i.retriesSinceLastError = 0
} else if h.i.state&FSRetryWait != 0 {
h.i.retriesSinceLastError++
}
}
@@ -0,0 +1,35 @@
// Code generated by "stringer -type=ReplicationState"; DO NOT EDIT.
package mainfsm
import "strconv"
const (
_ReplicationState_name_0 = "PlanningPlanningError"
_ReplicationState_name_1 = "Working"
_ReplicationState_name_2 = "WorkingWait"
_ReplicationState_name_3 = "Completed"
_ReplicationState_name_4 = "ContextDone"
)
var (
_ReplicationState_index_0 = [...]uint8{0, 8, 21}
)
func (i ReplicationState) String() string {
switch {
case 1 <= i && i <= 2:
i -= 1
return _ReplicationState_name_0[_ReplicationState_index_0[i]:_ReplicationState_index_0[i+1]]
case i == 4:
return _ReplicationState_name_1
case i == 8:
return _ReplicationState_name_2
case i == 16:
return _ReplicationState_name_3
case i == 32:
return _ReplicationState_name_4
default:
return "ReplicationState(" + strconv.FormatInt(int64(i), 10) + ")"
}
}