.

wcfs/internal/xbtree/zrangemap_rebuildjob.go

-// Code generated by gen-rangemap _RangedMap_RebuildJob _RebuildJob; DO NOT EDIT.
+// Code generated by gen-rangemap _RangedMap_RebuildJob *_RebuildJob; DO NOT EDIT.
 
 // Copyright (C) 2021  Nexedi SA and Contributors.
 //                     Kirill Smelkov <kirr@nexedi.com>
@@ -33,7 +33,7 @@ import (
 const trace_RangedMap_RebuildJob = false
 const debug_RangedMap_RebuildJob = false
 
-// _RangedMap_RebuildJob is Key->_RebuildJob map with adjacent keys mapped to the same value coalesced into Ranges.
+// _RangedMap_RebuildJob is Key->*_RebuildJob map with adjacent keys mapped to the same value coalesced into Ranges.
 //
 // Zero value represents empty map.
 type _RangedMap_RebuildJob struct {
@@ -45,19 +45,19 @@ type _RangedMap_RebuildJob struct {
 
 // _RangedMap_RebuildJobEntry represents one entry in _RangedMap_RebuildJob.
 type _RangedMap_RebuildJobEntry struct {
-	Value    _RebuildJob
+	Value    *_RebuildJob
 	blib.KeyRange
 }
 
 
 // Get returns value associated with key k.
-func (M *_RangedMap_RebuildJob) Get(k Key) _RebuildJob {
+func (M *_RangedMap_RebuildJob) Get(k Key) *_RebuildJob {
 	v, _ := M.Get_(k)
 	return v
 }
 
 // Set changes M to map key k to value v.
-func (M *_RangedMap_RebuildJob) Set(k Key, v _RebuildJob) {
+func (M *_RangedMap_RebuildJob) Set(k Key, v *_RebuildJob) {
 	M.SetRange(blib.KeyRange{Lo: k, Hi_: k}, v)
 }
 
@@ -75,7 +75,7 @@ func (M *_RangedMap_RebuildJob) Has(k Key) bool {
 
 
 // Get_ is comma-ok version of Get.
-func (M *_RangedMap_RebuildJob) Get_(k Key) (v _RebuildJob, ok bool) {
+func (M *_RangedMap_RebuildJob) Get_(k Key) (v *_RebuildJob, ok bool) {
 	if trace_RangedMap_RebuildJob {
 		fmt.Printf("\n\nGet_:\n")
 		fmt.Printf("  M: %s\n", M)
@@ -108,7 +108,7 @@ func (M *_RangedMap_RebuildJob) Get_(k Key) (v _RebuildJob, ok bool) {
 }
 
 // SetRange changes M to map key range r to value v.
-func (M *_RangedMap_RebuildJob) SetRange(r blib.KeyRange, v _RebuildJob) {
+func (M *_RangedMap_RebuildJob) SetRange(r blib.KeyRange, v *_RebuildJob) {
 	e := _RangedMap_RebuildJobEntry{v,r}
 	if trace_RangedMap_RebuildJob {
 		fmt.Printf("\n\nSetRange:\n")
@@ -390,7 +390,7 @@ func (M *_RangedMap_RebuildJob) verify() {
 	}()
 
 	hi_Prev := KeyMin
-	var v_Prev _RebuildJob
+	var v_Prev *_RebuildJob
 	for i, e := range M.entryv {
 		hiPrev := hi_Prev + 1
 		if i > 0 {

wcfs/internal/xbtree/δbtail.go

@@ -67,13 +67,19 @@ package xbtree
 //
 // XXX concurrency
 //
+// trackSet, ktrackNew, krebuildJobs + explain rebuild algo (query lock, check ktrackNew, krebuildJob, go/merge/...)
+//
+// This locking organization allows non-overlapping queries/track-requests to
+// run simultaneously. Without this property WCFS would not be able to serve
+// several non-overlapping READ requests to one file in parallel.
 //
 // --------
 //
 // (*) implemented in treediff.go
 // (+) full database scan
 
-//go:generate ./blib/gen-rangemap _RangedMap_RebuildJob _RebuildJob zrangemap_rebuildjob.go
+////go:generate ./blib/gen-rangemap _RangedMap_Path       []zodbOid    zrangemap_path.go
+//go:generate ./blib/gen-rangemap _RangedMap_RebuildJob *_RebuildJob zrangemap_rebuildjob.go
 
 import (
 	"context"
@@ -89,6 +95,7 @@ import (
 	"lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/xtail"
 )
 
+//type zodbOid = zodb.Oid	XXX kill probably
 const traceΔBtail = false
 const debugΔBtail = false
 
@@ -141,11 +148,11 @@ type ΔBtail struct {
 
 	// set of tracked nodes as of @head state.
 	// For this set all vδT are fully computed.
-	// The set of nodes that were requested to be tracked, but were not yet
-	// taken into account, is kept in _ΔTtail.trackNew & co.
+	// The set of keys(nodes) that were requested to be tracked, but were
+	// not yet taken into account, is kept in _ΔTtail.ktrackNew & co.
 	trackSet blib.PPTreeSubSet
 
-	// set of trees for which _ΔTtail.trackNew is non-empty
+	// set of trees for which _ΔTtail.ktrackNew is non-empty
 	trackNewRoots setOid
 
 	// handle to make connections to access database.
@@ -159,13 +166,18 @@ type ΔBtail struct {
 type _ΔTtail struct {
 	vδT []ΔTree // changes to tree keys; rev↑. covers keys ∈ tracked subset
 
-	// set of nodes that were requested to be tracked in this tree, but for
-	// which vδT was not yet rebuilt
+//	// set of keys(nodes) that were requested to be tracked in this tree,
+//	// but for which vδT rebuild was not yet started
+//	ktrackNew _RangedMap_Path          // {} keycov -> path
+
+	// set of keys that were requested to be tracked in this tree,
+	// but for which vδT rebuild was not yet started
+	ktrackNew blib.RangedKeySet        // {keycov}
+	// set of nodes corresponding to ktrackNew
 	trackNew blib.PPTreeSubSet
 
-	// XXX + trackNewKeys RangedKeySet (concurrency)
-	// XXX + trackSetKeys RangedKeySet
-	rebuildNew _RangedMap_RebuildJob // keycov -> _RebuildJob
+	// set of keys(nodes) for which rebuild is in progress
+	krebuildJobs _RangedMap_RebuildJob // {} keycov -> job
 }
 
 // _ΔBroots represents roots-only part of ΔB.
@@ -189,9 +201,11 @@ type ΔTree struct {
 }
 
 
+// _RebuildJob represents currently in-progress rebuilding job. XXX
 // XXX place
 type _RebuildJob struct {
-	// XXX
+	ready chan struct{} // closed when job completes
+	err   error
 }
 
 
@@ -407,6 +421,87 @@ func (δBtail *ΔBtail) rebuild1IfNeeded(root zodb.Oid) error {
 	return δBtail.rebuild1(root)
 }
 
+// rebuild1KeyIfNeeded rebuilds ΔBtail for single root if that root[key] needs rebuilding.
+func (δBtail *ΔBtail) rebuild1KeyIfNeeded(root zodb.Oid, key Key) error {
+	// XXX δBtail.lock
+	_, ok := δBtail.trackNewRoots[root]
+	if !ok {
+		// XXX δBtail.unlock
+		return nil
+	}
+
+	// XXX move -> ΔTtail.rebuild1KeyIfNeeded?
+	δTtail := δBtail.byRoot[root] // must be there
+	// XXX δTtail.lock
+
+//	_, inNew := δTtail.ktrackNew.Get_(key)
+	inNew := δTtail.ktrackNew.Has(key)
+	if !inNew {
+		// key ∉ ktrackNew
+		job, inJobs := δTtail.krebuildJobs.Get_(key)
+		if !inJobs {
+			// key ∉ krebuildJobs -> it should be already in trackSet
+			// XXX δTtail.unlock
+			// XXX δBtail.unlock
+			return nil
+		}
+
+		// rebuild for root[key] is in progress -> wait for corresponding job to complete
+		// XXX δTtail.unlock
+		// XXX δBtail.unlock
+		<-job.ready
+		return job.err
+	}
+
+
+	// key ∈ ktrackNew  ->  this goroutine becomes responsible to start rebuilding vδT for it
+	// lauch rebuild job for all keys queued in ktrackNew so far
+	job := &_RebuildJob{ready: make(chan struct{})}
+
+/*
+	trackNewSet := blib.PPTreeSubSet{} // trackNew corresponding to ktrackNew
+	rebuildKeys := blib.RangedKeySet{} // keys(ktrackNew)
+	for _, e := range δTtail.ktrackNew.AllRanges() {
+		trackNewSet.AddPath(e.Value)
+		rebuildKeys.AddRange(e.KeyRange)
+	}
+*/
+	trackNew    := δTtail.trackNew
+	rebuildKeys := δTtail.ktrackNew
+	δTtail.trackNew  = blib.PPTreeSubSet{}
+	δTtail.ktrackNew = blib.RangedKeySet{}
+
+	// krebuildJobs += rebuildKeys
+	for _, r := range rebuildKeys.AllRanges() {
+		// XXX assert !krebuildJobs.IntersectsRange(e.KeyRange)
+		δTtail.krebuildJobs.SetRange(r, job)
+	}
+	delete(δBtail.trackNewRoots, root)
+
+	// XXX δTtail.unlock
+	// XXX δBtail.unlock
+
+	// XXX δTtail.rebuild(for trackNew) -> err
+	_ = trackNew
+
+	// XXX δBtail.lock ? (to update vδBroots)
+	// XXX δTtail.lock
+	// XXX merge rebuild result
+
+	// krebuildJobs -= rebuildKeys
+	for _, r := range rebuildKeys.AllRanges() {
+		// XXX assert krebuildJobs[r] == job
+		δTtail.krebuildJobs.DelRange(r)
+	}
+
+	// we are done
+	job.err = nil // XXX stub
+	close(job.ready)
+
+	// XXX unlock
+	return job.err
+}
+
 // rebuild1 rebuilds ΔBtail for single root.
 func (δBtail *ΔBtail) rebuild1(root zodb.Oid) error {
 	// XXX locking
@@ -895,6 +990,7 @@ func (δBtail *ΔBtail) GetAt(root zodb.Oid, key Key, at zodb.Tid) (value Value,
 
 	// XXX need to rebuild only if key was not rebuilt yet
 	// XXX need to rebuild only for key, not for whole trackNew
+//	err = δBtail.rebuild1KeyIfNeeded(root, key)	XXX reenable
 	err = δBtail.rebuild1IfNeeded(root)
 	if err != nil {
 		return value, rev, valueExact, revExact, err
@@ -904,11 +1000,12 @@ func (δBtail *ΔBtail) GetAt(root zodb.Oid, key Key, at zodb.Tid) (value Value,
 	if δTtail == nil {
 		panicf("δBtail: root<%s> not tracked", root)
 	}
+	vδT := δTtail.vδT
 	// TODO key not tracked	-> panic  (check key ∈ lastRevOf  -- see vvv)
 
 	// TODO -> index lastRevOf(key) | linear scan ↓ looking for change ≤ at
-	for i := len(δTtail.vδT)-1; i >= 0; i-- {
-		δT := δTtail.vδT[i]
+	for i := len(vδT)-1; i >= 0; i-- {
+		δT := vδT[i]
 		δvalue, ok_ := δT.KV[key]
 		if ok_ {
 			valueExact = true
@@ -951,7 +1048,7 @@ func (δBtail *ΔBtail) SliceByRootRev(root zodb.Oid, lo, hi zodb.Tid) /*readonl
 
 	δTtail, ok := δBtail.byRoot[root]
 	if !ok {
-		return []ΔTree{}
+		return []ΔTree{}	// XXX -> panic (root must be tracked)
 	}
 
 	vδT := δTtail.vδT