/
mount.go
399 lines (342 loc) · 7.88 KB
/
mount.go
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// Package mount provides a Datastore that has other Datastores
// mounted at various key prefixes and is threadsafe
package mount
import (
"container/heap"
"errors"
"fmt"
"sort"
"strings"
"sync"
ds "github.com/ipfs/go-datastore"
"github.com/ipfs/go-datastore/query"
)
var (
ErrNoMount = errors.New("no datastore mounted for this key")
)
type Mount struct {
Prefix ds.Key
Datastore ds.Datastore
}
func New(mounts []Mount) *Datastore {
// make a copy so we're sure it doesn't mutate
m := make([]Mount, len(mounts))
for i, v := range mounts {
m[i] = v
}
sort.Slice(m, func(i, j int) bool { return m[i].Prefix.String() > m[j].Prefix.String() })
return &Datastore{mounts: m}
}
type Datastore struct {
mounts []Mount
}
var _ ds.Datastore = (*Datastore)(nil)
func (d *Datastore) lookup(key ds.Key) (ds.Datastore, ds.Key, ds.Key) {
for _, m := range d.mounts {
if m.Prefix.Equal(key) || m.Prefix.IsAncestorOf(key) {
s := strings.TrimPrefix(key.String(), m.Prefix.String())
k := ds.NewKey(s)
return m.Datastore, m.Prefix, k
}
}
return nil, ds.NewKey("/"), key
}
type queryResults struct {
mount ds.Key
results query.Results
next query.Result
}
func (qr *queryResults) advance() bool {
if qr.results == nil {
return false
}
qr.next = query.Result{}
r, more := qr.results.NextSync()
if !more {
err := qr.results.Close()
qr.results = nil
if err != nil {
// One more result, the error.
qr.next = query.Result{Error: err}
return true
}
return false
}
r.Key = qr.mount.Child(ds.RawKey(r.Key)).String()
qr.next = r
return true
}
type querySet struct {
query query.Query
heads []*queryResults
}
func (h *querySet) Len() int {
return len(h.heads)
}
func (h *querySet) Less(i, j int) bool {
return query.Less(h.query.Orders, h.heads[i].next.Entry, h.heads[j].next.Entry)
}
func (h *querySet) Swap(i, j int) {
h.heads[i], h.heads[j] = h.heads[j], h.heads[i]
}
func (h *querySet) Push(x interface{}) {
h.heads = append(h.heads, x.(*queryResults))
}
func (h *querySet) Pop() interface{} {
i := len(h.heads) - 1
last := h.heads[i]
h.heads[i] = nil
h.heads = h.heads[:i]
return last
}
func (h *querySet) close() error {
var errs []error
for _, qr := range h.heads {
err := qr.results.Close()
if err != nil {
errs = append(errs, err)
}
}
h.heads = nil
if len(errs) > 0 {
return errs[0]
}
return nil
}
func (h *querySet) addResults(mount ds.Key, results query.Results) {
r := &queryResults{
results: results,
mount: mount,
}
if r.advance() {
heap.Push(h, r)
}
}
func (h *querySet) next() (query.Result, bool) {
if len(h.heads) == 0 {
return query.Result{}, false
}
head := h.heads[0]
next := head.next
for head.advance() {
heap.Fix(h, 0)
return next, true
}
heap.Remove(h, 0)
return next, true
}
// lookupAll returns all mounts that might contain keys that are descendant of <key>
//
// Matching: /ao/e
//
// / B /ao/e
// /a/ not matching
// /ao/ B /e
// /ao/e/ A /
// /ao/e/uh/ A /
// /aoe/ not matching
func (d *Datastore) lookupAll(key ds.Key) (dst []ds.Datastore, mountpoint, rest []ds.Key) {
for _, m := range d.mounts {
p := m.Prefix.String()
if len(p) > 1 {
p = p + "/"
}
if strings.HasPrefix(p, key.String()) {
dst = append(dst, m.Datastore)
mountpoint = append(mountpoint, m.Prefix)
rest = append(rest, ds.NewKey("/"))
} else if strings.HasPrefix(key.String(), p) {
r := strings.TrimPrefix(key.String(), m.Prefix.String())
dst = append(dst, m.Datastore)
mountpoint = append(mountpoint, m.Prefix)
rest = append(rest, ds.NewKey(r))
}
}
return dst, mountpoint, rest
}
func (d *Datastore) Put(key ds.Key, value []byte) error {
cds, _, k := d.lookup(key)
if cds == nil {
return ErrNoMount
}
return cds.Put(k, value)
}
func (d *Datastore) Get(key ds.Key) (value []byte, err error) {
cds, _, k := d.lookup(key)
if cds == nil {
return nil, ds.ErrNotFound
}
return cds.Get(k)
}
func (d *Datastore) Has(key ds.Key) (exists bool, err error) {
cds, _, k := d.lookup(key)
if cds == nil {
return false, nil
}
return cds.Has(k)
}
func (d *Datastore) GetSize(key ds.Key) (size int, err error) {
cds, _, k := d.lookup(key)
if cds == nil {
return -1, ds.ErrNotFound
}
return cds.GetSize(k)
}
func (d *Datastore) Delete(key ds.Key) error {
cds, _, k := d.lookup(key)
if cds == nil {
return ds.ErrNotFound
}
return cds.Delete(k)
}
func (d *Datastore) Query(master query.Query) (query.Results, error) {
childQuery := query.Query{
Prefix: master.Prefix,
Limit: master.Limit,
Orders: master.Orders,
KeysOnly: master.KeysOnly,
ReturnExpirations: master.ReturnExpirations,
}
prefix := ds.NewKey(childQuery.Prefix)
dses, mounts, rests := d.lookupAll(prefix)
queries := &querySet{
query: childQuery,
heads: make([]*queryResults, 0, len(dses)),
}
for i := range dses {
mount := mounts[i]
dstore := dses[i]
rest := rests[i]
qi := childQuery
qi.Prefix = rest.String()
results, err := dstore.Query(qi)
if err != nil {
_ = queries.close()
return nil, err
}
queries.addResults(mount, results)
}
qr := query.ResultsFromIterator(childQuery, query.Iterator{
Next: queries.next,
Close: queries.close,
})
if len(master.Filters) > 0 {
for _, f := range master.Filters {
qr = query.NaiveFilter(qr, f)
}
}
if master.Offset > 0 {
qr = query.NaiveOffset(qr, master.Offset)
}
if childQuery.Limit > 0 {
qr = query.NaiveLimit(qr, childQuery.Limit)
}
return qr, nil
}
func (d *Datastore) Close() error {
for _, d := range d.mounts {
err := d.Datastore.Close()
if err != nil {
return err
}
}
return nil
}
// DiskUsage returns the sum of DiskUsages for the mounted datastores.
// Non PersistentDatastores will not be accounted.
func (d *Datastore) DiskUsage() (uint64, error) {
var duTotal uint64 = 0
for _, d := range d.mounts {
du, err := ds.DiskUsage(d.Datastore)
duTotal += du
if err != nil {
return duTotal, err
}
}
return duTotal, nil
}
type mountBatch struct {
mounts map[string]ds.Batch
lk sync.Mutex
d *Datastore
}
func (d *Datastore) Batch() (ds.Batch, error) {
return &mountBatch{
mounts: make(map[string]ds.Batch),
d: d,
}, nil
}
func (mt *mountBatch) lookupBatch(key ds.Key) (ds.Batch, ds.Key, error) {
mt.lk.Lock()
defer mt.lk.Unlock()
child, loc, rest := mt.d.lookup(key)
t, ok := mt.mounts[loc.String()]
if !ok {
bds, ok := child.(ds.Batching)
if !ok {
return nil, ds.NewKey(""), ds.ErrBatchUnsupported
}
var err error
t, err = bds.Batch()
if err != nil {
return nil, ds.NewKey(""), err
}
mt.mounts[loc.String()] = t
}
return t, rest, nil
}
func (mt *mountBatch) Put(key ds.Key, val []byte) error {
t, rest, err := mt.lookupBatch(key)
if err != nil {
return err
}
return t.Put(rest, val)
}
func (mt *mountBatch) Delete(key ds.Key) error {
t, rest, err := mt.lookupBatch(key)
if err != nil {
return err
}
return t.Delete(rest)
}
func (mt *mountBatch) Commit() error {
mt.lk.Lock()
defer mt.lk.Unlock()
for _, t := range mt.mounts {
err := t.Commit()
if err != nil {
return err
}
}
return nil
}
func (d *Datastore) Check() error {
for _, m := range d.mounts {
if c, ok := m.Datastore.(ds.CheckedDatastore); ok {
if err := c.Check(); err != nil {
return fmt.Errorf("checking datastore at %s: %s", m.Prefix.String(), err.Error())
}
}
}
return nil
}
func (d *Datastore) Scrub() error {
for _, m := range d.mounts {
if c, ok := m.Datastore.(ds.ScrubbedDatastore); ok {
if err := c.Scrub(); err != nil {
return fmt.Errorf("scrubbing datastore at %s: %s", m.Prefix.String(), err.Error())
}
}
}
return nil
}
func (d *Datastore) CollectGarbage() error {
for _, m := range d.mounts {
if c, ok := m.Datastore.(ds.GCDatastore); ok {
if err := c.CollectGarbage(); err != nil {
return fmt.Errorf("gc on datastore at %s: %s", m.Prefix.String(), err.Error())
}
}
}
return nil
}