155 lines
2.9 KiB
Go
155 lines
2.9 KiB
Go
package stores
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import (
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"context"
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"sync"
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"golang.org/x/xerrors"
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"github.com/filecoin-project/specs-actors/actors/abi"
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)
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type sectorLock struct {
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cond *ctxCond
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r [FileTypes]uint
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w SectorFileType
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refs uint // access with indexLocks.lk
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}
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func (l *sectorLock) canLock(read SectorFileType, write SectorFileType) bool {
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for i, b := range write.All() {
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if b && l.r[i] > 0 {
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return false
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}
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}
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// check that there are no locks taken for either read or write file types we want
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return l.w&read == 0 && l.w&write == 0
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}
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func (l *sectorLock) tryLock(read SectorFileType, write SectorFileType) bool {
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if !l.canLock(read, write) {
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return false
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}
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for i, set := range read.All() {
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if set {
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l.r[i]++
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}
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}
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l.w |= write
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return true
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}
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type lockFn func(l *sectorLock, ctx context.Context, read SectorFileType, write SectorFileType) (bool, error)
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func (l *sectorLock) tryLockSafe(ctx context.Context, read SectorFileType, write SectorFileType) (bool, error) {
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l.cond.L.Lock()
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defer l.cond.L.Unlock()
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return l.tryLock(read, write), nil
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}
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func (l *sectorLock) lock(ctx context.Context, read SectorFileType, write SectorFileType) (bool, error) {
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l.cond.L.Lock()
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defer l.cond.L.Unlock()
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for !l.tryLock(read, write) {
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if err := l.cond.Wait(ctx); err != nil {
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return false, err
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}
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}
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return true, nil
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}
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func (l *sectorLock) unlock(read SectorFileType, write SectorFileType) {
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l.cond.L.Lock()
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defer l.cond.L.Unlock()
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for i, set := range read.All() {
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if set {
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l.r[i]--
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}
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}
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l.w &= ^write
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l.cond.Broadcast()
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}
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type indexLocks struct {
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lk sync.Mutex
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locks map[abi.SectorID]*sectorLock
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}
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func (i *indexLocks) lockWith(ctx context.Context, lockFn lockFn, sector abi.SectorID, read SectorFileType, write SectorFileType) (bool, error) {
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if read|write == 0 {
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return false, nil
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}
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if read|write > (1<<FileTypes)-1 {
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return false, xerrors.Errorf("unknown file types specified")
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}
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i.lk.Lock()
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slk, ok := i.locks[sector]
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if !ok {
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slk = §orLock{}
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slk.cond = newCtxCond(&sync.Mutex{})
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i.locks[sector] = slk
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}
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slk.refs++
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i.lk.Unlock()
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locked, err := lockFn(slk, ctx, read, write)
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if err != nil {
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return false, err
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}
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if !locked {
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return false, nil
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}
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go func() {
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// TODO: we can avoid this goroutine with a bit of creativity and reflect
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<-ctx.Done()
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i.lk.Lock()
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slk.unlock(read, write)
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slk.refs--
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if slk.refs == 0 {
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delete(i.locks, sector)
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}
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i.lk.Unlock()
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}()
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return true, nil
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}
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func (i *indexLocks) StorageLock(ctx context.Context, sector abi.SectorID, read SectorFileType, write SectorFileType) error {
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ok, err := i.lockWith(ctx, (*sectorLock).lock, sector, read, write)
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if err != nil {
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return err
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}
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if !ok {
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return xerrors.Errorf("failed to acquire lock")
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}
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return nil
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}
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func (i *indexLocks) StorageTryLock(ctx context.Context, sector abi.SectorID, read SectorFileType, write SectorFileType) (bool, error) {
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return i.lockWith(ctx, (*sectorLock).tryLockSafe, sector, read, write)
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}
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