mirror of https://github.com/restic/restic.git
88 lines
2.1 KiB
Go
88 lines
2.1 KiB
Go
package sema
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import (
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"context"
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"io"
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"github.com/cenkalti/backoff/v4"
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"github.com/restic/restic/internal/errors"
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"github.com/restic/restic/internal/restic"
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)
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// make sure that SemaphoreBackend implements restic.Backend
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var _ restic.Backend = &SemaphoreBackend{}
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// SemaphoreBackend limits the number of concurrent operations.
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type SemaphoreBackend struct {
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restic.Backend
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sem semaphore
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}
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// New creates a backend that limits the concurrent operations on the underlying backend
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func New(be restic.Backend) *SemaphoreBackend {
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sem, err := newSemaphore(be.Connections())
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if err != nil {
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panic(err)
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}
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return &SemaphoreBackend{
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Backend: be,
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sem: sem,
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}
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}
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// Save adds new Data to the backend.
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func (be *SemaphoreBackend) Save(ctx context.Context, h restic.Handle, rd restic.RewindReader) error {
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if err := h.Valid(); err != nil {
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return backoff.Permanent(err)
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}
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be.sem.GetToken()
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defer be.sem.ReleaseToken()
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return be.Backend.Save(ctx, h, rd)
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}
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// Load runs fn with a reader that yields the contents of the file at h at the
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// given offset.
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func (be *SemaphoreBackend) Load(ctx context.Context, h restic.Handle, length int, offset int64, fn func(rd io.Reader) error) error {
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if err := h.Valid(); err != nil {
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return backoff.Permanent(err)
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}
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if offset < 0 {
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return backoff.Permanent(errors.New("offset is negative"))
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}
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if length < 0 {
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return backoff.Permanent(errors.Errorf("invalid length %d", length))
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}
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be.sem.GetToken()
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defer be.sem.ReleaseToken()
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return be.Backend.Load(ctx, h, length, offset, fn)
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}
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// Stat returns information about a file in the backend.
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func (be *SemaphoreBackend) Stat(ctx context.Context, h restic.Handle) (restic.FileInfo, error) {
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if err := h.Valid(); err != nil {
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return restic.FileInfo{}, backoff.Permanent(err)
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}
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be.sem.GetToken()
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defer be.sem.ReleaseToken()
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return be.Backend.Stat(ctx, h)
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}
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// Remove deletes a file from the backend.
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func (be *SemaphoreBackend) Remove(ctx context.Context, h restic.Handle) error {
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if err := h.Valid(); err != nil {
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return backoff.Permanent(err)
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}
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be.sem.GetToken()
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defer be.sem.ReleaseToken()
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return be.Backend.Remove(ctx, h)
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}
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