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mirror of https://github.com/octoleo/restic.git synced 2024-11-26 14:56:29 +00:00
restic/internal/restic/backend.go
Alexander Neumann 99f7fd74e3 backend: Improve Save()
As mentioned in issue [#1560](https://github.com/restic/restic/pull/1560#issuecomment-364689346)
this changes the signature for `backend.Save()`. It now takes a
parameter of interface type `RewindReader`, so that the backend
implementations or our `RetryBackend` middleware can reset the reader to
the beginning and then retry an upload operation.

The `RewindReader` interface also provides a `Length()` method, which is
used in the backend to get the size of the data to be saved. This
removes several ugly hacks we had to do to pull the size back out of the
`io.Reader` passed to `Save()` before. In the `s3` and `rest` backend
this is actively used.
2018-03-03 15:49:44 +01:00

62 lines
1.9 KiB
Go

package restic
import (
"context"
"io"
)
// Backend is used to store and access data.
type Backend interface {
// Location returns a string that describes the type and location of the
// repository.
Location() string
// Test a boolean value whether a File with the name and type exists.
Test(ctx context.Context, h Handle) (bool, error)
// Remove removes a File described by h.
Remove(ctx context.Context, h Handle) error
// Close the backend
Close() error
// Save stores the data from rd under the given handle.
Save(ctx context.Context, h Handle, rd RewindReader) error
// Load runs fn with a reader that yields the contents of the file at h at the
// given offset. If length is larger than zero, only a portion of the file
// is read.
//
// The function fn may be called multiple times during the same Load invocation
// and therefore must be idempotent.
//
// Implementations are encouraged to use backend.DefaultLoad
Load(ctx context.Context, h Handle, length int, offset int64, fn func(rd io.Reader) error) error
// Stat returns information about the File identified by h.
Stat(ctx context.Context, h Handle) (FileInfo, error)
// List runs fn for each file in the backend which has the type t. When an
// error occurs (or fn returns an error), List stops and returns it.
//
// The function fn is called exactly once for each file during successful
// execution and at most once in case of an error.
//
// The function fn is called in the same Goroutine that List() is called
// from.
List(ctx context.Context, t FileType, fn func(FileInfo) error) error
// IsNotExist returns true if the error was caused by a non-existing file
// in the backend.
IsNotExist(err error) bool
// Delete removes all data in the backend.
Delete(ctx context.Context) error
}
// FileInfo is contains information about a file in the backend.
type FileInfo struct {
Size int64
Name string
}