9aa2eff384
This enables the backends to request the calculation of a backend-specific hash. For the currently supported backends this will always be MD5. The hash calculation happens as early as possible, for pack files this is during assembly of the pack file. That way the hash would even capture corruptions of the temporary pack file on disk.
71 lines
2.3 KiB
Go
71 lines
2.3 KiB
Go
package restic
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import (
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"context"
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"hash"
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"io"
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)
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// Backend is used to store and access data.
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//
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// Backend operations that return an error will be retried when a Backend is
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// wrapped in a RetryBackend. To prevent that from happening, the operations
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// should return a github.com/cenkalti/backoff/v4.PermanentError. Errors from
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// the context package need not be wrapped, as context cancellation is checked
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// separately by the retrying logic.
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type Backend interface {
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// Location returns a string that describes the type and location of the
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// repository.
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Location() string
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// Hasher may return a hash function for calculating a content hash for the backend
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Hasher() hash.Hash
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// Test a boolean value whether a File with the name and type exists.
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Test(ctx context.Context, h Handle) (bool, error)
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// Remove removes a File described by h.
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Remove(ctx context.Context, h Handle) error
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// Close the backend
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Close() error
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// Save stores the data from rd under the given handle.
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Save(ctx context.Context, h Handle, rd RewindReader) error
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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. If length is larger than zero, only a portion of the file
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// is read.
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//
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// The function fn may be called multiple times during the same Load invocation
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// and therefore must be idempotent.
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//
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// Implementations are encouraged to use backend.DefaultLoad
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Load(ctx context.Context, h Handle, length int, offset int64, fn func(rd io.Reader) error) error
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// Stat returns information about the File identified by h.
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Stat(ctx context.Context, h Handle) (FileInfo, error)
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// List runs fn for each file in the backend which has the type t. When an
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// error occurs (or fn returns an error), List stops and returns it.
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//
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// The function fn is called exactly once for each file during successful
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// execution and at most once in case of an error.
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//
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// The function fn is called in the same Goroutine that List() is called
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// from.
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List(ctx context.Context, t FileType, fn func(FileInfo) error) error
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// IsNotExist returns true if the error was caused by a non-existing file
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// in the backend.
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IsNotExist(err error) bool
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// Delete removes all data in the backend.
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Delete(ctx context.Context) error
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}
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// FileInfo is contains information about a file in the backend.
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type FileInfo struct {
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Size int64
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Name string
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}
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