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48 lines
2.4 KiB
Go
48 lines
2.4 KiB
Go
package blobinfocache
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import (
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"github.com/containers/image/types"
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"github.com/opencontainers/go-digest"
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)
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// noCache implements a dummy BlobInfoCache which records no data.
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type noCache struct {
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}
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// NoCache implements BlobInfoCache by not recording any data.
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//
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// This exists primarily for implementations of configGetter for Manifest.Inspect,
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// because configs only have one representation.
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// Any use of BlobInfoCache with blobs should usually use at least a short-lived cache.
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var NoCache types.BlobInfoCache = noCache{}
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// UncompressedDigest returns an uncompressed digest corresponding to anyDigest.
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// May return anyDigest if it is known to be uncompressed.
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// Returns "" if nothing is known about the digest (it may be compressed or uncompressed).
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func (noCache) UncompressedDigest(anyDigest digest.Digest) digest.Digest {
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return ""
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}
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// RecordDigestUncompressedPair records that the uncompressed version of anyDigest is uncompressed.
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// It’s allowed for anyDigest == uncompressed.
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// WARNING: Only call this for LOCALLY VERIFIED data; don’t record a digest pair just because some remote author claims so (e.g.
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// because a manifest/config pair exists); otherwise the cache could be poisoned and allow substituting unexpected blobs.
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// (Eventually, the DiffIDs in image config could detect the substitution, but that may be too late, and not all image formats contain that data.)
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func (noCache) RecordDigestUncompressedPair(anyDigest digest.Digest, uncompressed digest.Digest) {
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}
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// RecordKnownLocation records that a blob with the specified digest exists within the specified (transport, scope) scope,
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// and can be reused given the opaque location data.
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func (noCache) RecordKnownLocation(transport types.ImageTransport, scope types.BICTransportScope, blobDigest digest.Digest, location types.BICLocationReference) {
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}
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// CandidateLocations returns a prioritized, limited, number of blobs and their locations that could possibly be reused
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// within the specified (transport scope) (if they still exist, which is not guaranteed).
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//
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// If !canSubstitute, the returned cadidates will match the submitted digest exactly; if canSubstitute,
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// data from previous RecordDigestUncompressedPair calls is used to also look up variants of the blob which have the same
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// uncompressed digest.
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func (noCache) CandidateLocations(transport types.ImageTransport, scope types.BICTransportScope, digest digest.Digest, canSubstitute bool) []types.BICReplacementCandidate {
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return nil
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}
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