Make it more similar to testGenericCandidateLocations, and
include both locations for the same digest on the same line,
to make the relationships between the digests's entries a bit clearer.

Should not change behavior.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

We will add a long/unwieldy CandidateLocations2Options parameter,
and adding that inline would make readability even more challenging.

So, split that out; the new parameter will be added shortly.

Should not change (test) behavior.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

We will soon be looking up the actual compression alghorithms in the BIC code, so use
real algorithm names in the tests.

Should not change (test) behavior.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

…internal/manifest

We will want to call this from the pkg/blobinfocache code, and for that we need
to make it dependent on neither internal/private nor internal/blobinfocache
(otherwise the interface definitions would create a dependency loop).

This only moves ~unchanged code, should not change behavior.

Eventually CandidateMatchesTryReusingBlobOptions will be removed entirely.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

... and move the canSubstitute parameter to it.

We will add more options, and we well want to carry them around
as a unit.

Should not change behavior.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

…ions

... into candidateLocations and appendReplacementCandidates.

We will add more conditions there soon.

Should not change behavior.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

This is
- more similar to the other BIC implementations
- probably faster: we hold a transaction open anyway, this is all local,
  so making fewer queries is unlikely to be notably less costly,
  and we only read the value once instead of getting a column all containing
  the same value
- necessary for future changes, were we need to do local checks on compressorName
  before consuming the other data, and those checks are in Go and can't be reasonably
  done by the SQLite query

Should not change behavior.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

… ones

Append to candidates directly, avoid a separate allocation of a temporary
array.

Should not change behavior.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

The primary benefit is that we now filter the algorithms _before_ collecting
and trimming the list of candidates, i.e. if the most recent candidates
are not matching the requirements, CandidateLocations2 will return older
candidates instead of returning just some unwanted candidates which will be rejected.

This requires us to look up the actual compression in the BIC code, so this also
changes pkg/blobinfocache/internal/test to use real algorithm names.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

Inline it into the only remaining caller.

Should not change behavior.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

... dropping various unreachable/redundant code paths,
now that the semantics is clear and tested.

Removes the unfortunate dependency of c/image/docker on
c/image/pkg/compression, making it cheaper to use c/image/docker
as a simple registry client.

Should not change behavior.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

…e field

Should not change behavior.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>