feat: Use single DB query to iterate for index

[Peeja]

PR Dependency Tree

• PR feat: Use single DB query to iterate for index #354 👈

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[volmedo]

LGTM, just a couple nits if you wanna take a look.

[volmedo]

nit: what do you think of using the idiomatic iterator syntax?

We could create a new NodeInIndex type as:

type NodeInIndex struct {
    Cid                cid.Cid
    Size               uint64
    ShardDigest multihash.Multihash
    ShardOffset uint64

and then have this function be:

func (r *Repo) NodesInIndex(ctx context.Context, indexID id.IndexID) iter.Seq2[NodeInIndex, error]

and then the caller can range over the results and do whatever is needed with them.

[volmedo]

nit: why not build the map here directly instead of adding to a list and then converting that to a map?

Also, to DRY the assertions afterwards, I'd build a map with the expected results indexed by CID and then do the requires here:

nodeInIndex := expectedNodesByCID[nodeCID.String()]
require.Equal(t, nodeInIndex.ShardDigest, []byte(shardDigest))
require.Equal(t, nodeInIndex.Size, nodeSize)
require.Equal(t, nodeInIndex.ShardOffset, shardOffset)

To ensure we are getting the expected 4 nodes, we can add a simple counter.