This implements #5133 introducing an option to limit how deep we fetch and store
the DAG associated to a recursive pin ("--max-depth"). This feature
comes motivated by the need to fetch and pin partial DAGs in order to do
DAG sharding with IPFS Cluster.
This means that, when pinning something to --max-depth, the DAG will be
fetched only to that depth and not more.
In order to get this, the PR introduces new recursive pin types: "recursive1"
means: the given CID is pinned along with its direct children (maxDepth=1)
"recursive2" means: the given CID is pinned along with its direct children
and its grandchildren.
And so on...
This required introducing "maxDepth" limits to all the functions walking down
DAGs (in merkledag, pin, core/commands, core/coreapi, exchange/reprovide modules).
maxDepth == -1 effectively acts as no-limit, and all these functions behave like
they did before.
In order to facilitate the task, a new CID Set type has been added:
thirdparty/recpinset. This set carries the MaxDepth associated to every Cid.
This allows to shortcut exploring already explored branches just like the original
cid.Set does. It also allows to store the Recursive pinset (and replaces cid.Set).
recpinset should be moved outside to a different repo eventually.
TODO: tests
TODO: refs -r with --max-depth
License: MIT
Signed-off-by: Hector Sanjuan <code@hector.link>
