ColoredSet computes the set of nodes in the graph that are pinned by the pins in the given pinner.

Descendants recursively finds all the descendants of the given roots and adds them to the given cid.Set, using the provided dag.GetLinks function to walk the tree.

GC performs a mark and sweep garbage collection of the blocks in the blockstore first, it creates a 'marked' set and adds to it the following: - all recursively pinned blocks, plus all of their descendants (recursively) - bestEffortRoots, plus all of its descendants (recursively) - all directly pinned blocks - all blocks utilized internally by the pinner The routine then iterates over every block in the blockstore and deletes any block that is not found in the marked set.

ErrCannotDeleteSomeBlocks is returned when removing blocks marked for deletion fails as the last Result in GC output channel.

ErrCannotFetchAllLinks is returned as the last Result in the GC output channel when there was an error creating the marked set because of a problem when finding descendants.

CannotDeleteBlockError provides detailed information about which blocks could not be deleted and can appear as a Result in the GC output channel.

CannotFetchLinksError provides detailed information about which links could not be fetched and can appear as a Result in the GC output channel.

Result represents an incremental output from a garbage collection run.