This is the implementation of EIP-8070 Sparse Blobpool. It introduces
protocol version eth/72 which relays blob transaction cells instead of
full blobs.
The blobpool now store 'incomplete' transactions, where only some of
the cells are provided. The stored cell indexes are taken from the
custody bitmap, which is provided by the consensus layer in
forkchoiceUpdatedV4. This method will be called once Glamsterdam
activates, and the default custody is full custody, so for now there
is no change in the amount of stored cells for now.
The main entities added are the BlobBuffer and BlobFetcher, which work
together to track and fetch missing cells from connected peers. The
partial transactions become available for inclusion in blocks when
they are covered by enough peers that hold all cells.
This change also introduces engine_getBlobsV4, which allows for
cell-based responses (and partial blobs with only some of the cells).
We maintain backward compatibility with getBlobsV3 which expects full
blob responses by recovering the blob from available cells. Since this
process is resource-intensive, we proactively cache the conversion so
it is ready in time for getBlobsV3 calls. This mechanism will be
removed once support for getBlobsV4 is universal across all consensus
layer implementations.
devp2p tests for eth/72 are not part of this initial change. This is
to avoid breaking test success status for execution clients that do
not have eth/72 implemented yet. The tests will be added in a
subsequent change.
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Co-authored-by: Felix Lange <fjl@twurst.com>
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