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>
This PR drops support for v0 blob sidecar in blobpool. Since the
osaka fork activation time has passed, these code paths are
now unused. It is assumed that only v1 transactions exist in
the blobpool.
This PR introduces a cache for GetBlobs request.
The main purpose of this PR is to reduce the getBlobs latency by reading and
decoding blobs from the pool in advance of the actual query. This is important
especially in the context of a sparse blobpool, since it may be necessary to
recover blobs from cells on a getBlobs request.
Previously, the Engine API read and decoded blobs from the pool on every call.
Now those calls check the cache and only fall back to the pool on a miss.
The cache has two modes:
- In topK mode (default), it wakes up periodically, picks the most profitable
pending blob transactions up to the current fork's maxBlobsPerBlock, and loads
their blobs. The selection logic is shared with the miner's block-building
logic. The selection size is derived from eip4844.MaxBlobsPerBlock at the
current head.
- When the CL calls HasBlobs, the cache switches to hasBlobs mode and tries to
pin the set it just reported as available. Cache updates (read, decode, and
optionally conversion in the future) run in background goroutines.
---------
Co-authored-by: Felix Lange <fjl@twurst.com>
