Expose Blockchain Object

[AusIV]

Rationale

Some plugins would like to be able to get information from the blockchain or even add blocks to the blockchain.

Implementation

The core.Blockchain object is pretty tightly coupled with the Geth codebase, so it will require a wrapper / interface.

In PluGeth utils, create an object with the following interface:

type Blockchain interface{
  func SetHead(head uint64) error
  func SnapSyncCommitHead(hash core.Hash) error
  func Reset() error
  func ResetWithGenesisBlock(genesis []byte) error // RLP encoded *types.Block
  func Export(w io.Writer) error
  func ExportN(w io.Writer, first uint64, last uint64) error
  func Stop()
  func StopInsert()
  func InsertReceiptChain(blockChain [][]byte, receiptChain [][]byte, ancientLimit uint64) (int, error) // List of RLP encoded blocks, list of RLP encoded receipts
  func InsertChain(chain [][]byte) (int, error) // List of RLP encoded blocks
  func InsertBlockWithoutSetHead(block []byte) error // RLP encoded *types.BLock
  func SetChainHead(head []byte) error // RLP encoded *types.Block
  func InsertHeaderChain(chain [][]byte, checkFreq int) (int, error) // List of rlp encoded *types.Header
}

(Comments indicate when []bytes are RLP encoded values)

Then we would need to implement a wrapper object to translate between the types in the above interface and the types required by the *core.BlockChain object. We would then need to expose this to the plugeth backend by way of the Ethereum object in eth/backend.go