Documentation
¶
Overview ¶
Package exchange contains the ChainExchange server and client components.
ChainExchange is the basic chain synchronization protocol of Filecoin. ChainExchange is an RPC-oriented protocol, with a single operation to request blocks for now.
A request contains a start anchor block (referred to with a CID), and a amount of blocks requested beyond the anchor (including the anchor itself).
A client can also pass options, encoded as a 64-bit bitfield. Lotus supports two options at the moment:
- include block contents
- include block messages
The response will include a status code, an optional message, and the response payload in case of success. The payload is a slice of serialized tipsets.
Index ¶
Constants ¶
const ( // Extracted constants from the code. // FIXME: Should be reviewed and confirmed. SuccessPeerTagValue = 25 WriteReqDeadline = 5 * time.Second ReadResDeadline = WriteReqDeadline ReadResMinSpeed = 50 << 10 ShufflePeersPrefix = 16 WriteResDeadline = 60 * time.Second )
const ( Headers = 1 << iota Messages )
Request options. When fetching the chain segment we can fetch either block headers, messages, or both.
const ( Ok status = 0 // We could not fetch all blocks requested (but at least we returned // the `Head` requested). Not considered an error. Partial = 101 // Errors NotFound = 201 GoAway = 202 InternalError = 203 BadRequest = 204 )
const ( // ChainExchangeProtocolID is the protocol ID of the chain exchange // protocol. ChainExchangeProtocolID = "/fil/chain/xchg/0.0.1" )
Variables ¶
var MaxRequestLength = uint64(build.ForkLengthThreshold)
FIXME: Bumped from original 800 to this to accommodate `syncFork()`
use of `GetBlocks()`. It seems the expectation of that API is to fetch any amount of blocks leaving it to the internal logic here to partition and reassemble the requests if they go above the maximum. (Also as a consequence of this temporarily removing the `const` qualifier to avoid "const initializer [...] is not a constant" error.)
Functions ¶
This section is empty.
Types ¶
type BSTipSet ¶
type BSTipSet struct {
// List of blocks belonging to a single tipset to which the
// `CompactedMessages` are linked.
Blocks []*types.BlockHeader
Messages *CompactedMessages
}
FIXME: Rename.
type Client ¶
type Client interface {
// GetBlocks fetches block headers from the network, from the provided
// tipset *backwards*, returning as many tipsets as the count parameter,
// or less.
GetBlocks(ctx context.Context, tsk types.TipSetKey, count int) ([]*types.TipSet, error)
// GetChainMessages fetches messages from the network, starting from the first provided tipset
// and returning messages from as many tipsets as requested or less.
GetChainMessages(ctx context.Context, tipsets []*types.TipSet) ([]*CompactedMessages, error)
// GetFullTipSet fetches a full tipset from a given peer. If successful,
// the fetched object contains block headers and all messages in full form.
GetFullTipSet(ctx context.Context, peer peer.ID, tsk types.TipSetKey) (*store.FullTipSet, error)
// AddPeer adds a peer to the pool of peers that the Client requests
// data from.
AddPeer(peer peer.ID)
// RemovePeer removes a peer from the pool of peers that the Client
// requests data from.
RemovePeer(peer peer.ID)
}
Client is the requesting side of the ChainExchange protocol. It acts as a proxy for other components to request chain data from peers. It is chiefly used by the Syncer.
type CompactedMessages ¶
type CompactedMessages struct {
Bls []*types.Message
BlsIncludes [][]uint64
Secpk []*types.SignedMessage
SecpkIncludes [][]uint64
}
All messages of a single tipset compacted together instead of grouped by block to save space, since there are normally many repeated messages per tipset in different blocks.
`BlsIncludes`/`SecpkIncludes` matches `Bls`/`Secpk` messages to blocks in the tipsets with the format: `BlsIncludes[BI][MI]`
- BI: block index in the tipset.
- MI: message index in `Bls` list
FIXME: The logic to decompress this structure should belong
to itself, not to the consumer.
func (*CompactedMessages) MarshalCBOR ¶
func (t *CompactedMessages) MarshalCBOR(w io.Writer) error
func (*CompactedMessages) UnmarshalCBOR ¶
func (t *CompactedMessages) UnmarshalCBOR(r io.Reader) (err error)
type Request ¶
type Request struct {
// List of ordered CIDs comprising a `TipSetKey` from where to start
// fetching backwards.
// FIXME: Consider using `TipSetKey` now (introduced after the creation
// of this protocol) instead of converting back and forth.
Head []cid.Cid
// Number of block sets to fetch from `Head` (inclusive, should always
// be in the range `[1, MaxRequestLength]`).
Length uint64
// Request options, see `Options` type for more details. Compressed
// in a single `uint64` to save space.
Options uint64
}
FIXME: Rename. Make private.
type Response ¶
type Response struct {
Status status
// String that complements the error status when converting to an
// internal error (see `statusToError()`).
ErrorMessage string
Chain []*BSTipSet
}
FIXME: Rename. Make private.
type Server ¶
type Server interface {
// HandleStream is the protocol handler to be registered on a libp2p
// protocol router.
//
// In the current version of the protocol, streams are single-use. The
// server will read a single Request, and will respond with a single
// Response. It will dispose of the stream straight after.
HandleStream(stream network.Stream)
}
Server is the responder side of the ChainExchange protocol. It accepts requests from clients and services them by returning the requested chain data.
func NewServer ¶
func NewServer(cs *store.ChainStore) Server
NewServer creates a new libp2p-based exchange.Server. It services requests for the libp2p ChainExchange protocol.
Source Files