js-libp2p/doc/DIALER.md
2020-01-24 14:40:40 +01:00

2.5 KiB

js-libp2p Dialer

Synopsis

  • All Dial Requests in js-libp2p must request a token(s) from the Dialer.
    • The number of tokens requested should be between 1 and the MAX_PER_PEER_DIALS max set in the Dialer.
    • If the number of available tokens is less than requested, the Dialer may return less than requested.
  • The number of tokens a DialRequest obtains reflects the maximum number of parallel Multiaddr Dials it can make.
  • If no tokens are available a DialRequest should immediately end and throw.
  • As tokens are limited, DialRequests should be given a prioritized list of Multiaddrs to minimize the potential request time.
  • Once a Multiaddr Dial has succeeded, all pending dials in that Dial Request should be aborted.
  • If DIAL_TIMEOUT time has elapsed before any one Multiaddr Dial succeeds, all remaining dials in the DialRequest should be aborted.
  • When a Multiaddr Dial is settled, if there are no more addresses to dial, its token should be released back to the dialer.
  • Once the DialRequest is settled, any remaining tokens should be released to the dialer.

Multiaddr Confidence

An effective dialing system should involve the inclusion of a Confidence system for Multiaddrs. This enables ranking of Multiaddrs so that a prioritized list can be passed to DialRequests to maximize usage of Dialer Tokens, and minimize connection times.

Not Yet Implemented: This system will be designed and implemented in a future update.

Notes

  • A DialRequest gets a set of tokens from the Dialer, up to the MAX_PER_PEER_DIALS max.
  • A DialRequest SHOULD fail if no dial tokens are available. The DialRequest MAY proceed without tokens, but this should be reserved for High Priority actions and should be rare.
  • A DialRequest MUST NOT request more tokens than it has addresses to dial. Example: If the MAX_PER_PEER_DIALS is 4 and a DialRequest has 1 address, it should only request 1 token.
  • A DialRequest SHOULD execute parallel dials for each of its addresses up the total number of tokens it has.
  • On a successful dial, the DialRequest MUST abort any other in progress dials, return the successful connection and release all tokens.
  • A new DialRequest SHOULD be given a descending list of prioritized Multiaddrs, based on their confidence. Having higher confidence Multiaddrs first can help minimize the time a DialRequest is active.
  • A failed dial to a Multiaddr SHOULD add that Multiaddr to a temporary denyList.
  • A failed dial to a Multiaddr SHOULD lower the confidence of that Multiaddr.
  • A successful dial to a Multiaddr SHOULD increase the confidence of that Multiaddr.