ssb-conn-query

Module that helps querying potential SSB peer connections. For use with the SSB CONN family of modules.

Usage

This module is only used to create an SSB CONN plugin, not used directly by applications. A ConnQuery instance should be available on the CONN plugin, with the following API:

Types

All "peers" returned by these APIs are key-value arrays, of the format:

type Peer = [Address, Data]

where

type Address = string;

type Data = {pool: 'db' | 'hub' | 'staging'} &
  Partial<DBData> &
  Partial<HubData> &
  Partial<StagingData>;

In other words, a peer is an array where the first element is the multiserver address for that peer, and the second element is an object that is either the ConnDB data or the ConnHub or the ConnStaging data (plus an additional field pool).

Instance API

These methods are available on instances of the ConnQuery class:

• connQuery.peersAll(): returns an array of all known peers, from all sources (ConnDB, ConnHub, ConnStaging), either connected or disconnected.
• connQuery.peersConnected(): returns an array of peer objects that we are currently connected to.
• connQuery.peersConnecting(): returns an array of peer objects that we are currently attempting to connect with.
• connQuery.peersInConnection(): returns an array of peer objects that are either: currently connected to, or currently attempting to connect with.
• connQuery.peersConnectable(pool): returns an array of peer objects that are candidates for potential connection, given a specified pool of candidates.
  • pool (optional, default is 'db') A string with the possible values: 'db', 'staging', 'dbAndStaging', referring to the pools ssb-conn-db and ssb-conn-staging.

Static API

These functions are available as statics on the ConnQuery class:

• ConnQuery.passesExpBackoff(step, max, timestamp): peer => boolean: Answers whether a peer has passed an 'exponential backoff' check, relative to a given timestamp (or Date.now() if no timestamp is provided). The exponential backoff is a certain time gap counting from the latest stateChange timestamp, and this gap grows with the number of connection failures that have occurred for this peer. Returns a function where the input is a peer object and the output is a boolean.
  • step A temporal parameter (measured in milliseconds) for how much the exponential backoff grows for each connection failure.
  • max (optional, default is Infinity) The maximum time gap (in milliseconds) for the exponential backoff.
  • timestamp (optional, default is Date.now()) The timestamp to compare the exponential backoff with. If the time gap between the latest stateChange and the exponential backoff is less than this timestamp, this check passes.
• ConnQuery.passesGroupDebounce(groupMin, timestamp): peersArray => boolean: Answers whether a group of peers (as an array) has had enough time gap since the last stateChange for any peer. This is known as a "debounce". The time gap is determined by the 'groupMin' argument, the first argument. Returns a function where the input is an array of peers and the output is a boolean.
  • groupMin A temporal parameter (measured in milliseconds) for how long the time gap should last.
  • timestamp (optional, default is Date.now()) The timestamp to compare the time gap with. If the time gap between the latest stateChange (for any peer) is less than this timestapm, this check passes.
• ConnQuery.hasNoAttempts(peer) Answers a boolean whether a peer has not had a connection attempt yet.
• ConnQuery.hasOnlyFailedAttempts(peer) Answers a boolean whether a peer has never been successfully connected to yet, but has been tried.
• ConnQuery.hasSuccessfulAttempts(peer) Answers a boolean whether a peer has had some successful connection in the past.
• ConnQuery.hasPinged(peer) Answers a boolean whether a peer has successfully pinged us in the past.
• ConnQuery.sortByStateChange(peers) Sorts an array of peers from oldest 'stateChange' timestamp to newest.

License

MIT