refactor: connection manager (#511)

* refactor: initial refactor of the connection manager

* fix: start/stop issues

* fix: add tests and resolve pruning issues

* chore: fix lint

* test: move conn manager tests to node only for now

* chore: apply suggestions from code review

Co-Authored-By: Vasco Santos <[email protected]>

* fix: assert min max connection options

* test: fix assertion check for browser

* docs: add api and config docs for conn manager

doc/API.md

@@ -643,6 +643,36 @@ const handler = (msg) => {
 libp2p.pubsub.unsubscribe(topic, handler)
 ```
 
+### connectionManager.setPeerValue
+
+Enables users to change the value of certain peers in a range of 0 to 1. Peers with the lowest values will have their Connections pruned first, if any Connection Manager limits are exceeded. See [./CONFIGURATION.md#configuring-connection-manager](./CONFIGURATION.md#configuring-connection-manager) for details on how to configure these limits.
+
+`libp2p.connectionManager.setPeerValue(peerId, value)`
+
+#### Parameters
+
+| Name | Type | Description |
+|------|------|-------------|
+| peerId | `PeerId` | The peer to set the value for |
+| value | `number` | The value of the peer from 0 to 1 |
+
+#### Returns
+
+| Type | Description |
+|------|-------------|
+| `void` |  |
+
+#### Example
+
+```js
+const topic = 'topic'
+const handler = (msg) => {
+  // msg.data - pubsub data received
+}
+
+libp2p.pubsub.unsubscribe(topic, handler)
+```
+
 ### metrics.global
 
 A [`Stats`](#stats) object of tracking the global bandwidth of the libp2p node.

doc/CONFIGURATION.md

@@ -15,10 +15,12 @@
     - [Examples](#examples)
       - [Basic setup](#basic-setup)
       - [Customizing Peer Discovery](#customizing-peer-discovery)
+      - [Setup webrtc transport and discovery](#setup-webrtc-transport-and-discovery)
       - [Customizing Pubsub](#customizing-pubsub)
       - [Customizing DHT](#customizing-dht)
       - [Setup with Content and Peer Routing](#setup-with-content-and-peer-routing)
       - [Setup with Relay](#setup-with-relay)
+      - [Configuring Connection Manager](#configuring-connection-manager)
       - [Configuring Metrics](#configuring-metrics)
   - [Configuration examples](#configuration-examples)
 
@@ -412,6 +414,37 @@ const node = await Libp2p.create({
 })
 ```
 
+#### Configuring Connection Manager
+
+The Connection Manager prunes Connections in libp2p whenever certain limits are exceeded. If Metrics are enabled, you can also configure the Connection Manager to monitor the bandwidth of libp2p and prune connections as needed. You can read more about what Connection Manager does at [./CONNECTION_MANAGER.md](./CONNECTION_MANAGER.md). The configuration values below show the defaults for Connection Manager. See [./CONNECTION_MANAGER.md](./CONNECTION_MANAGER.md#options) for a full description of the parameters.
+
+```js
+const Libp2p = require('libp2p')
+const TCP = require('libp2p-tcp')
+const MPLEX = require('libp2p-mplex')
+const SECIO = require('libp2p-secio')
+
+const node = await Libp2p.create({
+  modules: {
+    transport: [TCP],
+    streamMuxer: [MPLEX],
+    connEncryption: [SECIO]
+  },
+  connectionManager: {
+    maxConnections: Infinity,
+    minConnections: 0,
+    pollInterval: 2000,
+    defaultPeerValue: 1,
+    // The below values will only be taken into account when Metrics are enabled
+    maxData: Infinity,
+    maxSentData: Infinity,
+    maxReceivedData: Infinity,
+    maxEventLoopDelay: Infinity,
+    movingAverageInterval: 60000
+  }
+})
+```
+
 #### Configuring Metrics
 
 Metrics are disabled in libp2p by default. You can enable and configure them as follows. Aside from enabled being `false` by default, the configuration options listed here are the current defaults.

doc/CONNECTION_MANAGER.md

@@ -0,0 +1,20 @@
+# Connection Manager
+
+The Connection Manager works with the Registrar to keep connections across libp2p within acceptable ranges, which can be configured. By default Connection Manager will monitor:
+- The total number of open connections
+- The latency/delay of the event loop
+
+If Metrics are enabled for libp2p, see [./CONFIGURATION.md#configuring-metrics](./CONFIGURATION.md#configuring-metrics) on how to configure metrics, the Connection Manager can be used to prune connections when certain limits are exceeded.
+
+The following is a list of available options for setting limits for the Connection Manager to enforce.
+
+## Options
+- `maxConnections`: the maximum number of connections libp2p is willing to have before it starts disconnecting. Defaults to `Infinity`
+- `minConnections`: the minimum number of connections below which libp2p not activate preemptive disconnections. Defaults to `0`.
+- `maxData`: sets the maximum data — in bytes per second -  (sent and received) this node is willing to endure before it starts disconnecting peers. Defaults to `Infinity`.
+- `maxSentData`: sets the maximum sent data — in bytes per second -  this node is willing to endure before it starts disconnecting peers. Defaults to `Infinity`.
+- `maxReceivedData`: sets the maximum received data — in bytes per second -  this node is willing to endure before it starts disconnecting peers. Defaults to `Infinity`.
+- `maxEventLoopDelay`: sets the maximum event loop delay (measured in milliseconds) this node is willing to endure before it starts disconnecting peers. Defaults to `Infinity`.
+- `pollInterval`: sets the poll interval (in milliseconds) for assessing the current state and determining if this peer needs to force a disconnect. Defaults to `2000` (2 seconds).
+- `movingAverageInterval`: the interval used to calculate moving averages (in milliseconds). Defaults to `60000` (1 minute). This must be an available interval configured in `Metrics`
+- `defaultPeerValue`: number between 0 and 1. Defaults to 1.