refactor: convert stats API to async/await

Depends on:

* [ ] libp2p 0.27
* [ ] #2659
* [ ] #2674

Author: Alan Shaw

src/core/components/init.js

@@ -301,7 +301,12 @@ function createApi ({
     add,
     config: Commands.config({ repo }),
     init: () => { throw new AlreadyInitializedError() },
-    start
+    start,
+    stats: {
+      bitswap: () => { throw new NotStartedError() },
+      bw: () => { throw new NotStartedError() },
+      repo: Commands.repo.stat({ repo })
+    }
   }
 
   return api

src/core/components/start.js

@@ -134,6 +134,11 @@ function createApi ({
     config: Commands.config({ repo }),
     init: () => { throw new AlreadyInitializedError() },
     start: () => apiManager.api,
+    stats: {
+      bitswap: Commands.bitswap.stat({ bitswap }),
+      bw: Commands.stats.bw({ libp2p }),
+      repo: Commands.repo.stat({ repo })
+    },
     stop
   }
 

src/core/components/stats.js

@@ -0,0 +1,63 @@
+'use strict'
+
+const Big = require('bignumber.js')
+const human = require('human-to-milliseconds')
+const errCode = require('err-code')
+
+function getBandwidthStats (libp2p, opts) {
+  let stats
+
+  if (opts.peer) {
+    stats = libp2p.metrics.forPeer(opts.peer)
+  } else if (opts.proto) {
+    stats = libp2p.metrics.forProtocol(opts.proto)
+  } else {
+    stats = libp2p.metrics.global
+  }
+
+  if (!stats) {
+    return {
+      totalIn: new Big(0),
+      totalOut: new Big(0),
+      rateIn: new Big(0),
+      rateOut: new Big(0)
+    }
+  }
+
+  const { movingAverages, snapshot } = stats
+
+  return {
+    totalIn: snapshot.dataReceived,
+    totalOut: snapshot.dataSent,
+    rateIn: new Big(movingAverages.dataReceived[60000].movingAverage() / 60),
+    rateOut: new Big(movingAverages.dataSent[60000].movingAverage() / 60)
+  }
+}
+
+module.exports = ({ libp2p }) => {
+  return async function * (options) {
+    options = options || {}
+
+    if (!options.poll) {
+      yield getBandwidthStats(libp2p, options)
+      return
+    }
+
+    let interval
+    try {
+      interval = human(options.interval || '1s')
+    } catch (err) {
+      throw errCode(err, 'ERR_INVALID_POLL_INTERVAL')
+    }
+
+    let timeoutId
+    try {
+      while (true) {
+        yield getBandwidthStats(libp2p, options)
+        await new Promise(resolve => { timeoutId = setTimeout(resolve, interval) })
+      }
+    } finally {
+      clearTimeout(timeoutId)
+    }
+  }
+}

src/core/components/stats/bw.js

@@ -101,6 +101,11 @@ function createApi ({
     config: Commands.config({ repo }),
     init: () => { throw new AlreadyInitializedError() },
     start,
+    stats: {
+      bitswap: () => { throw new NotStartedError() },
+      bw: () => { throw new NotStartedError() },
+      repo: Commands.repo.stat({ repo })
+    },
     stop: () => apiManager.api
   }