feat: async peerstore backed by datastores (#1058)

We have a peerstore that keeps all data for all observed peers in memory with no eviction.

This is fine when you don't discover many peers but when using the DHT you encounter a significant number of peers so our peer storage grows and grows over time.

We have a persistent peer store, but it just periodically writes peers into the datastore to be read at startup, still keeping them in memory.

It also means a restart doesn't give you any temporary reprieve from the memory leak as the previously observed peer data is read into memory at startup.

This change refactors the peerstore to use a datastore by default, reading and writing peer info as it arrives.  It can be configured with a MemoryDatastore if desired.

It was necessary to change the peerstore and *book interfaces to be asynchronous since the datastore api is asynchronous.

BREAKING CHANGE: `libp2p.handle`, `libp2p.registrar.register` and the peerstore methods have become async

examples/peer-and-content-routing/1.js

@@ -38,8 +38,8 @@ const createNode = async () => {
     createNode()
   ])
 
-  node1.peerStore.addressBook.set(node2.peerId, node2.multiaddrs)
-  node2.peerStore.addressBook.set(node3.peerId, node3.multiaddrs)
+  await node1.peerStore.addressBook.set(node2.peerId, node2.multiaddrs)
+  await node2.peerStore.addressBook.set(node3.peerId, node3.multiaddrs)
 
   await Promise.all([
     node1.dial(node2.peerId),

examples/peer-and-content-routing/2.js

@@ -40,8 +40,8 @@ const createNode = async () => {
     createNode()
   ])
 
-  node1.peerStore.addressBook.set(node2.peerId, node2.multiaddrs)
-  node2.peerStore.addressBook.set(node3.peerId, node3.multiaddrs)
+  await node1.peerStore.addressBook.set(node2.peerId, node2.multiaddrs)
+  await node2.peerStore.addressBook.set(node3.peerId, node3.multiaddrs)
 
   await Promise.all([
     node1.dial(node2.peerId),

examples/peer-and-content-routing/README.md

@@ -43,8 +43,8 @@ const node1 = nodes[0]
 const node2 = nodes[1]
 const node3 = nodes[2]
 
-node1.peerStore.addressBook.set(node2.peerId, node2.multiaddrs)
-node2.peerStore.addressBook.set(node3.peerId, node3.multiaddrs)
+await node1.peerStore.addressBook.set(node2.peerId, node2.multiaddrs)
+await node2.peerStore.addressBook.set(node3.peerId, node3.multiaddrs)
 
 await Promise.all([
   node1.dial(node2.peerId),

examples/peer-and-content-routing/test-1.js

@@ -2,35 +2,28 @@
 
 const path = require('path')
 const execa = require('execa')
-const pWaitFor = require('p-wait-for')
 const { toString: uint8ArrayToString } = require('uint8arrays/to-string')
 
 async function test() {
   process.stdout.write('1.js\n')
 
-  const addrs = []
-  let foundIt = false
   const proc = execa('node', [path.join(__dirname, '1.js')], {
     cwd: path.resolve(__dirname),
     all: true
   })
 
+  let output = ''
+
   proc.all.on('data', async (data) => {
     process.stdout.write(data)
 
-    const line = uint8ArrayToString(data)
+    output += uint8ArrayToString(data)
 
-    // Discovered peer
-    if (!foundIt && line.includes('Found it, multiaddrs are:')) {
-      foundIt = true
+    // Discovered peers
+    if (output.includes('Found it, multiaddrs are:')) {
+      proc.kill()
     }
-
-    addrs.push(line)
   })
-
-  await pWaitFor(() => addrs.length === 2)
-
-  proc.kill()
 }
 
 module.exports = test

examples/peer-and-content-routing/test-2.js

@@ -2,39 +2,27 @@
 
 const path = require('path')
 const execa = require('execa')
-const pDefer = require('p-defer')
 const { toString: uint8ArrayToString } = require('uint8arrays/to-string')
 
-const providedCopy = 'is providing'
-const foundCopy = 'Found provider:'
-
 async function test() {
   process.stdout.write('2.js\n')
-  const providedDefer = pDefer()
-  const foundDefer = pDefer()
 
   const proc = execa('node', [path.join(__dirname, '2.js')], {
     cwd: path.resolve(__dirname),
     all: true
   })
 
+  let output = ''
+
   proc.all.on('data', async (data) => {
     process.stdout.write(data)
 
-    const line = uint8ArrayToString(data)
+    output += uint8ArrayToString(data)
 
-    if (line.includes(providedCopy)) {
-      providedDefer.resolve()
-    } else if (line.includes(foundCopy)) {
-      foundDefer.resolve()
+    if (output.includes('Found provider:')) {
+      proc.kill()
     }
   })
-
-  await Promise.all([
-    providedDefer.promise,
-    foundDefer.promise
-  ])
-  proc.kill()
 }
 
 module.exports = test