Add fromCorestore init

index.js

@@ -333,6 +333,30 @@ class HypercoreStats {
       }
     })
   }
+
+  static fromCorestore (store) {
+    const hypercoreStats = new this()
+    store.on('core-open', core => {
+      hypercoreStats.addCore(core)
+    })
+
+    // TODO: we never delete cores when they close
+    // since we care mostly about the history (sum) of metrics.
+    // A proper solution is to detect when a core closes,
+    // sum each metric to a separate variable,
+    // and then deleting the hypercore
+
+    // Add already-opened cores
+    for (const core of [...store.cores.values()]) {
+      // DEVNOTE: core-open is emitted after a core is ready
+      // so if not yet opened, we will process it then
+      if (core.opened === true) {
+        this.metrics.addCore(core)
+      }
+    }
+
+    return hypercoreStats
+  }
 }
 
 class HypercoreStatsSnapshot {

test.js

@@ -4,7 +4,7 @@ const RAM = require('random-access-memory')
 const HypercoreStats = require('.')
 const promClient = require('prom-client')
 
-const DEBUG = true
+const DEBUG = false
 
 test('Can register and get prometheus metrics', async (t) => {
   const store = new Corestore(RAM)
@@ -101,16 +101,6 @@ test('Can register and get prometheus metrics', async (t) => {
   }
 })
 
-function getMetricValue (lines, name) {
-  const match = lines.find((l) => l.startsWith(`${name} `))
-  if (!match) throw new Error(`No match for ${name}`)
-
-  const value = parseInt(match.split(' ')[1])
-  if (DEBUG) console.log(name, '->', value)
-
-  return value
-}
-
 test('Cache-expiry logic', async (t) => {
   const store = new Corestore(RAM)
   const core = store.get({ name: 'core' })
@@ -146,3 +136,26 @@ test('Cache-expiry logic', async (t) => {
     t.is(getMetricValue(lines, 'hypercore_total_cores'), 1, 'cache busted after expire time')
   }
 })
+
+test('fromCorestore init', async (t) => {
+  const store = new Corestore(RAM)
+  const core = store.get({ name: 'core' })
+
+  const stats = HypercoreStats.fromCorestore(store)
+  await core.ready()
+  t.is(stats.cores.size, 1, 'init core added')
+
+  const core2 = store.get({ name: 'core2' })
+  await core2.ready()
+  t.is(stats.cores.size, 2, 'new core added')
+})
+
+function getMetricValue (lines, name) {
+  const match = lines.find((l) => l.startsWith(`${name} `))
+  if (!match) throw new Error(`No match for ${name}`)
+
+  const value = parseInt(match.split(' ')[1])
+  if (DEBUG) console.log(name, '->', value)
+
+  return value
+}