From 4fb9e4848364550d967b7eef768db5aaa2981305 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ga=C3=ABtan=20Renaudeau?= <gaetan.renaudeau@ledger.fr>
Date: Sat, 26 May 2018 14:01:16 +0200
Subject: [PATCH] add a retry mecanism on the open()

---
 src/helpers/deviceAccess.js |  9 ++++++---
 src/helpers/promise.js      | 27 +++++++++++++++++++++++++++
 2 files changed, 33 insertions(+), 3 deletions(-)
 create mode 100644 src/helpers/promise.js

diff --git a/src/helpers/deviceAccess.js b/src/helpers/deviceAccess.js
index 68a74958..637faaa4 100644
--- a/src/helpers/deviceAccess.js
+++ b/src/helpers/deviceAccess.js
@@ -1,7 +1,8 @@
 // @flow
 import createSemaphore from 'semaphore'
 import type Transport from '@ledgerhq/hw-transport'
-import CommNodeHid from '@ledgerhq/hw-transport-node-hid'
+import TransportNodeHid from '@ledgerhq/hw-transport-node-hid'
+import { retry } from './promise'
 
 // all open to device must use openDevice so we can prevent race conditions
 // and guarantee we do one device access at a time. It also will handle the .close()
@@ -18,17 +19,19 @@ export const withDevice: WithDevice = devicePath => {
       `deviceAccess is only expected to be used in process 'devices'. Any other usage may lead to race conditions. (Got: '${FORK_TYPE}')`,
     )
   }
+
   const sem =
     semaphorePerDevice[devicePath] || (semaphorePerDevice[devicePath] = createSemaphore(1))
+
   return job =>
     takeSemaphorePromise(sem, async () => {
-      const t = await CommNodeHid.open(devicePath)
+      const t = await retry(() => TransportNodeHid.open(devicePath))
       try {
         const res = await job(t)
         // $FlowFixMe
         return res
       } finally {
-        t.close()
+        await t.close()
       }
     })
 }
diff --git a/src/helpers/promise.js b/src/helpers/promise.js
new file mode 100644
index 00000000..210c94ae
--- /dev/null
+++ b/src/helpers/promise.js
@@ -0,0 +1,27 @@
+// @flow
+
+// small utilities for Promises
+
+export const delay = (ms: number): Promise<void> => new Promise(f => setTimeout(f, ms))
+
+const defaults = {
+  maxRetry: 4,
+  interval: 300,
+  intervalMultiplicator: 1.5,
+}
+export function retry<A>(f: () => Promise<A>, options?: $Shape<typeof defaults>): Promise<A> {
+  const { maxRetry, interval, intervalMultiplicator } = { ...defaults, ...options }
+
+  return rec(maxRetry, interval)
+
+  function rec(remainingTry, interval) {
+    const result = f()
+    if (remainingTry <= 0) {
+      return result
+    }
+    // In case of failure, wait the interval, retry the action
+    return result.catch(() =>
+      delay(interval).then(() => rec(remainingTry - 1, interval * intervalMultiplicator)),
+    )
+  }
+}