add property apiCallRate

Author: dutu

.travis.yml

@@ -1,10 +1,6 @@
 language: node_js
 node_js:
-  - "4"
-  - "5"
-  - "6"
-  - "7"
-  - "8"
+  - "11"
 sudo: false
 after_success:
   - npm run codecov

CHANGELOG.md

@@ -1,3 +1,8 @@
+### 1.10.0 (2022-06-20)
+
+* Add `apiCallRate` property
+* Update tests
+
 ### 1.9.1 (2022-06-20)
 
 * Fix https request error handling when no `callback` parameter (promises)

README.md

@@ -25,6 +25,23 @@ The optional `options` argument can be used to override the default options. The
 }
 ```
 
+## Properties
+
+### apiCallRate
+
+Gives the current rate per minute of API calls. The property is read only.
+It can be used by applications to limit the API call rate to prevent HTTP error code `429` (too many requests) responses from Luno server.
+See Luno API documentation for applicable rate limitations: https://www.luno.com/en/developers/api#tag/Rate-Limiting
+
+> API calls which result in error code `429` or `ErrTooManyRequests` are considered failed/unprocessed server request and are not added to the `apiCallRate` counter
+
+Example:
+
+```javascript
+console.log(bitx.apiCallRate)
+```
+
+
 ## Methods
 For details about the API endpoints see https://www.luno.com/en/developers/api.
 

lib/BitX.js

@@ -25,6 +25,37 @@ function BitX (keyId, keySecret, options) {
   this.port = options.port || 443
   this.ca = options.ca
   this.pair = options.pair || 'XBTZAR'
+  this._requestMts = []
+  this._requestsRefresh = this._requestsRefresh.bind(this)
+  this._timeoutId = null
+  this._timeoutId = setTimeout(this._requestsRefresh, 60000)
+}
+
+Object.defineProperty(BitX.prototype, 'apiCallRate', {
+  get: function () {
+    return this._requestsRefresh()
+  }
+})
+
+BitX.prototype._requestsRefresh = function () {
+  var maxMts = Date.now() - 60000
+  while (this._requestMts.length > 0) {
+    if (this._requestMts[0] < maxMts) {
+      this._requestMts.shift()
+    } else {
+      break
+    }
+  }
+
+  if (this._requestMts.length > 0) {
+    this._timeoutId.refresh()
+    this._timeoutId.unref()
+  } else {
+    clearTimeout(this._timeoutId)
+    this._timeoutId = null
+  }
+
+  return this._requestMts.length
 }
 
 BitX.prototype._request = function (method, resourcePath, data, callback) {
@@ -51,6 +82,14 @@ BitX.prototype._request = function (method, resourcePath, data, callback) {
     options.agent = new https.Agent(options)
   }
 
+  var mts = Date.now()
+  var requestMts = this._requestMts
+  requestMts.push(mts)
+  if (this._timeoutId === null) {
+    this._timeoutId = setTimeout(this._requestsRefresh, 60000)
+    this._timeoutId.unref()
+  }
+
   var promise = new Promise(function (resolve, reject) {
     var req = https.request(options)
 
@@ -70,6 +109,16 @@ BitX.prototype._request = function (method, resourcePath, data, callback) {
             response = JSON.parse(response)
             lunoApiError = new Error('luno API error ' + response.error_code + ': ' + response.error)
             lunoApiError.error_code = response.error_code
+            if (response.error_code.includes('429') || response.error_code.includes('ErrTooManyRequests')) {
+              var i = requestMts.length - 1
+              while (i >= 0) {
+                if (requestMts[i] === mts) {
+                  requestMts.splice(i, 1)
+                  break
+                }
+                i -= 1
+              }
+            }
           } catch (err) {
             lunoApiError = new Error('luno API error ' + res.statusCode + ': ' + response)
           }