Removing Current

TaskServer/node_modules/ccxt/js/base/functions/throttle.js

@@ -0,0 +1,64 @@
+"use strict";
+
+/*  ------------------------------------------------------------------------ */
+
+const { sleep
+      , now } = require ('./time')
+
+/*  ------------------------------------------------------------------------ */
+
+module.exports = {
+
+    throttle: function throttle (cfg) {
+
+        let   lastTimestamp = now ()
+            , numTokens     = (cfg.numTokens !== undefined) ? cfg.numTokens : cfg.capacity
+            , running       = false
+            , counter       = 0
+
+        const queue = []
+
+        return Object.assign ((rateLimit, cost) => {
+
+            if (queue.length > cfg.maxCapacity)
+                throw new Error ('Backlog is over max capacity of ' + cfg.maxCapacity)
+
+            return new Promise (async (resolve, reject) => {
+
+                try {
+                    queue.push ({ cost, resolve, reject })
+
+                    if (!running) {
+                        running = true
+                        while (queue.length > 0) {
+                            const hasEnoughTokens = cfg.capacity ? (numTokens > 0) : (numTokens >= 0)
+                            if (hasEnoughTokens) {
+                                if (queue.length > 0) {
+                                    let { cost, resolve, reject } = queue[0]
+                                    cost = (cost || cfg.defaultCost)
+                                    if (numTokens >= Math.min (cost, cfg.capacity)) {
+                                        numTokens -= cost
+                                        queue.shift ()
+                                        resolve ()
+                                    }
+                                }
+                            }
+                            const t = now ()
+                                , elapsed = t - lastTimestamp
+                            lastTimestamp = t
+                            numTokens = Math.min (cfg.capacity, numTokens + elapsed * (1 / rateLimit))
+                            await sleep (cfg.delay)
+                        }
+                        running = false
+                    }
+
+                } catch (e) {
+                    reject (e)
+                }
+            })
+
+        }, cfg, { configure: newCfg => throttle (Object.assign ({}, cfg, newCfg)) })
+    }
+}
+
+/*  ------------------------------------------------------------------------ */