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node_modules/backoff/lib/strategy/exponential.js

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+//      Copyright (c) 2012 Mathieu Turcotte
+//      Licensed under the MIT license.
+
+var util = require('util');
+var precond = require('precond');
+
+var BackoffStrategy = require('./strategy');
+
+// Exponential backoff strategy.
+function ExponentialBackoffStrategy(options) {
+    BackoffStrategy.call(this, options);
+    this.backoffDelay_ = 0;
+    this.nextBackoffDelay_ = this.getInitialDelay();
+    this.factor_ = ExponentialBackoffStrategy.DEFAULT_FACTOR;
+
+    if (options && options.factor !== undefined) {
+        precond.checkArgument(options.factor > 1,
+            'Exponential factor should be greater than 1 but got %s.',
+            options.factor);
+        this.factor_ = options.factor;
+    }
+}
+util.inherits(ExponentialBackoffStrategy, BackoffStrategy);
+
+// Default multiplication factor used to compute the next backoff delay from
+// the current one. The value can be overridden by passing a custom factor as
+// part of the options.
+ExponentialBackoffStrategy.DEFAULT_FACTOR = 2;
+
+ExponentialBackoffStrategy.prototype.next_ = function() {
+    this.backoffDelay_ = Math.min(this.nextBackoffDelay_, this.getMaxDelay());
+    this.nextBackoffDelay_ = this.backoffDelay_ * this.factor_;
+    return this.backoffDelay_;
+};
+
+ExponentialBackoffStrategy.prototype.reset_ = function() {
+    this.backoffDelay_ = 0;
+    this.nextBackoffDelay_ = this.getInitialDelay();
+};
+
+module.exports = ExponentialBackoffStrategy;