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node_modules/backoff/lib/backoff.js

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+//      Copyright (c) 2012 Mathieu Turcotte
+//      Licensed under the MIT license.
+
+var events = require('events');
+var precond = require('precond');
+var util = require('util');
+
+// A class to hold the state of a backoff operation. Accepts a backoff strategy
+// to generate the backoff delays.
+function Backoff(backoffStrategy) {
+    events.EventEmitter.call(this);
+
+    this.backoffStrategy_ = backoffStrategy;
+    this.maxNumberOfRetry_ = -1;
+    this.backoffNumber_ = 0;
+    this.backoffDelay_ = 0;
+    this.timeoutID_ = -1;
+
+    this.handlers = {
+        backoff: this.onBackoff_.bind(this)
+    };
+}
+util.inherits(Backoff, events.EventEmitter);
+
+// Sets a limit, greater than 0, on the maximum number of backoffs. A 'fail'
+// event will be emitted when the limit is reached.
+Backoff.prototype.failAfter = function(maxNumberOfRetry) {
+    precond.checkArgument(maxNumberOfRetry > 0,
+        'Expected a maximum number of retry greater than 0 but got %s.',
+        maxNumberOfRetry);
+
+    this.maxNumberOfRetry_ = maxNumberOfRetry;
+};
+
+// Starts a backoff operation. Accepts an optional parameter to let the
+// listeners know why the backoff operation was started.
+Backoff.prototype.backoff = function(err) {
+    precond.checkState(this.timeoutID_ === -1, 'Backoff in progress.');
+
+    if (this.backoffNumber_ === this.maxNumberOfRetry_) {
+        this.emit('fail', err);
+        this.reset();
+    } else {
+        this.backoffDelay_ = this.backoffStrategy_.next();
+        this.timeoutID_ = setTimeout(this.handlers.backoff, this.backoffDelay_);
+        this.emit('backoff', this.backoffNumber_, this.backoffDelay_, err);
+    }
+};
+
+// Handles the backoff timeout completion.
+Backoff.prototype.onBackoff_ = function() {
+    this.timeoutID_ = -1;
+    this.emit('ready', this.backoffNumber_, this.backoffDelay_);
+    this.backoffNumber_++;
+};
+
+// Stops any backoff operation and resets the backoff delay to its inital value.
+Backoff.prototype.reset = function() {
+    this.backoffNumber_ = 0;
+    this.backoffStrategy_.reset();
+    clearTimeout(this.timeoutID_);
+    this.timeoutID_ = -1;
+};
+
+module.exports = Backoff;