Turn throttle into config option instead of instance property

As was documented in command comments.

That allows to set global throttle as well as dynamically change
throttle command-wise

index.js

@@ -62,7 +62,6 @@ function Osmosis(url, params) {
     this.queue    = new Queue(this);
     this.command  = new Command(this);
     this.id       = ++instanceId;
-    this.throttle = new RateLimiter(999, 1, true);
 }
 
 
@@ -74,6 +73,7 @@ function Osmosis(url, params) {
  * @property {string} accept             - HTTP Accept header
  * @property {bool}   compressed         - Compress HTTP requests
  * @property {number} concurrency        - Number of simultaneous HTTP requests
+ * @property {RateLimiter} throttle      - RateLimiter object to throttle following requests
  * @property {bool}   decode_response    - Decode compressed HTTP responses
  * @property {number} follow             - Number of redirects to follow
  * @property {bool}   follow_set_cookies - Set cookies for redirects
@@ -93,6 +93,7 @@ Osmosis.prototype.opts = {
                             'application/xml;q=0.9,*/*;q=0.8',
     compressed:             true,
     concurrency:            5,
+    throttle:               new RateLimiter(999, 1, true),
     decode_response:        true,
     follow:                 3,
     follow_set_cookies:     true,
@@ -182,7 +183,7 @@ Osmosis.prototype.request = function (url, opts, callback, tries) {
     this.queue.requests++;
     this.queue.push();
 
-    this.throttle.removeTokens(1, function(err, remainingRequests) {
+    opts.throttle.removeTokens(1, function(err, remainingRequests) {
     request(url.method,
             url,
             url.params,
@@ -325,7 +326,7 @@ Osmosis.prototype.resources = function () {
                 'requests: '  + this.requests +
                               ' (' + this.queue.requests + ' queued), ' +
 
-                'throttled: ' + parseInt(this.throttle.getTokensRemaining()) + ', ' +
+                'throttled: ' + parseInt(this.opts.throttle.getTokensRemaining()) + ', ' +
 
                 'RAM: '       + toMB(mem.rss) + ' (' + memDiff + '), ' +
 

lib/commands/throttle.js

@@ -13,7 +13,9 @@
 var RateLimiter = require('limiter').RateLimiter;
 
 module.exports = function (tokensPerInterval, interval) {
-    this.instance.throttle = new RateLimiter(
+    var opts = this.getOpts();
+
+    opts.throttle = new RateLimiter(
         tokensPerInterval || 1000,
         interval || 1
     );

test/throttle.js

@@ -1,5 +1,6 @@
 var osmosis = require('../index'),
     server  = require('./server'),
+    RateLimiter = require('limiter').RateLimiter,
     url     = server.host + ':' + server.port;
 
 
@@ -26,6 +27,90 @@ module.exports.on = function (assert) {
     });
 };
 
+
+module.exports.global_throttle = function (assert) {
+  var date0 = +Date.now(), interval = 2000;
+  osmosis.config('throttle', new RateLimiter(2, interval));
+  osmosis.get(url + '/get')
+    .then(function () {
+      var date = +Date.now();
+      assert.ok(date - date0 < interval);
+    })
+    .set({
+      test: osmosis
+            .get(url + '/get')
+            .then(function () {
+                var date = +Date.now();
+                assert.ok(date - date0 < interval);
+            })
+            .get(url + '/get')
+            .then(function () {
+                var date = +Date.now();
+                assert.ok(date - date0 >= interval);
+            })
+    })
+    .done(function () {
+      assert.done();
+      // Turn global throttling off, so it won't affect other tests
+      osmosis.config('throttle', new RateLimiter(999, 1));
+    });
+};
+
+
+module.exports.dynamic_change = function (assert) {
+  var date0 = +Date.now(), interval = 2000, date1, date2;
+  osmosis.get(url + '/get')
+    .then(function () {
+      var date = +Date.now();
+      assert.ok(date - date0 < interval);
+    })
+    .get(url + '/get')
+    .then(function () {
+      var date = +Date.now();
+      assert.ok(date - date0 < interval);
+    })
+    .get(url + '/get')
+    .then(function () {
+      var date = date1 = +Date.now();
+      assert.ok(date - date0 < interval);
+    })
+    .throttle(2, interval)
+    .get(url + '/get')
+    .then(function () {
+      var date = +Date.now();
+      assert.ok(date - date1 < interval);
+    })
+    .get(url + '/get')
+    .then(function () {
+      var date = +Date.now();
+      assert.ok(date - date1 < interval);
+    })
+    .get(url + '/get')
+    .then(function () {
+      var date = date2 = +Date.now();
+      assert.ok(date - date1 >= interval);
+    })
+    .throttle() // relax
+    .get(url + '/get')
+    .then(function () {
+      var date = +Date.now();
+      assert.ok(date - date2 < interval);
+    })
+    .get(url + '/get')
+    .then(function () {
+      var date = +Date.now();
+      assert.ok(date - date2 < interval);
+    })
+    .get(url + '/get')
+    .then(function () {
+      var date = +Date.now();
+      assert.ok(date - date2 < interval);
+    })
+    .done(function () {
+      assert.done();
+    });
+};
+
 module.exports.off = function (assert) {
     var date0 = +Date.now(), interval = 2000;
     osmosis.get(url + '/get')