Simulator first commit

node_modules/limiter/lib/clock.js

@@ -0,0 +1,13 @@
+var getMilliseconds = function() {
+  if (typeof process !== 'undefined' && process.hrtime) {
+    var hrtime = process.hrtime();
+    var seconds = hrtime[0];
+    var nanoseconds = hrtime[1];
+
+    return seconds * 1e3 +  Math.floor(nanoseconds / 1e6);
+  }
+
+  return new Date().getTime();
+}
+
+module.exports = getMilliseconds;

node_modules/limiter/lib/rateLimiter.js

@@ -0,0 +1,137 @@
+var TokenBucket = require('./tokenBucket');
+var getMilliseconds = require('./clock');
+
+/**
+ * A generic rate limiter. Underneath the hood, this uses a token bucket plus
+ * an additional check to limit how many tokens we can remove each interval.
+ * @author John Hurliman <jhurliman@jhurliman.org>
+ *
+ * @param {Number} tokensPerInterval Maximum number of tokens that can be
+ *  removed at any given moment and over the course of one interval.
+ * @param {String|Number} interval The interval length in milliseconds, or as
+ *  one of the following strings: 'second', 'minute', 'hour', day'.
+ * @param {Boolean} fireImmediately Optional. Whether or not the callback
+ *  will fire immediately when rate limiting is in effect (default is false).
+ */
+var RateLimiter = function(tokensPerInterval, interval, fireImmediately) {
+  this.tokenBucket = new TokenBucket(tokensPerInterval, tokensPerInterval,
+    interval, null);
+
+  // Fill the token bucket to start
+  this.tokenBucket.content = tokensPerInterval;
+
+  this.curIntervalStart = getMilliseconds();
+  this.tokensThisInterval = 0;
+  this.fireImmediately = fireImmediately;
+};
+
+RateLimiter.prototype = {
+  tokenBucket: null,
+  curIntervalStart: 0,
+  tokensThisInterval: 0,
+  fireImmediately: false,
+
+  /**
+   * Remove the requested number of tokens and fire the given callback. If the
+   * rate limiter contains enough tokens and we haven't spent too many tokens
+   * in this interval already, this will happen immediately. Otherwise, the
+   * removal and callback will happen when enough tokens become available.
+   * @param {Number} count The number of tokens to remove.
+   * @param {Function} callback(err, remainingTokens)
+   * @returns {Boolean} True if the callback was fired immediately, otherwise
+   *  false.
+   */
+  removeTokens: function(count, callback) {
+    // Make sure the request isn't for more than we can handle
+    if (count > this.tokenBucket.bucketSize) {
+      process.nextTick(callback.bind(null, 'Requested tokens ' + count +
+        ' exceeds maximum tokens per interval ' + this.tokenBucket.bucketSize,
+        null));
+      return false;
+    }
+
+    var self = this;
+    var now = getMilliseconds();
+
+    // Advance the current interval and reset the current interval token count
+    // if needed
+    if (now < this.curIntervalStart
+      || now - this.curIntervalStart >= this.tokenBucket.interval) {
+      this.curIntervalStart = now;
+      this.tokensThisInterval = 0;
+    }
+
+    // If we don't have enough tokens left in this interval, wait until the
+    // next interval
+    if (count > this.tokenBucket.tokensPerInterval - this.tokensThisInterval) {
+      if (this.fireImmediately) {
+        process.nextTick(callback.bind(null, null, -1));
+      } else {
+        var waitInterval = Math.ceil(
+          this.curIntervalStart + this.tokenBucket.interval - now);
+
+        setTimeout(function() {
+          self.tokenBucket.removeTokens(count, afterTokensRemoved);
+        }, waitInterval);
+      }
+      return false;
+    }
+
+    // Remove the requested number of tokens from the token bucket
+    return this.tokenBucket.removeTokens(count, afterTokensRemoved);
+
+    function afterTokensRemoved(err, tokensRemaining) {
+      if (err) return callback(err, null);
+
+      self.tokensThisInterval += count;
+      callback(null, tokensRemaining);
+    }
+  },
+
+  /**
+   * Attempt to remove the requested number of tokens and return immediately.
+   * If the bucket (and any parent buckets) contains enough tokens and we
+   * haven't spent too many tokens in this interval already, this will return
+   * true. Otherwise, false is returned.
+   * @param {Number} count The number of tokens to remove.
+   * @param {Boolean} True if the tokens were successfully removed, otherwise
+   *  false.
+   */
+  tryRemoveTokens: function(count) {
+    // Make sure the request isn't for more than we can handle
+    if (count > this.tokenBucket.bucketSize)
+      return false;
+
+    var now = getMilliseconds();
+
+    // Advance the current interval and reset the current interval token count
+    // if needed
+    if (now < this.curIntervalStart
+      || now - this.curIntervalStart >= this.tokenBucket.interval) {
+      this.curIntervalStart = now;
+      this.tokensThisInterval = 0;
+    }
+
+    // If we don't have enough tokens left in this interval, return false
+    if (count > this.tokenBucket.tokensPerInterval - this.tokensThisInterval)
+      return false;
+
+    // Try to remove the requested number of tokens from the token bucket
+    var removed = this.tokenBucket.tryRemoveTokens(count);
+    if (removed) {
+      this.tokensThisInterval += count;
+    }
+    return removed;
+  },
+
+  /**
+   * Returns the number of tokens remaining in the TokenBucket.
+   * @returns {Number} The number of tokens remaining.
+   */
+  getTokensRemaining: function () {
+    this.tokenBucket.drip();
+    return this.tokenBucket.content;
+  }
+};
+
+module.exports = RateLimiter;

node_modules/limiter/lib/tokenBucket.js

@@ -0,0 +1,167 @@
+
+/**
+ * A hierarchical token bucket for rate limiting. See
+ * http://en.wikipedia.org/wiki/Token_bucket for more information.
+ * @author John Hurliman <jhurliman@cull.tv>
+ *
+ * @param {Number} bucketSize Maximum number of tokens to hold in the bucket.
+ *  Also known as the burst rate.
+ * @param {Number} tokensPerInterval Number of tokens to drip into the bucket
+ *  over the course of one interval.
+ * @param {String|Number} interval The interval length in milliseconds, or as
+ *  one of the following strings: 'second', 'minute', 'hour', day'.
+ * @param {TokenBucket} parentBucket Optional. A token bucket that will act as
+ *  the parent of this bucket.
+ */
+var TokenBucket = function(bucketSize, tokensPerInterval, interval, parentBucket) {
+  this.bucketSize = bucketSize;
+  this.tokensPerInterval = tokensPerInterval;
+
+  if (typeof interval === 'string') {
+    switch (interval) {
+      case 'sec': case 'second':
+        this.interval = 1000; break;
+      case 'min': case 'minute':
+        this.interval = 1000 * 60; break;
+      case 'hr': case 'hour':
+        this.interval = 1000 * 60 * 60; break;
+      case 'day':
+        this.interval = 1000 * 60 * 60 * 24; break;
+      default:
+        throw new Error('Invaid interval ' + interval);
+    }
+  } else {
+    this.interval = interval;
+  }
+
+  this.parentBucket = parentBucket;
+  this.content = 0;
+  this.lastDrip = +new Date();
+};
+
+TokenBucket.prototype = {
+  bucketSize: 1,
+  tokensPerInterval: 1,
+  interval: 1000,
+  parentBucket: null,
+  content: 0,
+  lastDrip: 0,
+
+  /**
+   * Remove the requested number of tokens and fire the given callback. If the
+   * bucket (and any parent buckets) contains enough tokens this will happen
+   * immediately. Otherwise, the removal and callback will happen when enough
+   * tokens become available.
+   * @param {Number} count The number of tokens to remove.
+   * @param {Function} callback(err, remainingTokens)
+   * @returns {Boolean} True if the callback was fired immediately, otherwise
+   *  false.
+   */
+  removeTokens: function(count, callback) {
+    var self = this;
+
+    // Is this an infinite size bucket?
+    if (!this.bucketSize) {
+      process.nextTick(callback.bind(null, null, count, Number.POSITIVE_INFINITY));
+      return true;
+    }
+
+    // Make sure the bucket can hold the requested number of tokens
+    if (count > this.bucketSize) {
+      process.nextTick(callback.bind(null, 'Requested tokens ' + count + ' exceeds bucket size ' +
+        this.bucketSize, null));
+      return false;
+    }
+
+    // Drip new tokens into this bucket
+    this.drip();
+
+    // If we don't have enough tokens in this bucket, come back later
+    if (count > this.content)
+      return comeBackLater();
+
+    if (this.parentBucket) {
+      // Remove the requested from the parent bucket first
+      return this.parentBucket.removeTokens(count, function(err, remainingTokens) {
+        if (err) return callback(err, null);
+
+        // Check that we still have enough tokens in this bucket
+        if (count > self.content)
+          return comeBackLater();
+
+        // Tokens were removed from the parent bucket, now remove them from
+        // this bucket and fire the callback. Note that we look at the current
+        // bucket and parent bucket's remaining tokens and return the smaller
+        // of the two values
+        self.content -= count;
+        callback(null, Math.min(remainingTokens, self.content));
+      });
+    } else {
+      // Remove the requested tokens from this bucket and fire the callback
+      this.content -= count;
+      process.nextTick(callback.bind(null, null, this.content));
+      return true;
+    }
+
+    function comeBackLater() {
+      // How long do we need to wait to make up the difference in tokens?
+      var waitInterval = Math.ceil(
+        (count - self.content) * (self.interval / self.tokensPerInterval));
+      setTimeout(function() { self.removeTokens(count, callback); }, waitInterval);
+      return false;
+    }
+  },
+
+  /**
+   * Attempt to remove the requested number of tokens and return immediately.
+   * If the bucket (and any parent buckets) contains enough tokens this will
+   * return true, otherwise false is returned.
+   * @param {Number} count The number of tokens to remove.
+   * @param {Boolean} True if the tokens were successfully removed, otherwise
+   *  false.
+   */
+  tryRemoveTokens: function(count) {
+    // Is this an infinite size bucket?
+    if (!this.bucketSize)
+      return true;
+
+    // Make sure the bucket can hold the requested number of tokens
+    if (count > this.bucketSize)
+      return false;
+
+    // Drip new tokens into this bucket
+    this.drip();
+
+    // If we don't have enough tokens in this bucket, return false
+    if (count > this.content)
+      return false;
+
+    // Try to remove the requested tokens from the parent bucket
+    if (this.parentBucket && !this.parentBucket.tryRemoveTokens(count))
+      return false;
+
+    // Remove the requested tokens from this bucket and return
+    this.content -= count;
+    return true;
+  },
+
+  /**
+   * Add any new tokens to the bucket since the last drip.
+   * @returns {Boolean} True if new tokens were added, otherwise false.
+   */
+  drip: function() {
+    if (!this.tokensPerInterval) {
+      this.content = this.bucketSize;
+      return;
+    }
+
+    var now = +new Date();
+    var deltaMS = Math.max(now - this.lastDrip, 0);
+    this.lastDrip = now;
+
+    var dripAmount = deltaMS * (this.tokensPerInterval / this.interval);
+    this.content = Math.min(this.content + dripAmount, this.bucketSize);
+  }
+};
+
+module.exports = TokenBucket;