cueball - npm Package Compare versions

Comparing version 1.1.5 to 1.1.6

lib/pool.js

		@@ -34,2 +34,67 @@ /*
		/*
		* Parameters for the EMA/low-pass filter that is used to limit pool shrinkage
		* under sustained load. The idea is to stop the pool from shrinking too
		* rapidly if the average load has been high recently. This stops us from
		* over-reacting to small transients in load and generally stablizes behavior.
		*/
		/* Sample rate of the filter, in Hz. */
		var LP_RATE = 5;
		/* One sampling interval. */
		var LP_INT = Math.round(1000 / LP_RATE);
		/* The filter taps array. See below for parameters' meaning. */
		var LP_TAPS = genTaps(128, -0.2);

		/*
		* Generates a set of EMA taps: count is the number of taps to generate, and
		* tc is the value of the time constant of decay. This should be negative
		* and fractional. The closer it gets to 0.0 (while remaining negative), the
		* lower its low-pass cutoff frequency will be and the sharper the filter
		* roll-off becomes.
		*
		* A tc of -0.2 at 5Hz creates an EMA filter with a pass band extending out
		* to about 0.25Hz (4-second period), -10dB point at 0.5Hz, -20dB point at
		* 2.5Hz. This means that the filter reacts most strongly to trends with
		* principal components of around 4 seconds period or more -- any faster
		* trends will be gradually suppressed, and for trends of 400ms or less, down
		* to about 1% of their original magnitude.
		*/
		function genTaps(count, tc) {
		var taps = new Float64Array(count);
		var sum = 0.0;
		for (var i = 0; i < count; ++i) {
		taps[i] = Math.exp(tc * i);
		sum += taps[i];
		}
		for (i = 0; i < count; ++i) {
		taps[i] /= sum;
		}
		return (taps);
		}

		/* A simple FIR filter with a circular buffer. */
		function FIRFilter(taps) {
		this.f_taps = taps;
		this.f_buf = new Float64Array(taps.length);
		this.f_ptr = 0;
		}
		FIRFilter.prototype.put = function (v) {
		this.f_buf[this.f_ptr++] = v;
		/* Wrap around to zero if we go off the end. */
		if (this.f_ptr === this.f_taps.length)
		this.f_ptr = 0;
		};
		FIRFilter.prototype.get = function () {
		var i = this.f_ptr - 1;
		if (i < 0)
		i += this.f_taps.length;
		var acc = 0.0;
		for (var j = 0; j < this.f_taps.length; ++j) {
		acc += this.f_buf[i] * this.f_taps[j];
		if (--i < 0)
		i += this.f_taps.length;
		}
		return (acc);
		};

		/*
		* A ConnectionPool holds a pool of ConnectionFSMs that are kept up to date
		@@ -108,2 +173,3 @@ * based on the output of a Resolver. At any given time the pool may contain:
		this.p_startedResolver = false;
		this.p_lpf = new FIRFilter(LP_TAPS);

		@@ -150,2 +216,18 @@ this.p_idleq = new Queue();

		this.p_lastRebalClamped = false;

		this.p_lpTimer = setInterval(function () {
		var conns = 0;
		Object.keys(self.p_connections).forEach(function (k) {
		conns += self.p_connections[k].length;
		});
		var spares = self.p_idleq.length + self.p_initq.length;
		var busy = conns - spares;
		self.p_lpf.put(busy + self.p_spares);

		if (self.p_lastRebalClamped)
		self.rebalance();
		}, LP_INT);
		this.p_lpTimer.unref();

		FSM.call(this, 'starting');
		@@ -350,2 +432,3 @@ }
		clearInterval(this.p_shuffleTimerInst);
		clearInterval(this.p_lpTimer);
		};
		@@ -427,2 +510,11 @@
		var target = busy + extras + this.p_spares;

		var min = Math.ceil(this.p_lpf.get());
		if (target < min * 1.05) {
		target = min;
		this.p_lastRebalClamped = true;
		} else {
		this.p_lastRebalClamped = false;
		}

		if (target > this.p_max)
		@@ -607,2 +699,4 @@ target = this.p_max;

		this._incrCounter('claim');

		if (this.isInState('stopping') \|\| this.isInState('stopped')) {
		@@ -609,0 +703,0 @@ setImmediate(function () {

package.json

		{
		"name": "cueball",
		"version": "1.1.5",
		"version": "1.1.6",
		"description": "",
		@@ -5,0 +5,0 @@ "main": "lib/index.js",

lib/connection-fsm.js.orig

lib/connection-fsm.js.rej

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