diff --git a/vendor/github.com/hashicorp/serf/coordinate/coordinate.go b/vendor/github.com/hashicorp/serf/coordinate/coordinate.go
new file mode 100644
index 0000000..fbe792c
--- /dev/null
+++ b/vendor/github.com/hashicorp/serf/coordinate/coordinate.go
@@ -0,0 +1,203 @@
+package coordinate
+
+import (
+	"math"
+	"math/rand"
+	"time"
+)
+
+// Coordinate is a specialized structure for holding network coordinates for the
+// Vivaldi-based coordinate mapping algorithm. All of the fields should be public
+// to enable this to be serialized. All values in here are in units of seconds.
+type Coordinate struct {
+	// Vec is the Euclidean portion of the coordinate. This is used along
+	// with the other fields to provide an overall distance estimate. The
+	// units here are seconds.
+	Vec []float64
+
+	// Err reflects the confidence in the given coordinate and is updated
+	// dynamically by the Vivaldi Client. This is dimensionless.
+	Error float64
+
+	// Adjustment is a distance offset computed based on a calculation over
+	// observations from all other nodes over a fixed window and is updated
+	// dynamically by the Vivaldi Client. The units here are seconds.
+	Adjustment float64
+
+	// Height is a distance offset that accounts for non-Euclidean effects
+	// which model the access links from nodes to the core Internet. The access
+	// links are usually set by bandwidth and congestion, and the core links
+	// usually follow distance based on geography.
+	Height float64
+}
+
+const (
+	// secondsToNanoseconds is used to convert float seconds to nanoseconds.
+	secondsToNanoseconds = 1.0e9
+
+	// zeroThreshold is used to decide if two coordinates are on top of each
+	// other.
+	zeroThreshold = 1.0e-6
+)
+
+// ErrDimensionalityConflict will be panic-d if you try to perform operations
+// with incompatible dimensions.
+type DimensionalityConflictError struct{}
+
+// Adds the error interface.
+func (e DimensionalityConflictError) Error() string {
+	return "coordinate dimensionality does not match"
+}
+
+// NewCoordinate creates a new coordinate at the origin, using the given config
+// to supply key initial values.
+func NewCoordinate(config *Config) *Coordinate {
+	return &Coordinate{
+		Vec:        make([]float64, config.Dimensionality),
+		Error:      config.VivaldiErrorMax,
+		Adjustment: 0.0,
+		Height:     config.HeightMin,
+	}
+}
+
+// Clone creates an independent copy of this coordinate.
+func (c *Coordinate) Clone() *Coordinate {
+	vec := make([]float64, len(c.Vec))
+	copy(vec, c.Vec)
+	return &Coordinate{
+		Vec:        vec,
+		Error:      c.Error,
+		Adjustment: c.Adjustment,
+		Height:     c.Height,
+	}
+}
+
+// componentIsValid returns false if a floating point value is a NaN or an
+// infinity.
+func componentIsValid(f float64) bool {
+	return !math.IsInf(f, 0) && !math.IsNaN(f)
+}
+
+// IsValid returns false if any component of a coordinate isn't valid, per the
+// componentIsValid() helper above.
+func (c *Coordinate) IsValid() bool {
+	for i := range c.Vec {
+		if !componentIsValid(c.Vec[i]) {
+			return false
+		}
+	}
+
+	return componentIsValid(c.Error) &&
+		componentIsValid(c.Adjustment) &&
+		componentIsValid(c.Height)
+}
+
+// IsCompatibleWith checks to see if the two coordinates are compatible
+// dimensionally. If this returns true then you are guaranteed to not get
+// any runtime errors operating on them.
+func (c *Coordinate) IsCompatibleWith(other *Coordinate) bool {
+	return len(c.Vec) == len(other.Vec)
+}
+
+// ApplyForce returns the result of applying the force from the direction of the
+// other coordinate.
+func (c *Coordinate) ApplyForce(config *Config, force float64, other *Coordinate) *Coordinate {
+	if !c.IsCompatibleWith(other) {
+		panic(DimensionalityConflictError{})
+	}
+
+	ret := c.Clone()
+	unit, mag := unitVectorAt(c.Vec, other.Vec)
+	ret.Vec = add(ret.Vec, mul(unit, force))
+	if mag > zeroThreshold {
+		ret.Height = (ret.Height+other.Height)*force/mag + ret.Height
+		ret.Height = math.Max(ret.Height, config.HeightMin)
+	}
+	return ret
+}
+
+// DistanceTo returns the distance between this coordinate and the other
+// coordinate, including adjustments.
+func (c *Coordinate) DistanceTo(other *Coordinate) time.Duration {
+	if !c.IsCompatibleWith(other) {
+		panic(DimensionalityConflictError{})
+	}
+
+	dist := c.rawDistanceTo(other)
+	adjustedDist := dist + c.Adjustment + other.Adjustment
+	if adjustedDist > 0.0 {
+		dist = adjustedDist
+	}
+	return time.Duration(dist * secondsToNanoseconds)
+}
+
+// rawDistanceTo returns the Vivaldi distance between this coordinate and the
+// other coordinate in seconds, not including adjustments. This assumes the
+// dimensions have already been checked to be compatible.
+func (c *Coordinate) rawDistanceTo(other *Coordinate) float64 {
+	return magnitude(diff(c.Vec, other.Vec)) + c.Height + other.Height
+}
+
+// add returns the sum of vec1 and vec2. This assumes the dimensions have
+// already been checked to be compatible.
+func add(vec1 []float64, vec2 []float64) []float64 {
+	ret := make([]float64, len(vec1))
+	for i := range ret {
+		ret[i] = vec1[i] + vec2[i]
+	}
+	return ret
+}
+
+// diff returns the difference between the vec1 and vec2. This assumes the
+// dimensions have already been checked to be compatible.
+func diff(vec1 []float64, vec2 []float64) []float64 {
+	ret := make([]float64, len(vec1))
+	for i := range ret {
+		ret[i] = vec1[i] - vec2[i]
+	}
+	return ret
+}
+
+// mul returns vec multiplied by a scalar factor.
+func mul(vec []float64, factor float64) []float64 {
+	ret := make([]float64, len(vec))
+	for i := range vec {
+		ret[i] = vec[i] * factor
+	}
+	return ret
+}
+
+// magnitude computes the magnitude of the vec.
+func magnitude(vec []float64) float64 {
+	sum := 0.0
+	for i := range vec {
+		sum += vec[i] * vec[i]
+	}
+	return math.Sqrt(sum)
+}
+
+// unitVectorAt returns a unit vector pointing at vec1 from vec2. If the two
+// positions are the same then a random unit vector is returned. We also return
+// the distance between the points for use in the later height calculation.
+func unitVectorAt(vec1 []float64, vec2 []float64) ([]float64, float64) {
+	ret := diff(vec1, vec2)
+
+	// If the coordinates aren't on top of each other we can normalize.
+	if mag := magnitude(ret); mag > zeroThreshold {
+		return mul(ret, 1.0/mag), mag
+	}
+
+	// Otherwise, just return a random unit vector.
+	for i := range ret {
+		ret[i] = rand.Float64() - 0.5
+	}
+	if mag := magnitude(ret); mag > zeroThreshold {
+		return mul(ret, 1.0/mag), 0.0
+	}
+
+	// And finally just give up and make a unit vector along the first
+	// dimension. This should be exceedingly rare.
+	ret = make([]float64, len(ret))
+	ret[0] = 1.0
+	return ret, 0.0
+}