413 lines
12 KiB
Go
413 lines
12 KiB
Go
package consul
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import (
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"fmt"
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"math"
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"sort"
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"github.com/hashicorp/consul/consul/structs"
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"github.com/hashicorp/serf/coordinate"
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)
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// computeDistance returns the distance between the two network coordinates in
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// seconds. If either of the coordinates is nil then this will return positive
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// infinity.
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func computeDistance(a *coordinate.Coordinate, b *coordinate.Coordinate) float64 {
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if a == nil || b == nil {
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return math.Inf(1.0)
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}
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return a.DistanceTo(b).Seconds()
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}
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// nodeSorter takes a list of nodes and a parallel vector of distances and
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// implements sort.Interface, keeping both structures coherent and sorting by
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// distance.
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type nodeSorter struct {
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Nodes structs.Nodes
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Vec []float64
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}
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// newNodeSorter returns a new sorter for the given source coordinate and set of
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// nodes.
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func (s *Server) newNodeSorter(c *coordinate.Coordinate, nodes structs.Nodes) (sort.Interface, error) {
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state := s.fsm.State()
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vec := make([]float64, len(nodes))
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for i, node := range nodes {
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coord, err := state.CoordinateGetRaw(node.Node)
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if err != nil {
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return nil, err
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}
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vec[i] = computeDistance(c, coord)
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}
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return &nodeSorter{nodes, vec}, nil
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}
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// See sort.Interface.
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func (n *nodeSorter) Len() int {
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return len(n.Nodes)
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}
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// See sort.Interface.
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func (n *nodeSorter) Swap(i, j int) {
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n.Nodes[i], n.Nodes[j] = n.Nodes[j], n.Nodes[i]
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n.Vec[i], n.Vec[j] = n.Vec[j], n.Vec[i]
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}
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// See sort.Interface.
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func (n *nodeSorter) Less(i, j int) bool {
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return n.Vec[i] < n.Vec[j]
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}
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// serviceNodeSorter takes a list of service nodes and a parallel vector of
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// distances and implements sort.Interface, keeping both structures coherent and
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// sorting by distance.
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type serviceNodeSorter struct {
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Nodes structs.ServiceNodes
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Vec []float64
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}
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// newServiceNodeSorter returns a new sorter for the given source coordinate and
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// set of service nodes.
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func (s *Server) newServiceNodeSorter(c *coordinate.Coordinate, nodes structs.ServiceNodes) (sort.Interface, error) {
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state := s.fsm.State()
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vec := make([]float64, len(nodes))
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for i, node := range nodes {
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coord, err := state.CoordinateGetRaw(node.Node)
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if err != nil {
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return nil, err
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}
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vec[i] = computeDistance(c, coord)
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}
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return &serviceNodeSorter{nodes, vec}, nil
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}
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// See sort.Interface.
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func (n *serviceNodeSorter) Len() int {
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return len(n.Nodes)
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}
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// See sort.Interface.
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func (n *serviceNodeSorter) Swap(i, j int) {
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n.Nodes[i], n.Nodes[j] = n.Nodes[j], n.Nodes[i]
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n.Vec[i], n.Vec[j] = n.Vec[j], n.Vec[i]
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}
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// See sort.Interface.
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func (n *serviceNodeSorter) Less(i, j int) bool {
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return n.Vec[i] < n.Vec[j]
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}
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// serviceNodeSorter takes a list of health checks and a parallel vector of
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// distances and implements sort.Interface, keeping both structures coherent and
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// sorting by distance.
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type healthCheckSorter struct {
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Checks structs.HealthChecks
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Vec []float64
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}
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// newHealthCheckSorter returns a new sorter for the given source coordinate and
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// set of health checks with nodes.
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func (s *Server) newHealthCheckSorter(c *coordinate.Coordinate, checks structs.HealthChecks) (sort.Interface, error) {
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state := s.fsm.State()
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vec := make([]float64, len(checks))
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for i, check := range checks {
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coord, err := state.CoordinateGetRaw(check.Node)
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if err != nil {
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return nil, err
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}
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vec[i] = computeDistance(c, coord)
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}
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return &healthCheckSorter{checks, vec}, nil
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}
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// See sort.Interface.
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func (n *healthCheckSorter) Len() int {
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return len(n.Checks)
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}
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// See sort.Interface.
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func (n *healthCheckSorter) Swap(i, j int) {
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n.Checks[i], n.Checks[j] = n.Checks[j], n.Checks[i]
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n.Vec[i], n.Vec[j] = n.Vec[j], n.Vec[i]
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}
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// See sort.Interface.
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func (n *healthCheckSorter) Less(i, j int) bool {
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return n.Vec[i] < n.Vec[j]
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}
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// checkServiceNodeSorter takes a list of service nodes and a parallel vector of
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// distances and implements sort.Interface, keeping both structures coherent and
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// sorting by distance.
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type checkServiceNodeSorter struct {
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Nodes structs.CheckServiceNodes
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Vec []float64
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}
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// newCheckServiceNodeSorter returns a new sorter for the given source coordinate
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// and set of nodes with health checks.
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func (s *Server) newCheckServiceNodeSorter(c *coordinate.Coordinate, nodes structs.CheckServiceNodes) (sort.Interface, error) {
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state := s.fsm.State()
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vec := make([]float64, len(nodes))
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for i, node := range nodes {
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coord, err := state.CoordinateGetRaw(node.Node.Node)
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if err != nil {
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return nil, err
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}
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vec[i] = computeDistance(c, coord)
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}
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return &checkServiceNodeSorter{nodes, vec}, nil
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}
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// See sort.Interface.
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func (n *checkServiceNodeSorter) Len() int {
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return len(n.Nodes)
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}
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// See sort.Interface.
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func (n *checkServiceNodeSorter) Swap(i, j int) {
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n.Nodes[i], n.Nodes[j] = n.Nodes[j], n.Nodes[i]
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n.Vec[i], n.Vec[j] = n.Vec[j], n.Vec[i]
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}
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// See sort.Interface.
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func (n *checkServiceNodeSorter) Less(i, j int) bool {
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return n.Vec[i] < n.Vec[j]
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}
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// newSorterByDistanceFrom returns a sorter for the given type.
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func (s *Server) newSorterByDistanceFrom(c *coordinate.Coordinate, subj interface{}) (sort.Interface, error) {
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switch v := subj.(type) {
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case structs.Nodes:
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return s.newNodeSorter(c, v)
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case structs.ServiceNodes:
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return s.newServiceNodeSorter(c, v)
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case structs.HealthChecks:
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return s.newHealthCheckSorter(c, v)
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case structs.CheckServiceNodes:
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return s.newCheckServiceNodeSorter(c, v)
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default:
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panic(fmt.Errorf("Unhandled type passed to newSorterByDistanceFrom: %#v", subj))
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}
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}
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// sortNodesByDistanceFrom is used to sort results from our service catalog based
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// on the round trip time from the given source node. Nodes with missing coordinates
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// will get stable sorted at the end of the list.
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//
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// If coordinates are disabled this will be a no-op.
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func (s *Server) sortNodesByDistanceFrom(source structs.QuerySource, subj interface{}) error {
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// Make it safe to call this without having to check if coordinates are
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// disabled first.
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if s.config.DisableCoordinates {
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return nil
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}
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// We can't sort if there's no source node.
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if source.Node == "" {
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return nil
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}
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// We can't compare coordinates across DCs.
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if source.Datacenter != s.config.Datacenter {
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return nil
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}
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// There won't always be a coordinate for the source node. If there's not
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// one then we can bail out because there's no meaning for the sort.
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state := s.fsm.State()
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coord, err := state.CoordinateGetRaw(source.Node)
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if err != nil {
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return err
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}
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if coord == nil {
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return nil
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}
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// Do the sort!
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sorter, err := s.newSorterByDistanceFrom(coord, subj)
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if err != nil {
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return err
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}
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sort.Stable(sorter)
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return nil
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}
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// serfer provides the coordinate information we need from the Server in an
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// interface that's easy to mock out for testing. Without this, we'd have to
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// do some really painful setup to get good unit test coverage of all the cases.
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type serfer interface {
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GetDatacenter() string
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GetCoordinate() (*coordinate.Coordinate, error)
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GetCachedCoordinate(node string) (*coordinate.Coordinate, bool)
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GetNodesForDatacenter(dc string) []string
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}
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// serverSerfer wraps a Server with the serfer interface.
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type serverSerfer struct {
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server *Server
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}
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// See serfer.
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func (s *serverSerfer) GetDatacenter() string {
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return s.server.config.Datacenter
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}
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// See serfer.
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func (s *serverSerfer) GetCoordinate() (*coordinate.Coordinate, error) {
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return s.server.serfWAN.GetCoordinate()
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}
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// See serfer.
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func (s *serverSerfer) GetCachedCoordinate(node string) (*coordinate.Coordinate, bool) {
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return s.server.serfWAN.GetCachedCoordinate(node)
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}
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// See serfer.
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func (s *serverSerfer) GetNodesForDatacenter(dc string) []string {
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s.server.remoteLock.RLock()
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defer s.server.remoteLock.RUnlock()
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nodes := make([]string, 0)
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for _, part := range s.server.remoteConsuls[dc] {
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nodes = append(nodes, part.Name)
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}
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return nodes
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}
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// getDatacenterDistance will return the median round trip time estimate for
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// the given DC from the given serfer, in seconds. This will return positive
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// infinity if no coordinates are available.
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func getDatacenterDistance(s serfer, dc string) (float64, error) {
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// If this is the serfer's DC then just bail with zero RTT.
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if dc == s.GetDatacenter() {
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return 0.0, nil
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}
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// Otherwise measure from the serfer to the nodes in the other DC.
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coord, err := s.GetCoordinate()
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if err != nil {
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return 0.0, err
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}
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// Fetch all the nodes in the DC and record their distance, if available.
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nodes := s.GetNodesForDatacenter(dc)
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subvec := make([]float64, 0, len(nodes))
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for _, node := range nodes {
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if other, ok := s.GetCachedCoordinate(node); ok {
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subvec = append(subvec, computeDistance(coord, other))
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}
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}
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// Compute the median by sorting and taking the middle item.
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if len(subvec) > 0 {
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sort.Float64s(subvec)
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return subvec[len(subvec)/2], nil
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}
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// Return the default infinity value.
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return computeDistance(coord, nil), nil
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}
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// datacenterSorter takes a list of DC names and a parallel vector of distances
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// and implements sort.Interface, keeping both structures coherent and sorting
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// by distance.
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type datacenterSorter struct {
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Names []string
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Vec []float64
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}
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// See sort.Interface.
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func (n *datacenterSorter) Len() int {
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return len(n.Names)
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}
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// See sort.Interface.
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func (n *datacenterSorter) Swap(i, j int) {
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n.Names[i], n.Names[j] = n.Names[j], n.Names[i]
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n.Vec[i], n.Vec[j] = n.Vec[j], n.Vec[i]
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}
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// See sort.Interface.
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func (n *datacenterSorter) Less(i, j int) bool {
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return n.Vec[i] < n.Vec[j]
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}
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// sortDatacentersByDistance will sort the given list of DCs based on the
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// median RTT to all nodes the given serfer knows about from the WAN gossip
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// pool). DCs with missing coordinates will be stable sorted to the end of the
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// list.
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func sortDatacentersByDistance(s serfer, dcs []string) error {
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// Build up a list of median distances to the other DCs.
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vec := make([]float64, len(dcs))
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for i, dc := range dcs {
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rtt, err := getDatacenterDistance(s, dc)
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if err != nil {
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return err
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}
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vec[i] = rtt
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}
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sorter := &datacenterSorter{dcs, vec}
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sort.Stable(sorter)
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return nil
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}
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// getDatacenterMaps returns the raw coordinates of all the nodes in the
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// given list of DCs (the output list will preserve the incoming order).
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func (s *Server) getDatacenterMaps(dcs []string) []structs.DatacenterMap {
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serfer := serverSerfer{s}
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return getDatacenterMaps(&serfer, dcs)
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}
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// getDatacenterMaps returns the raw coordinates of all the nodes in the
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// given list of DCs (the output list will preserve the incoming order).
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func getDatacenterMaps(s serfer, dcs []string) []structs.DatacenterMap {
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maps := make([]structs.DatacenterMap, 0, len(dcs))
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for _, dc := range dcs {
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m := structs.DatacenterMap{Datacenter: dc}
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nodes := s.GetNodesForDatacenter(dc)
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for _, node := range nodes {
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if coord, ok := s.GetCachedCoordinate(node); ok {
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entry := &structs.Coordinate{Node: node, Coord: coord}
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m.Coordinates = append(m.Coordinates, entry)
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}
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}
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maps = append(maps, m)
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}
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return maps
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}
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// getDatacentersByDistance will return the list of DCs, sorted in order
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// of increasing distance based on the median distance to that DC from all
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// servers we know about in the WAN gossip pool. This will sort by name all
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// other things being equal (or if coordinates are disabled).
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func (s *Server) getDatacentersByDistance() ([]string, error) {
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s.remoteLock.RLock()
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defer s.remoteLock.RUnlock()
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var dcs []string
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for dc := range s.remoteConsuls {
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dcs = append(dcs, dc)
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}
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// Sort by name first, since the coordinate sort is stable.
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sort.Strings(dcs)
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// Make it safe to call this without having to check if coordinates are
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// disabled first.
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if s.config.DisableCoordinates {
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return dcs, nil
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}
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// Do the sort!
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serfer := serverSerfer{s}
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if err := sortDatacentersByDistance(&serfer, dcs); err != nil {
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return nil, err
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}
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return dcs, nil
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}
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