samueleresca

//Search given some nodes, and a SearchOptions instance, returns the optimal strategy and quorum system in respect of the optimization target and constraints.
func Search(nodes []Expr, option SearchOptions) (SearchResult, error) {
	return performQuorumSearch(nodes, initializeSearchOptions(option))
}

func performQuorumSearch(nodes []Expr, opts ...func(options *SearchOptions) error) (SearchResult, error) {
	sb := &SearchOptions{}

	// ... (write initializations with default values)...
	for _, op := range opts {

samueleresca

// Strategy defines a strategy related to a QuorumSystem.
type Strategy struct {
	Qs                     QuorumSystem
	SigmaR                 Sigma
	SigmaW                 Sigma
	nodeToReadProbability  map[Node]Probability
	nodeToWriteProbability map[Node]Probability
}

// Sigma defines the probabilities of a specific Strategy. Each Expr (quorum) has a probability of being choose associated.

samueleresca

func (qs QuorumSystem) loadOptimalStrategy(
	optimize OptimizeType,
	readQuorums []ExprSet,
	writeQuorums []ExprSet,
	readFraction DistributionValues,
	loadLimit *float64,
	networkLimit *float64,
	latencyLimit *float64) (*Strategy, error) {
  
  ...

samueleresca

func (qs QuorumSystem) loadOptimalStrategy(
	optimize OptimizeType,
	readQuorums []ExprSet,
	writeQuorums []ExprSet,
	readFraction DistributionValues,
	loadLimit *float64,
	networkLimit *float64,
	latencyLimit *float64) (*Strategy, error) {

  ...

samueleresca

func (qs QuorumSystem) loadOptimalStrategy(
	optimize OptimizeType,
	readQuorums []ExprSet,
	writeQuorums []ExprSet,
	readFraction DistributionValues,
	loadLimit *float64,
	networkLimit *float64,
	latencyLimit *float64) (*Strategy, error) {
	
...

samueleresca

func (qs QuorumSystem) loadOptimalStrategy(
	optimize OptimizeType,
	readQuorums []ExprSet,
	writeQuorums []ExprSet,
	readFraction DistributionValues,
	loadLimit *float64,
	networkLimit *float64,
	latencyLimit *float64) (*Strategy, error) {
 ...
 

samueleresca

problemDefinition := lpDefinition {
	Vars: []float64 {1.0, 1.0, 1.0}, // dice A , dice B, dice C
	Constraints: [][2]float64{
		{1, 6}, // Index 0: dice A
		{1, 6}, // Index 1: dice B
		{1, 6}, // Index 2: dice C
	},
	Objectives: [][]float64{
		// LB   A    B    C    UB
		{1.0, 1.0, -1.0, 0.0, math.Inf(1)},  // 1 ≤ a - b ≤ ∞ | Dice A cannot be equal to dice B

samueleresca

// lpDefinition defines a linear programming expression with its own Vars, Constraints, Objectives.
type lpDefinition struct {
	Vars        []float64
	Constraints [][2]float64
	Objectives  [][]float64
}

samueleresca

// NewQuorumSystemWithReads defines a new quorum system given a read Expr, the write Expr is derived using DualOperator.Dual operation.
func NewQuorumSystemWithReads(reads Expr) QuorumSystem {
	qs, _ := NewQuorumSystem(reads, reads.Dual())

	qs.nameToNode = nameToNode{}

	for node := range qs.GetNodes() {
		qs.nameToNode[node.Name] = node
	}

samueleresca

// OptimizeType describes an optimization type
type OptimizeType string

const (
	Load    OptimizeType = "Load"
	Network OptimizeType = "Network"
	Latency OptimizeType = "Latency"
)

// StrategyOptions describes the quorum system strategy options.