Added Entry type. Basic implementation of Router and Table

router/table.go

@@ -2,7 +2,12 @@ package router
 
 import (
 	"errors"
+	"fmt"
+	"hash/fnv"
+	"strings"
 	"sync"
+
+	"github.com/olekukonko/tablewriter"
 )
 
 var (
@@ -10,77 +15,151 @@ var (
 	ErrRouteNotFound = errors.New("route not found")
 	// ErrDuplicateRoute is return when route already exists
 	ErrDuplicateRoute = errors.New("duplicate route")
+	// ErrNotImplemented is returned when some functionality has not been implemented
+	ErrNotImplemented = errors.New("not implemented")
 )
 
 // Table is routing table
 type Table interface {
 	// Add adds new route to the table
-	Add(*Entry) error
+	Add(Entry) error
 	// Remove removes route from the table
-	Remove(*Entry) error
+	Remove(Entry) error
 	// Update updates route in the table
-	Update(*Entry) error
+	Update(...EntryOption) error
 	// Lookup looks up routes in the table
-	Lookup(Query) ([]*Entry, error)
+	Lookup(Query) ([]Entry, error)
 	// Size returns the size of the table
 	Size() int
 	// String prints the routing table
 	String() string
 }
 
-// Entry is micro network routing table entry
-type Entry struct {
-	// Addr is destination address
-	Addr string
-	// NetID is micro network ID
-	NetID string
-	// Hop is the next route hop
-	Hop Router
-	// Metric is route cost metric
-	Metric int
-}
-
 // table is routing table
 // It maps service name to routes
 type table struct {
 	// m stores routing table map
-	m map[string][]Entry
+	m map[string]map[uint64]Entry
 	sync.RWMutex
 }
 
 // NewTable creates new routing table and returns it
 func NewTable() Table {
 	return &table{
-		m: make(map[string][]Entry),
+		m: make(map[string]map[uint64]Entry),
 	}
 }
 
 // Add adds new routing entry
-func (t *table) Add(e *Entry) error {
-	return nil
+func (t *table) Add(e Entry) error {
+	t.Lock()
+	defer t.Unlock()
+
+	destAddr := e.Options().DestAddr
+	h := fnv.New64()
+	h.Write([]byte(e.Options().DestAddr + e.Options().Hop.Address()))
+
+	if _, ok := t.m[destAddr]; !ok {
+		// create new map for DestAddr routes
+		t.m[destAddr] = make(map[uint64]Entry)
+		t.m[destAddr][h.Sum64()] = e
+		return nil
+	}
+
+	if _, ok := t.m[destAddr][h.Sum64()]; ok && e.Options().Policy == OverrideIfExists {
+		t.m[destAddr][h.Sum64()] = e
+		return nil
+	}
+
+	return ErrDuplicateRoute
 }
 
 // Remove removes entry from the routing table
-func (t *table) Remove(e *Entry) error {
+func (t *table) Remove(e Entry) error {
+	t.Lock()
+	defer t.Unlock()
+
+	destAddr := e.Options().DestAddr
+	h := fnv.New64()
+	h.Write([]byte(e.Options().DestAddr + e.Options().Hop.Address()))
+
+	if _, ok := t.m[destAddr]; !ok {
+		return ErrRouteNotFound
+	} else {
+		delete(t.m[destAddr], h.Sum64())
+		return nil
+	}
+
 	return nil
 }
 
-// Update updates routin entry
-func (t *table) Update(e *Entry) error {
-	return nil
+// Update updates routing entry
+func (t *table) Update(opts ...EntryOption) error {
+	t.Lock()
+	defer t.Unlock()
+
+	e := NewEntry(opts...)
+
+	destAddr := e.Options().DestAddr
+	h := fnv.New64()
+	h.Write([]byte(e.Options().DestAddr + e.Options().Hop.Address()))
+
+	if _, ok := t.m[destAddr]; !ok {
+		return ErrRouteNotFound
+	}
+
+	if _, ok := t.m[destAddr][h.Sum64()]; ok {
+		t.m[destAddr][h.Sum64()] = e
+		return nil
+	}
+
+	return ErrRouteNotFound
 }
 
 // Lookup looks up entry in the routing table
-func (t *table) Lookup(q Query) ([]*Entry, error) {
-	return nil, nil
+func (t *table) Lookup(q Query) ([]Entry, error) {
+	return nil, ErrNotImplemented
 }
 
 // Size returns the size of the routing table
 func (t *table) Size() int {
+	t.RLock()
+	defer t.RUnlock()
+
 	return len(t.m)
 }
 
 // String returns text representation of routing table
 func (t *table) String() string {
-	return ""
+	t.RLock()
+	defer t.RUnlock()
+
+	// this will help us build routing table string
+	sb := &strings.Builder{}
+
+	// create nice table printing structure
+	table := tablewriter.NewWriter(sb)
+	table.SetHeader([]string{"Dest", "Hop", "Src", "Metric"})
+
+	var destAddr, prevAddr string
+
+	for _, entries := range t.m {
+		for _, entry := range entries {
+			destAddr = entry.Options().DestAddr
+			// we want to avoid printing the same dest address
+			if prevAddr == destAddr {
+				destAddr = ""
+			}
+			strEntry := []string{
+				destAddr,
+				entry.Options().Hop.Address(),
+				fmt.Sprintf("%d", entry.Options().SrcAddr),
+				fmt.Sprintf("%d", entry.Options().Metric),
+			}
+			table.Append(strEntry)
+			prevAddr = destAddr
+		}
+	}
+
+	return sb.String()
 }