map: Make the Examples all testable examples.

Signed-off-by: Alun Evans <alun@badgerous.net>

map_test.go

@@ -2186,12 +2186,20 @@ func ExampleMap_perCPU() {
 	}
 	defer arr.Close()
 
-	first := []uint32{4, 5}
+	possibleCpus := MustPossibleCPU()
+
+	first := make([]uint32, possibleCpus)
+	for i := range first {
+		first[i] = uint32(4)
+	}
 	if err := arr.Put(uint32(0), first); err != nil {
 		panic(err)
 	}
 
-	second := []uint32{2, 8}
+	second := make([]uint32, possibleCpus)
+	for i := range second {
+		second[i] = uint32(5)
+	}
 	if err := arr.Put(uint32(1), second); err != nil {
 		panic(err)
 	}
@@ -2200,7 +2208,7 @@ func ExampleMap_perCPU() {
 	if err := arr.Lookup(uint32(0), &values); err != nil {
 		panic(err)
 	}
-	fmt.Println("First two values:", values[:2])
+	fmt.Println("First-key value[0]:", values[0])
 
 	var (
 		key     uint32
@@ -2213,12 +2221,15 @@ func ExampleMap_perCPU() {
 		for _, n := range values {
 			sum += n
 		}
-		fmt.Printf("Sum of %d: %d\n", key, sum)
+		fmt.Printf("Mean of %d: %d\n", key, sum/uint32(possibleCpus))
 	}
 
 	if err := entries.Err(); err != nil {
 		panic(err)
 	}
+	// Output: First-key value[0]: 4
+	// Mean of 0: 4
+	// Mean of 1: 5
 }
 
 // It is possible to use unsafe.Pointer to avoid marshalling
@@ -2275,17 +2286,17 @@ func ExampleMap_NextKey() {
 		panic(err)
 	}
 
-	var firstKey string
-	if err := hash.NextKey(nil, &firstKey); err != nil {
+	keys := make([]string, 2)
+	if err := hash.NextKey(nil, &keys[0]); err != nil {
 		panic(err)
 	}
 
-	var nextKey string
-	if err := hash.NextKey(firstKey, &nextKey); err != nil {
+	if err := hash.NextKey(keys[0], &keys[1]); err != nil {
 		panic(err)
 	}
-
-	// Order of keys is non-deterministic due to randomized map seed
+	sort.Strings(keys)
+	fmt.Printf("Keys are %v\n", keys)
+	// Output: Keys are [hello world]
 }
 
 // ExampleMap_Iterate demonstrates how to iterate over all entries
@@ -2316,37 +2327,91 @@ func ExampleMap_Iterate() {
 		entries = hash.Iterate()
 	)
 
+	m := make(map[string]uint32)
 	for entries.Next(&key, &value) {
 		// Order of keys is non-deterministic due to randomized map seed
-		fmt.Printf("key: %s, value: %d\n", key, value)
+		m[key] = value
 	}
 
 	if err := entries.Err(); err != nil {
 		panic(fmt.Sprint("Iterator encountered an error:", err))
 	}
+
+	keys := make([]string, 0, len(m))
+	for k := range m {
+		keys = append(keys, k)
+	}
+	sort.Strings(keys)
+
+	for _, k := range keys {
+		fmt.Printf("key: %s, value: %d\n", k, m[k])
+	}
+	// Output: key: hello, value: 21
+	// key: world, value: 42
 }
 
 // It is possible to iterate nested maps and program arrays by
 // unmarshaling into a *Map or *Program.
 func ExampleMap_Iterate_nestedMapsAndProgramArrays() {
-	var arrayOfMaps *Map // Set this up somehow
-
+	spec := &MapSpec{
+		Type: ArrayOfMaps,
+		InnerMap: &MapSpec{
+			Type:       Array,
+			KeySize:    4,
+			ValueSize:  4,
+			MaxEntries: 2,
+		},
+		KeySize:    4,
+		ValueSize:  4,
+		MaxEntries: 10,
+	}
+	arrayOfMaps, err := NewMap(spec)
+	if err != nil {
+		panic(err)
+	}
+	defer arrayOfMaps.Close()
+	inner, err := NewMap(spec.InnerMap)
+	if err != nil {
+		panic(err)
+	}
+	defer inner.Close()
 	var (
 		key     uint32
 		m       *Map
 		entries = arrayOfMaps.Iterate()
 	)
 
-	// Make sure that the iterated map is closed after
-	// we are done.
-	defer m.Close()
+	if err := inner.Put(uint32(1), uint32(2)); err != nil {
+		panic(err)
+	}
+
+	if err := arrayOfMaps.Put(uint32(0), inner); err != nil {
+		panic(err)
+	}
 
 	for entries.Next(&key, &m) {
+		// Make sure that the iterated map is closed after
+		// we are done.
+		defer m.Close()
+
 		// Order of keys is non-deterministic due to randomized map seed
-		fmt.Printf("key: %v, map: %v\n", key, m)
+		fmt.Printf("key: %v\n", key)
+		items := m.Iterate()
+		var innerKey, innerValue uint32
+
+		for items.Next(&innerKey, &innerValue) {
+			fmt.Printf("\tinnerKey %v innerValue %v\n", innerKey, innerValue)
+		}
+		if err := items.Err(); err != nil {
+			panic(fmt.Sprint("Inner Iterator encountered an error:", err))
+		}
 	}
 
 	if err := entries.Err(); err != nil {
 		panic(fmt.Sprint("Iterator encountered an error:", err))
 	}
+	// Output:
+	// key: 0
+	//	innerKey 0 innerValue 0
+	// 	innerKey 1 innerValue 2
 }