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Source file src/runtime/map_test.go

Documentation: runtime

  // Copyright 2013 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  package runtime_test
  
  import (
  	"fmt"
  	"math"
  	"reflect"
  	"runtime"
  	"sort"
  	"strconv"
  	"strings"
  	"sync"
  	"testing"
  )
  
  // negative zero is a good test because:
  //  1) 0 and -0 are equal, yet have distinct representations.
  //  2) 0 is represented as all zeros, -0 isn't.
  // I'm not sure the language spec actually requires this behavior,
  // but it's what the current map implementation does.
  func TestNegativeZero(t *testing.T) {
  	m := make(map[float64]bool, 0)
  
  	m[+0.0] = true
  	m[math.Copysign(0.0, -1.0)] = true // should overwrite +0 entry
  
  	if len(m) != 1 {
  		t.Error("length wrong")
  	}
  
  	for k := range m {
  		if math.Copysign(1.0, k) > 0 {
  			t.Error("wrong sign")
  		}
  	}
  
  	m = make(map[float64]bool, 0)
  	m[math.Copysign(0.0, -1.0)] = true
  	m[+0.0] = true // should overwrite -0.0 entry
  
  	if len(m) != 1 {
  		t.Error("length wrong")
  	}
  
  	for k := range m {
  		if math.Copysign(1.0, k) < 0 {
  			t.Error("wrong sign")
  		}
  	}
  }
  
  // nan is a good test because nan != nan, and nan has
  // a randomized hash value.
  func TestNan(t *testing.T) {
  	m := make(map[float64]int, 0)
  	nan := math.NaN()
  	m[nan] = 1
  	m[nan] = 2
  	m[nan] = 4
  	if len(m) != 3 {
  		t.Error("length wrong")
  	}
  	s := 0
  	for k, v := range m {
  		if k == k {
  			t.Error("nan disappeared")
  		}
  		if (v & (v - 1)) != 0 {
  			t.Error("value wrong")
  		}
  		s |= v
  	}
  	if s != 7 {
  		t.Error("values wrong")
  	}
  }
  
  // Maps aren't actually copied on assignment.
  func TestAlias(t *testing.T) {
  	m := make(map[int]int, 0)
  	m[0] = 5
  	n := m
  	n[0] = 6
  	if m[0] != 6 {
  		t.Error("alias didn't work")
  	}
  }
  
  func TestGrowWithNaN(t *testing.T) {
  	m := make(map[float64]int, 4)
  	nan := math.NaN()
  	m[nan] = 1
  	m[nan] = 2
  	m[nan] = 4
  	cnt := 0
  	s := 0
  	growflag := true
  	for k, v := range m {
  		if growflag {
  			// force a hashtable resize
  			for i := 0; i < 100; i++ {
  				m[float64(i)] = i
  			}
  			growflag = false
  		}
  		if k != k {
  			cnt++
  			s |= v
  		}
  	}
  	if cnt != 3 {
  		t.Error("NaN keys lost during grow")
  	}
  	if s != 7 {
  		t.Error("NaN values lost during grow")
  	}
  }
  
  type FloatInt struct {
  	x float64
  	y int
  }
  
  func TestGrowWithNegativeZero(t *testing.T) {
  	negzero := math.Copysign(0.0, -1.0)
  	m := make(map[FloatInt]int, 4)
  	m[FloatInt{0.0, 0}] = 1
  	m[FloatInt{0.0, 1}] = 2
  	m[FloatInt{0.0, 2}] = 4
  	m[FloatInt{0.0, 3}] = 8
  	growflag := true
  	s := 0
  	cnt := 0
  	negcnt := 0
  	// The first iteration should return the +0 key.
  	// The subsequent iterations should return the -0 key.
  	// I'm not really sure this is required by the spec,
  	// but it makes sense.
  	// TODO: are we allowed to get the first entry returned again???
  	for k, v := range m {
  		if v == 0 {
  			continue
  		} // ignore entries added to grow table
  		cnt++
  		if math.Copysign(1.0, k.x) < 0 {
  			if v&16 == 0 {
  				t.Error("key/value not updated together 1")
  			}
  			negcnt++
  			s |= v & 15
  		} else {
  			if v&16 == 16 {
  				t.Error("key/value not updated together 2", k, v)
  			}
  			s |= v
  		}
  		if growflag {
  			// force a hashtable resize
  			for i := 0; i < 100; i++ {
  				m[FloatInt{3.0, i}] = 0
  			}
  			// then change all the entries
  			// to negative zero
  			m[FloatInt{negzero, 0}] = 1 | 16
  			m[FloatInt{negzero, 1}] = 2 | 16
  			m[FloatInt{negzero, 2}] = 4 | 16
  			m[FloatInt{negzero, 3}] = 8 | 16
  			growflag = false
  		}
  	}
  	if s != 15 {
  		t.Error("entry missing", s)
  	}
  	if cnt != 4 {
  		t.Error("wrong number of entries returned by iterator", cnt)
  	}
  	if negcnt != 3 {
  		t.Error("update to negzero missed by iteration", negcnt)
  	}
  }
  
  func TestIterGrowAndDelete(t *testing.T) {
  	m := make(map[int]int, 4)
  	for i := 0; i < 100; i++ {
  		m[i] = i
  	}
  	growflag := true
  	for k := range m {
  		if growflag {
  			// grow the table
  			for i := 100; i < 1000; i++ {
  				m[i] = i
  			}
  			// delete all odd keys
  			for i := 1; i < 1000; i += 2 {
  				delete(m, i)
  			}
  			growflag = false
  		} else {
  			if k&1 == 1 {
  				t.Error("odd value returned")
  			}
  		}
  	}
  }
  
  // make sure old bucket arrays don't get GCd while
  // an iterator is still using them.
  func TestIterGrowWithGC(t *testing.T) {
  	m := make(map[int]int, 4)
  	for i := 0; i < 16; i++ {
  		m[i] = i
  	}
  	growflag := true
  	bitmask := 0
  	for k := range m {
  		if k < 16 {
  			bitmask |= 1 << uint(k)
  		}
  		if growflag {
  			// grow the table
  			for i := 100; i < 1000; i++ {
  				m[i] = i
  			}
  			// trigger a gc
  			runtime.GC()
  			growflag = false
  		}
  	}
  	if bitmask != 1<<16-1 {
  		t.Error("missing key", bitmask)
  	}
  }
  
  func testConcurrentReadsAfterGrowth(t *testing.T, useReflect bool) {
  	t.Parallel()
  	if runtime.GOMAXPROCS(-1) == 1 {
  		defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(16))
  	}
  	numLoop := 10
  	numGrowStep := 250
  	numReader := 16
  	if testing.Short() {
  		numLoop, numGrowStep = 2, 500
  	}
  	for i := 0; i < numLoop; i++ {
  		m := make(map[int]int, 0)
  		for gs := 0; gs < numGrowStep; gs++ {
  			m[gs] = gs
  			var wg sync.WaitGroup
  			wg.Add(numReader * 2)
  			for nr := 0; nr < numReader; nr++ {
  				go func() {
  					defer wg.Done()
  					for range m {
  					}
  				}()
  				go func() {
  					defer wg.Done()
  					for key := 0; key < gs; key++ {
  						_ = m[key]
  					}
  				}()
  				if useReflect {
  					wg.Add(1)
  					go func() {
  						defer wg.Done()
  						mv := reflect.ValueOf(m)
  						keys := mv.MapKeys()
  						for _, k := range keys {
  							mv.MapIndex(k)
  						}
  					}()
  				}
  			}
  			wg.Wait()
  		}
  	}
  }
  
  func TestConcurrentReadsAfterGrowth(t *testing.T) {
  	testConcurrentReadsAfterGrowth(t, false)
  }
  
  func TestConcurrentReadsAfterGrowthReflect(t *testing.T) {
  	testConcurrentReadsAfterGrowth(t, true)
  }
  
  func TestBigItems(t *testing.T) {
  	var key [256]string
  	for i := 0; i < 256; i++ {
  		key[i] = "foo"
  	}
  	m := make(map[[256]string][256]string, 4)
  	for i := 0; i < 100; i++ {
  		key[37] = fmt.Sprintf("string%02d", i)
  		m[key] = key
  	}
  	var keys [100]string
  	var values [100]string
  	i := 0
  	for k, v := range m {
  		keys[i] = k[37]
  		values[i] = v[37]
  		i++
  	}
  	sort.Strings(keys[:])
  	sort.Strings(values[:])
  	for i := 0; i < 100; i++ {
  		if keys[i] != fmt.Sprintf("string%02d", i) {
  			t.Errorf("#%d: missing key: %v", i, keys[i])
  		}
  		if values[i] != fmt.Sprintf("string%02d", i) {
  			t.Errorf("#%d: missing value: %v", i, values[i])
  		}
  	}
  }
  
  func TestMapHugeZero(t *testing.T) {
  	type T [4000]byte
  	m := map[int]T{}
  	x := m[0]
  	if x != (T{}) {
  		t.Errorf("map value not zero")
  	}
  	y, ok := m[0]
  	if ok {
  		t.Errorf("map value should be missing")
  	}
  	if y != (T{}) {
  		t.Errorf("map value not zero")
  	}
  }
  
  type empty struct {
  }
  
  func TestEmptyKeyAndValue(t *testing.T) {
  	a := make(map[int]empty, 4)
  	b := make(map[empty]int, 4)
  	c := make(map[empty]empty, 4)
  	a[0] = empty{}
  	b[empty{}] = 0
  	b[empty{}] = 1
  	c[empty{}] = empty{}
  
  	if len(a) != 1 {
  		t.Errorf("empty value insert problem")
  	}
  	if b[empty{}] != 1 {
  		t.Errorf("empty key returned wrong value")
  	}
  }
  
  // Tests a map with a single bucket, with same-lengthed short keys
  // ("quick keys") as well as long keys.
  func TestSingleBucketMapStringKeys_DupLen(t *testing.T) {
  	testMapLookups(t, map[string]string{
  		"x":    "x1val",
  		"xx":   "x2val",
  		"foo":  "fooval",
  		"bar":  "barval", // same key length as "foo"
  		"xxxx": "x4val",
  		strings.Repeat("x", 128): "longval1",
  		strings.Repeat("y", 128): "longval2",
  	})
  }
  
  // Tests a map with a single bucket, with all keys having different lengths.
  func TestSingleBucketMapStringKeys_NoDupLen(t *testing.T) {
  	testMapLookups(t, map[string]string{
  		"x":                      "x1val",
  		"xx":                     "x2val",
  		"foo":                    "fooval",
  		"xxxx":                   "x4val",
  		"xxxxx":                  "x5val",
  		"xxxxxx":                 "x6val",
  		strings.Repeat("x", 128): "longval",
  	})
  }
  
  func testMapLookups(t *testing.T, m map[string]string) {
  	for k, v := range m {
  		if m[k] != v {
  			t.Fatalf("m[%q] = %q; want %q", k, m[k], v)
  		}
  	}
  }
  
  // Tests whether the iterator returns the right elements when
  // started in the middle of a grow, when the keys are NaNs.
  func TestMapNanGrowIterator(t *testing.T) {
  	m := make(map[float64]int)
  	nan := math.NaN()
  	const nBuckets = 16
  	// To fill nBuckets buckets takes LOAD * nBuckets keys.
  	nKeys := int(nBuckets * *runtime.HashLoad)
  
  	// Get map to full point with nan keys.
  	for i := 0; i < nKeys; i++ {
  		m[nan] = i
  	}
  	// Trigger grow
  	m[1.0] = 1
  	delete(m, 1.0)
  
  	// Run iterator
  	found := make(map[int]struct{})
  	for _, v := range m {
  		if v != -1 {
  			if _, repeat := found[v]; repeat {
  				t.Fatalf("repeat of value %d", v)
  			}
  			found[v] = struct{}{}
  		}
  		if len(found) == nKeys/2 {
  			// Halfway through iteration, finish grow.
  			for i := 0; i < nBuckets; i++ {
  				delete(m, 1.0)
  			}
  		}
  	}
  	if len(found) != nKeys {
  		t.Fatalf("missing value")
  	}
  }
  
  func TestMapIterOrder(t *testing.T) {
  	for _, n := range [...]int{3, 7, 9, 15} {
  		for i := 0; i < 1000; i++ {
  			// Make m be {0: true, 1: true, ..., n-1: true}.
  			m := make(map[int]bool)
  			for i := 0; i < n; i++ {
  				m[i] = true
  			}
  			// Check that iterating over the map produces at least two different orderings.
  			ord := func() []int {
  				var s []int
  				for key := range m {
  					s = append(s, key)
  				}
  				return s
  			}
  			first := ord()
  			ok := false
  			for try := 0; try < 100; try++ {
  				if !reflect.DeepEqual(first, ord()) {
  					ok = true
  					break
  				}
  			}
  			if !ok {
  				t.Errorf("Map with n=%d elements had consistent iteration order: %v", n, first)
  				break
  			}
  		}
  	}
  }
  
  // Issue 8410
  func TestMapSparseIterOrder(t *testing.T) {
  	// Run several rounds to increase the probability
  	// of failure. One is not enough.
  NextRound:
  	for round := 0; round < 10; round++ {
  		m := make(map[int]bool)
  		// Add 1000 items, remove 980.
  		for i := 0; i < 1000; i++ {
  			m[i] = true
  		}
  		for i := 20; i < 1000; i++ {
  			delete(m, i)
  		}
  
  		var first []int
  		for i := range m {
  			first = append(first, i)
  		}
  
  		// 800 chances to get a different iteration order.
  		// See bug 8736 for why we need so many tries.
  		for n := 0; n < 800; n++ {
  			idx := 0
  			for i := range m {
  				if i != first[idx] {
  					// iteration order changed.
  					continue NextRound
  				}
  				idx++
  			}
  		}
  		t.Fatalf("constant iteration order on round %d: %v", round, first)
  	}
  }
  
  func TestMapStringBytesLookup(t *testing.T) {
  	// Use large string keys to avoid small-allocation coalescing,
  	// which can cause AllocsPerRun to report lower counts than it should.
  	m := map[string]int{
  		"1000000000000000000000000000000000000000000000000": 1,
  		"2000000000000000000000000000000000000000000000000": 2,
  	}
  	buf := []byte("1000000000000000000000000000000000000000000000000")
  	if x := m[string(buf)]; x != 1 {
  		t.Errorf(`m[string([]byte("1"))] = %d, want 1`, x)
  	}
  	buf[0] = '2'
  	if x := m[string(buf)]; x != 2 {
  		t.Errorf(`m[string([]byte("2"))] = %d, want 2`, x)
  	}
  
  	var x int
  	n := testing.AllocsPerRun(100, func() {
  		x += m[string(buf)]
  	})
  	if n != 0 {
  		t.Errorf("AllocsPerRun for m[string(buf)] = %v, want 0", n)
  	}
  
  	x = 0
  	n = testing.AllocsPerRun(100, func() {
  		y, ok := m[string(buf)]
  		if !ok {
  			panic("!ok")
  		}
  		x += y
  	})
  	if n != 0 {
  		t.Errorf("AllocsPerRun for x,ok = m[string(buf)] = %v, want 0", n)
  	}
  }
  
  func TestMapLargeKeyNoPointer(t *testing.T) {
  	const (
  		I = 1000
  		N = 64
  	)
  	type T [N]int
  	m := make(map[T]int)
  	for i := 0; i < I; i++ {
  		var v T
  		for j := 0; j < N; j++ {
  			v[j] = i + j
  		}
  		m[v] = i
  	}
  	runtime.GC()
  	for i := 0; i < I; i++ {
  		var v T
  		for j := 0; j < N; j++ {
  			v[j] = i + j
  		}
  		if m[v] != i {
  			t.Fatalf("corrupted map: want %+v, got %+v", i, m[v])
  		}
  	}
  }
  
  func TestMapLargeValNoPointer(t *testing.T) {
  	const (
  		I = 1000
  		N = 64
  	)
  	type T [N]int
  	m := make(map[int]T)
  	for i := 0; i < I; i++ {
  		var v T
  		for j := 0; j < N; j++ {
  			v[j] = i + j
  		}
  		m[i] = v
  	}
  	runtime.GC()
  	for i := 0; i < I; i++ {
  		var v T
  		for j := 0; j < N; j++ {
  			v[j] = i + j
  		}
  		v1 := m[i]
  		for j := 0; j < N; j++ {
  			if v1[j] != v[j] {
  				t.Fatalf("corrupted map: want %+v, got %+v", v, v1)
  			}
  		}
  	}
  }
  
  // Test that making a map with a large or invalid hint
  // doesn't panic. (Issue 19926).
  func TestIgnoreBogusMapHint(t *testing.T) {
  	for _, hint := range []int64{-1, 1 << 62} {
  		_ = make(map[int]int, hint)
  	}
  }
  
  func benchmarkMapPop(b *testing.B, n int) {
  	m := map[int]int{}
  	for i := 0; i < b.N; i++ {
  		for j := 0; j < n; j++ {
  			m[j] = j
  		}
  		for j := 0; j < n; j++ {
  			// Use iterator to pop an element.
  			// We want this to be fast, see issue 8412.
  			for k := range m {
  				delete(m, k)
  				break
  			}
  		}
  	}
  }
  
  func BenchmarkMapPop100(b *testing.B)   { benchmarkMapPop(b, 100) }
  func BenchmarkMapPop1000(b *testing.B)  { benchmarkMapPop(b, 1000) }
  func BenchmarkMapPop10000(b *testing.B) { benchmarkMapPop(b, 10000) }
  
  func TestNonEscapingMap(t *testing.T) {
  	n := testing.AllocsPerRun(1000, func() {
  		m := make(map[int]int)
  		m[0] = 0
  	})
  	if n != 0 {
  		t.Fatalf("want 0 allocs, got %v", n)
  	}
  }
  
  func benchmarkMapAssignInt32(b *testing.B, n int) {
  	a := make(map[int32]int)
  	for i := 0; i < b.N; i++ {
  		a[int32(i&(n-1))] = i
  	}
  }
  
  func benchmarkMapDeleteInt32(b *testing.B, n int) {
  	a := make(map[int32]int)
  	for i := 0; i < n*b.N; i++ {
  		a[int32(i)] = i
  	}
  	b.ResetTimer()
  	for i := 0; i < n*b.N; i = i + n {
  		delete(a, int32(i))
  	}
  }
  
  func benchmarkMapAssignInt64(b *testing.B, n int) {
  	a := make(map[int64]int)
  	for i := 0; i < b.N; i++ {
  		a[int64(i&(n-1))] = i
  	}
  }
  
  func benchmarkMapDeleteInt64(b *testing.B, n int) {
  	a := make(map[int64]int)
  	for i := 0; i < n*b.N; i++ {
  		a[int64(i)] = i
  	}
  	b.ResetTimer()
  	for i := 0; i < n*b.N; i = i + n {
  		delete(a, int64(i))
  	}
  }
  
  func benchmarkMapAssignStr(b *testing.B, n int) {
  	k := make([]string, n)
  	for i := 0; i < len(k); i++ {
  		k[i] = strconv.Itoa(i)
  	}
  	b.ResetTimer()
  	a := make(map[string]int)
  	for i := 0; i < b.N; i++ {
  		a[k[i&(n-1)]] = i
  	}
  }
  
  func benchmarkMapDeleteStr(b *testing.B, n int) {
  	k := make([]string, n*b.N)
  	for i := 0; i < n*b.N; i++ {
  		k[i] = strconv.Itoa(i)
  	}
  	a := make(map[string]int)
  	for i := 0; i < n*b.N; i++ {
  		a[k[i]] = i
  	}
  	b.ResetTimer()
  	for i := 0; i < n*b.N; i = i + n {
  		delete(a, k[i])
  	}
  }
  
  func runWith(f func(*testing.B, int), v ...int) func(*testing.B) {
  	return func(b *testing.B) {
  		for _, n := range v {
  			b.Run(strconv.Itoa(n), func(b *testing.B) { f(b, n) })
  		}
  	}
  }
  
  func BenchmarkMapAssign(b *testing.B) {
  	b.Run("Int32", runWith(benchmarkMapAssignInt32, 1<<8, 1<<16))
  	b.Run("Int64", runWith(benchmarkMapAssignInt64, 1<<8, 1<<16))
  	b.Run("Str", runWith(benchmarkMapAssignStr, 1<<8, 1<<16))
  }
  
  func BenchmarkMapDelete(b *testing.B) {
  	b.Run("Int32", runWith(benchmarkMapDeleteInt32, 1, 2, 4))
  	b.Run("Int64", runWith(benchmarkMapDeleteInt64, 1, 2, 4))
  	b.Run("Str", runWith(benchmarkMapDeleteStr, 1, 2, 4))
  }
  

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