fix: make it sorted when marshalling integer key map (#117)

encoder/mapiter.go

@@ -27,7 +27,7 @@ import (
 )
 
 type _MapPair struct {
-    k string
+    k string  // when the map key is integer, k is pointed to m
     v unsafe.Pointer
     m [32]byte
 }

encoder/sort.go

@@ -19,12 +19,16 @@ package encoder
 // Algorithm 3-way Radix Quicksort, d means the radix.
 // Reference: https://algs4.cs.princeton.edu/51radix/Quick3string.java.html
 func radixQsort(kvs []_MapPair, d, maxDepth int) {
+    for len(kvs) > 11 {
+        // To avoid the worst case of quickSort (time: O(n^2)), use introsort here.
+        // Reference: https://en.wikipedia.org/wiki/Introsort and
+        // https://github.com/golang/go/issues/467
         if maxDepth == 0 {
             heapSort(kvs, 0, len(kvs))
             return
         }
         maxDepth--
-    for len(kvs) > 11 {
+
         p := pivot(kvs, d)
         lt, i, gt := 0, 0, len(kvs)
         for i < gt {
@@ -42,13 +46,13 @@ func radixQsort(kvs []_MapPair, d, maxDepth int) {
         }
 
         // kvs[0:lt] < v = kvs[lt:gt] < kvs[gt:len(kvs)]
-        // Native:
+        // Native implemention:
         //     radixQsort(kvs[:lt], d, maxDepth)
         //     if p > -1 {
         //         radixQsort(kvs[lt:gt], d+1, maxDepth)
         //     }
         //     radixQsort(kvs[gt:], d, maxDepth)
-        // Optimize: make recursive calls only for the smaller parts.
+        // Optimize as follows: make recursive calls only for the smaller parts.
         // Reference: https://www.geeksforgeeks.org/quicksort-tail-call-optimization-reducing-worst-case-space-log-n/
         if p == -1 {
             if lt > len(kvs) - gt {
@@ -82,7 +86,7 @@ func radixQsort(kvs []_MapPair, d, maxDepth int) {
 func insertRadixSort(kvs []_MapPair, d int) {
     for i := 1; i < len(kvs); i++ {
         for j := i; j > 0 && lessFrom(kvs[j].k, kvs[j-1].k, d); j-- {
-            kvs[j], kvs[j-1] = kvs[j-1], kvs[j]
+            swap(kvs, j, j-1)
         }
     }
 }
@@ -173,8 +177,10 @@ func heapSort(kvs []_MapPair, a, b int) {
     }
 }
 
+// Note that _MapPair.k is NOT pointed to _MapPair.m when map key is integer after swap
 func swap(kvs []_MapPair, a, b int) {
-    kvs[a], kvs[b] = kvs[b], kvs[a]
+    kvs[a].k, kvs[b].k = kvs[b].k, kvs[a].k
+    kvs[a].v, kvs[b].v = kvs[b].v, kvs[a].v
 }
 
 // Compare two strings from the pos d.

issue_test/issue115_test.go

@@ -0,0 +1,90 @@
+/*
+ * Copyright 2021 ByteDance Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+ package issue_test
+
+ import (
+    `encoding`
+    `encoding/json`
+    `strconv`
+    `testing`
+
+    `github.com/bytedance/sonic/encoder`
+    `github.com/stretchr/testify/require`
+)
+
+type ptrTextMarshaler string
+
+func (k *ptrTextMarshaler) MarshalText() ([]byte, error) {
+    if k == nil {
+        return []byte("ptrisnil"), nil
+    }
+    return []byte("ptrto" + string(*k)), nil
+}
+
+type textMarshaler string
+
+func (k textMarshaler) MarshalText() ([]byte, error) {
+    return []byte(string(k)), nil
+}
+
+func TestIssue115_MarshalMapWithSort(t *testing.T) {
+    nptext := (*ptrTextMarshaler)(nil)
+    ptext  := ptrTextMarshaler("key")
+    text0  := textMarshaler("")
+    text1  := textMarshaler("1")
+    text2  := textMarshaler("2")
+    testCases := []struct {
+        v    interface{}
+        want string
+    }{
+        { v: map[string]int{"b":2, "a":1, "c":3}, want: `{"a":1,"b":2,"c":3}`},
+        { v: map[int64]int{1:-1, -2:2, 0:0}, want: `{"-2":2,"0":0,"1":-1}`},
+        { v: map[uint]int{1:-1, ^uint(0):2, 0:0}, want: `{"0":0,"1":-1,"18446744073709551615":2}`},
+        { v: map[uintptr]int{uintptr(0xf):0xf, uintptr(0x0):0}, want: `{"0":0,"15":15}`}, 
+        { v: map[encoding.TextMarshaler]interface{}{
+               nptext : nil,
+               &ptext : struct{}{},
+               text0  : "", 
+               &text1 : 1, 
+               text2  : text2,
+            },
+          want: `{"":"","1":1,"2":"2","ptrisnil":null,"ptrtokey":{}}`,
+        },
+    }
+
+    for _, tt := range testCases {
+        out, err := encoder.Encode(tt.v, encoder.SortMapKeys)
+        require.NoError(t, err)
+        require.Equal(t, tt.want, string(out))
+    }
+}
+
+func TestIssue115_MarshalLargeIntKeyMapWitSort(t *testing.T) {
+    N := 10000
+    m := map[int]string{}
+    for i := 0; i < N; i++ {
+        a := strconv.Itoa(i)
+        m[i] = a
+    }
+
+    exp, err := json.Marshal(&m)
+    require.NoError(t, err)
+    got, err := encoder.Encode(&m, encoder.SortMapKeys)
+    require.NoError(t, err)
+    require.Equal(t, string(exp), string(got))
+}
+

issue_test/issue8_test.go

@@ -17,10 +17,11 @@
 package issue_test
 
 import (
+    `encoding/json`
+    `reflect`
+    `testing`
+
     . `github.com/bytedance/sonic`
-    "encoding/json"
-    "reflect"
-    "testing"
 )
 
 func TestFloat(t *testing.T) {

issue_test/issue90_test.go

@@ -18,9 +18,9 @@ package issue_test
 
 import (
     . `github.com/bytedance/sonic`
-    "encoding/json"
-    "fmt"
-    "testing"
+    `encoding/json`
+    `fmt`
+    `testing`
 )
 
 func TestUnmarshalInfinity(t *testing.T) {