Add mutex for protect Context.Keys map (gin-gonic#1391)

* Add mutex for protect Context.Keys map

* Fix tests

Co-authored-by: Nikolay Tolkachov <nik.tolkachov@gmail.com>
Co-authored-by: Bo-Yi Wu <appleboy.tw@gmail.com>

context.go

@@ -16,6 +16,7 @@ import (
 	"net/url"
 	"os"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/gin-contrib/sse"
@@ -52,6 +53,9 @@ type Context struct {
 
 	engine *Engine
 
+	// This mutex protect Keys map
+	KeysMutex *sync.RWMutex
+
 	// Keys is a key/value pair exclusively for the context of each request.
 	Keys map[string]interface{}
 
@@ -78,6 +82,7 @@ func (c *Context) reset() {
 	c.Params = c.Params[0:0]
 	c.handlers = nil
 	c.index = -1
+	c.KeysMutex = &sync.RWMutex{}
 	c.fullPath = ""
 	c.Keys = nil
 	c.Errors = c.Errors[0:0]
@@ -219,16 +224,21 @@ func (c *Context) Error(err error) *Error {
 // Set is used to store a new key/value pair exclusively for this context.
 // It also lazy initializes  c.Keys if it was not used previously.
 func (c *Context) Set(key string, value interface{}) {
+	c.KeysMutex.Lock()
 	if c.Keys == nil {
 		c.Keys = make(map[string]interface{})
 	}
+
 	c.Keys[key] = value
+	c.KeysMutex.Unlock()
 }
 
 // Get returns the value for the given key, ie: (value, true).
 // If the value does not exists it returns (nil, false)
 func (c *Context) Get(key string) (value interface{}, exists bool) {
+	c.KeysMutex.RLock()
 	value, exists = c.Keys[key]
+	c.KeysMutex.RUnlock()
 	return
 }
 

gin.go

@@ -162,7 +162,7 @@ func Default() *Engine {
 }
 
 func (engine *Engine) allocateContext() *Context {
-	return &Context{engine: engine}
+	return &Context{engine: engine, KeysMutex: &sync.RWMutex{}}
 }
 
 // Delims sets template left and right delims and returns a Engine instance.