Merge 443ef770a76e15ee1175d06c8587f1767e0ad94a into 8763f33c65f7df8be5b9fe7504ab7fcf20abb41d

context.go

@@ -5,6 +5,7 @@
 package gin
 
 import (
+	"context"
 	"errors"
 	"io"
 	"io/fs"
@@ -90,6 +91,9 @@ type Context struct {
 	// SameSite allows a server to define a cookie attribute making it impossible for
 	// the browser to send this cookie along with cross-site requests.
 	sameSite http.SameSite
+
+	internalContextMu sync.RWMutex
+	internalContext   context.Context
 }
 
 /************************************/
@@ -111,6 +115,10 @@ func (c *Context) reset() {
 	c.sameSite = 0
 	*c.params = (*c.params)[:0]
 	*c.skippedNodes = (*c.skippedNodes)[:0]
+
+	if c.useInternalContext() {
+		c.WithInternalContext(context.Background())
+	}
 }
 
 // Copy returns a copy of the current context that can be safely used outside the request's scope.
@@ -1307,6 +1315,49 @@ func (c *Context) SetAccepted(formats ...string) {
 /***** GOLANG.ORG/X/NET/CONTEXT *****/
 /************************************/
 
+// WithInternalContext replaces the internal context stored with the provided one in a thread safe manner.
+// It's important that any context you pass in is not something the wraps *gin.Context,
+// if you want to wrap a context and then provide it to WithInternalContext, use InternalContext().
+// If you don't plan to provide the context back to WithInternalContext you can safely use *Context directly.
+// Otherwise you'll end up with a stack overflow.
+//
+// For example:
+// var c *Context // given a context
+// // you can safely wrap it and pass it downstream
+// myDownstreamFunction(context.WithValue(c, ...))
+//
+// // but when you want to call WithInternalContext you should do it like this
+// c.WithInternalContext(context.WithValue(c.InternalContext(), ...))
+func (c *Context) WithInternalContext(ctx context.Context) {
+	if !c.useInternalContext() {
+		panic("Can't use WithInternalContext when UseInternalContext is false")
+	}
+
+	c.internalContextMu.Lock()
+	defer c.internalContextMu.Unlock()
+
+	c.internalContext = ctx
+}
+
+// InternalContext provides the currently stored internal context in a thread safe manner.
+// Use this if you want to wrap a context.Context which you'll end up providing to WithInternalContext.
+// If you don't plan to provide the context back to WithInternalContext you can safely use *Context directly.
+func (c *Context) InternalContext() context.Context {
+	if !c.useInternalContext() {
+		panic("Can't use InternalContext when UseInternalContext is false")
+	}
+
+	c.internalContextMu.RLock()
+	defer c.internalContextMu.RUnlock()
+
+	return c.internalContext
+}
+
+// hasRequestContext returns whether c.Request has Context and fallback.
+func (c *Context) useInternalContext() bool {
+	return c.engine != nil && c.engine.UseInternalContext
+}
+
 // hasRequestContext returns whether c.Request has Context and fallback.
 func (c *Context) hasRequestContext() bool {
 	hasFallback := c.engine != nil && c.engine.ContextWithFallback
@@ -1316,26 +1367,44 @@ func (c *Context) hasRequestContext() bool {
 
 // Deadline returns that there is no deadline (ok==false) when c.Request has no Context.
 func (c *Context) Deadline() (deadline time.Time, ok bool) {
-	if !c.hasRequestContext() {
-		return
+	if c.useInternalContext() {
+		c.internalContextMu.RLock()
+		defer c.internalContextMu.RUnlock()
+
+		return c.internalContext.Deadline()
+	} else if c.hasRequestContext() {
+		return c.Request.Context().Deadline()
 	}
-	return c.Request.Context().Deadline()
+
+	return
 }
 
 // Done returns nil (chan which will wait forever) when c.Request has no Context.
 func (c *Context) Done() <-chan struct{} {
-	if !c.hasRequestContext() {
-		return nil
+	if c.useInternalContext() {
+		c.internalContextMu.RLock()
+		defer c.internalContextMu.RUnlock()
+
+		return c.internalContext.Done()
+	} else if c.hasRequestContext() {
+		return c.Request.Context().Done()
 	}
-	return c.Request.Context().Done()
+
+	return nil
 }
 
 // Err returns nil when c.Request has no Context.
 func (c *Context) Err() error {
-	if !c.hasRequestContext() {
-		return nil
+	if c.useInternalContext() {
+		c.internalContextMu.RLock()
+		defer c.internalContextMu.RUnlock()
+
+		return c.internalContext.Err()
+	} else if c.hasRequestContext() {
+		return c.Request.Context().Err()
 	}
-	return c.Request.Context().Err()
+
+	return nil
 }
 
 // Value returns the value associated with this context for key, or nil
@@ -1353,8 +1422,14 @@ func (c *Context) Value(key any) any {
 			return val
 		}
 	}
-	if !c.hasRequestContext() {
-		return nil
+	if c.useInternalContext() {
+		c.internalContextMu.RLock()
+		defer c.internalContextMu.RUnlock()
+
+		return c.internalContext.Value(key)
+	} else if c.hasRequestContext() {
+		return c.Request.Context().Value(key)
 	}
-	return c.Request.Context().Value(key)
+
+	return nil
 }

context_test.go

@@ -2952,6 +2952,142 @@ func TestContextWithFallbackValueFromRequestContext(t *testing.T) {
 	}
 }
 
+func TestContextUseInternalContextDeadline(t *testing.T) {
+	c, _ := CreateTestContext(httptest.NewRecorder(), func(c *Context) {
+		// enable UseInternalContext feature flag
+		c.engine.UseInternalContext = true
+	})
+
+	deadline, ok := c.Deadline()
+	assert.Zero(t, deadline)
+	assert.False(t, ok)
+
+	c2, _ := CreateTestContext(httptest.NewRecorder(), func(c *Context) {
+		// enable UseInternalContext feature flag
+		c.engine.UseInternalContext = true
+	})
+
+	d := time.Now().Add(time.Second)
+	ctx, cancel := context.WithDeadline(context.Background(), d)
+	defer cancel()
+	c2.WithInternalContext(ctx)
+	deadline, ok = c2.Deadline()
+	assert.Equal(t, d, deadline)
+	assert.True(t, ok)
+}
+
+func TestContextUseInternalContextDone(t *testing.T) {
+	c, _ := CreateTestContext(httptest.NewRecorder(), func(c *Context) {
+		// enable UseInternalContext feature flag
+		c.engine.UseInternalContext = true
+	})
+
+	assert.Nil(t, c.Done())
+
+	c2, _ := CreateTestContext(httptest.NewRecorder(), func(c *Context) {
+		// enable UseInternalContext feature flag
+		c.engine.UseInternalContext = true
+	})
+
+	ctx, cancel := context.WithCancel(context.Background())
+	c2.WithInternalContext(ctx)
+	cancel()
+	assert.NotNil(t, <-c2.Done())
+}
+
+func TestContextUseInternalContextErr(t *testing.T) {
+	c, _ := CreateTestContext(httptest.NewRecorder(), func(c *Context) {
+		// enable UseInternalContext feature flag
+		c.engine.UseInternalContext = true
+	})
+
+	require.NoError(t, c.Err())
+
+	c2, _ := CreateTestContext(httptest.NewRecorder(), func(c *Context) {
+		// enable UseInternalContext feature flag
+		c.engine.UseInternalContext = true
+	})
+
+	ctx, cancel := context.WithCancel(context.Background())
+	c2.WithInternalContext(ctx)
+	cancel()
+
+	assert.EqualError(t, c2.Err(), context.Canceled.Error())
+}
+
+func TestContextUseInternalContextValue(t *testing.T) {
+	type contextKey string
+
+	tests := []struct {
+		name             string
+		getContextAndKey func() (*Context, any)
+		value            any
+	}{
+		{
+			name: "c with struct context key",
+			getContextAndKey: func() (*Context, any) {
+				type KeyStruct struct{} // https://staticcheck.dev/docs/checks/#SA1029
+				var key KeyStruct
+				c, _ := CreateTestContext(httptest.NewRecorder(), func(c *Context) {
+					// enable UseInternalContext feature flag
+					c.engine.UseInternalContext = true
+				})
+				c.WithInternalContext(context.WithValue(context.TODO(), key, "value"))
+				return c, key
+			},
+			value: "value",
+		},
+		{
+			name: "c with struct context key and request context with different value",
+			getContextAndKey: func() (*Context, any) {
+				type KeyStruct struct{} // https://staticcheck.dev/docs/checks/#SA1029
+				var key KeyStruct
+				c, _ := CreateTestContext(httptest.NewRecorder(), func(c *Context) {
+					// enable UseInternalContext feature flag
+					c.engine.UseInternalContext = true
+					// enable ContextWithFallback feature flag
+					c.engine.ContextWithFallback = true
+					c.Request, _ = http.NewRequest(http.MethodPost, "/", nil)
+				})
+				c.WithInternalContext(context.WithValue(context.TODO(), key, "value"))
+				c.Request = c.Request.WithContext(context.WithValue(context.TODO(), key, "other value"))
+				return c, key
+			},
+			value: "value",
+		},
+		{
+			name: "c with string context key",
+			getContextAndKey: func() (*Context, any) {
+				c, _ := CreateTestContext(httptest.NewRecorder(), func(c *Context) {
+					// enable UseInternalContext feature flag
+					c.engine.UseInternalContext = true
+				})
+				c.WithInternalContext(context.WithValue(context.TODO(), contextKey("key"), "value"))
+				return c, contextKey("key")
+			},
+			value: "value",
+		},
+		{
+			name: "c with background internal context",
+			getContextAndKey: func() (*Context, any) {
+				c, _ := CreateTestContext(httptest.NewRecorder(), func(c *Context) {
+					// enable UseInternalContext feature flag
+					c.engine.UseInternalContext = true
+				})
+				c.WithInternalContext(context.Background())
+				return c, "key"
+			},
+			value: nil,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			c, key := tt.getContextAndKey()
+			assert.Equal(t, tt.value, c.Value(key))
+		})
+	}
+}
+
 func TestContextCopyShouldNotCancel(t *testing.T) {
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
 		w.WriteHeader(http.StatusOK)

gin.go

@@ -17,7 +17,6 @@ import (
 
 	"github.com/gin-gonic/gin/internal/bytesconv"
 	"github.com/gin-gonic/gin/render"
-
 	"github.com/quic-go/quic-go/http3"
 	"golang.org/x/net/http2"
 	"golang.org/x/net/http2/h2c"
@@ -161,9 +160,14 @@ type Engine struct {
 	// UseH2C enable h2c support.
 	UseH2C bool
 
-	// ContextWithFallback enable fallback Context.Deadline(), Context.Done(), Context.Err() and Context.Value() when Context.Request.Context() is not nil.
+	// ContextWithFallback enable fallback Context.Deadline(), Context.Done(), Context.Err() and Context.Value()
+	// through Context.Request when Context.Request.Context() is not nil.
 	ContextWithFallback bool
 
+	// UseInternalContext enable fallback Context.Deadline(), Context.Done(), Context.Err()
+	// through InternalContext and supersedes ContextWithFallback
+	UseInternalContext bool
+
 	delims           render.Delims
 	secureJSONPrefix string
 	HTMLRender       render.HTMLRender

test_helpers.go

@@ -7,9 +7,12 @@ package gin
 import "net/http"
 
 // CreateTestContext returns a fresh engine and context for testing purposes
-func CreateTestContext(w http.ResponseWriter) (c *Context, r *Engine) {
+func CreateTestContext(w http.ResponseWriter, opts ...func(c *Context)) (c *Context, r *Engine) {
 	r = New()
 	c = r.allocateContext(0)
+	for _, opt := range opts {
+		opt(c)
+	}
 	c.reset()
 	c.writermem.reset(w)
 	return