添加context

.idea/vcs.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$" vcs="Git" />
+  </component>
+</project>

context_demo/contextDemo1.go

@@ -0,0 +1,21 @@
+package main
+
+import (
+	"fmt"
+	"golang.org/x/net/context"
+	"time"
+)
+
+const shortDuration = 1 * time.Millisecond
+
+func main() {
+	ctx, cancel := context.WithTimeout(context.Background(), shortDuration)
+	defer cancel()
+
+	select {
+	case <-time.After(1 * time.Second):
+		fmt.Println("脑子进煎鱼了")
+	case <-ctx.Done():
+		fmt.Println(ctx.Err())
+	}
+}

context_demo/demo2.go

@@ -0,0 +1,27 @@
+package main
+
+import (
+	"fmt"
+	"golang.org/x/net/context"
+	"net/http"
+	"time"
+)
+
+func main() {
+	req, err := http.NewRequest("GET", "https://eddycjy.com/", nil)
+	if err != nil {
+		fmt.Printf("http.NewRequest err: %+v", err)
+		return
+	}
+
+	ctx, cancel := context.WithTimeout(req.Context(), 50*time.Millisecond)
+	defer cancel()
+
+	req = req.WithContext(ctx)
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		fmt.Printf("http.DefaultClient.Do err: %+v", err)
+		return
+	}
+	defer resp.Body.Close()
+}

context_demo/demo3.go

@@ -0,0 +1,23 @@
+package main
+
+import (
+	"fmt"
+	"golang.org/x/net/context"
+)
+
+func main() {
+	type favContextKey string
+	f := func(ctx context.Context, k favContextKey) {
+		if v := ctx.Value(k); v != nil {
+			fmt.Println("found value:", v)
+			return
+		}
+		fmt.Println("key not found:", k)
+	}
+
+	k := favContextKey("脑子进")
+	ctx := context.WithValue(context.Background(), k, "煎鱼")
+
+	f(ctx, k)
+	f(ctx, favContextKey("小咸鱼"))
+}

go.sum

@@ -32,6 +32,7 @@ golang.org/x/mod v0.4.2/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20201021035429-f5854403a974 h1:IX6qOQeG5uLjB/hjjwjedwfjND0hgjPMMyO1RoIXQNI=
 golang.org/x/net v0.0.0-20201021035429-f5854403a974/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=