database-filesystem, demo log tailing in term

routers/web/dev/termdemo.go

@@ -0,0 +1,51 @@
+package dev
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"sync"
+	"time"
+
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/models/dbfs"
+	"code.gitea.io/gitea/modules/context"
+)
+
+var demoLogWriterOnce sync.Once
+
+func TermDemo(ctx *context.Context) {
+	demoLogWriterOnce.Do(func() {
+		go func() {
+			f, _ := dbfs.OpenFile(db.DefaultContext, "termdemo.log", os.O_RDWR|os.O_CREATE|os.O_TRUNC|os.O_APPEND)
+			count := 0
+			for {
+				count++
+				s := fmt.Sprintf("\x1B[1;3;31mDemo Log\x1B[0m, count=%d\r\n", count)
+				_, _ = f.Write([]byte(s))
+				time.Sleep(time.Second)
+			}
+		}()
+	})
+
+	cmd := ctx.FormString("cmd")
+	if cmd == "tail" {
+		offset := ctx.FormInt64("offset")
+		f, _ := dbfs.OpenFile(db.DefaultContext, "termdemo.log", os.O_RDONLY)
+		if offset == -1 {
+			_, _ = f.Seek(0, io.SeekEnd)
+		} else {
+			_, _ = f.Seek(offset, io.SeekStart)
+		}
+		buf, _ := io.ReadAll(f)
+		offset, _ = f.Seek(0, io.SeekCurrent)
+		ctx.JSON(http.StatusOK, map[string]interface{}{
+			"offset":  offset,
+			"content": string(buf),
+		})
+		return
+	}
+
+	ctx.HTML(http.StatusOK, "dev/termdemo")
+}