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handler.go
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/
handler.go
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package log
import (
"net/http"
"os"
"strings"
"github.com/0chain/gosdk/core/sys"
)
// HandleFunc returns handle function that writes logs to http.ResponseWriter with provided buffer size.
// Buffered length represented in kilobytes.
func HandleFunc(buffLen int64) func(http.ResponseWriter, *http.Request) {
return func(w http.ResponseWriter, _ *http.Request) {
file, err := os.Open(logName)
if err != nil {
w.WriteHeader(http.StatusInternalServerError)
return
}
defer func() {
_ = file.Close()
}()
stat, err := sys.Files.Stat(logName)
if err != nil {
w.WriteHeader(http.StatusInternalServerError)
return
}
var (
writeLen = buffLen * 1024
brokenLines = true // flag that describes existence of broken lines
)
if writeLen > stat.Size() {
writeLen = stat.Size()
brokenLines = false
}
buf := make([]byte, writeLen)
_, err = file.ReadAt(buf, stat.Size()-writeLen)
if err != nil {
w.WriteHeader(http.StatusInternalServerError)
return
}
// cut broken lines if it exist
if brokenLines {
lbInd := strings.Index(string(buf), "\n")
buf = buf[lbInd+1:]
}
if _, err := w.Write(buf); err != nil {
w.WriteHeader(http.StatusInternalServerError)
return
}
}
}