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general_utilities.go
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/
general_utilities.go
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// Metrics Runner (a simple data collection tool to gather analytics)
// Copyright (C) 2019 Bryan C. Callahan
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
package utilities
import (
"encoding/json"
"log"
"net/http"
"os"
"os/signal"
"syscall"
)
func WaitForOSSignal(terminate func() error) {
signalChannel := make(chan os.Signal, 2)
signal.Notify(signalChannel, os.Interrupt, syscall.SIGTERM)
go func() {
sig := <-signalChannel
log.Println("received", sig, "signal from OS")
var err error
err = terminate()
log.Println("terminating")
if err == nil {
os.Exit(0)
} else {
os.Exit(1)
}
}()
}
// ServeJSON writes status and response as JSON.
func ServeJSON(w http.ResponseWriter, r *http.Request, status int, response interface{}) {
w.Header().Set("Content-Type", "application/json; charset=UTF-8")
w.WriteHeader(status)
if response == nil {
response = struct{}{}
}
err := json.NewEncoder(w).Encode(response)
if err != nil {
log.Println("Could not encode json response", err)
}
}