feat(wip): sketch out the scheduling strategy

agent/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"fmt"
 	"io"
 	"log/slog"
 	"math"
@@ -18,6 +19,11 @@ type cpuHandler struct {
 	logger    *slog.Logger
 }
 
+type memHandler struct {
+	amount int64
+	logger *slog.Logger
+}
+
 // readIntFromFile reads the given file until the end
 // and converts the contained string into an integer
 func readIntFromFile(path string) (int, error) {
@@ -28,6 +34,25 @@ func readIntFromFile(path string) (int, error) {
 	return strconv.Atoi(strings.TrimSpace(string(b)))
 }
 
+func readTotalMemoryKb() (int, error) {
+	b, err := os.ReadFile("/proc/meminfo")
+	if err != nil {
+		return 0, err
+	}
+	s := string(b)
+	for line := range strings.Lines(s) {
+		if !strings.Contains(line, "MemTotal:") {
+			continue
+		}
+		fields := strings.Fields(line)
+		if len(fields) < 2 {
+			return 0, fmt.Errorf("expected line '%s' to have at least 2 fields", line)
+		}
+		return strconv.Atoi(fields[1])
+	}
+	return 0, fmt.Errorf("failed to find MemTotal in /proc/meminfo")
+}
+
 func enumerateCPUCores(logger *slog.Logger) ([]string, int, int, error) {
 	files, err := os.ReadDir("/sys/devices/system/cpu/")
 	if err != nil {
@@ -135,6 +160,17 @@ func (s *cpuHandler) handleCurrent(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+func (s *cpuHandler) handleCount(w http.ResponseWriter, r *http.Request) {
+	if r.Method != "GET" {
+		s.logger.Error("unexepcted method for cpu count", "method", r.Method)
+		writeResponse("invalid method", http.StatusBadRequest, w, s.logger)
+		return
+	}
+
+	count := len(s.corePaths)
+	writeResponse(strconv.Itoa(count), http.StatusOK, w, s.logger)
+}
+
 func (s *cpuHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	requestedPath := getStrippedRequestPath(r.URL, r.Pattern)
 	switch requestedPath {
@@ -147,12 +183,25 @@ func (s *cpuHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	case "frequency/current":
 		s.handleCurrent(w, r)
 		return
+	case "count":
+		s.handleCount(w, r)
+		return
 	default:
 		s.logger.Error("unknown resource", "path", requestedPath)
 		writeResponse("not found", http.StatusNotFound, w, s.logger)
 	}
 }
 
+func (m *memHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	requestedPath := getStrippedRequestPath(r.URL, r.Pattern)
+	if requestedPath == "amount" {
+		writeResponse(strconv.FormatInt(m.amount, 10), http.StatusOK, w, m.logger)
+	} else {
+		m.logger.Error("unknown resource", "path", requestedPath)
+		writeResponse("not found", http.StatusNotFound, w, m.logger)
+	}
+}
+
 func main() {
 	appEnv := os.Getenv("AGENT_ENV")
 	loggerOpts := &slog.HandlerOptions{
@@ -176,6 +225,18 @@ func main() {
 		minFreq:   minF,
 		corePaths: freqPaths,
 	}
+
+	memKb, err := readTotalMemoryKb()
+	if err != nil {
+		logger.Error("failed to read memory size", "err", err.Error())
+		os.Exit(1)
+	}
+	memHandler := &memHandler{
+		amount: int64(memKb) * 1024,
+		logger: logger,
+	}
+
 	http.Handle("/cpu/", logRequests(logger, cpuHandler))
+	http.Handle("/mem/", logRequests(logger, memHandler))
 	logger.Info("exit", "result", http.ListenAndServe(":8080", nil))
 }