initial

cmd/cache-service/main.go

@@ -0,0 +1,22 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"net/http"
+)
+
+func main() {
+	port := flag.Int("p", 8080, "port to listen on")
+	flag.Parse()
+
+	server := NewServer()
+
+	addr := fmt.Sprintf(":%d", *port) // check port >0 // accept IP for mvp security
+	// add signal catching for clean shutdown via context and httpServer or the like
+	log.Printf("listening on %s", addr)
+	if err := http.ListenAndServe(addr, server); err != nil {
+		panic(err)
+	}
+}

cmd/cache-service/oplog.go

@@ -0,0 +1,77 @@
+package main
+
+import (
+	"fmt"
+	"render231011/internal/thestore"
+	"slices"
+	"sync"
+	"time"
+)
+
+type Oplog struct {
+	mutex         *sync.RWMutex
+	events        []timestampedEvent
+	idx           int // todo
+	lastTruncated time.Time
+}
+
+type timestampedEvent struct {
+	t time.Time
+	e thestore.Event
+}
+
+func (timestampedEvent timestampedEvent) String() string {
+	return fmt.Sprintf("@%v: %+v", timestampedEvent.t.Unix(), timestampedEvent.e)
+}
+
+// gotcha duration? bigger N? whatever
+func NewOplog() *Oplog {
+	return &Oplog{
+		events: make([]timestampedEvent, 2),
+		mutex:  &sync.RWMutex{},
+	}
+}
+
+// todo circular queue if we got time
+func (oplog *Oplog) Push(event thestore.Event) {
+	oplog.push(time.Now(), event)
+}
+
+func (oplog *Oplog) push(t time.Time, event thestore.Event) {
+	oplog.mutex.Lock()
+	defer oplog.mutex.Unlock()
+	oplog.lastTruncated = oplog.events[oplog.idx].t
+	oplog.events[oplog.idx] = timestampedEvent{
+		t: t,
+		e: event,
+	}
+	oplog.idx++
+	if oplog.idx >= len(oplog.events) {
+		oplog.idx = 0
+	}
+}
+
+func (oplog *Oplog) Since(t time.Time) ([]thestore.Event, bool) {
+	oplog.mutex.RLock()
+	defer oplog.mutex.RUnlock()
+
+	if !t.After(oplog.lastTruncated) {
+		return nil, false
+	}
+
+	result := make([]thestore.Event, 0, 5)
+	i := (oplog.idx + len(oplog.events) - 1) % len(oplog.events)
+	for i != oplog.idx {
+		if !oplog.events[i].t.After(t) {
+			break
+		}
+		result = append(result, oplog.events[i].e)
+
+		i--
+		if i < 0 {
+			i = len(oplog.events)
+		}
+	}
+	slices.Reverse(result)
+	return result, len(result) > 0
+}

cmd/cache-service/oplog_test.go

@@ -0,0 +1,27 @@
+package main
+
+import (
+	"render231011/internal/thestore"
+	"testing"
+	"time"
+)
+
+func TestOplog(t *testing.T) {
+	oplog := NewOplog()
+	oplog.push(time.Unix(1, 0), thestore.Event{ID: "1"})
+	oplog.push(time.Unix(2, 0), thestore.Event{ID: "2"})
+	oplog.push(time.Unix(3, 0), thestore.Event{ID: "3"})
+	oplog.push(time.Unix(4, 0), thestore.Event{ID: "4"})
+
+	t.Logf("%+v, %s", oplog, oplog.lastTruncated.UTC())
+
+	got, _ := oplog.Since(time.Unix(2, 0))
+	if len(got) != 2 {
+		t.Error(got)
+	} else if got[0].ID != "3" {
+		t.Error(got[0])
+	} else if got[1].ID != "4" {
+		t.Error(got[1])
+	}
+	t.Logf("%+v", got)
+}

cmd/cache-service/server.go

@@ -0,0 +1,68 @@
+package main
+
+import (
+	"encoding/json"
+	"log"
+	"net/http"
+	"render231011/internal/thestore"
+	"strconv"
+	"strings"
+	"time"
+)
+
+type Server struct {
+	store *thestore.Store
+	oplog *Oplog
+}
+
+func NewServer() Server {
+	return Server{
+		store: thestore.NewStore(),
+		oplog: NewOplog(),
+	}
+}
+
+func (server Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	// todo middleware: rate limit
+	// todo middleware: timeout requests
+	// todo: replace with an actual router
+	if strings.HasPrefix(r.URL.Path, "/event") && r.Method == http.MethodPost {
+		server.servePostEvent(w, r)
+	} else if r.URL.Path == "/events" && r.Method == http.MethodGet {
+		server.serveGetEvents(w, r)
+	}
+}
+
+func (server Server) servePostEvent(w http.ResponseWriter, r *http.Request) {
+	var newEvent thestore.Event
+	if err := json.NewDecoder(r.Body).Decode(&newEvent); err != nil {
+		w.WriteHeader(http.StatusBadRequest)
+		// todo error msg pls
+		return
+	}
+
+	// todo check if action==updated service-id already exists
+	server.store.Push(newEvent)
+	log.Printf("ingested event %+v", newEvent)
+
+	// todo store the op log
+	server.oplog.Push(newEvent)
+}
+
+func (server Server) serveGetEvents(w http.ResponseWriter, r *http.Request) {
+	// todo my circular queue magic
+	sinceString := r.URL.Query().Get("since")
+	sinceInt, err := strconv.ParseInt(sinceString, 10, 64)
+	if err != nil {
+		// todo emit helpful err message
+		w.WriteHeader(http.StatusBadRequest)
+		return
+	}
+	since := time.Unix(sinceInt, 0)
+
+	result, ok := server.oplog.Since(since)
+	if !ok {
+		result = server.store.Dump()
+	}
+	json.NewEncoder(w).Encode(result)
+}