merged with fixes

internal/mtprotoedge/circular_history_test.go

@@ -0,0 +1,29 @@
+package mtprotoedge
+
+import "testing"
+
+func TestInboundSeenHistoryUsesStableCircularBacking(t *testing.T) {
+	state := newConnState()
+	for id := int64(1); id <= maxTrackedClientMsgIDs; id++ {
+		state.trackInbound(id, int32(id*2+1), true, false, msgStateReceived)
+	}
+	if len(state.order) != maxTrackedClientMsgIDs || len(state.seen) != maxTrackedClientMsgIDs {
+		t.Fatalf("initial seen history = order:%d map:%d", len(state.order), len(state.seen))
+	}
+	backing := &state.order[0]
+	for id := int64(maxTrackedClientMsgIDs + 1); id <= 4*maxTrackedClientMsgIDs; id++ {
+		state.trackInbound(id, int32(id*2+1), true, false, msgStateReceived)
+	}
+	if &state.order[0] != backing {
+		t.Fatal("full seen history replaced its circular backing")
+	}
+	if len(state.order) != maxTrackedClientMsgIDs || len(state.seen) != maxTrackedClientMsgIDs {
+		t.Fatalf("steady seen history = order:%d map:%d", len(state.order), len(state.seen))
+	}
+	if _, ok := state.seenRecord(1); ok {
+		t.Fatal("seen history retained its oldest ID")
+	}
+	if _, ok := state.seenRecord(4 * maxTrackedClientMsgIDs); !ok {
+		t.Fatal("seen history lost its newest ID")
+	}
+}