1 files changed, 34 insertions, 11 deletions

diff --git a/pw_rpc/nanopb/public/pw_rpc/nanopb/fake_channel_output.h b/pw_rpc/nanopb/public/pw_rpc/nanopb/fake_channel_output.h
index 360cfc1d5..f71c87795 100644
--- a/pw_rpc/nanopb/public/pw_rpc/nanopb/fake_channel_output.h
+++ b/pw_rpc/nanopb/public/pw_rpc/nanopb/fake_channel_output.h
@@ -15,16 +15,28 @@
 
 #include <cstddef>
 #include <cstdint>
+#include <mutex>
 
 #include "pw_assert/assert.h"
 #include "pw_bytes/span.h"
 #include "pw_containers/vector.h"
 #include "pw_containers/wrapped_iterator.h"
 #include "pw_rpc/internal/fake_channel_output.h"
+#include "pw_rpc/internal/lock.h"
 #include "pw_rpc/nanopb/internal/common.h"
 #include "pw_rpc/nanopb/internal/method.h"
 
 namespace pw::rpc {
+namespace internal {
+
+// Forward declare for a friend statement.
+template <typename, size_t, size_t, size_t>
+class ForwardingChannelOutput;
+
+}  // namespace internal
+}  // namespace pw::rpc
+
+namespace pw::rpc {
 namespace internal::test::nanopb {
 
 // Forward declare for a friend statement.
@@ -44,7 +56,7 @@ class NanopbPayloadsView {
     // Access the payload (rather than packet) with operator*.
     Payload operator*() const {
       Payload payload{};
-      PW_ASSERT(serde_.Decode(Base::value(), &payload));
+      PW_ASSERT_OK(serde_.Decode(Base::value(), payload));
       return payload;
     }
 
@@ -60,7 +72,7 @@ class NanopbPayloadsView {
 
   Payload operator[](size_t index) const {
     Payload payload{};
-    PW_ASSERT(serde_.Decode(view_[index], &payload));
+    PW_ASSERT_OK(serde_.Decode(view_[index], payload));
     return payload;
   }
 
@@ -112,11 +124,12 @@ class NanopbFakeChannelOutput final
   // thread accesses the FakeChannelOutput.
   template <auto kMethod>
   NanopbPayloadsView<Request<kMethod>> requests(
-      uint32_t channel_id = Channel::kUnassignedChannelId) const {
-    constexpr internal::PacketType packet_type =
+      uint32_t channel_id = Channel::kUnassignedChannelId) const
+      PW_NO_LOCK_SAFETY_ANALYSIS {
+    constexpr internal::pwpb::PacketType packet_type =
         HasClientStream(internal::MethodInfo<kMethod>::kType)
-            ? internal::PacketType::CLIENT_STREAM
-            : internal::PacketType::REQUEST;
+            ? internal::pwpb::PacketType::CLIENT_STREAM
+            : internal::pwpb::PacketType::REQUEST;
     return NanopbPayloadsView<Request<kMethod>>(
         internal::MethodInfo<kMethod>::serde().request(),
         Base::packets(),
@@ -136,11 +149,12 @@ class NanopbFakeChannelOutput final
   // thread accesses the FakeChannelOutput.
   template <auto kMethod>
   NanopbPayloadsView<Response<kMethod>> responses(
-      uint32_t channel_id = Channel::kUnassignedChannelId) const {
-    constexpr internal::PacketType packet_type =
+      uint32_t channel_id = Channel::kUnassignedChannelId) const
+      PW_NO_LOCK_SAFETY_ANALYSIS {
+    constexpr internal::pwpb::PacketType packet_type =
         HasServerStream(internal::MethodInfo<kMethod>::kType)
-            ? internal::PacketType::SERVER_STREAM
-            : internal::PacketType::RESPONSE;
+            ? internal::pwpb::PacketType::SERVER_STREAM
+            : internal::pwpb::PacketType::RESPONSE;
     return NanopbPayloadsView<Response<kMethod>>(
         internal::MethodInfo<kMethod>::serde().response(),
         Base::packets(),
@@ -153,6 +167,7 @@ class NanopbFakeChannelOutput final
 
   template <auto kMethod>
   Response<kMethod> last_response() const {
+    std::lock_guard lock(internal::test::FakeChannelOutput::mutex());
     NanopbPayloadsView<Response<kMethod>> payloads = responses<kMethod>();
     PW_ASSERT(!payloads.empty());
     return payloads.back();
@@ -161,6 +176,8 @@ class NanopbFakeChannelOutput final
  private:
   template <typename, auto, uint32_t, size_t, size_t>
   friend class internal::test::nanopb::NanopbInvocationContext;
+  template <typename, size_t, size_t, size_t>
+  friend class internal::ForwardingChannelOutput;
 
   using Base =
       internal::test::FakeChannelOutputBuffer<kMaxPackets,
@@ -168,12 +185,18 @@ class NanopbFakeChannelOutput final
 
   using internal::test::FakeChannelOutput::last_packet;
 
+  // !!! WARNING !!!
+  //
+  // Access to the FakeChannelOutput through the NanopbPayloadsView is NOT
+  // synchronized! The NanopbPayloadsView is immediately invalidated if any
+  // thread accesses the FakeChannelOutput.
   template <typename T>
   NanopbPayloadsView<T> payload_structs(const internal::NanopbSerde& serde,
                                         MethodType type,
                                         uint32_t channel_id,
                                         uint32_t service_id,
-                                        uint32_t method_id) const {
+                                        uint32_t method_id) const
+      PW_NO_LOCK_SAFETY_ANALYSIS {
     return NanopbPayloadsView<T>(
         serde, Base::packets(), type, channel_id, service_id, method_id);
   }