ShmPathBuilder extension for inter-VM shm path construction

score/mw/com/impl/bindings/lola/shm_path_builder.cpp

@@ -30,6 +30,7 @@ constexpr auto kDataChannelPrefix = "lola-data-";
 constexpr auto kControlChannelPrefix = "lola-ctl-";
 constexpr auto kMethodChannelPrefix = "lola-methods-";
 constexpr auto kAsilBControlChannelSuffix = "-b";
+constexpr auto kInterVmSharedShmPrefix = "/intervm-shared-shmem/";
 
 /// Emit file name of the control file to an ostream
 ///
@@ -110,15 +111,17 @@ void EmitMethodFileName(std::ostream& out,
 
 std::string ShmPathBuilder::GetDataChannelShmName(const LolaServiceInstanceId::InstanceId instance_id) const noexcept
 {
-    return EmitWithPrefix('/', [this, instance_id](auto& out) {
+    const auto prefix = inter_vm_support_ ? kInterVmSharedShmPrefix : "/";
+    return EmitWithPrefix(prefix, [this, instance_id](auto& out) {
         EmitDataFileName(out, service_id_, instance_id);
     });
 }
 
 std::string ShmPathBuilder::GetControlChannelShmName(const LolaServiceInstanceId::InstanceId instance_id,
                                                      const QualityType channel_type) const noexcept
 {
-    return EmitWithPrefix('/', [this, channel_type, instance_id](auto& out) noexcept {
+    const auto prefix = inter_vm_support_ ? kInterVmSharedShmPrefix : "/";
+    return EmitWithPrefix(prefix, [this, channel_type, instance_id](auto& out) noexcept {
         EmitControlFileName(out, channel_type, service_id_, instance_id);
     });
 }
@@ -127,7 +130,8 @@ std::string ShmPathBuilder::GetMethodChannelShmName(
     const LolaServiceInstanceId::InstanceId instance_id,
     const ProxyInstanceIdentifier& proxy_instance_identifier) const noexcept
 {
-    return EmitWithPrefix('/', [this, instance_id, proxy_instance_identifier](auto& out) noexcept {
+    const auto prefix = inter_vm_support_ ? kInterVmSharedShmPrefix : "/";
+    return EmitWithPrefix(prefix, [this, instance_id, proxy_instance_identifier](auto& out) noexcept {
         EmitMethodFileName(out, service_id_, instance_id, proxy_instance_identifier);
     });
 }

score/mw/com/impl/bindings/lola/shm_path_builder.h

@@ -29,7 +29,19 @@ namespace score::mw::com::impl::lola
 class ShmPathBuilder : public IShmPathBuilder
 {
   public:
-    explicit ShmPathBuilder(const std::uint16_t service_id) noexcept : IShmPathBuilder{}, service_id_{service_id} {}
+    /// \brief Constructs a ShmPathBuilder for the given service.
+    ///
+    /// \param service_id       Numeric identifier of the LoLa service.
+    /// \param inter_vm_support When \c true, the prefix \c "/intervm-shared-shmem/" is prepended
+    ///                         to all generated SHM object path names.
+    ///                         \note This is an interim solution to express the intent to have a
+    ///                         shared-memory object that supports sharing across VMs by encoding it
+    ///                         into the path name. A future solution will be based on a redesigned
+    ///                         \c lib/memory/shared API abstraction.
+    explicit ShmPathBuilder(const std::uint16_t service_id, const bool inter_vm_support = false) noexcept
+        : IShmPathBuilder{}, service_id_{service_id}, inter_vm_support_{inter_vm_support}
+    {
+    }
 
     std::string GetDataChannelShmName(const LolaServiceInstanceId::InstanceId instance_id) const noexcept override;
 
@@ -42,6 +54,7 @@ class ShmPathBuilder : public IShmPathBuilder
 
   private:
     const std::uint16_t service_id_;
+    const bool inter_vm_support_;
 };
 
 }  // namespace score::mw::com::impl::lola

score/mw/com/impl/bindings/lola/shm_path_builder_test.cpp

@@ -136,6 +136,62 @@ TEST_P(ShmPathBuilderMethodParamaterizedTestFixture, TestBuildingMethodChannelSh
     EXPECT_EQ(expected_path, actual_path);
 }
 
+TEST(ShmPathBuilderInterVmSupportTest, BuildsDataChannelShmNamePathWithInterVmPrefix)
+{
+    constexpr LolaServiceInstanceId::InstanceId instance_id{1};
+
+    // Given a ShmPathBuilder with inter-vm support enabled
+    ShmPathBuilder builder{kServiceId, true};
+
+    // When creating the data channel shm name
+    const auto actual_path = builder.GetDataChannelShmName(instance_id);
+
+    // Then the returned path should use the inter-vm prefix with standard padding
+    EXPECT_EQ("/intervm-shared-shmem/lola-data-0000000000004660-00001", actual_path);
+}
+
+TEST(ShmPathBuilderInterVmSupportTest, BuildsControlChannelShmNamePathWithInterVmPrefix)
+{
+    constexpr LolaServiceInstanceId::InstanceId instance_id{1};
+
+    // Given a ShmPathBuilder with inter-vm support enabled
+    ShmPathBuilder builder{kServiceId, true};
+
+    // When creating the control channel shm name
+    const auto actual_path = builder.GetControlChannelShmName(instance_id, QualityType::kASIL_B);
+
+    // Then the returned path should use the inter-vm prefix with standard padding
+    EXPECT_EQ("/intervm-shared-shmem/lola-ctl-0000000000004660-00001-b", actual_path);
+}
+
+TEST(ShmPathBuilderInterVmSupportTest, BuildsMethodChannelShmNamePathWithInterVmPrefix)
+{
+    constexpr LolaServiceInstanceId::InstanceId instance_id{1};
+    constexpr ProxyInstanceIdentifier proxy_instance_identifier{2U, 3U};
+
+    // Given a ShmPathBuilder with inter-vm support enabled
+    ShmPathBuilder builder{kServiceId, true};
+
+    // When creating the method channel shm name
+    const auto actual_path = builder.GetMethodChannelShmName(instance_id, proxy_instance_identifier);
+
+    // Then the returned path should use the inter-vm prefix with standard padding
+    EXPECT_EQ("/intervm-shared-shmem/lola-methods-0000000000004660-00001-00002-00003", actual_path);
+}
+
+TEST(ShmPathBuilderInterVmSupportDeathTests, GetControlChannelShmNameDiesWithInvalidQualityType)
+{
+    constexpr LolaServiceInstanceId::InstanceId instance_id{1};
+    constexpr QualityType invalid_quality_type = QualityType::kInvalid;
+
+    // Given a ShmPathBuilder with inter-vm support enabled
+    ShmPathBuilder builder{kServiceId, true};
+
+    // When creating the control channel shm name with an invalid quality type
+    // Then we expect it to die
+    EXPECT_DEATH(builder.GetControlChannelShmName(instance_id, invalid_quality_type), "");
+}
+
 INSTANTIATE_TEST_SUITE_P(
     ShmPathBuilderMethodTests,
     ShmPathBuilderMethodParamaterizedTestFixture,