Don't use exceptions for expected control flow

canonical · Oct 24, 2023 · b3e221d · b3e221d
1 parent 1822b55
commit b3e221d
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Showing 3 changed files with 18 additions and 26 deletions.
diff --git a/src/platforms/virtual/CMakeLists.txt b/src/platforms/virtual/CMakeLists.txt
@@ -8,6 +8,8 @@ configure_file(
 )
 set(symbol_map ${CMAKE_CURRENT_BINARY_DIR}/symbols.map)
 
+add_compile_definitions(MIR_LOG_COMPONENT="mir::virtual")
+
 add_library(mirplatformgraphicsvirtualobjects OBJECT
     graphics.cpp
     platform.cpp

diff --git a/src/platforms/virtual/platform.cpp b/src/platforms/virtual/platform.cpp
@@ -18,6 +18,7 @@
 #include "display.h"
 #include "mir/graphics/platform.h"
 #include "mir/graphics/egl_error.h"
+#include "mir/log.h"
 #include "options_parsing_helpers.h"
 #include <drm_fourcc.h>
 
@@ -41,18 +42,11 @@ class mgv::Platform::VirtualDisplayInterfaceProvider : public mg::DisplayInterfa
         class VirtualEGLDisplayProvider : public GenericEGLDisplayProvider
         {
         public:
+
+            explicit VirtualEGLDisplayProvider(EGLDisplay const egl_display) : egl_display{egl_display} {}
+
             auto get_egl_display() -> EGLDisplay override
             {
-                auto const egl_display = eglGetDisplay(EGL_DEFAULT_DISPLAY);
-                if (egl_display == EGL_NO_DISPLAY)
-                {
-                    BOOST_THROW_EXCEPTION((std::runtime_error{"Failed to create EGL display"}));
-                }
-                EGLint major, minor;
-                if (eglInitialize(egl_display, &major, &minor) == EGL_FALSE)
-                {
-                    BOOST_THROW_EXCEPTION(egl_error("Failed to initialize EGL display"));
-                }
                 return egl_display;
             }
 
@@ -79,6 +73,7 @@ class mgv::Platform::VirtualDisplayInterfaceProvider : public mg::DisplayInterfa
             }
 
         private:
+            EGLDisplay const egl_display;
         };
 
         class VirtualCPUAddressableDisplayProvider: public CPUAddressableDisplayProvider
@@ -130,17 +125,18 @@ class mgv::Platform::VirtualDisplayInterfaceProvider : public mg::DisplayInterfa
 
         if (dynamic_cast<mg::GenericEGLDisplayProvider::Tag const*>(&type_tag))
         {
-            auto egl_display_provider = std::make_shared<VirtualEGLDisplayProvider>();
-            try
+            auto const egl_display = eglGetDisplay(EGL_DEFAULT_DISPLAY);
+            if (egl_display == EGL_NO_DISPLAY)
+            {
+                log_info("Failed to create EGL display");
+            }
+            else if (eglInitialize(egl_display, nullptr, nullptr) == EGL_FALSE)
             {
-                // If we cannot get the egl display, we can ignore it in the hopes
-                // that we can use the CPUAddressableDisplayProvider later on instead.
-                egl_display_provider->get_egl_display();
-                return egl_display_provider;
+                log_debug("Failed to initialise EGL: %s", mg::egl_category().message(eglGetError()).c_str());
             }
-            catch (std::runtime_error const&)
+            else
             {
-                return nullptr;
+                return std::make_shared<VirtualEGLDisplayProvider>(egl_display);
             }
         }
 

diff --git a/tests/unit-tests/platforms/virtual/test_platform.cpp b/tests/unit-tests/platforms/virtual/test_platform.cpp
@@ -80,10 +80,7 @@ TEST_F(VirtualGraphicsPlatformTest, can_acquire_interface_for_generic_egl_displa
     ON_CALL(mock_egl, eglGetDisplay(_))
         .WillByDefault(Return(fake_display));
     ON_CALL(mock_egl, eglInitialize(_,_,_))
-        .WillByDefault(DoAll(
-            SetArgPointee<1>(1),
-            SetArgPointee<2>(4),
-            Return(EGL_TRUE)));
+        .WillByDefault(Return(EGL_TRUE));
     auto platform = create_platform();
     auto interface = mg::DisplayPlatform::interface_for(platform);
     EXPECT_TRUE(interface->acquire_interface<mg::GenericEGLDisplayProvider>() != nullptr);
@@ -94,10 +91,7 @@ TEST_F(VirtualGraphicsPlatformTest, cannot_acquire_interface_for_generic_egl_dis
     ON_CALL(mock_egl, eglGetDisplay(_))
         .WillByDefault(Return(EGL_NO_DISPLAY));
     ON_CALL(mock_egl, eglInitialize(_,_,_))
-        .WillByDefault(DoAll(
-            SetArgPointee<1>(1),
-            SetArgPointee<2>(4),
-            Return(EGL_TRUE)));
+        .WillByDefault(Return(EGL_TRUE));
     auto platform = create_platform();
     auto interface = mg::DisplayPlatform::interface_for(platform);
     EXPECT_THAT(interface->acquire_interface<mg::GenericEGLDisplayProvider>(), nullptr);