ezStartup Class Reference

The startup system makes sure to initialize and shut down all known subsystems in the proper order. More...

#include <Startup.h>

Static Public Member Functions
static void	AddApplicationTag (const char *szTag)
	Stores the const char* as a tag. Does not copy the string, so this must be a string embedded in the application code. More...
static bool	HasApplicationTag (const char *szTag)
	Query whether a tag was added with AddApplicationTag()
static void	StartupBaseSystems ()
	Runs the 'base' startup sequence of all subsystems in the proper order. More...
static void	StartupCoreSystems ()
	Runs the 'core' startup sequence of all subsystems in the proper order. More...
static void	ShutdownCoreSystems ()
	Runs the 'core' shutdown sequence of all subsystems in the proper order (reversed startup order). More...
static void	StartupHighLevelSystems ()
	Runs the 'high level' startup sequence of all subsystems in the proper order. More...
static void	ShutdownHighLevelSystems ()
	Runs the 'high level' shutdown sequence of all subsystems in the proper order (reversed startup order). More...
static void	PrintAllSubsystems ()
	Output info about all known subsystems via the logging system (can change when DLLs are loaded dynamically).
static void	ReinitToCurrentState ()
	Calls StartupBaseSystems(), StartupCoreSystems() or StartupHighLevelSystems() again, depending on what was done last. More...

Detailed Description

The startup system makes sure to initialize and shut down all known subsystems in the proper order.

Each subsystem can define on which other subsystems (or entire group) it is dependent (i.e. which other code it needs in an initialized state, before it can run itself). The startup system will sort all subsystems by their dependencies and then initialize them in the proper order. The startup and shutdown sequence consists of two steps. First the 'core' functionality is initialized. This is usually all the functionality that does not depend on a working rendering context. After all systems have had their 'core' functionality initialized, the 'high level' functionality can be initialized. In between these steps the rendering context should be created. Tools that might not create a window or do not want to actually load GPU resources, might get away with only doing the 'core' initialization. Thus a subsystem should do all the initialization that is independent from a window or rendering context in 'core' startup, and it should be able to work (with some features disabled), even when 'high level' startup is not done.

A subsystem startup configuration for a static subsystem needs to be put in some cpp file of the subsystem and looks like this:

// clang-format off EZ_BEGIN_SUBSYSTEM_DECLARATION(ExampleGroup, ExampleSubSystem)

BEGIN_SUBSYSTEM_DEPENDENCIES "SomeOtherSubSystem", "SomeOtherSubSystem2", "SomeGroup" END_SUBSYSTEM_DEPENDENCIES

ON_CORESYSTEMS_STARTUP { ezExampleSubSystem::BasicStartup(); }

ON_CORESYSTEMS_SHUTDOWN { ezExampleSubSystem::BasicShutdown(); }

ON_HIGHLEVELSYSTEMS_STARTUP { ezExampleSubSystem::EngineStartup(); }

ON_HIGHLEVELSYSTEMS_SHUTDOWN { ezExampleSubSystem::EngineShutdown(); }

EZ_END_SUBSYSTEM_DECLARATION; // clang-format on

This will automatically register the subsystem, once the code is being loaded (can be dynamically loaded from a DLL). The next time any of the ezStartup functions are called (StartupCoreSystems, StartupHighLevelSystems) the subsystem will be initialized.

If however your subsystem is implemented as a normal class, you need to derive from the base class 'ezSubSystem' and override the virtual functions. Then when you have an instance of that class and call ezStartup::StartupCore etc., that instance will be properly initialized as well. However, you must ensure that the subsystem is properly shut down, before its instance is destroyed. Also you should never have two instances of the same subsystem.

All startup / shutdown procedures broadcast global events before and after they execute.

Member Function Documentation

AddApplicationTag()

void ezStartup::AddApplicationTag ( const char *  szTag )

static

Stores the const char* as a tag. Does not copy the string, so this must be a string embedded in the application code.

Before executing the startup routines an application should set tags that allow plugins to identify the context in which they are running. This makes it possible for the startup functions to conditionally configure things.

Strings that should be used for common things: 'runtime' : For all applications that run the full engine, automatically added by ezGameApplication. Be aware that some tool applications have this set, even though they don't use graphical output. 'editor' : for all applications that run the editor framework, set on the Editor and the EditorProcessor 'testframework' : for applications that execute the ezTestFramework 'tool' : for all stand-alone tool applications, set by the editor, editorprocessor, fileserve, etc.

ReinitToCurrentState()

void ezStartup::ReinitToCurrentState ( )

static

Calls StartupBaseSystems(), StartupCoreSystems() or StartupHighLevelSystems() again, depending on what was done last.

This can be used to first unload plugins and reload them, and then reinit the engine to the state that it was in again.

ShutdownCoreSystems()

static void ezStartup::ShutdownCoreSystems ( )

inlinestatic

Runs the 'core' shutdown sequence of all subsystems in the proper order (reversed startup order).

Call this AFTER window and graphics context have been destroyed already, shortly before application exit. Makes sure that the 'high level' shutdown has been run first. Broadcasts the global event EZ_GLOBALEVENT_SHUTDOWN_CORESYSTEMS_BEGIN and EZ_GLOBALEVENT_SHUTDOWN_CORESYSTEMS_END

ShutdownHighLevelSystems()

static void ezStartup::ShutdownHighLevelSystems ( )

inlinestatic

Runs the 'high level' shutdown sequence of all subsystems in the proper order (reversed startup order).

Run this BEFORE the window and graphics context have been destroyed, such that code that requires those can do its deinitialization first. Broadcasts the global event EZ_GLOBALEVENT_SHUTDOWN_HIGHLEVELSYSTEMS_BEGIN and EZ_GLOBALEVENT_SHUTDOWN_HIGHLEVELSYSTEMS_END

StartupBaseSystems()

static void ezStartup::StartupBaseSystems ( )

inlinestatic

Runs the 'base' startup sequence of all subsystems in the proper order.

Run this, if you only require very low level systems to be initialized. Otherwise prefer StartupCore. There is NO ShutdownBaseSystems, everything that gets initialized during the 'Base Startup' should not need any deinitialization. This function is automatically called by StartupCore, if it hasn't been called before already.

StartupCoreSystems()

static void ezStartup::StartupCoreSystems ( )

inlinestatic

Runs the 'core' startup sequence of all subsystems in the proper order.

Run this BEFORE any window and graphics context have been created. Broadcasts the global event EZ_GLOBALEVENT_STARTUP_CORESYSTEMS_BEGIN and EZ_GLOBALEVENT_STARTUP_CORESYSTEMS_END

StartupHighLevelSystems()

static void ezStartup::StartupHighLevelSystems ( )

inlinestatic

Runs the 'high level' startup sequence of all subsystems in the proper order.

Run this AFTER a window and graphics context have been created, such that anything that depends on that can now do its initialization. Makes sure that the 'core' initialization has been run first. Broadcasts the global event EZ_GLOBALEVENT_STARTUP_HIGHLEVELSYSTEMS_BEGIN and EZ_GLOBALEVENT_STARTUP_HIGHLEVELSYSTEMS_END

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The documentation for this class was generated from the following files:

• /home/runner/work/ezEngine/ezEngine/Code/Engine/Foundation/Configuration/Startup.h
• /home/runner/work/ezEngine/ezEngine/Code/Engine/Foundation/Configuration/Implementation/Startup.cpp