13. Gradle编译其他应用代码流程（二 )

接着上一篇博客开始讲：

5. Gradle编译其他应用程序流程(一)

一. BuildActionsFactory.runBuildInProcess

private Runnable runBuildInProcess(StartParameter startParameter, DaemonParameters daemonParameters, ServiceRegistry loggingServices) {
    ServiceRegistry globalServices = ServiceRegistryBuilder.builder()
       .displayName("Global services")
       .parent(loggingServices)
       .parent(NativeServices.getInstance())
       .provider(new GlobalScopeServices(startParameter.isContinuous()))
       .build();

    return runBuildAndCloseServices(startParameter, daemonParameters, globalServices.get(BuildExecuter.class), globalServices);
}

这个方法就是很绕的地方了！看了半天才大概明白。

首先runBuildInProcess这个方法分成两个部分

1. 初始化

2. 执行

首先来看初始化，也就是：

ServiceRegistry globalServices = ServiceRegistryBuilder.builder()
        .displayName("Global services")
        .parent(loggingServices)
        .parent(NativeServices.getInstance())
        .provider(new GlobalScopeServices(startParameter.isContinuous()))
        .build();

直接看build():

public ServiceRegistry build() {
    DefaultServiceRegistry registry = new DefaultServiceRegistry(displayName, parents);
    for (Object provider : providers) {
        registry.addProvider(provider);
    }
    return registry;
}

实例化的是DefaultServiceRegistry对象，那来看看DefaultServiceRegistry的Javadoc，看看怎么描述的。

org.gradle.internal.service.DefaultServiceRegistry


A hierarchical ServiceRegistry implementation. 

Subclasses can register services by:

Calling add(Class, Object) to register a service instance. 
Calling addProvider(Object) to register a service provider bean. A provider bean may have factory, decorator and configuration methods as described below. 
Adding a factory method. A factory method should have a name that starts with 'create', and have a non-void return type. For example, protected SomeService createSomeService() { .... }. Parameters are injected using services from this registry or its parents. Note that factory methods with a single parameter and an return type equal to that parameter type are interpreted as decorator methods. 
Adding a decorator method. A decorator method should have a name that starts with 'decorate', take a single parameter, and a have return type equal to the parameter type. Before invoking the method, the parameter is located in the parent service registry and then passed to the method. 
Adding a configure method. A configure method should be called 'configure', take a ServiceRegistration parameter, and a have a void return type. Additional parameters are injected using services from this registry or its parents. 
Service instances are created on demand. getFactory(Class) looks for a service instance which implements Factory<T> where T is the expected type.

Service instances and factories are closed when the registry that created them is closed using close(). If a service instance or factory implements java.io.Closeable or org.gradle.internal.concurrent.Stoppable then the appropriate close() or stop() method is called. Instances are closed in reverse dependency order.

Service registries are arranged in a hierarchy. If a service of a given type cannot be located, the registry uses its parent registry, if any, to locate the service.


主要意思就是DefaultServiceRegistry可以通过add(xxx)方法接受服务对象，通过addProvider(xxx)方法接受service provider bean对象。
而service provider bean可以有3种类型的方法

factory 方法
'create'开头，不是void的返回值，等等

decorator 方法
'decorator'开头，等等

configure 方法
'configure'方法，有个ServiceRegistration参数，void返回类型，等等。

那我们回过头来看初始化方法，里面传入了GlobalScopeServices作为provider，所以看下GlobalScopeServices。

二. GlobalScopeServices

public class GlobalScopeServices {
    ...

    void configure(ServiceRegistration registration, ClassLoaderRegistry classLoaderRegistry) {
    	System.out.println("GlobalScopeServices configure registration : " + registration
    			+ " classLoaderRegistry: " + classLoaderRegistry);
        final List<PluginServiceRegistry> pluginServiceFactories = new DefaultServiceLocator(classLoaderRegistry.getRuntimeClassLoader(), classLoaderRegistry.getPluginsClassLoader()).getAll(PluginServiceRegistry.class);
        for (PluginServiceRegistry pluginServiceRegistry : pluginServiceFactories) {
            registration.add(PluginServiceRegistry.class, pluginServiceRegistry);
            pluginServiceRegistry.registerGlobalServices(registration);
        }
    }

	...
	
    ClassLoaderRegistry createClassLoaderRegistry(ClassPathRegistry classPathRegistry, HashingClassLoaderFactory classLoaderFactory) {
        if (GradleRuntimeShadedJarDetector.isLoadedFrom(getClass())) {
            return new FlatClassLoaderRegistry(getClass().getClassLoader());
        }
        System.out.println("createClassLoaderRegistry");

        return new DefaultClassLoaderRegistry(classPathRegistry, classLoaderFactory);
    }
	
	...
}

首先看configure方法

pluginServiceRegistry.registerGlobalServices(registration);

这行代码registerGlobalServices其实调用的是LauncherServices.registerGlobalServices

也就是：

public class LauncherServices implements PluginServiceRegistry {
    public void registerGlobalServices(ServiceRegistration registration) {
        registration.addProvider(new ToolingGlobalScopeServices());
    }
	
	static class ToolingGlobalScopeServices {
        BuildExecuter createBuildExecuter(GradleLauncherFactory gradleLauncherFactory, ServiceRegistry globalServices, ListenerManager listenerManager, FileWatcherFactory fileWatcherFactory, ExecutorFactory executorFactory, StyledTextOutputFactory styledTextOutputFactory) {
            List<BuildActionRunner> buildActionRunners = globalServices.getAll(BuildActionRunner.class);
            BuildActionExecuter<BuildActionParameters> delegate = new InProcessBuildActionExecuter(gradleLauncherFactory, new ChainingBuildActionRunner(buildActionRunners));
            return new ContinuousBuildActionExecuter(delegate, fileWatcherFactory, listenerManager, styledTextOutputFactory, executorFactory);
        }

        ExecuteBuildActionRunner createExecuteBuildActionRunner() {
            return new ExecuteBuildActionRunner();
        }

        ClassLoaderCache createClassLoaderCache() {
            return new ClassLoaderCache();
        }
    }
}	

registerGlobalServices的时候，实例化并添加了ToolingGlobalScopeServices对象。

最主要的是实例化了一个InProcessBuildActionExecuter对象，当然这里又不能免俗的使用了装饰者模式(ContinuousBuildActionExecuter包含了InProcessBuildActionExecuter，其实还是调用InProcessBuildActionExecuter.execute)

---------------------------分割线----------------------------------------

这个中间的逻辑非常绕，就是怎么回调到provider的factory和config方法？

有兴趣的同学可以自己去看。我贴一段中间回调createXXX的代码调用堆栈(也就是factory方法的调用)

java.lang.Exception: Sandy DefaultModule init
	at org.gradle.api.internal.classpath.DefaultModuleRegistry$DefaultModule.<init>(DefaultModuleRegistry.java:256)
	at org.gradle.api.internal.classpath.DefaultModuleRegistry.module(DefaultModuleRegistry.java:121)
	at org.gradle.api.internal.classpath.DefaultModuleRegistry.loadModule(DefaultModuleRegistry.java:89)
	at org.gradle.api.internal.classpath.DefaultModuleRegistry.getModule(DefaultModuleRegistry.java:77)
	at org.gradle.api.internal.DynamicModulesClassPathProvider.findClassPath(DynamicModulesClassPathProvider.java:38)
	at org.gradle.api.internal.DefaultClassPathRegistry.getClassPath(DefaultClassPathRegistry.java:34)
	at org.gradle.initialization.DefaultClassLoaderRegistry.<init>(DefaultClassLoaderRegistry.java:32)
	at org.gradle.internal.service.scopes.GlobalScopeServices.createClassLoaderRegistry(GlobalScopeServices.java:212)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:483)
	at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:75)
	at org.gradle.internal.service.DefaultServiceRegistry.invoke(DefaultServiceRegistry.java:468)
	at org.gradle.internal.service.DefaultServiceRegistry.access$1200(DefaultServiceRegistry.java:84)
	at org.gradle.internal.service.DefaultServiceRegistry$FactoryMethodService.invokeMethod(DefaultServiceRegistry.java:803)
	at org.gradle.internal.service.DefaultServiceRegistry$FactoryService.create(DefaultServiceRegistry.java:758)
	at org.gradle.internal.service.DefaultServiceRegistry$ManagedObjectProvider.getInstance(DefaultServiceRegistry.java:595)
	at org.gradle.internal.service.DefaultServiceRegistry$SingletonService.get(DefaultServiceRegistry.java:640)
	at org.gradle.internal.service.DefaultServiceRegistry.applyConfigureMethod(DefaultServiceRegistry.java:257)
	at org.gradle.internal.service.DefaultServiceRegistry.findProviderMethods(DefaultServiceRegistry.java:216)
	at org.gradle.internal.service.DefaultServiceRegistry.addProvider(DefaultServiceRegistry.java:358)
	at org.gradle.internal.service.ServiceRegistryBuilder.build(ServiceRegistryBuilder.java:52)
	at org.gradle.launcher.cli.BuildActionsFactory.runBuildInProcess(BuildActionsFactory.java:135)
	at org.gradle.launcher.cli.BuildActionsFactory.createAction(BuildActionsFactory.java:91)
	at org.gradle.launcher.cli.CommandLineActionFactory$ParseAndBuildAction.createAction(CommandLineActionFactory.java:255)
	at org.gradle.launcher.cli.CommandLineActionFactory$ParseAndBuildAction.execute(CommandLineActionFactory.java:240)
	at org.gradle.launcher.cli.CommandLineActionFactory$ParseAndBuildAction.execute(CommandLineActionFactory.java:217)
	at org.gradle.launcher.cli.JavaRuntimeValidationAction.execute(JavaRuntimeValidationAction.java:33)
	at org.gradle.launcher.cli.JavaRuntimeValidationAction.execute(JavaRuntimeValidationAction.java:24)
	at org.gradle.launcher.cli.ExceptionReportingAction.execute(ExceptionReportingAction.java:33)
	at org.gradle.launcher.cli.ExceptionReportingAction.execute(ExceptionReportingAction.java:22)
	at org.gradle.launcher.cli.CommandLineActionFactory$WithLogging.execute(CommandLineActionFactory.java:210)
	at org.gradle.launcher.cli.CommandLineActionFactory$WithLogging.execute(CommandLineActionFactory.java:174)
	at org.gradle.launcher.Main.doAction(Main.java:33)
	at org.gradle.launcher.bootstrap.EntryPoint.run(EntryPoint.java:45)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:483)
	at org.gradle.launcher.bootstrap.ProcessBootstrap.runNoExit(ProcessBootstrap.java:60)
	at org.gradle.launcher.bootstrap.ProcessBootstrap.run(ProcessBootstrap.java:37)
	at org.gradle.launcher.GradleMain.main(GradleMain.java:24)

三. 执行

private Runnable runBuildInProcess(StartParameter startParameter, DaemonParameters daemonParameters, ServiceRegistry loggingServices) {
    ServiceRegistry globalServices = ServiceRegistryBuilder.builder()
                .displayName("Global services")
                .parent(loggingServices)
                .parent(NativeServices.getInstance())
                .provider(new GlobalScopeServices(startParameter.isContinuous()))
                .build();

    return runBuildAndCloseServices(startParameter, daemonParameters, globalServices.get(BuildExecuter.class), globalServices);
}


private Runnable runBuildAndCloseServices(StartParameter startParameter, DaemonParameters daemonParameters, BuildActionExecuter<BuildActionParameters> executer, ServiceRegistry sharedServices, Object... stopBeforeSharedServices) {
    BuildActionParameters parameters = createBuildActionParamters(startParameter, daemonParameters);
    Stoppable stoppable = new CompositeStoppable().add(stopBeforeSharedServices).add(sharedServices);
    return new RunBuildAction(executer, startParameter, clientMetaData(), getBuildStartTime(), parameters, sharedServices, stoppable);
}

public class RunBuildAction implements Runnable {
    ServiceRegistry globalServices = ServiceRegistryBuilder.builder()
            .displayName("Global services")
            .parent(loggingServices)
            .parent(NativeServices.getInstance())
            .provider(new GlobalScopeServices(startParameter.isContinuous()))
            .build();

    public void run() {
        try {
        	System.out.println("RunBuildAction executer: " + executer
        			+ " startParameter: " + startParameter
        			+ " buildActionParameters: " + buildActionParameters);
            executer.execute(
                    new ExecuteBuildAction(startParameter),
                    new DefaultBuildRequestContext(new DefaultBuildRequestMetaData(clientMetaData, startTime), new DefaultBuildCancellationToken(), new NoOpBuildEventConsumer()),
                    buildActionParameters,
                    sharedServices);
        } finally {
            if (stoppable != null) {
                stoppable.stop();
            }
        }
    }
}

在RunBuildAction里面执行的还是executer.execute，也就是第三个参数globalServices.get(BuildExecuter.class)

globalServices是build出来的DefaultServiceRegistry对象

其实就是GlobalScopeServices.configure方法里面的ServiceRegistration对象。

void configure(ServiceRegistration registration, ClassLoaderRegistry classLoaderRegistry) {
  	System.out.println("GlobalScopeServices configure registration : " + registration
    			+ " classLoaderRegistry: " + classLoaderRegistry);
    final List<PluginServiceRegistry> pluginServiceFactories = new DefaultServiceLocator(classLoaderRegistry.getRuntimeClassLoader(), classLoaderRegistry.getPluginsClassLoader()).getAll(PluginServiceRegistry.class);
    for (PluginServiceRegistry pluginServiceRegistry : pluginServiceFactories) {
        registration.add(PluginServiceRegistry.class, pluginServiceRegistry);
        pluginServiceRegistry.registerGlobalServices(registration);
    }
}

打印日志：

GlobalScopeServices configure registration : org.gradle.internal.service.DefaultServiceRegistry$1@56620197 classLoaderRegistry: org.gradle.initialization.DefaultClassLoaderRegistry@393671df

接下来又继续在configure然后调用

pluginServiceRegistry.registerGlobalServices(registration);

根据前面说明的分析，这个registerGlobalServices方法就是调用LauncherServices.registerGlobalServices(registration)，参数是DefaultServiceRegistry registration

public class LauncherServices implements PluginServiceRegistry {
    public void registerGlobalServices(ServiceRegistration registration) {
        registration.addProvider(new ToolingGlobalScopeServices());
    }
	
	static class ToolingGlobalScopeServices {
        BuildExecuter createBuildExecuter(GradleLauncherFactory gradleLauncherFactory, ServiceRegistry globalServices, ListenerManager listenerManager, FileWatcherFactory fileWatcherFactory, ExecutorFactory executorFactory, StyledTextOutputFactory styledTextOutputFactory) {
            List<BuildActionRunner> buildActionRunners = globalServices.getAll(BuildActionRunner.class);
            BuildActionExecuter<BuildActionParameters> delegate = new InProcessBuildActionExecuter(gradleLauncherFactory, new ChainingBuildActionRunner(buildActionRunners));
            return new ContinuousBuildActionExecuter(delegate, fileWatcherFactory, listenerManager, styledTextOutputFactory, executorFactory);
        }
	}	
}

所以也就是给DefaultServiceRegistry registration add了一个ToolingGlobalScopeServices对象。

这样就关联起来了，也就是说RunBuildAction.run方法里面执行的executer.execute走的就是ContinuousBuildActionExecuter.execute，然后通过装饰者模式，最后走的是InProcessBuildActionExecuter.execute方法。

很绕！！！

下面来看InProcessBuildActionExecuter.execute方法。

四. InProcessBuildActionExecuter

@Override
public GradleLauncher newInstance(StartParameter startParameter, BuildRequestContext requestContext, ServiceRegistry parentRegistry) {
    // This should only be used for top-level builds
    if (tracker.getCurrentBuild() != null) {
        throw new IllegalStateException("Cannot have a current build");
    }

    BuildScopeServices buildScopeServices = createBuildScopeServices(parentRegistry);

    DefaultGradleLauncher launcher = doNewInstance(startParameter, false, requestContext.getCancellationToken(), requestContext, requestContext.getEventConsumer(), buildScopeServices);
    DeploymentRegistry deploymentRegistry = parentRegistry.get(DeploymentRegistry.class);
    deploymentRegistry.onNewBuild(launcher.getGradle());
    return launcher;
}
	
	

public class InProcessBuildActionExecuter implements BuildActionExecuter<BuildActionParameters> {
    private final GradleLauncherFactory gradleLauncherFactory;
    private final BuildActionRunner buildActionRunner;

    public InProcessBuildActionExecuter(GradleLauncherFactory gradleLauncherFactory, BuildActionRunner buildActionRunner) {
        this.gradleLauncherFactory = gradleLauncherFactory;
        this.buildActionRunner = buildActionRunner;
    }

    public Object execute(BuildAction action, BuildRequestContext buildRequestContext, BuildActionParameters actionParameters, ServiceRegistry contextServices) {
        GradleLauncher gradleLauncher = gradleLauncherFactory.newInstance(action.getStartParameter(), buildRequestContext, contextServices);
        try {
            gradleLauncher.addStandardOutputListener(buildRequestContext.getOutputListener());
            gradleLauncher.addStandardErrorListener(buildRequestContext.getErrorListener());
            GradleBuildController buildController = new GradleBuildController(gradleLauncher);
            buildActionRunner.run(action, buildController);
            
            System.out.println("Sandy buildController.getResult(): " + buildController.getResult());
            return buildController.getResult();
        } finally {
            gradleLauncher.stop();
        }
    }
}

从代码来看newInstance返回的对象是DefaultGradleLauncher，那么接下来就真正走到开始编译的过程了，这个下篇再继续分析。

最后，附上一点DefaultGradleLauncher源代码：

public class DefaultGradleLauncher extends GradleLauncher {

    private enum Stage {
        Load, Configure, Build
    }

    ...

    @Override
    public BuildResult run() {
        return doBuild(Stage.Build);
    }

    @Override
    public BuildResult getBuildAnalysis() {
        return doBuild(Stage.Configure);
    }

    @Override
    public BuildResult load() throws ReportedException {
        return doBuild(Stage.Load);
    }

    private BuildResult doBuild(final Stage upTo) {
        return buildOperationExecutor.run("Run build", new Factory<BuildResult>() {
            @Override
            public BuildResult create() {
                ...
                doBuildStages(upTo);
                ...
            }
        });
    }

    private void doBuildStages(Stage upTo) {
        if (stage == Stage.Build) {
            throw new IllegalStateException("Cannot build with GradleLauncher multiple times");
        }

        if (stage == null) {
            // Evaluate init scripts
            initScriptHandler.executeScripts(gradle);

            // Build `buildSrc`, load settings.gradle, and construct composite (if appropriate)
            settings = settingsLoader.findAndLoadSettings(gradle);

            stage = Stage.Load;
        }

        if (upTo == Stage.Load) {
            return;
        }

        if (stage == Stage.Load) {
            // Configure build
            buildOperationExecutor.run("Configure build", new Runnable() {
                @Override
                public void run() {
                    buildConfigurer.configure(gradle);

                    if (!gradle.getStartParameter().isConfigureOnDemand()) {
                        buildListener.projectsEvaluated(gradle);
                    }

                    modelConfigurationListener.onConfigure(gradle);
                }
            });

            stage = Stage.Configure;
        }

        if (upTo == Stage.Configure) {
            return;
        }

        // After this point, the GradleLauncher cannot be reused
        stage = Stage.Build;

        // Populate task graph
        buildOperationExecutor.run("Calculate task graph", new Runnable() {
            @Override
            public void run() {
                buildConfigurationActionExecuter.select(gradle);
                if (gradle.getStartParameter().isConfigureOnDemand()) {
                    buildListener.projectsEvaluated(gradle);
                }
            }
        });

        // Execute build
        buildOperationExecutor.run("Run tasks", new Runnable() {
            @Override
            public void run() {
                buildExecuter.execute(gradle);
            }
        });
    }
	
	...
}