import java.io.IOException;

/**
 * Contains some daemon diagnostics information useful for the client.
 */
public class DaemonDiagnostics {

    @Nullable
    private final Long pid;
    private final File daemonLog;
    private final static int TAIL_SIZE = 20;

    public DaemonDiagnostics(File daemonLog, @Nullable Long pid) {
        this.daemonLog = daemonLog;
        this.pid = pid;
    }

    /**

package org.gradle.launcher.daemon.protocol;

import org.gradle.launcher.daemon.diagnostics.DaemonDiagnostics;

/**
 * Returned when the daemon starts a build command, signifying that it has begun processing it.
 */
public class BuildStarted extends Message {

    private final DaemonDiagnostics diagnostics;

    public BuildStarted(DaemonDiagnostics diagnostics) {
        this.diagnostics = diagnostics;
    }

public class StartBuildOrRespondWithBusy extends BuildCommandOnly {
    
    private static final Logger LOGGER = Logging.getLogger(StartBuildOrRespondWithBusy.class);
    private final DaemonDiagnostics diagnostics;

    public StartBuildOrRespondWithBusy(DaemonDiagnostics diagnostics) {
        this.diagnostics = diagnostics;
    }

    @Override
    protected void doBuild(final DaemonCommandExecution execution, final Build build) {

import javax.annotation.Nullable;

public class DaemonStartupInfo {
    private final String uid;
    private final Address address;
    private final DaemonDiagnostics diagnostics;

    public DaemonStartupInfo(String uid, Address address, DaemonDiagnostics diagnostics) {
        this.uid = uid;
        this.address = address;
        this.diagnostics = diagnostics;
    }

    public String getUid() {

        DaemonLogFile daemonLogFile,
        GradleUserHomeScopeServiceRegistry userHomeServiceRegistry,
        ListenerManager listenerManager
    ) {
        DaemonDiagnostics daemonDiagnostics = new DaemonDiagnostics(daemonLogFile.getFile(), daemonContext.getPid());
        return ImmutableList.of(
            new HandleStop(listenerManager),
            new HandleInvalidateVirtualFileSystem(userHomeServiceRegistry),

    @Rule TestNameTestDirectoryProvider temp = new TestNameTestDirectoryProvider(getClass())

    def "tailing the daemon log is always safe"() {
        given:
        def diagnostics = new DaemonDiagnostics(new File("does not exist"), 123)

        when:
        def description = diagnostics.describe()

        then:
        noExceptionThrown()
        description.contains("Unable to read from the daemon log file")

    private final LoggingOutputInternal loggingOutput;
    private final DaemonDiagnostics diagnostics;

    private volatile AsynchronousLogDispatcher dispatcher;

    public LogToClient(LoggingOutputInternal loggingOutput, DaemonDiagnostics diagnostics) {
        this.loggingOutput = loggingOutput;
        this.diagnostics = diagnostics;
    }

    @Override

import org.gradle.internal.serialize.InputStreamBackedDecoder;
import org.gradle.internal.serialize.OutputStreamBackedEncoder;
import org.gradle.internal.stream.EncodedStream;
import org.gradle.launcher.daemon.diagnostics.DaemonDiagnostics;
import org.gradle.launcher.daemon.diagnostics.DaemonStartupInfo;
import org.gradle.launcher.daemon.logging.DaemonMessages;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;

import org.gradle.internal.logging.events.OutputEventListener;
import org.gradle.internal.nativeintegration.ProcessEnvironment;
import org.gradle.launcher.daemon.context.DaemonContext;
import org.gradle.launcher.daemon.diagnostics.DaemonDiagnostics;
import org.gradle.launcher.daemon.protocol.Build;
import org.gradle.launcher.daemon.protocol.BuildEvent;
import org.gradle.launcher.daemon.protocol.BuildStarted;
import org.gradle.launcher.daemon.protocol.CloseInput;

        expect:
        def diagnostics = new DaemonDiagnostics(new File("log"), 1234L)
        def message = new BuildStarted(diagnostics)
        def result = serialize(message, serializer)
        result instanceof BuildStarted
        result.diagnostics.daemonLog == message.diagnostics.daemonLog
        result.diagnostics.pid == message.diagnostics.pid

        def diagnostics2 = new DaemonDiagnostics(new File("log"), null)