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IEventSource Interface

Definition

This interface defines the events raised by the build engine. Loggers use this interface to subscribe to the events they are interested in receiving.

public interface class IEventSource
public interface IEventSource
type IEventSource = interface
Public Interface IEventSource
Derived

Examples

The following example shows how to write a basic logger that responds to build events.

using System;
using System.IO;
using System.Security;
using Microsoft.Build.Framework;
using Microsoft.Build.Utilities;

namespace MyLoggers
{
    // This logger will derive from the Microsoft.Build.Utilities.Logger class,
    // which provides it with getters and setters for Verbosity and Parameters,
    // and a default empty Shutdown() implementation.
    public class BasicFileLogger : Logger
    {
        /// <summary>
        /// Initialize is guaranteed to be called by MSBuild at the start of the build
        /// before any events are raised.
        /// </summary>
        public override void Initialize(IEventSource eventSource)
        {
            // The name of the log file should be passed as the first item in the
            // "parameters" specification in the /logger switch.  It is required
            // to pass a log file to this logger. Other loggers may have zero or more than
            // one parameters.
            if (null == Parameters)
            {
                throw new LoggerException("Log file was not set.");
            }
            string[] parameters = Parameters.Split(';');
            
            string logFile = parameters[0];
            if (String.IsNullOrEmpty(logFile))
            {
                throw new LoggerException("Log file was not set.");
            }
            
            if (parameters.Length > 1)
            {
                throw new LoggerException("Too many parameters passed.");
            }
            
            try
            {
                // Open the file
                this.streamWriter = new StreamWriter(logFile);
            }
            catch (Exception ex)
            {
                if
                (
                    ex is UnauthorizedAccessException
                    || ex is ArgumentNullException
                    || ex is PathTooLongException
                    || ex is DirectoryNotFoundException
                    || ex is NotSupportedException
                    || ex is ArgumentException
                    || ex is SecurityException
                    || ex is IOException
                )
                {
                    throw new LoggerException("Failed to create log file: " + ex.Message);
                }
                else
                {
                    // Unexpected failure
                    throw;
                }
            }

            // For brevity, we'll only register for certain event types. Loggers can also
            // register to handle TargetStarted/Finished and other events.
            eventSource.ProjectStarted += new ProjectStartedEventHandler(eventSource_ProjectStarted);
            eventSource.TaskStarted += new TaskStartedEventHandler(eventSource_TaskStarted);
            eventSource.MessageRaised += new BuildMessageEventHandler(eventSource_MessageRaised);
            eventSource.WarningRaised += new BuildWarningEventHandler(eventSource_WarningRaised);
            eventSource.ErrorRaised += new BuildErrorEventHandler(eventSource_ErrorRaised);
            eventSource.ProjectFinished += new ProjectFinishedEventHandler(eventSource_ProjectFinished);
        }

        void eventSource_ErrorRaised(object sender, BuildErrorEventArgs e)
        {
            // BuildErrorEventArgs adds LineNumber, ColumnNumber, File, amongst other parameters
            string line = String.Format(": ERROR {0}({1},{2}): ", e.File, e.LineNumber, e.ColumnNumber);
            WriteLineWithSenderAndMessage(line, e);
        }
        
        void eventSource_WarningRaised(object sender, BuildWarningEventArgs e)
        {
            // BuildWarningEventArgs adds LineNumber, ColumnNumber, File, amongst other parameters
            string line = String.Format(": Warning {0}({1},{2}): ", e.File, e.LineNumber, e.ColumnNumber);
            WriteLineWithSenderAndMessage(line, e);
        }

        void eventSource_MessageRaised(object sender, BuildMessageEventArgs e)
        {
            // BuildMessageEventArgs adds Importance to BuildEventArgs
            // Let's take account of the verbosity setting we've been passed in deciding whether to log the message
            if ((e.Importance == MessageImportance.High && IsVerbosityAtLeast(LoggerVerbosity.Minimal))
                || (e.Importance == MessageImportance.Normal && IsVerbosityAtLeast(LoggerVerbosity.Normal))
                || (e.Importance == MessageImportance.Low && IsVerbosityAtLeast(LoggerVerbosity.Detailed))				
                )
            {
                WriteLineWithSenderAndMessage(String.Empty, e);
            }
        }

        void eventSource_TaskStarted(object sender, TaskStartedEventArgs e)
        {
            // TaskStartedEventArgs adds ProjectFile, TaskFile, TaskName
            // To keep this log clean, this logger will ignore these events.
        }
        
        void eventSource_ProjectStarted(object sender, ProjectStartedEventArgs e)
        {
            // ProjectStartedEventArgs adds ProjectFile, TargetNames
            // Just the regular message string is good enough here, so just display that.
            WriteLine(String.Empty, e);
            indent++;
        }

        void eventSource_ProjectFinished(object sender, ProjectFinishedEventArgs e)
        {
            // The regular message string is good enough here too.
            indent--;
            WriteLine(String.Empty, e);
        }
        
        /// <summary>
        /// Write a line to the log, adding the SenderName and Message
        /// (these parameters are on all MSBuild event argument objects)
        /// </summary>
        private void WriteLineWithSenderAndMessage(string line, BuildEventArgs e)
        {
            if (0 == String.Compare(e.SenderName, "MSBuild", true /*ignore case*/))
            {
                // Well, if the sender name is MSBuild, let's leave it out for prettiness
                WriteLine(line, e);
            }
            else
            {
                WriteLine(e.SenderName + ": " + line, e);
            }
        }
        
        /// <summary>
        /// Just write a line to the log
        /// </summary>
        private void WriteLine(string line, BuildEventArgs e)
        {
            for (int i = indent; i > 0; i--)
            {
                streamWriter.Write("\t");
            }
            streamWriter.WriteLine(line + e.Message);
        }
        
        /// <summary>
        /// Shutdown() is guaranteed to be called by MSBuild at the end of the build, after all
        /// events have been raised.
        /// </summary>
        public override void Shutdown()
        {
            // Done logging, let go of the file
            streamWriter.Close();
        }

        private StreamWriter streamWriter;
        private int indent;
    }
}

Events

AnyEventRaised

this event is raised to log any build event. These events do not include telemetry. To receive telemetry, you must attach to the TelemetryLogged event.

BuildFinished

this event is raised to log the end of a build

BuildStarted

this event is raised to log the start of a build

CustomEventRaised

this event is raised to log custom events

ErrorRaised

this event is raised to log an error

MessageRaised

this event is raised to log a message

ProjectFinished

this event is raised to log the end of a project build

ProjectStarted

this event is raised to log the start of a project build

StatusEventRaised

this event is raised to log any build status event

TargetFinished

this event is raised to log the end of a target build

TargetStarted

this event is raised to log the start of a target build

TaskFinished

this event is raised to log the end of task execution

TaskStarted

this event is raised to log the start of task execution

WarningRaised

this event is raised to log a warning

Extension Methods

HandleAnyEventRaised(IEventSource, AnyEventHandler)

Helper method ensuring single deduplicated subscription to the AnyEventRaised event.

HandleBuildFinished(IEventSource, BuildFinishedEventHandler)

Helper method ensuring single deduplicated subscription to the BuildFinished event.

HandleBuildStarted(IEventSource, BuildStartedEventHandler)

Helper method ensuring single deduplicated subscription to the BuildStarted event.

HandleCustomEventRaised(IEventSource, CustomBuildEventHandler)

Helper method ensuring single deduplicated subscription to the CustomEventRaised event.

HandleErrorRaised(IEventSource, BuildErrorEventHandler)

Helper method ensuring single deduplicated subscription to the ErrorRaised event.

HandleMessageRaised(IEventSource, BuildMessageEventHandler)

Helper method ensuring single deduplicated subscription to the MessageRaised event.

HandleProjectFinished(IEventSource, ProjectFinishedEventHandler)

Helper method ensuring single deduplicated subscription to the ProjectFinished event.

HandleProjectStarted(IEventSource, ProjectStartedEventHandler)

Helper method ensuring single deduplicated subscription to the ProjectStarted event.

HandleStatusEventRaised(IEventSource, BuildStatusEventHandler)

Helper method ensuring single deduplicated subscription to the StatusEventRaised event.

HandleTargetFinished(IEventSource, TargetFinishedEventHandler)

Helper method ensuring single deduplicated subscription to the TargetFinished event.

HandleTargetStarted(IEventSource, TargetStartedEventHandler)

Helper method ensuring single deduplicated subscription to the TargetStarted event.

HandleTaskFinished(IEventSource, TaskFinishedEventHandler)

Helper method ensuring single deduplicated subscription to the TaskFinished event.

HandleTaskStarted(IEventSource, TaskStartedEventHandler)

Helper method ensuring single deduplicated subscription to the TaskStarted event.

HandleWarningRaised(IEventSource, BuildWarningEventHandler)

Helper method ensuring single deduplicated subscription to the WarningRaised event.

Applies to