I want to disallow code like this:
private static final Logger LOGGER = LogManager.getLogger(...)
...
...
LOGGER.info("User(%s) not found.", userId);
It is better to do like this:
LOGGER.info("User({}) not found.", userId);
how to configure checkstyle for catching these errors?
Related
I'm using log4net in a Windows Service. This Service processes some RFID Reader. Currently we are logging all tasks of all Reader in one Logfile. This works fine.
But now I want to log the tasks of each Reader in a separate File. The Readers are identified by their IP Address. So I want to take the IP Address as part of the Filename.
The option in log4net to create dynamic file appenders seems not to fit for me, because I would have to manage the assignment from Reader to log file, each time I write a log.
Is there an appropriate way to do this in log4net, or is it not possible?
In my Logclass I used a Dictionary<string, ILog> for my Loggers. I've overloaded methods, either they use the Default-Logger or they get the Key for the Dictionary to use the specified Logger.
public static class Log
{
private static readonly Dictionary<string, ILog> loggers = new Dictionary<string, ILog>();
static Log()
{
XmlConfigurator.Configure();
}
public static void Debug(string message)
{
Debug(Logger.Default, message);
}
public static void Debug(string readerIp, string message)
{
GetLoggerInternal(readerIp).Debug(message);
}
private static ILog GetLoggerInternal(string logger)
{
if (!loggers.ContainsKey(logger))
{
var appender = CreateRollingFileAppender(logger);
appender.ActivateOptions();
loggers.Add(logger, LogManager.GetLogger(logger));
((log4net.Repository.Hierarchy.Logger)loggers[logger].Logger).AddAppender(appender);
}
return loggers[logger];
}
private static RollingFileAppender CreateRollingFileAppender(string readingPointIp)
{
var layout = new PatternLayout
{
ConversionPattern = "%date [%thread] %-5level %logger [%property{NDC}] - %message%newline"
};
layout.ActivateOptions();
return new RollingFileAppender
{
Name = readingPointIp,
AppendToFile = true,
DatePattern = "yyyyMMdd",
MaximumFileSize = "1MB",
MaxSizeRollBackups = 10,
RollingStyle = RollingFileAppender.RollingMode.Composite,
File = $"..\\Log\\{readingPointIp}_log.txt",
Layout = layout
};
}
}
It is important to call the .ActivateOptions(); methods, they instantiate the Appender and Layout Classes. I use LogManager.GetLogger to create a new Logger. To add the appender I've to cast the logger, to use AddAppender.
Now I just have to call Log.Debug(readingPoint.IpAddress, "Some readingpoint specific log message."); and I've this message in a file, with the IP Address in it's name.
I upgraded to Azure SDK 2.5 and switched to semantic logging with EventSources.
Logging works locally with a custom EventListener.
When deployed, logs are written to a storage table, but only the EventId, Pid, Tid etc. are populated, the really interesting fields (Message, Task, Keyword, Opcode) are left blank.
The diagnostics infrastructure log is full of errors with regards to ETW, but I don't know what to make of them:
Failed to load backup EventSource manifest file C:\Resources\{13b7ec61-6424-d4d3-9972-a83e58d8d6bb}\directory\f71b19461fcf494d89d3717b3a13cadf. something.WorkerRole.DiagnosticStore\WAD0103\Configuration\EventSource_Manifest_fe06b63d-39aa-5419-0529-18c4dacf4f68_Ver_20.backup.xml;
EventSource events will be logged without a proper schema until provider sends the manifest packets
Load manifest file failed for C:\Resources\{13b7ec61-6424-d4d3-9972-a83e58d8d6bb}\directory\f71b19461fcf494d89d3717b3a13cadf.something. WorkerRole. DiagnosticStore\WAD0103\Configuration\EventSource_Manifest_fe06b63d-39aa-5419-0529-18c4dacf4f68_Ver_20.xml
Failed to manage manifest version for file C:\Resources\{13b7ec61-6424-d4d3-9972-a83e58d8d6bb}\directory\f71b19461fcf494d89d3717b3a13cadf. something. WorkerRole.DiagnosticStore\WAD0103\Configuration\EventSource_Manifest_fe06b63d-39aa-5419-0529-18c4dacf4f68_Pid_3436.xml
Failed to process EventSource manifest event GUID:fe06b63d-39aa-5419-0529-18c4dacf4f68, event id:0xFFFE
Change in the number of events lost since the last sample: EventsCaptured=2 EventsLogged=1 EventsLost=0
I do not use a manifest file and specify the EventSource via class / attribute name:
<EtwEventSourceProviderConfiguration scheduledTransferPeriod="PT3M" scheduledTransferLogLevelFilter="Information" provider="something.Core">
<DefaultEvents eventDestination="CoreEvents" />
</EtwEventSourceProviderConfiguration>
I must be missing something, but I do not know what.
The remaining diagnostic services all work (infrastructure logs, performance counter etc.).
The EventId that is being logged is the correct one, but all the important information of the log is missing, I suppose because of an incomplete configuration?
Edit: here is my EventSource code. I won't post the entire thing because it's quite large. I use another type that calls the EventSource methods and handles formatting of parameters (if the source is enabled in that level). Most method arguments are of type string, there are no objects or other complex types passed around (that handles the other type).
[EventSource(Name = "something.Core")]
public sealed class CoreEventSource : EventSource {
private static readonly CoreEventSource SoleInstance = new CoreEventSource();
static CoreEventSource() {}
private CoreEventSource() {}
public static CoreEventSource Instance {
get { return SoleInstance; }
}
public static EventKeywords AllKeywords = (EventKeywords)(-1);
public class Keywords {
public const EventKeywords None = (EventKeywords)(1 << 1);
public const EventKeywords Infrastructure = (EventKeywords)(1 << 2);
[...]
}
public class Tasks {
public const EventTask None = EventTask.None;
// generic operations
public const EventTask Create = (EventTask)11;
public const EventTask Update = (EventTask)12;
public const EventTask Delete = (EventTask)13;
public const EventTask Get = (EventTask)14;
public const EventTask Put = (EventTask)15;
public const EventTask Remove = (EventTask)16;
public const EventTask Process = (EventTask)17;
}
[Event(1, Message = "Initialization of {0} failed: {1}.", Level = EventLevel.Critical, Keywords = Keywords.Infrastructure)]
public void CriticalInitializationFailure(string component, string details, string exception) {
this.WriteEvent(1, component, details, exception);
}
[Event(2, Message = "[Role '{0}'] Startup: {1}", Level = EventLevel.Informational, Keywords = Keywords.Infrastructure)]
public void RoleStartup(string roleName, string message) {
this.WriteEvent(2, roleName, message);
}
[Event(3, Message = "[Role '{0}'] Stop failed: {1}.", Level = EventLevel.Error, Keywords = Keywords.Infrastructure)]
public void RoleStopFailed(string roleName, string details, string exception) {
this.WriteEvent(3, roleName, details, exception);
}
[Event(4, Message = "An unhandled exception occurred.", Level = EventLevel.Critical, Keywords = Keywords.Infrastructure)]
public void UnhandledException(string exception) {
this.WriteEvent(4, exception);
}
[Event(5, Message = "An unobserved exception occurred in a faulted task.", Level = EventLevel.Critical, Keywords = Keywords.Infrastructure)]
public void UnobservedTaskException(string exception) {
this.WriteEvent(5, exception);
}
[...]
}
Turns out there were quite a few problems with my EventSource. The first thing I'd recommend to anyone working with ETW is to use the Microsoft TraceEvent Library from NuGet, even if you use System.Diagnostics.Tracing, because it comes with a tool that will verify your EventSource code and notify you about problems.
I had to fix the following:
EventSource names must not contain a period .
Task/Opcode pairs must be unique within an EventSource
One must not declare a None field in a custom Keywords or Tasks enumeration
Hope this is of some use to anyone who encounters a similar problem.
Another thing that should be taken care of (which fixed our case)
- EventSources should only have a Name or a Guid, not both.
In our case, having both caused
- The EtwEventSourceProvider to not log anything
- The EtwEventManifestProvider to log the same way you outlined, with empty data points.
Rather than roll a log after a date/time or specified maximum size, I want to be able to call a method like "ResetLog" that copies my "log.txt" to "log.txt.1" and then clears log.txt.
I've tried to implement that by doing something like this with a FileAppender, rather than a RollingFileAppender:
var appenders = log4net.LogManager.GetRepository().GetAppenders();
foreach (var appender in appenders) {
var fa = appender as log4net.Appender.FileAppender;
if (fa != null) {
string logfile = fa.File;
fa.Close();
string new_file_path = CreateNextLogFile(logfile);
fa.File = new_file_path;
fa.ActivateOptions();
}
}
The file is closed and CreateNextLogFile() renames it. I then create a new log file and set the FileAppender to use it. However, I thought that ActivateOptions would go ahead and reconfigure the FileAppender with the desired settings. I've looked over the log4net documentation and don't see any other public methods that allow me to reopen the FileAppender after closing it. Can anyone recommend a way to implement the rollover? It would be nice if the RollingFileAppender had something like this, but I didn't see anything useful it its documentation, either.
If we look at the RollingFileAppender we can see that the mechanism for rolling over consists of closing the file, renaming existing files (optional) and opening it again:
// log4net.Appender.RollingFileAppender
protected void RollOverSize()
{
base.CloseFile();
// debug info removed
this.RollOverRenameFiles(this.File);
if (!this.m_staticLogFileName && this.m_countDirection >= 0)
{
this.m_curSizeRollBackups++;
}
this.SafeOpenFile(this.m_baseFileName, false);
}
Unfortunately the CloseFile/SafeOpenFile methods are protected which means you cannot access it from the outside (not easily). So your best bet would be to write an appender inheriting from RollingFileAppender, and to override the virtual AdjustFileBeforeAppend which is called before any logging event is added to the appender.
There you can decide what are the conditions of the roll if any must occur. An idea would be to create a static event that your custom rolling appender suscribes to: when the event is triggered the appender makes a note of it (rollBeforeNextAppend = true;). As soon as you try and log next entry the appender will roll.
public class CustomRollingAppender: RollingFileAppender
{
public CustomRollingAppender()
{
MyStaticCommandCenter.RollEvent += Roll;
}
public void Roll()
{
rollBeforeNextAppend = true;
}
public bool rollBeforeNextAppend {get; set;}
public override void AdjustFileBeforeAppend()
{
if (rollBeforeNextAppend) {
CloseFile();
RollOverRenameFiles(File);
SafeOpenFile(Filename, false);
rollBeforeNextAppend = false;
}
}
}
Since I have a global exception handler that reports uncaught errors via e-mail, next step is to add some context to it by having some 10-20 last lines of log that are collected.
So I am using MemoryTarget like so:
MemoryTarget _logTarget;
_logTarget = new MemoryTarget();
_logTarget.Layout = "${longdate}|${level:uppercase=true}|${logger}|${message}${exception}";
LoggingRule loggingRule = new LoggingRule("*", LogLevel.Debug, _logTarget);
LogManager.Configuration.AddTarget("exceptionMemory", _logTarget);
LogManager.Configuration.LoggingRules.Add(loggingRule);
LogManager.Configuration.Reload();
Apps containing this should run forever, and if I leave logs in memory, unchecked, I'll have neatly designed memory leak.
How to address this? How to truncate MemoryTarget.Logs to have at most say 100 lines?
Your best bet is probably to write your own MemoryTarget... Something like this (untested) should work.
namespace NLog.Targets
{
using System.Collections.Generic;
[Target("LimitedMemory")]
public sealed class LimitedMemoryTarget : TargetWithLayout
{
private Queue<string> logs = new Queue<string>();
public LimitedMemoryTarget()
{
this.Logs = new List<string>();
}
public IEnumerable<string> Logs
{
get { return logs; }
private set { logs = value; }
}
[DefaultValue(100)]
public int Limit { get; set; }
protected override void Write(LogEventInfo logEvent)
{
string msg = this.Layout.Render(logEvent);
logs.Enqueue(msg);
if (logs.Count > Limit)
{
logs.Dequeue();
}
}
}
}
This example is based on the NLog MemoryTarget, the source code for which you can find here:
https://github.com/NLog/NLog
NLog docs are here:
http://nlog-project.org/documentation/v2.0.1/
I didn't see anything like you are asking about in either location.
Is it possible/easy to mock NLog log methods, using Rhino Mocks or similar?
Using Nuget : install-package NLog.Interface
Then: ILogger logger = new LoggerAdapter([logger-from-NLog]);
You can only mock virtual methods. But if You create some interface for logging and then implement it using NLog You can use dependency injection and in Your tests use mocked interface to see if system under test (SUT) is logging what You expect it to log.
public class SUT
{
private readonly ILogger logger;
SUT(ILogger logger) { this.logger = logger;}
MethodUnderTest() {
// ...
logger.LogSomething();
// ...
}
}
// and in tests
var mockLogger = new MockLogger();
var sut = new SUT(mockLogger);
sut.MethodUnderTest();
Assert.That("Expected log message", Is.Equal.To(mockLogger.LastLoggedMessage));
The simple answer, is 'no'. Looking at the code, dependency-injection is not supported, which seems rather an oversight, especially as it doesn't look difficult to implement (at first glance).
The only interfaces in the project are there to support COM interop objects and a few other things. The main Logger concrete class neither implements an interface, nor provides virtual methods.
You could either provide an interface yourself, or use Moles/TypeMock/ another isolation framework to mock the dependency.
I've used code like this to stub out the NLog logging code. You can make use of NLog's MemoryTarget which just keeps messages in memory until it's disposed of. You can query the content of the log using Linq or whatever (this example uses FluentAssertions)
using FluentAssertions
using Microsoft.VisualStudio.TestTools.UnitTesting;
using NLog;
using NLog.Config;
using NLog.Targets;
...
private MemoryTarget _stubLogger;
[TestInitialize]
public void Setup()
{
ConfigureTestLogging();
}
protected virtual LoggingConfiguration GetLoggingConfiguration()
{
var config = new NLog.Config.LoggingConfiguration();
this._stubLogger = new MemoryTarget();
_stubLogger.Layout = "${level}|${message}";
config.AddRule(LogLevel.Debug, LogLevel.Fatal, this._stubLogger);
return config;
}
protected virtual void ConfigureTestLogging()
{
var config = GetLoggingConfiguration();
NLog.LogManager.Configuration = config;
}
[TestMethod]
public void ApiCallErrors_ShouldNotThrow()
{
// arrange
var target = new Thing();
// act
target.DoThing();
// assert
this._stubLogger.Logs.Should().Contain(l =>
l.Contains("Error|") &&
l.Contains("Expected Message"));
}