前言
本節開始整理日誌相關的東西。先整理一下日誌的基本原理。
正文
首先介紹一下包:
- Microsoft.Extengsion.Logging.Abstrations
這個是介面包。
- Microsoft.Extengsion.Logging
這個是實現包
- Microsoft.Extengsion.Logging.Console
這個是擴充套件包
程式碼如下:
static void Main(string[] args)
{
IConfigurationBuilder configurationBuilder = new ConfigurationBuilder();
configurationBuilder.AddJsonFile("appsettings.json",optional:false,reloadOnChange:true);
var config = configurationBuilder.Build();
IServiceCollection serviceCollection = new ServiceCollection();
serviceCollection.AddSingleton<IConfiguration>(p=>config);
serviceCollection.AddLogging(builder =>
{
builder.AddConfiguration(config.GetSection("Logging"));
builder.AddConsole();
});
IServiceProvider service = serviceCollection.BuildServiceProvider();
ILoggerFactory loggerFactory = service.GetService<ILoggerFactory>();
var loggerObj = loggerFactory.CreateLogger("Default");
loggerObj.LogInformation(2021, "Default,now that is 2021");
var loggerObj2 = loggerFactory.CreateLogger("loggerObj");
loggerObj2.LogDebug(2021, "loggerObj,now that is 2021");
Console.ReadKey();
}
配置檔案:
{
"Logging": {
"LogLevel": {
"Default": "Debug",
"Microsoft": "Warning",
"Microsoft.Hosting.Lifetime": "Information"
},
"Console": {
"LogLevel": {
"Default": "Information",
"Program": "Trace",
"loggerObj": "Debug"
}
}
}
}
結果:
首先是配置級別的問題,檢視loglevel 檔案:
public enum LogLevel
{
/// <summary>Logs that contain the most detailed messages. These messages may contain sensitive application data.
/// These messages are disabled by default and should never be enabled in a production environment.</summary>
Trace,
/// <summary>Logs that are used for interactive investigation during development. These logs should primarily contain
/// information useful for debugging and have no long-term value.</summary>
Debug,
/// <summary>Logs that track the general flow of the application. These logs should have long-term value.</summary>
Information,
/// <summary>Logs that highlight an abnormal or unexpected event in the application flow, but do not otherwise cause the
/// application execution to stop.</summary>
Warning,
/// <summary>Logs that highlight when the current flow of execution is stopped due to a failure. These should indicate a
/// failure in the current activity, not an application-wide failure.</summary>
Error,
/// <summary>Logs that describe an unrecoverable application or system crash, or a catastrophic failure that requires
/// immediate attention.</summary>
Critical,
/// <summary>Not used for writing log messages. Specifies that a logging category should not write any messages.</summary>
None,
}
從上之下，依次提高log級別。
比如說設定了log 級別是Error，那麼Debug、Information、Warning 都不會被答應出來。
那麼就來分析一下程式碼吧。
AddLogging:
public static IServiceCollection AddLogging(this IServiceCollection services, Action<ILoggingBuilder> configure)
{
if (services == null)
{
throw new ArgumentNullException(nameof(services));
}
services.AddOptions();
services.TryAdd(ServiceDescriptor.Singleton<ILoggerFactory, LoggerFactory>());
services.TryAdd(ServiceDescriptor.Singleton(typeof(ILogger<>), typeof(Logger<>)));
services.TryAddEnumerable(ServiceDescriptor.Singleton<IConfigureOptions<LoggerFilterOptions>>(
new DefaultLoggerLevelConfigureOptions(LogLevel.Information)));
configure(new LoggingBuilder(services));
return services;
}
這裡面給註冊了ILoggerFactory和ILogger。然後設定了一個列印log的級別配置，LogLevel.Information，這個就是如果我們沒有配置檔案預設就是Information這種級別了。
configure(new LoggingBuilder(services)) 給我們的委託提供了一個LoggingBuilder的例項化物件。這個物件就是用來專門做擴充套件的，是解耦的一種方式。
internal class LoggingBuilder : ILoggingBuilder
{
public LoggingBuilder(IServiceCollection services)
{
Services = services;
}
public IServiceCollection Services { get; }
}
這個LoggingBuilder 類基本什麼功能都沒有，但是因為有了這樣一個類，就可以作為擴充套件的標誌了。
比如說上文的:
builder.AddConfiguration(config.GetSection("Logging"));
builder.AddConsole();
看下AddConfiguration:
public static ILoggingBuilder AddConfiguration(this ILoggingBuilder builder, IConfiguration configuration)
{
builder.AddConfiguration();
builder.Services.AddSingleton<IConfigureOptions<LoggerFilterOptions>>(new LoggerFilterConfigureOptions(configuration));
builder.Services.AddSingleton<IOptionsChangeTokenSource<LoggerFilterOptions>>(new ConfigurationChangeTokenSource<LoggerFilterOptions>(configuration));
builder.Services.AddSingleton(new LoggingConfiguration(configuration));
return builder;
}
這裡面給我們注入了配置檔案的配置:builder.Services.AddSingleton<IConfigureOptions>(new LoggerFilterConfigureOptions(configuration))
同時給我們註冊監聽令牌:builder.Services.AddSingleton<IOptionsChangeTokenSource>(new ConfigurationChangeTokenSource(configuration));
這裡給我們註冊配置儲存在LoggingConfiguration中：builder.Services.AddSingleton(new LoggingConfiguration(configuration));
因為LoggingConfiguration 儲存了，故而我們隨時可以獲取到LoggingConfiguration 的配置。
看下AddConsole:
/// <param name="builder">The <see cref="ILoggingBuilder"/> to use.</param>
public static ILoggingBuilder AddConsole(this ILoggingBuilder builder)
{
builder.AddConfiguration();
builder.AddConsoleFormatter<JsonConsoleFormatter, JsonConsoleFormatterOptions>();
builder.AddConsoleFormatter<SystemdConsoleFormatter, ConsoleFormatterOptions>();
builder.AddConsoleFormatter<SimpleConsoleFormatter, SimpleConsoleFormatterOptions>();
builder.Services.TryAddEnumerable(ServiceDescriptor.Singleton<ILoggerProvider, ConsoleLoggerProvider>());
LoggerProviderOptions.RegisterProviderOptions<ConsoleLoggerOptions, ConsoleLoggerProvider>(builder.Services);
return builder;
}
builder.Services.TryAddEnumerable(ServiceDescriptor.Singleton<ILoggerProvider, ConsoleLoggerProvider>()) 裡面給我們ILoggerProvider 增加了一個ConsoleLoggerProvider，故而我們多了一個列印的功能。
LoggerProviderOptions.RegisterProviderOptions<ConsoleLoggerOptions, ConsoleLoggerProvider>(builder.Services) 給我們加上了ConsoleLoggerOptions 繫結為ConsoleLoggerProvider的配置。
RegisterProviderOptions 如下:
public static void RegisterProviderOptions<TOptions, TProvider>(IServiceCollection services) where TOptions : class
{
services.TryAddEnumerable(ServiceDescriptor.Singleton<IConfigureOptions<TOptions>, LoggerProviderConfigureOptions<TOptions, TProvider>>());
services.TryAddEnumerable(ServiceDescriptor.Singleton<IOptionsChangeTokenSource<TOptions>, LoggerProviderOptionsChangeTokenSource<TOptions, TProvider>>());
}
接下來就是呼叫服務:
var loggerObj = loggerFactory.CreateLogger("Default");
loggerObj.LogInformation(2021, "Default,now that is 2021");
看下LoggerFactory的CreateLogger：
public ILogger CreateLogger(string categoryName)
{
if (CheckDisposed())
{
throw new ObjectDisposedException(nameof(LoggerFactory));
}
lock (_sync)
{
if (!_loggers.TryGetValue(categoryName, out Logger logger))
{
logger = new Logger
{
Loggers = CreateLoggers(categoryName),
};
(logger.MessageLoggers, logger.ScopeLoggers) = ApplyFilters(logger.Loggers);
_loggers[categoryName] = logger;
}
return logger;
}
}
裡面做了快取，如果categoryName有快取的話直接使用快取，如果沒有那麼呼叫CreateLoggers建立。
檢視CreateLoggers:
private LoggerInformation[] CreateLoggers(string categoryName)
{
var loggers = new LoggerInformation[_providerRegistrations.Count];
for (int i = 0; i < _providerRegistrations.Count; i++)
{
loggers[i] = new LoggerInformation(_providerRegistrations[i].Provider, categoryName);
}
return loggers;
}
這裡面就用我們前面註冊過的全部logger的provider，封裝進LoggerInformation。
檢視LoggerInformation:
internal readonly struct LoggerInformation
{
public LoggerInformation(ILoggerProvider provider, string category) : this()
{
ProviderType = provider.GetType();
Logger = provider.CreateLogger(category);
Category = category;
ExternalScope = provider is ISupportExternalScope;
}
public ILogger Logger { get; }
public string Category { get; }
public Type ProviderType { get; }
public bool ExternalScope { get; }
}
裡面呼叫了我們，每個provider的CreateLogger。
那麼這個時候我們就找一個provider 看下CreateLogger到底做了什麼，這裡就找一下ConsoleLoggerProvider，因為我們添加了這個。
[ProviderAlias("Console")]
public class ConsoleLoggerProvider : ILoggerProvider, ISupportExternalScope
{
private readonly IOptionsMonitor<ConsoleLoggerOptions> _options;
public ILogger CreateLogger(string name)
{
if (_options.CurrentValue.FormatterName == null || !_formatters.TryGetValue(_options.CurrentValue.FormatterName, out ConsoleFormatter logFormatter))
{
#pragma warning disable CS0618
logFormatter = _options.CurrentValue.Format switch
{
ConsoleLoggerFormat.Systemd => _formatters[ConsoleFormatterNames.Systemd],
_ => _formatters[ConsoleFormatterNames.Simple],
};
if (_options.CurrentValue.FormatterName == null)
{
UpdateFormatterOptions(logFormatter, _options.CurrentValue);
}
#pragma warning disable CS0618
}
return _loggers.GetOrAdd(name, loggerName => new ConsoleLogger(name, _messageQueue)
{
Options = _options.CurrentValue,
ScopeProvider = _scopeProvider,
Formatter = logFormatter,
});
}
}
看到這個IOptionsMonitor，就知道console 配置是支援熱更新的，裡面建立了ConsoleLogger，這個ConsoleLogger就是用來打log正在的呼叫類。
值得注意的是_messageQueue這個，看了列印log還是有一個佇列的，按照先進先出原則。
那麼最後來看一下loggerObj.LogInformation(2021, "Default,now that is 2021");:
第一層
public static void LogInformation(this ILogger logger, EventId eventId, string message, params object[] args)
{
logger.Log(LogLevel.Information, eventId, message, args);
}
第二層
public static void Log(this ILogger logger, LogLevel logLevel, EventId eventId, string message, params object[] args)
{
logger.Log(logLevel, eventId, null, message, args);
}
第三層
public static void Log(this ILogger logger, LogLevel logLevel, EventId eventId, Exception exception, string message, params object[] args)
{
if (logger == null)
{
throw new ArgumentNullException(nameof(logger));
}
logger.Log(logLevel, eventId, new FormattedLogValues(message, args), exception, _messageFormatter);
}
那麼這個logger.Log 是呼叫具體某個logger，像consoleLogger 嗎？ 不是，我們看LoggerFactory的CreateLogger時候封裝了：
logger = new Logger
{
Loggers = CreateLoggers(categoryName),
};
那麼看下Logger的Log到底幹了什麼。
internal class Logger : ILogger
{
public LoggerInformation[] Loggers { get; set; }
public MessageLogger[] MessageLoggers { get; set; }
public ScopeLogger[] ScopeLoggers { get; set; }
public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception exception, Func<TState, Exception, string> formatter)
{
MessageLogger[] loggers = MessageLoggers;
if (loggers == null)
{
return;
}
List<Exception> exceptions = null;
for (int i = 0; i < loggers.Length; i++)
{
ref readonly MessageLogger loggerInfo = ref loggers[i];
if (!loggerInfo.IsEnabled(logLevel))
{
continue;
}
LoggerLog(logLevel, eventId, loggerInfo.Logger, exception, formatter, ref exceptions, state);
}
if (exceptions != null && exceptions.Count > 0)
{
ThrowLoggingError(exceptions);
}
static void LoggerLog(LogLevel logLevel, EventId eventId, ILogger logger, Exception exception, Func<TState, Exception, string> formatter, ref List<Exception> exceptions, in TState state)
{
try
{
logger.Log(logLevel, eventId, state, exception, formatter);
}
catch (Exception ex)
{
if (exceptions == null)
{
exceptions = new List<Exception>();
}
exceptions.Add(ex);
}
}
}
}
裡面迴圈判斷是否當前級別能夠輸出：!loggerInfo.IsEnabled(logLevel)
然後呼叫對應的具體ILog實現的Log，這裡貼一下ConsoleLogger 的實現:
[ThreadStatic]
private static StringWriter t_stringWriter;
public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception exception, Func<TState, Exception, string> formatter)
{
if (!IsEnabled(logLevel))
{
return;
}
if (formatter == null)
{
throw new ArgumentNullException(nameof(formatter));
}
t_stringWriter ??= new StringWriter();
LogEntry<TState> logEntry = new LogEntry<TState>(logLevel, _name, eventId, state, exception, formatter);
Formatter.Write(in logEntry, ScopeProvider, t_stringWriter);
var sb = t_stringWriter.GetStringBuilder();
if (sb.Length == 0)
{
return;
}
string computedAnsiString = sb.ToString();
sb.Clear();
if (sb.Capacity > 1024)
{
sb.Capacity = 1024;
}
_queueProcessor.EnqueueMessage(new LogMessageEntry(computedAnsiString, logAsError: logLevel >= Options.LogToStandardErrorThreshold));
}
把這個佇列的也貼一下，比較經典吧。
internal class ConsoleLoggerProcessor : IDisposable
{
private const int _maxQueuedMessages = 1024;
private readonly BlockingCollection<LogMessageEntry> _messageQueue = new BlockingCollection<LogMessageEntry>(_maxQueuedMessages);
private readonly Thread _outputThread;
public IConsole Console;
public IConsole ErrorConsole;
public ConsoleLoggerProcessor()
{
// Start Console message queue processor
_outputThread = new Thread(ProcessLogQueue)
{
IsBackground = true,
Name = "Console logger queue processing thread"
};
_outputThread.Start();
}
public virtual void EnqueueMessage(LogMessageEntry message)
{
if (!_messageQueue.IsAddingCompleted)
{
try
{
_messageQueue.Add(message);
return;
}
catch (InvalidOperationException) { }
}
// Adding is completed so just log the message
try
{
WriteMessage(message);
}
catch (Exception) { }
}
// for testing
internal virtual void WriteMessage(LogMessageEntry entry)
{
IConsole console = entry.LogAsError ? ErrorConsole : Console;
console.Write(entry.Message);
}
private void ProcessLogQueue()
{
try
{
foreach (LogMessageEntry message in _messageQueue.GetConsumingEnumerable())
{
WriteMessage(message);
}
}
catch
{
try
{
_messageQueue.CompleteAdding();
}
catch { }
}
}
public void Dispose()
{
_messageQueue.CompleteAdding();
try
{
_outputThread.Join(1500); // with timeout in-case Console is locked by user input
}
catch (ThreadStateException) { }
}
}
結
因為是實踐篇，只是具體執行過程帶過一下，細節篇的時候，會詳細介紹一下機制，比如說ConsoleLoggerProcessor的這種佇列機制，又比如說Logger模型設計等。
以上只是個人整理，如有錯誤，望請指出。
下一節，服務與logger系統之間。