Make the logger service more robust to exceptions

Added documentation to the public methods of the service
Moved the SimpleLoggerServiceImpl into LoggerServiceImpl in order to make it the default logger
Added a NullLoggerServiceImpl that can be used if all else fails, ensuring that the logger does not fail, even if it doesn't log
Removed needless custom metadata for the logging service

framework/default/modules/logger/services/logger/classes/LoggerService.cls

@@ -1,29 +1,93 @@
+/**
+ * Provides the ability to generate log entries.
+ * The precise output of the logging will depend on the implementation that is configured.
+ *
+ * In all cases, whether a message or exception is sent to the logging implementation is governed by
+ * the Custom Setting 'Logging Configuration'.
+ *
+ * All exceptions from this service are swallowed in order to ensure that a badly configured logger does not
+ * result in a broken system.
+ */
 public inherited sharing class LoggerService
 {
 	public enum Level { INFO, WARNING, ERROR }
 
 	public static final Level EXCEPTION_LOG_LEVEL = Level.ERROR;
 
+	@testVisible
+	private static Logging_Configuration__c config
+	{
+		get
+		{
+			if ( config == null )
+			{
+				try
+				{
+					config = Logging_Configuration__c.getInstance();
+				}
+				catch ( Exception e ) // We swallow the exception and create an empty logging configuration because the logger should never throw
+										// an exception.  We just want the default values to apply in the situation that the config can't be loaded
+				{
+					config = new Logging_Configuration__c();
+				}
+			}
+			return config;
+		}
+		set;
+	}
+
+	/**
+	 * Log the given message at the given level
+	 *
+	 * @param	LoggerService.Level	The level of the log
+	 * @param	String				The message to log
+	 */
     public static void log( LoggerService.Level logLevel, String message )
 	{
 		if ( ! shouldLog( logLevel ) )
 		{
 			return;
 		}
 
-		service().log( logLevel, message );
+		try
+		{
+			service().log( logLevel, message );
+		}
+		catch ( Exception e )
+		{
+			System.debug( LoggingLevel.ERROR, 'Exception when attempting to log ' + message + ' - ' + e );
+		}
 	}
 
+	/**
+	 * Log the given message at the given level
+	 *
+	 * @param	LoggerService.Level	The level of the log
+	 * @param	String				The message to log
+	 * @param	Id					The Id of the SObject that this log entry relates to.
+	 */
     public static void log( LoggerService.Level logLevel, String message, Id relatedSobjectId )
 	{
 		if ( ! shouldLog( logLevel ) )
 		{
 			return;
 		}
 
-		service().log( logLevel, message, relatedSobjectId );
+		try
+		{
+			service().log( logLevel, message, relatedSobjectId );
+		}
+		catch ( Exception e )
+		{
+			System.debug( LoggingLevel.ERROR, 'Exception when attempting to log ' + message + ' against ' + relatedSobjectId + ' - ' + e );
+		}
 	}
 
+	/**
+	 * Log the given exception
+	 *
+	 * @param	Exception	The exception to log
+	 */
 	public static void log( Exception exceptionToLog )
 	{
 		if ( ! shouldLogExceptions() )
@@ -42,49 +106,84 @@ public inherited sharing class LoggerService
 		service().log( exceptionToLog );
 	}
 
+	/**
+	 * Log the given DmlException
+	 *
+	 * @param	DmlException	The exception to log
+	 */
 	public static void log( DmlException exceptionToLog )
 	{
 		if ( ! shouldLogExceptions() )
 		{
 			return;
 		}
 
-		service().log( exceptionToLog );
+		try
+		{
+			service().log( exceptionToLog );
+		}
+		catch ( Exception e )
+		{
+			System.debug( LoggingLevel.ERROR, 'Exception when attempting to log ' + exceptionToLog + ' - ' + e );
+		}
 	}
 
+	/**
+	 * Log the given ortoo_Exception
+	 *
+	 * @param	ortoo_Exception	The exception to log
+	 */
 	public static void log( ortoo_Exception exceptionToLog )
 	{
 		if ( ! shouldLogExceptions() )
 		{
 			return;
 		}
 
-		service().log( exceptionToLog );
+		try
+		{
+			service().log( exceptionToLog );
+		}
+		catch ( Exception e )
+		{
+			System.debug( LoggingLevel.ERROR, 'Exception when attempting to log ' + exceptionToLog + ' - ' + e );
+		}
 	}
 
+	/**
+	 * Log the given exception against the given SObject Id
+	 *
+	 * @param	Exception	The exception to log
+	 * @param	Id			The SObject to relate this log to
+	 */
 	public static void log( Exception exceptionToLog, Id relatedSobjectId )
 	{
 		if ( ! shouldLogExceptions() )
 		{
 			return;
 		}
 
-		service().log( exceptionToLog, relatedSobjectId );
+		try
+		{
+			service().log( exceptionToLog, relatedSobjectId );
+		}
+		catch ( Exception e )
+		{
+			System.debug( LoggingLevel.ERROR, 'Exception when attempting to log ' + exceptionToLog + ' - ' + e );
+		}
 	}
 
 	private static Boolean shouldLog( LoggerService.Level logLevel )
 	{
-		Logging_Configuration__c config = Logging_Configuration__c.getInstance();
-
 		switch on logLevel {
 			when INFO {
-				return config.Id != null ? config.Log_INFO_Level_Messages__c : false; // if no config record exists, do not log INFO
+				return config.Name != null ? config.Log_INFO_Level_Messages__c : false; // if no config record exists, do not log INFO
 			}
 			when WARNING {
-				return config.Id != null ? config.Log_WARNING_Level_Messages__c : false; // if no config record exists, do not log WARNING
+				return config.Name != null ? config.Log_WARNING_Level_Messages__c : false; // if no config record exists, do not log WARNING
 			}
 		}
-		return config.Id != null ? config.Log_ERROR_Level_Messages__c : true; // if no config record exists, still log ERROR
+		return config.Name != null ? config.Log_ERROR_Level_Messages__c : true; // if no config record exists, still log ERROR
 	}
 
 	private static Boolean shouldLogExceptions()
@@ -94,6 +193,15 @@ public inherited sharing class LoggerService
 
     private static ILoggerService service()
 	{
-        return (ILoggerService)Application.SERVICE.newInstance( ILoggerService.class );
+		try
+		{
+	        return (ILoggerService)Application.SERVICE.newInstance( ILoggerService.class );
+		}
+		catch ( Exception e )
+		{
+			System.debug( LoggingLevel.ERROR, 'Exception when trying to instantiate the logger - ' + e ); // Logger failure should not stop the system,
+																							// so with nothing else available, instantiate a logger that does nothing
+			return new NullLoggerServiceImpl();
+		}
     }
 }

framework/default/modules/logger/services/simple-logger/SimpleLoggerServiceImpl.cls → framework/default/modules/logger/services/logger/classes/LoggerServiceImpl.cls

@@ -1,15 +1,15 @@
 /**
- * Provides a mechanism for performing a windowed, ordered search against an object as
- * defined by the passed searchConfigurationType.
+ * A simple logger that output all logs to System.debug.
+ *
+ * Provides a more thorough and structured output in the log.
+ *
  */
-public with sharing class SimpleLoggerServiceImpl implements ILoggerService
+public with sharing class LoggerServiceImpl implements ILoggerService
 {
-	// TODO: should we have a custom metadata record?  Or should this be LoggerServiceImpl?
 	// TODO: should we output more from the standard exceptions?
 	// TODO: what can we output in the UI?  Flag on custom settings to decide
-	// TODO: check limits for shipping custom settings in managed package
-	//
-    public void log( LoggerService.Level logLevel, String message )
+
+	public void log( LoggerService.Level logLevel, String message )
 	{
 		logMessage( logLevel, message );
 	}

framework/default/modules/logger/services/logger/classes/NullLoggerServiceImpl.cls

@@ -0,0 +1,13 @@
+/**
+ * An implementation of a logger that does nothing.
+ * This is the fallback logger that is used if the default or configured logger cannot be instantiated
+ */
+public inherited sharing class NullLoggerServiceImpl implements ILoggerService
+{
+    public void log( LoggerService.Level logLevel, String message ) {} // NOPMD: is a null implementation
+    public void log( LoggerService.Level logLevel, String message, Id relatedSobjectId ) {} // NOPMD: is a null implementation
+	public void log( Exception exceptionToLog ) {} // NOPMD: is a null implementation
+	public void log( Exception exceptionToLog, Id relatedSobject ) {} // NOPMD: is a null implementation
+	public void log( DmlException exceptionToLog ) {} // NOPMD: is a null implementation
+	public void log( ortoo_Exception exceptionToLog ) {} // NOPMD: is a null implementation
+}

framework/default/modules/logger/services/logger/classes/NullLoggerServiceImpl.cls-meta.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ApexClass xmlns="http://soap.sforce.com/2006/04/metadata">
+    <apiVersion>52.0</apiVersion>
+    <status>Active</status>
+</ApexClass>