/// <summary>
/// Return a new logger instance named as the first parameter using
/// <paramref name="factory"/>.
/// </summary>
/// <param name="name">The name of the logger to retrieve</param>
/// <param name="factory">The factory that will make the new logger instance</param>
/// <returns>The logger object with the name specified</returns>
/// <remarks>
/// <para>
/// If a logger of that name already exists, then it will be
/// returned. Otherwise, a new logger will be instantiated by the
/// <paramref name="factory"/> parameter and linked with its existing
/// ancestors as well as children.
/// </para>
/// </remarks>
public Logger GetLogger(string name, ILoggerFactory factory)
{
if (name == null)
{
throw new ArgumentNullException("name");
}
if (factory == null)
{
throw new ArgumentNullException("factory");
}
LoggerKey key = new LoggerKey(name);
// Synchronize to prevent write conflicts. Read conflicts (in
// GetEffectiveLevel() method) are possible only if variable
// assignments are non-atomic.
lock (m_ht)
{
Logger logger = null;
Object node = m_ht[key];
if (node == null)
{
logger = factory.CreateLogger(this, name);
logger.Hierarchy = this;
m_ht[key] = logger;
UpdateParents(logger);
OnLoggerCreationEvent(logger);
return(logger);
}
Logger nodeLogger = node as Logger;
if (nodeLogger != null)
{
return(nodeLogger);
}
ProvisionNode nodeProvisionNode = node as ProvisionNode;
if (nodeProvisionNode != null)
{
logger = factory.CreateLogger(this, name);
logger.Hierarchy = this;
m_ht[key] = logger;
UpdateChildren(nodeProvisionNode, logger);
UpdateParents(logger);
OnLoggerCreationEvent(logger);
return(logger);
}
// It should be impossible to arrive here but let's keep the compiler happy.
return(null);
}
}
/// <summary>
/// Updates all the parents of the specified logger
/// </summary>
/// <param name="log">The logger to update the parents for</param>
/// <remarks>
/// <para>
/// This method loops through all the <i>potential</i> parents of
/// <paramref name="log"/>. There 3 possible cases:
/// </para>
/// <list type="number">
/// <item>
/// <term>No entry for the potential parent of <paramref name="log"/> exists</term>
/// <description>
/// We create a ProvisionNode for this potential
/// parent and insert <paramref name="log"/> in that provision node.
/// </description>
/// </item>
/// <item>
/// <term>The entry is of type Logger for the potential parent.</term>
/// <description>
/// The entry is <paramref name="log"/>'s nearest existing parent. We
/// update <paramref name="log"/>'s parent field with this entry. We also break from
/// he loop because updating our parent's parent is our parent's
/// responsibility.
/// </description>
/// </item>
/// <item>
/// <term>The entry is of type ProvisionNode for this potential parent.</term>
/// <description>
/// We add <paramref name="log"/> to the list of children for this
/// potential parent.
/// </description>
/// </item>
/// </list>
/// </remarks>
private void UpdateParents(Logger log)
{
string name = log.Name;
int length = name.Length;
bool parentFound = false;
// if name = "w.x.y.z", loop through "w.x.y", "w.x" and "w", but not "w.x.y.z"
for (int i = name.LastIndexOf('.', length - 1); i >= 0; i = name.LastIndexOf('.', i - 1))
{
string substr = name.Substring(0, i);
LoggerKey key = new LoggerKey(substr); // simple constructor
Object node = m_ht[key];
// Create a provision node for a future parent.
if (node == null)
{
ProvisionNode pn = new ProvisionNode(log);
m_ht[key] = pn;
}
else
{
Logger nodeLogger = node as Logger;
if (nodeLogger != null)
{
parentFound = true;
log.Parent = nodeLogger;
break; // no need to update the ancestors of the closest ancestor
}
else
{
ProvisionNode nodeProvisionNode = node as ProvisionNode;
if (nodeProvisionNode != null)
{
nodeProvisionNode.Add(log);
}
else
{
LogLog.Error(declaringType, "Unexpected object type [" + node.GetType() + "] in ht.", new LogException());
}
}
}
}
// If we could not find any existing parents, then link with root.
if (!parentFound)
{
log.Parent = Root;
}
}
/// <summary>
/// Replace a <see cref="ProvisionNode"/> with a <see cref="Logger"/> in the hierarchy.
/// </summary>
/// <param name="pn"></param>
/// <param name="log"></param>
/// <remarks>
/// <para>
/// We update the links for all the children that placed themselves
/// in the provision node 'pn'. The second argument 'log' is a
/// reference for the newly created Logger, parent of all the
/// children in 'pn'.
/// </para>
/// <para>
/// We loop on all the children 'c' in 'pn'.
/// </para>
/// <para>
/// If the child 'c' has been already linked to a child of
/// 'log' then there is no need to update 'c'.
/// </para>
/// <para>
/// Otherwise, we set log's parent field to c's parent and set
/// c's parent field to log.
/// </para>
/// </remarks>
private static void UpdateChildren(ProvisionNode pn, Logger log)
{
for (int i = 0; i < pn.Count; i++)
{
Logger childLogger = (Logger)pn[i];
// Unless this child already points to a correct (lower) parent,
// make log.Parent point to childLogger.Parent and childLogger.Parent to log.
if (!childLogger.Parent.Name.StartsWith(log.Name))
{
log.Parent = childLogger.Parent;
childLogger.Parent = log;
}
}
}