public void Select(LoggerFilterOptions options, Type providerType, string category, out LogLevel?minLevel, out Func <string, string, LogLevel, bool> filter)
{
filter = null;
minLevel = options.MinLevel;// LogLevel.Information
// Filter rule selection:
// 1. Select rules for current logger type, if there is none, select ones without logger type specified
// 2. Select rules with longest matching categories
// 3. If there nothing matched by category take all rules without category
// 3. If there is only one rule use it's level and filter
// 4. If there are multiple rules use last
// 5. If there are no applicable rules use global minimal level
// 获取 特性 [ProviderAlias("Console")] 中的别名
var providerAlias = ProviderAliasUtilities.GetAlias(providerType);
LoggerFilterRule current = null;
foreach (var rule in options.Rules)
{
if (IsBetter(rule, current, providerType.FullName, category) ||
(!string.IsNullOrEmpty(providerAlias) && IsBetter(rule, current, providerAlias, category)))
{
current = rule;
}
}
if (current != null)
{
filter = current.Filter;
minLevel = current.LogLevel;
}
}
private static bool IsBetter(LoggerFilterRule rule, LoggerFilterRule current, string logger, string category)
{
// Skip rules with inapplicable type or category
// 如果rule 不是全局的，且rule不适用与logger，则跳过 该rule
if (rule.ProviderName != null && rule.ProviderName != logger)
{
return(false);
}
// 如果 rule.CategoryName !="Default"
if (rule.CategoryName != null)
{
var categoryParts = rule.CategoryName.Split(WildcardChar);
if (categoryParts.Length > 2)
{
throw new InvalidOperationException("Only one wildcard character is allowed in category name.");
}
var prefix = categoryParts[0];
var suffix = categoryParts.Length > 1 ? categoryParts[1] : string.Empty;
if (!category.StartsWith(prefix, StringComparison.OrdinalIgnoreCase) ||
!category.EndsWith(suffix, StringComparison.OrdinalIgnoreCase))
{
return(false);
}
}
if (current?.ProviderName != null)
{
if (rule.ProviderName == null)
{
return(false);
}
}
else
{
// We want to skip category check when going from no provider to having provider
if (rule.ProviderName != null)
{
return(true);
}
}
if (current?.CategoryName != null)
{
if (rule.CategoryName == null)
{
return(false);
}
if (current.CategoryName.Length > rule.CategoryName.Length)
{
return(false);
}
}
return(true);
}
private void LoadRules(LoggerFilterOptions options, IConfigurationSection configurationSection, string logger)
{
foreach (var section in configurationSection.AsEnumerable(true))
{
if (TryGetSwitch(section.Value, out var level))
{
var category = section.Key;
if (category.Equals(DefaultCategory, StringComparison.OrdinalIgnoreCase))
{
category = null;
}
var newRule = new LoggerFilterRule(logger, category, level, null);
options.Rules.Add(newRule);
}
}
}
