/// <summary>
/// 检查表达式是否能够被缓存。
/// </summary>
/// <param name="expression"></param>
/// <returns></returns>
public static bool Check(Expression expression)
{
var checker = new CachaebleChecker();
checker.Visit(expression);
return(checker.cacheable);
}
/// <summary>
/// 尝试获取指定表达式的缓存。
/// </summary>
/// <param name="expression"></param>
/// <param name="func">当缓存不存在时，创建缓存数据的函数。</param>
/// <returns></returns>
internal static Delegate TryGetDelegate(Expression expression, Func <LambdaExpression> func)
{
if (!CachaebleChecker.Check(expression))
{
return(func().Compile());
}
var section = ConfigurationUnity.GetSection <TranslatorConfigurationSection>();
var option = section == null ? TranslateOptions.Default : section.Options;
if (!option.ParseCacheEnabled)
{
return(func().Compile());
}
var lazy = new Lazy <Delegate>(() =>
{
//将表达式内的 Segment 替换成参数
var segParExp = Expression.Parameter(typeof(IDataSegment), "g");
var lambdaExp = func() as LambdaExpression;
var newExp = SegmentReplacer.Repalce(lambdaExp.Body, segParExp);
lambdaExp = Expression.Lambda(newExp, lambdaExp.Parameters[0], segParExp);
return(lambdaExp.Compile());
});
var cacheKey = ExpressionKeyGenerator.GetKey(expression, "Trans");
return(MemoryCacheManager.Instance.TryGet(cacheKey, () => lazy.Value, () => new RelativeTime(TimeSpan.FromSeconds(option.ParseCacheExpired))));
}
/// <summary>
/// 尝试获取指定表达式的缓存。
/// </summary>
/// <param name="expression"></param>
/// <param name="func">当缓存不存在时，创建缓存数据的函数。</param>
/// <returns></returns>
internal static Delegate TryGetDelegate(Expression expression, Func <LambdaExpression> func)
{
if (!CachaebleChecker.Check(expression))
{
return(func().Compile());
}
var section = ConfigurationUnity.GetSection <TranslatorConfigurationSection>();
var option = section == null ? TranslateOptions.Default : section.Options;
if (!option.ParseCacheEnabled)
{
return(func().Compile());
}
ClearExpiredKeys();
var lazy = new Lazy <CacheItem>(() =>
{
//将表达式内的 Segment 替换成参数
var segParExp = Expression.Parameter(typeof(IDataSegment), "g");
var lambdaExp = func() as LambdaExpression;
var newExp = SegmentReplacer.Repalce(lambdaExp.Body, segParExp);
lambdaExp = Expression.Lambda(newExp, lambdaExp.Parameters[0], segParExp);
return(new CacheItem
{
Delegate = lambdaExp.Compile(),
Expired = DateTime.Now.AddSeconds(option.ParseCacheExpired)
});
});
var cacheKey = GetKey(expression);
var result = cache.GetOrAdd(cacheKey, k => lazy.Value);
return(result.Delegate);
}
/// <summary>
/// 尝试获取指定表达式的缓存。
/// </summary>
/// <param name="expression"></param>
/// <param name="func">当缓存不存在时，创建缓存数据的函数。</param>
/// <returns></returns>
internal static Expression <Func <IDatabase, object> > TryGet(Expression expression, Func <Expression <Func <IDatabase, object> > > func)
{
if (!CachaebleChecker.Check(expression))
{
return(func());
}
var section = ConfigurationUnity.GetSection <TranslatorConfigurationSection>();
var option = section == null ? TranslateOptions.Default : section.Options;
if (!option.ParseCacheEnabled)
{
return(func());
}
ClearExpiredKeys();
var lazy = new Lazy <CacheItem>(() => new CacheItem
{
Expression = func(),
Expired = DateTime.Now.AddSeconds(option.ParseCacheExpired)
});
var cacheKey = GetKey(expression);
var result = cache.GetOrAdd(cacheKey, k => lazy.Value);
//在现有的表达式中查找 IDataSegment，去替换缓存中的 IDataSegment
//原因是前端需要获得分页信息，如果不进行替换，将无法返回信息
var segment = SegmentFinder.Find(expression);
if (segment != null)
{
result.Expression = (Expression <Func <IDatabase, object> >)SegmentReplacer.Repalce(result.Expression, segment);
}
return(result.Expression);
}
