/// <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)
{
var section = ConfigurationUnity.GetSection <TranslatorConfigurationSection>();
var option = section == null ? TranslateOptions.Default : section.Options;
var result = CacheableChecker.Check(expression);
if (!result.Required || (result.Enabled == null && !option.CacheParsing) || result.Enabled == false)
{
return(func().Compile());
}
var cacheKey = ExpressionKeyGenerator.GetKey(expression, "Trans");
cacheKey = NativeCacheKeyContext.GetKey(cacheKey);
return(MemoryCacheManager.Instance.TryGet(cacheKey, () =>
{
var lambdaExp = func() as LambdaExpression;
var segment = SegmentFinder.Find(expression);
if (segment != null)
{
//将表达式内的 Segment 替换成参数
var segParExp = Expression.Parameter(typeof(IDataSegment), "g");
var newExp = SegmentReplacer.Repalce(lambdaExp.Body, segParExp);
var parameters = new List <ParameterExpression>(lambdaExp.Parameters);
parameters.Insert(1, segParExp);
lambdaExp = Expression.Lambda(newExp, parameters.ToArray());
}
return lambdaExp.Compile();
},
() => new RelativeTime(result.Expired ?? TimeSpan.FromSeconds(option.CacheParsingTimes))));
}
/// <summary>
/// 将查询转换为带分页信息的结构输出。查询中需要使用 Segment 扩展方法带入 <see cref="IPager"/> 分页对象。
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="source"></param>
/// <returns></returns>
public static PaginalResult <T> ToPaginalResult <T>(this IQueryable <T> source)
{
var segment = SegmentFinder.Find(source.Expression);
var list = source.ToList();
return(new PaginalResult <T>(list, segment as IPager));
}
/// <summary>
/// 查找表达式中的 <see cref="IDataSegment"/> 对象。
/// </summary>
/// <param name="expression"></param>
/// <returns></returns>
public static IDataSegment Find(Expression expression)
{
var replaer = new SegmentFinder();
replaer.Visit(expression);
return(replaer.dataSegment);
}
/// <summary>
/// 尝试通过表达式获取执行后的结果缓存。
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="expression"></param>
/// <param name="func"></param>
/// <returns></returns>
internal static T TryGet <T>(Expression expression, Func <T> func)
{
var section = ConfigurationUnity.GetSection <TranslatorConfigurationSection>();
var option = section == null ? TranslateOptions.Default : section.Options;
var result = CacheableChecker.Check(expression);
//没有开启数据缓存
if ((result.Enabled == null && !option.CacheExecution) || result.Enabled == false)
{
return(func());
}
var cacheMgr = CacheManagerFactory.CreateManager();
if (cacheMgr == null)
{
return(func());
}
var cacheKey = ExpressionKeyGenerator.GetKey(expression, "Exec");
cacheKey = NativeCacheKeyContext.GetKey(cacheKey);
Reference(cacheKey, expression);
var segment = SegmentFinder.Find(expression);
var pager = segment as DataPager;
var cacheFunc = new Func <CacheItem <T> >(() =>
{
var data = EnumerateData(func());
var isEnumerable = typeof(T).IsGenericType && typeof(T).GetGenericTypeDefinition() == typeof(IEnumerable <>);
if (isEnumerable)
{
var elementType = typeof(T).GetEnumerableElementType();
var method = typeof(Enumerable).GetMethod(nameof(Enumerable.ToList)).MakeGenericMethod(elementType);
data = (T)method.Invoke(null, new object[] { data });
}
var total = 0;
if (pager != null)
{
total = pager.RecordCount;
}
return(new CacheItem <T> {
Data = data, Total = total
});
});
var cacheItem = cacheMgr.TryGet(cacheKey, cacheFunc, () => new RelativeTime(result.Expired ?? TimeSpan.FromSeconds(option.CacheExecutionTimes)));
if (pager != null)
{
pager.RecordCount = cacheItem.Total;
}
return(cacheItem.Data);
}
/// <summary>
/// 执行 <see cref="Expression"/> 的查询，返回查询结果。
/// </summary>
/// <param name="expression">表示 LINQ 查询的表达式树。</param>
/// <returns>单值对象。</returns>
/// <exception cref="TranslateException">对 LINQ 表达式解析失败时抛出此异常。</exception>
public object Execute(Expression expression)
{
var efn = TranslateCache.TryGetDelegate(expression, () => (LambdaExpression)GetExecutionPlan(expression));
if (efn.Method.GetParameters().Length == 2)
{
return(efn.DynamicInvoke(service.Database));
}
var segment = SegmentFinder.Find(expression);
return(efn.DynamicInvoke(service.Database, segment));
}
/// <summary>
/// 执行 <see cref="Expression"/> 的查询，返回查询结果。
/// </summary>
/// <param name="expression">表示 LINQ 查询的表达式树。</param>
/// <returns>单值对象。</returns>
/// <exception cref="TranslateException">对 LINQ 表达式解析失败时抛出此异常。</exception>
public object Execute(Expression expression)
{
var efn = TranslateCache.TryGetDelegate(expression, () => (LambdaExpression)GetExecutionPlan(expression));
var attrs = GetMethodAttributes(efn.Method);
if (!attrs.Item2)
{
return(efn.DynamicInvoke(service.Database));
}
var segment = SegmentFinder.Find(expression);
return(efn.DynamicInvoke(service.Database, segment));
}
/// <summary>
/// 尝试通过表达式获取执行后的结果缓存。
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="expression"></param>
/// <param name="func"></param>
/// <returns></returns>
internal static T TryGet <T>(Expression expression, Func <T> func)
{
var section = ConfigurationUnity.GetSection <TranslatorConfigurationSection>();
var option = section == null ? TranslateOptions.Default : section.Options;
//没有开启数据缓存
if (!option.DataCacheEnabled)
{
return(func());
}
var cacheMgr = CacheManagerFactory.CreateManager();
if (cacheMgr == null)
{
return(func());
}
var cacheKey = ExpressionKeyGenerator.GetKey(expression, "Exec");
Reference(cacheKey, expression);
var segment = SegmentFinder.Find(expression);
var pager = segment as DataPager;
var cacheFunc = new Func <CacheItem <T> >(() =>
{
var data = func();
var total = 0;
if (pager != null)
{
total = pager.RecordCount;
}
return(new CacheItem <T> {
Data = data, Total = total
});
});
var cacheItem = cacheMgr.TryGet(cacheKey, cacheFunc, () => new RelativeTime(TimeSpan.FromSeconds(option.DataCacheExpired)));
if (pager != null)
{
pager.RecordCount = cacheItem.Total;
}
return(cacheItem.Data);
}
/// <summary>
/// 执行 <see cref="Expression"/> 的查询，返回查询结果。
/// </summary>
/// <param name="expression">表示 LINQ 查询的表达式树。</param>
/// <returns>单值对象。</returns>
/// <exception cref="TranslateException">对 LINQ 表达式解析失败时抛出此异常。</exception>
public async Task <TResult> ExecuteAsync <TResult>(Expression expression, CancellationToken cancellationToken = default)
{
var efn = TranslateCache.TryGetDelegate(expression, () => (LambdaExpression)GetExecutionPlan(expression));
var attrs = GetMethodAttributes(efn.Method);
object result;
if (attrs.Item1)
{
if (attrs.Item2)
{
var segment = SegmentFinder.Find(expression);
result = efn.DynamicInvoke(service.Database, segment, cancellationToken);
}
else
{
result = efn.DynamicInvoke(service.Database, cancellationToken);
}
}
else
{
if (attrs.Item2)
{
var segment = SegmentFinder.Find(expression);
result = efn.DynamicInvoke(service.Database, segment);
}
else
{
result = efn.DynamicInvoke(service.Database);
}
}
if (result is TResult)
{
return((TResult)result);
}
else if (result is Task <TResult> task)
{
return(task.Result);
}
return(default);
/// <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);
}
