/// <summary>
/// 后台扫描全表数据
/// </summary>
/// <typeparam name="TEntity"></typeparam>
/// <param name="dbContext">上下文</param>
/// <param name="tableCacheTimeSpan">tableCache过期时间</param>
private static void ScanTableBackground <TEntity>(DbContext dbContext, TimeSpan tableCacheTimeSpan) where TEntity : class
{
string scanKey = $"{DefaultValue.CacheKey_TableScanning}{dbContext.TableName}";
//1.判断正在扫描键是否存在，如果存在，则返回null，继续等待扫描任务完成
if (CacheStorageManager.IsExist(dbContext, scanKey))
{
return;
}
//2.如果没有扫描键，则执行后台扫描任务
Task.Run(() =>
{
//设置扫描键，标识当前正在进行扫描
CacheStorageManager.Put(dbContext, scanKey, 1, DefaultValue.SpanScaningKeyExpiredTime);
//对扫描任务加锁，防止多线程环境多次执行任务
lock (tableScaningLocker)
{
//双重校验当前缓存是否存在TableCache，防止多个进程在锁外等待，所释放后再次执行
if (CacheStorageManager.IsExist(dbContext, GetTableCacheKey(dbContext)))
{
return;
}
//如果过期时间为0，则取上下文的过期时间
TimeSpan timeSpan = tableCacheTimeSpan == TimeSpan.Zero ? dbContext.TableCacheExpiredTimeSpan : tableCacheTimeSpan;
//执行扫描全表任务，并将结果存入缓存中
var data = GetFullTableData <TEntity>(dbContext);
if (data != null)
{
CacheStorageManager.Put(dbContext, GetTableCacheKey(dbContext), data, dbContext.TableCacheExpiredTimeSpan);
}
}
//将扫描键移除，表示已经扫描完成
CacheStorageManager.Delete(dbContext, scanKey);
});
}
/// <summary>
/// QueryCache级别存储
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="dbContext"></param>
/// <param name="cacheValue"></param>
internal static void CacheData <T>(DbContext dbContext, T cacheValue)
{
if (dbContext.OpenQueryCache)
{
if (cacheValue != null)
{
int sqlQueryCacheKey = dbContext.SqlStatement.GetHashCode();
//如果缓存中存在，则拿到表单位的缓存并更新
if (CacheStorageManager.IsExist(dbContext, GetQueryCacheKey(dbContext), out Dictionary <int, T> t))
{
if (t.ContainsKey(sqlQueryCacheKey))
{
t[sqlQueryCacheKey] = cacheValue;
}
else
{
t.Add(sqlQueryCacheKey, cacheValue);
}
}
//如果缓存中没有表单位的缓存，则直接新增表单位的sql键缓存
else
{
var dic = new Dictionary <int, T>();
dic.Add(sqlQueryCacheKey, cacheValue);
CacheStorageManager.Put(dbContext, GetQueryCacheKey(dbContext), dic, dbContext.QueryCacheExpiredTimeSpan);
}
}
}
}
/// <summary>
/// 清空所有缓存
/// </summary>
internal static void FlushAllCache(DbContext dbContext)
{
if (CacheStorageManager.IsExist(dbContext, DefaultValue.GetQueryCacheKeysCacheKey(dbContext.DataBaseName), out HashSet <string> keys))
{
foreach (var item in keys)
{
CacheStorageManager.Delete(dbContext, item);
}
}
}
private static string GetQueryCacheKey(DbContext dbContext)
{
string key = $"{DefaultValue.CacheKey_QueryCache}{dbContext.TableName}";
//缓存键更新
if (!CacheStorageManager.IsExist(dbContext, DefaultValue.GetQueryCacheKeysCacheKey(dbContext.DataBaseName), out HashSet <string> keys))
{
keys = new HashSet <string>();
}
keys.Add(key);
CacheStorageManager.Put(dbContext, DefaultValue.GetQueryCacheKeysCacheKey(dbContext.DataBaseName), keys, dbContext.MaxExpiredTimeSpan);
return(key);
}
/// <summary>
/// 从缓存中获取数据
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="dbContext"></param>
/// <returns></returns>
internal static T GetEntitiesFromCache <T>(DbContext dbContext)
{
//1.检查是否开启了Query缓存
if (dbContext.OpenQueryCache)
{
//2.如果QueryCache里面有该缓存键，则直接获取，并从单个表单位中获取到对应sql的值
if (CacheStorageManager.IsExist(dbContext, GetQueryCacheKey(dbContext), out Dictionary <int, T> t))
{
if (t.ContainsKey(dbContext.SqlStatement.GetHashCode()))
{
dbContext.IsFromCache = true;
return(t[dbContext.SqlStatement.GetHashCode()]);
}
}
}
return(default(T));
}
/// <summary>
/// 更新数据到缓存（Add）
/// </summary>
/// <typeparam name="TEntity"></typeparam>
/// <param name="dbContext"></param>
/// <param name="values"></param>
internal static void AddCache <TEntity>(DbContext dbContext, IEnumerable <TEntity> values)
{
if (dbContext.OpenTableCache)
{
//如果存在表级别缓存，则更新数据到缓存
if (CacheStorageManager.IsExist(dbContext, GetTableCacheKey(dbContext), out List <TEntity> entities))
{
if (TableCachingAttribute.IsExistTaleCaching(typeof(TEntity), out TimeSpan tableCacheTimeSpan))
{
//如果过期时间为0，则取上下文的过期时间
TimeSpan timeSpan = tableCacheTimeSpan == TimeSpan.Zero ? dbContext.TableCacheExpiredTimeSpan : tableCacheTimeSpan;
entities.AddRange(values);
CacheStorageManager.Put(dbContext, GetTableCacheKey(dbContext), entities, tableCacheTimeSpan);
}
}
}
}
/// <summary>
/// 更新数据到缓存（Delete）
/// </summary>
/// <typeparam name="TEntity"></typeparam>
/// <param name="dbContext"></param>
/// <param name="filter"></param>
internal static void DeleteCache <TEntity>(DbContext dbContext, Expression <Func <TEntity, bool> > filter)
{
if (dbContext.OpenTableCache)
{
//如果存在表级别缓存，则更新数据到缓存
if (CacheStorageManager.IsExist(dbContext, GetTableCacheKey(dbContext), out List <TEntity> entities))
{
if (TableCachingAttribute.IsExistTaleCaching(typeof(TEntity), out TimeSpan tableCacheTimeSpan))
{
//如果过期时间为0，则取上下文的过期时间
TimeSpan timeSpan = tableCacheTimeSpan == TimeSpan.Zero ? dbContext.TableCacheExpiredTimeSpan : tableCacheTimeSpan;
//从缓存集合中寻找该记录，如果找到，则更新该记录
var val = entities.Where(filter.Compile()).FirstOrDefault();
if (val != null)
{
entities.Remove(val);
CacheStorageManager.Put(dbContext, GetTableCacheKey(dbContext), entities, tableCacheTimeSpan);
}
}
}
}
}
/// <summary>
/// 从缓存中获取数据，如果没有，则后台执行扫描表任务
/// </summary>
/// <typeparam name="TEntity"></typeparam>
/// <param name="dbContext"></param>
/// <param name="filter"></param>
/// <returns></returns>
internal static List <TEntity> GetEntitiesFromCache <TEntity>(DbContext dbContext, Expression <Func <TEntity, bool> > filter) where TEntity : class
{
//1.检查是否开启了Table缓存
if (!dbContext.OpenTableCache)
{
return(null);
}
//2.如果TableCache里面有该缓存键，则直接获取
if (CacheStorageManager.IsExist(dbContext, GetTableCacheKey(dbContext), out List <TEntity> entities))
{
dbContext.IsFromCache = true;
return(entities.Where(filter.Compile()).ToList());
}
//3.则判断是否需要对该表进行扫描（含有TableCachingAttribute的标记的类才可以有扫描全表的权限）
if (TableCachingAttribute.IsExistTaleCaching(typeof(TEntity), out TimeSpan tableCacheTimeSpan))
{
//执行扫描全表数据任务
ScanTableBackground <TEntity>(dbContext, tableCacheTimeSpan);
}
return(null);
}
/// <summary>
/// 清空单个表相关的所有缓存
/// </summary>
/// <param name="dbContext"></param>
internal static void FlushTableCache(DbContext dbContext)
{
CacheStorageManager.Delete(dbContext, GetQueryCacheKey(dbContext));
}