/// <summary>
/// Checks file existence
/// </summary>
/// <param name="cacheKey">Will be used by CacheFileNameGenerator</param>
/// <returns>true if file with cache exists, false otherwise</returns>
public virtual async Task <bool> IsCacheExists(string cacheKey)
{
var fullFilePath = GetFullFilePath(CacheFileNameGenerator.GenerateCacheName(cacheKey));
try
{
await SF.GetFileAsync(fullFilePath);
return(true);
}
catch
{
ImageLog.Log("[error] can not check cache existence, file: " + fullFilePath);
return(false);
}
}
/// <summary>
/// Checks is cache existst and its last write time <= CacheMaxLifetimeInMillis
/// </summary>
/// <param name="cacheKey">Will be used by CacheFileNameGenerator</param>
/// <returns>true if cache exists and alive, false otherwise</returns>
public virtual async Task <bool> IsCacheExistsAndAlive(string cacheKey)
{
var fullFilePath = GetFullFilePath(CacheFileNameGenerator.GenerateCacheName(cacheKey));
try
{
var storageFile = await SF.GetFileAsync(fullFilePath);
return(CacheMaxLifetimeInMillis <= 0 ? true :
((DateTime.Now - storageFile.DateCreated.DateTime).TotalMilliseconds < CacheMaxLifetimeInMillis));
}
catch
{
ImageLog.Log("[error] can not check is cache exists and alive, file: " + fullFilePath);
}
return(false);
}
public async override Task <bool> SaveAsync(string cacheKey, IRandomAccessStream cacheStream)
{
var fullFileName = Path.Combine(CacheDirectory, CacheFileNameGenerator.GenerateCacheName(cacheKey));
var cacheSizeInBytes = cacheStream.AsStreamForRead().Length;
while (CurrentCacheSizeInBytes + cacheSizeInBytes > _cacheLimitInBytes)
{
if (!await RemoveOldestCacheFile())
{
break; // All cache deleted
}
}
var wasFileSaved = await base.InternalSaveAsync(fullFileName, cacheStream);
if (wasFileSaved)
{
_lastAccessTimeDictionary[Path.Combine(CacheDirectory, fullFileName)] = DateTimeHelper.CurrentTimeMillis();
CurrentCacheSizeInBytes += cacheSizeInBytes; // Updating current cache size
}
return(wasFileSaved);
}
/// <summary>
/// Async gets file stream by the cacheKey (cacheKey will be converted using CacheFileNameGenerator)
/// </summary>
/// <param name="cacheKey">key will be used by CacheFileNameGenerator to get cache's file name</param>
/// <returns>Stream of that file or null, if it does not exists</returns>
public async virtual Task <IRandomAccessStream> LoadCacheStreamAsync(string cacheKey)
{
var fullFilePath = GetFullFilePath(CacheFileNameGenerator.GenerateCacheName(cacheKey));
try
{
var cacheFileMemoryStream = new InMemoryRandomAccessStream();
var storageFile = await SF.GetFileAsync(fullFilePath);
using (var cacheFileStream = await storageFile.OpenAsync(FileAccessMode.Read))
{
await RandomAccessStream.CopyAsync(
cacheFileStream.GetInputStreamAt(0L),
cacheFileMemoryStream.GetOutputStreamAt(0L));
return(cacheFileMemoryStream);
}
}
catch (Exception ex)
{
ImageLog.Log("[error] can not load file stream from: " + fullFilePath);
return(null);
}
}
/// <summary>
/// Just calls StorageCacheBase.InternalSaveAsync() without any other operation
/// </summary>
/// <param name="cacheKey">will be used by CacheFileNameGenerator</param>
/// <param name="cacheStream">will be written to the cache file</param>
/// <returns>true if cache was saved, false otherwise</returns>
public override Task <bool> SaveAsync(string cacheKey, IRandomAccessStream cacheStream)
{
return(InternalSaveAsync(CacheFileNameGenerator.GenerateCacheName(cacheKey), cacheStream));
}