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Unified ImageFileCache implementations

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This commit is contained in:
Clemens 2021-06-30 17:56:02 +02:00
parent 8cb20f0544
commit f9347edf19
5 changed files with 92 additions and 118 deletions
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54
MapControl/WPF/ImageFileCache.WPF.cs
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@ -19,27 +19,13 @@ namespace MapControl.Caching
/// ObjectCache implementation based on local image files.
/// The only valid data type for cached values is MapControl.ImageCacheItem.
/// </summary>
public class ImageFileCache : ObjectCache
public partial class ImageFileCache : ObjectCache
{
private const string expiresTag = "EXPIRES:";
private static readonly FileSystemAccessRule fullControlRule = new FileSystemAccessRule(
new SecurityIdentifier(WellKnownSidType.BuiltinUsersSid, null),
FileSystemRights.FullControl, AccessControlType.Allow);
private readonly MemoryCache memoryCache = MemoryCache.Default;
private readonly string rootDirectory;
public ImageFileCache(string directory)
{
if (string.IsNullOrEmpty(directory))
{
throw new ArgumentException("The directory argument must not be null or empty.", nameof(directory));
}
rootDirectory = directory;
Debug.WriteLine("Created ImageFileCache in " + rootDirectory);
}
public Task Clean()
{
@ -115,7 +101,7 @@ namespace MapControl.Caching
try
{
var buffer = File.ReadAllBytes(path);
var expiration = GetExpiration(ref buffer);
var expiration = ReadExpiration(ref buffer);
imageCacheItem = new ImageCacheItem
{
@ -282,20 +268,6 @@ namespace MapControl.Caching
return null;
}
private string GetPath(string key)
{
try
{
return Path.Combine(rootDirectory, Path.Combine(key.Split('/', ':', ';', ',')));
}
catch (Exception ex)
{
Debug.WriteLine("ImageFileCache: Invalid key {0}/{1}: {2}", rootDirectory, key, ex.Message);
}
return null;
}
private async Task CleanRootDirectory()
{
foreach (var dir in new DirectoryInfo(rootDirectory).EnumerateDirectories())
@ -349,22 +321,9 @@ namespace MapControl.Caching
return deletedFileCount;
}
private static DateTime GetExpiration(ref byte[] buffer)
{
DateTime expiration = DateTime.Today;
if (buffer.Length > 16 && Encoding.ASCII.GetString(buffer, buffer.Length - 16, 8) == expiresTag)
{
expiration = new DateTime(BitConverter.ToInt64(buffer, buffer.Length - 8), DateTimeKind.Utc);
Array.Resize(ref buffer, buffer.Length - 16);
}
return expiration;
}
private static async Task<DateTime> ReadExpirationAsync(FileInfo file)
{
DateTime expiration = DateTime.Today;
DateTime? expiration = null;
if (file.Length > 16)
{
@ -374,15 +333,14 @@ namespace MapControl.Caching
{
stream.Seek(-16, SeekOrigin.End);
if (await stream.ReadAsync(buffer, 0, 16).ConfigureAwait(false) == 16 &&
Encoding.ASCII.GetString(buffer, 0, 8) == expiresTag)
if (await stream.ReadAsync(buffer, 0, 16).ConfigureAwait(false) == 16)
{
expiration = new DateTime(BitConverter.ToInt64(buffer, 8), DateTimeKind.Utc);
expiration = ReadExpiration(buffer);
}
}
}
return expiration;
return expiration ?? DateTime.Today;
}
}
}