singrdk/base/Services/Fat/Fs/FileCache.sg

///////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  File:   FileCache.sg
//
//  Note:
//
//  This cache is for recently closed files.  Opened
//  files are not stored here.  This cache exists because
//  opening a file entails a non-trivial amount of work.
//
//  File metadata does not have a fixed size and this cache
//  should probably take this into account.

namespace Microsoft.Singularity.Services.Fat.Fs
{
    internal class FileCache
    {
        FsObjectCache! cache;

        internal FileCache(uint capacity)
        {
            this.cache = new FsObjectCache(capacity);
        }

        internal void Add(int firstCluster, File! directory)
            requires firstCluster != 0; // 0-byte files have inval firstCluster
        {
            cache.Add(firstCluster, directory);
        }

        internal File Get(int firstCluster)
            requires firstCluster != 0; // 0-byte files have inval firstCluster
        {
            return (File)cache.Get(firstCluster);
        }
    }
}