public async Task <Maybe <TEntity> > GetAsync(TKey key)
{
try
{
var name = this.GetName(key);
StorageProfiler.CountReadRequest(name);
if (!File.Exists(name))
{
return(Maybe <TEntity> .Empty);
}
using (var fs = new FileStream(name, FileMode.Open, FileAccess.Read, FileShare.Read, 4096, FileOptions.Asynchronous))
{
if (fs.Length == 0)
{
return(Maybe <TEntity> .Empty);
}
var bytes = new byte[fs.Length];
var readBytes = await fs.ReadAsync(bytes, 0, bytes.Length).ConfigureAwait(false);
if (readBytes != bytes.Length)
{
throw new IOException("Not all bytes were read async. Need to implement better async reader.");
}
using (var ms = new MemoryStream(bytes))
return(this._strategy.Deserialize <TEntity>(ms));
}
}
catch (FileNotFoundException)
{
// if file happened to be deleted between the moment of check and actual read.
return(Maybe <TEntity> .Empty);
}
catch (DirectoryNotFoundException)
{
return(Maybe <TEntity> .Empty);
}
}
public async Task SaveAsync(TKey key, TEntity entity)
{
var name = this.GetName(key);
try
{
// This is fast and allows to have git-style subfolders in atomic strategy
// to avoid NTFS performance degradation (when there are more than
// 10000 files per folder). Kudos to Gabriel Schenker for pointing this out
var subfolder = Path.GetDirectoryName(name);
if (subfolder != null && !Directory.Exists(subfolder))
{
Directory.CreateDirectory(subfolder);
}
// we are locking this file.
using (var file = File.Open(name, FileMode.Create, FileAccess.ReadWrite, FileShare.None))
// some serializers have nasty habbit of closing the
// underling stream
using (var mem = new MemoryStream())
{
this._strategy.Serialize(entity, mem);
var data = mem.ToArray();
StorageProfiler.CountWriteRequest(name);
// upload only if we changed
await file.WriteAsync(data, 0, data.Length);
// truncate this file
file.SetLength(data.Length);
}
}
catch (DirectoryNotFoundException)
{
var s = string.Format(
"Container '{0}' does not exist.",
this._folder);
throw new InvalidOperationException(s);
}
}
public bool TryGet(TKey key, out TEntity view)
{
view = default(TEntity);
try
{
var name = this.GetName(key);
StorageProfiler.CountReadRequest(name);
if (!File.Exists(name))
{
return(false);
}
using (var stream = RetryPolicies.GetPolicy.Get(() => File.Open(name, FileMode.Open, FileAccess.Read, FileShare.Read)))
{
if (stream.Length == 0)
{
return(false);
}
view = this._strategy.Deserialize <TEntity>(stream);
return(true);
}
}
catch (FileNotFoundException)
{
// if file happened to be deleted between the moment of check and actual read.
return(false);
}
catch (DirectoryNotFoundException)
{
return(false);
}
catch (IOException)
{
return(false);
}
}
public async Task <TEntity> AddOrUpdateAsync(TKey key, Func <TEntity> addFactory, Func <TEntity, TEntity> update, AddOrUpdateHint hint = AddOrUpdateHint.ProbablyExists)
{
var name = this.GetName(key);
try
{
// This is fast and allows to have git-style subfolders in atomic strategy
// to avoid NTFS performance degradation (when there are more than
// 10000 files per folder). Kudos to Gabriel Schenker for pointing this out
var subfolder = Path.GetDirectoryName(name);
if (subfolder != null && !Directory.Exists(subfolder))
{
Directory.CreateDirectory(subfolder);
}
// we are locking this file.
using (var file = File.Open(name, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None))
{
var initial = new byte[0];
TEntity result;
if (file.Length == 0)
{
result = addFactory();
}
else
{
using (var mem = new MemoryStream())
{
StorageProfiler.CountReadRequest(name);
await file.CopyToAsync(mem);
mem.Seek(0, SeekOrigin.Begin);
var entity = this._strategy.Deserialize <TEntity>(mem);
initial = mem.ToArray();
result = update(entity);
}
}
// some serializers have nasty habbit of closing the
// underling stream
using (var mem = new MemoryStream())
{
this._strategy.Serialize(result, mem);
var data = mem.ToArray();
if (!data.SequenceEqual(initial))
{
StorageProfiler.CountWriteRequest(name);
// upload only if we changed
file.Seek(0, SeekOrigin.Begin);
await file.WriteAsync(data, 0, data.Length);
// truncate this file
file.SetLength(data.Length);
}
}
return(result);
}
}
catch (DirectoryNotFoundException)
{
var s = string.Format(
"Container '{0}' does not exist.",
this._folder);
throw new InvalidOperationException(s);
}
}
