public async Task Set <T>(string key, T item, CancellationToken cancel) where T : class, new()
{
var cachedItem = new CachedItem <T>(item);
string serializeObject = Serialize(cachedItem);
await multilayerCache.SetAsync(
key,
Encoding.UTF8.GetBytes(serializeObject),
cancel);
}
public T GetOrUpdate <T>(string key, Func <DateTimeOffset> getLastModificationTime, Func <T> getItem, CancellationToken cancel = default) where T : class, new()
{
logger.LogInformation($"get cached item, key={key}");
var value = multilayerCache.Get(key);
CachedItem <T> cachedItem;
T RefreshItem()
{
var item = getItem();
cachedItem = new CachedItem <T>(item);
string serializeObject = Serialize(cachedItem);
value = Encoding.UTF8.GetBytes(serializeObject);
Task.Run(() => multilayerCache.Set(key, value, cacheEntryOptions));
return(item);
}
if (value == null)
{
appTelemetry.RecordMetric("cache-miss", 1, ("key", key));
return(RefreshItem());
}
var json = Encoding.UTF8.GetString(value);
cachedItem = JsonConvert.DeserializeObject <CachedItem <T> >(json);
var needRefresh = false;
if (cachedItem.CreatedOn.Add(settings.TimeToLive) < DateTimeOffset.UtcNow)
{
appTelemetry.RecordMetric("cache-expired", 1, ("key", key));
needRefresh = true;
}
else
{
var lastUpdateTime = getLastModificationTime();
if (lastUpdateTime != default && lastUpdateTime > cachedItem.CreatedOn)
{
needRefresh = true;
}
}
if (needRefresh)
{
// ReSharper disable once MethodSupportsCancellation
Task.Factory.StartNew(RefreshItem, TaskCreationOptions.LongRunning);
}
return(cachedItem.Value);
}
private string Serialize <T>(CachedItem <T> cachedItem) where T : class, new()
{
var tempFile = Path.GetTempFileName();
if (File.Exists(tempFile))
{
File.Delete(tempFile);
}
using (var stream = File.OpenWrite(tempFile))
{
using (var writer = new StreamWriter(stream))
{
using (var jsonWriter = new JsonTextWriter(writer))
{
var serializer = new JsonSerializer
{
Formatting = Formatting.None,
MaxDepth = 3,
ReferenceLoopHandling = ReferenceLoopHandling.Ignore,
PreserveReferencesHandling = PreserveReferencesHandling.Objects,
NullValueHandling = NullValueHandling.Ignore
};
serializer.Serialize(jsonWriter, cachedItem);
jsonWriter.Flush();
}
}
}
var serializedString = File.ReadAllText(tempFile);
if (File.Exists(tempFile))
{
File.Delete(tempFile);
}
return(serializedString);
}
public async Task <T> GetOrUpdateAsync <T>(
string key,
Func <Task <DateTimeOffset> > getLastModificationTime,
Func <Task <T> > getItem,
CancellationToken cancel) where T : class, new()
{
logger.LogInformation($"get cached item, key={key}");
var value = await multilayerCache.GetAsync(key, cancel);
CachedItem <T> cachedItem;
async Task <T> RefreshItem()
{
var item = await getItem();
cachedItem = new CachedItem <T>(item);
string serializeObject = Serialize(cachedItem);
value = Encoding.UTF8.GetBytes(serializeObject);
logger.LogInformation($"updating cache {key}...");
#pragma warning disable 4014
// ReSharper disable once MethodSupportsCancellation
multilayerCache.SetAsync(key, value, cacheEntryOptions);
#pragma warning restore 4014
return(item);
}
if (value == null)
{
appTelemetry.RecordMetric("cache-miss", 1, ("key", key));
return(await RefreshItem());
}
var json = Encoding.UTF8.GetString(value);
cachedItem = JsonConvert.DeserializeObject <CachedItem <T> >(json);
var needRefresh = false;
if (cachedItem.CreatedOn.Add(settings.TimeToLive) < DateTimeOffset.UtcNow)
{
appTelemetry.RecordMetric("cache-expired", 1, ("key", key));
needRefresh = true;
}
else
{
var lastUpdateTime = await getLastModificationTime();
if (lastUpdateTime != default && lastUpdateTime > cachedItem.CreatedOn)
{
needRefresh = true;
}
}
if (needRefresh)
{
#pragma warning disable 4014
// ReSharper disable once MethodSupportsCancellation
Task.Factory.StartNew(RefreshItem);
#pragma warning restore 4014
}
return(cachedItem.Value);
}