public async Task <ReserveSpaceResult> TryReserveSpace(CacheEntry cacheEntry, string contentType, int byteCount,
bool allowEviction, AsyncLockProvider writeLocks,
CancellationToken cancellationToken)
{
var shard = Database.GetShardForKey(cacheEntry.RelativePath);
var shardSizeLimit = Options.MaxCacheBytes / Database.GetShardCount();
// When we're okay with deleting the database entry even though the file isn't written
var farFuture = DateTime.UtcNow.AddHours(1);
var maxAttempts = 30;
for (var attempts = 0; attempts < maxAttempts; attempts++)
{
var recordCreated =
await Database.CreateRecordIfSpace(shard, cacheEntry.RelativePath,
contentType,
EstimateEntryBytesWithOverhead(byteCount),
farFuture,
AccessCounter.GetHash(cacheEntry.Hash),
shardSizeLimit);
// Return true if we created the record
if (recordCreated)
{
return new ReserveSpaceResult()
{
Success = true
}
}
;
// We need to evict but we are not permitted
if (!allowEviction)
{
return new ReserveSpaceResult()
{
Success = false, Message = "Eviction disabled in sync mode"
}
}
;
var entryDiskSpace = EstimateEntryBytesWithOverhead(byteCount) +
Database.EstimateRecordDiskSpace(cacheEntry.RelativePath.Length + (contentType?.Length ?? 0));
var missingSpace = Math.Max(0, await Database.GetShardSize(shard) + entryDiskSpace - shardSizeLimit);
// Evict space
var evictResult = await EvictSpace(shard, missingSpace, writeLocks, cancellationToken);
if (!evictResult.Success)
{
return(evictResult); //We failed to evict enough space from the cache
}
}
return(new ReserveSpaceResult()
{
Success = false, Message = $"Eviction worked but CreateRecordIfSpace failed {maxAttempts} times."
});
}
public Task MarkFileCreated(CacheEntry cacheEntry, string contentType, long recordDiskSpace, DateTime createdDate)
{
return(Database.UpdateCreatedDateAtomic(
Database.GetShardForKey(cacheEntry.RelativePath),
cacheEntry.RelativePath,
contentType,
EstimateEntryBytesWithOverhead(recordDiskSpace),
createdDate,
AccessCounter.GetHash(cacheEntry.Hash)));
}
