public AzureIndexInput(AzureDirectory azuredirectory, ICloudBlob blob)
{
_name = blob.Uri.Segments[blob.Uri.Segments.Length - 1];
_azureDirectory = azuredirectory ?? throw new ArgumentNullException(nameof(azuredirectory));
#if FULLDEBUG
Trace.WriteLine($"opening {_name} ");
#endif
_fileMutex = SyncMutexManager.GrabMutex(_azureDirectory, _name);
_fileMutex.WaitOne();
try
{
_blobContainer = azuredirectory.BlobContainer;
_blob = blob;
var fileName = _name;
var fFileNeeded = false;
if (!CacheDirectory.FileExists(fileName))
{
fFileNeeded = true;
}
else
{
var cachedLength = CacheDirectory.FileLength(fileName);
var hasMetadataValue = blob.Metadata.TryGetValue("CachedLength", out var blobLengthMetadata);
var blobLength = blob.Properties.Length;
if (hasMetadataValue)
{
long.TryParse(blobLengthMetadata, out blobLength);
}
var blobLastModifiedUtc = blob.Properties.LastModified.Value.UtcDateTime;
if (blob.Metadata.TryGetValue("CachedLastModified", out var blobLastModifiedMetadata))
{
if (long.TryParse(blobLastModifiedMetadata, out var longLastModified))
{
blobLastModifiedUtc = new DateTime(longLastModified).ToUniversalTime();
}
}
if (cachedLength != blobLength)
{
fFileNeeded = true;
}
else
{
// cachedLastModifiedUTC was not ouputting with a date (just time) and the time was always off
var unixDate = CacheDirectory.FileModified(fileName);
var start = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
var cachedLastModifiedUtc = start.AddMilliseconds(unixDate).ToUniversalTime();
if (cachedLastModifiedUtc != blobLastModifiedUtc)
{
var timeSpan = blobLastModifiedUtc.Subtract(cachedLastModifiedUtc);
if (timeSpan.TotalSeconds > 1)
{
fFileNeeded = true;
}
else
{
#if FULLDEBUG
Trace.WriteLine(timeSpan.TotalSeconds);
#endif
// file not needed
}
}
}
}
// if the file does not exist
// or if it exists and it is older then the lastmodified time in the blobproperties (which always comes from the blob storage)
if (fFileNeeded)
{
if (_azureDirectory.ShouldCompressFile(_name))
{
InflateStream(fileName);
}
else
{
using (var fileStream = new StreamOutput(CacheDirectory.CreateOutput(fileName)))
{
// get the blob
_blob.DownloadToStream(fileStream);
fileStream.Flush();
#if FULLDEBUG
Trace.WriteLine($"GET {_name} RETREIVED {fileStream.Length} bytes");
#endif
}
}
// and open it as an input
_indexInput = CacheDirectory.OpenInput(fileName);
}
else
{
#if FULLDEBUG
Trace.WriteLine($"Using cached file for {_name}");
#endif
// open the file in read only mode
_indexInput = CacheDirectory.OpenInput(fileName);
}
}
finally
{
_fileMutex.ReleaseMutex();
}
}