/// <summary>
/// Initializes the structure by reading metadata and content from disk
/// </summary>
/// <remarks>
/// The file format is as follows:
///
/// int version - version for the format of the file
/// long metadataOffset - offset in the file to where the file metadata starts
/// Clean/Dirty - describes whether the file was closed cleanly. Used as a hint to avoid work when
/// not closed cleanly
/// byte[] fileContent - actual content of files. This is at the start so additional file and metadata can be
/// written to the end without rewriting the content at the beginning of the file
/// FileLocation[] - metadata of which files exist, their hashes, and where they are
/// </remarks>
private void Initialize()
{
Stopwatch sw = Stopwatch.StartNew();
try
{
if (!File.Exists(m_path))
{
TryCreateClean();
// Don't go through a many layers of exception handling if the file doesn't even exist.
return;
}
m_file = FileUtilities.CreateFileStream(m_path, FileMode.Open, FileAccess.ReadWrite, FileShare.Delete);
m_reader = new BuildXLReader(false, m_file, leaveOpen: true);
if (m_reader.ReadInt32() != Version)
{
Tracing.Logger.Log.FileCombinerVersionIncremented(m_loggingContext, m_usage.ToString());
CreateClean();
return;
}
m_nextItemLocation = m_reader.ReadInt64();
if (m_reader.ReadInt32() != Clean)
{
Tracing.Logger.Log.FileCombinerFailedToInitialize(m_loggingContext, m_usage.ToString(), Strings.FileCombiner_FileNotClosedCleanly);
CreateClean();
return;
}
m_contentStartLocation = m_reader.BaseStream.Position;
// Read out the file content in a single large read for best performance
m_reader.BaseStream.Position = 0;
Contract.Assume(m_maxReadChunkBytes > 0);
int contentArrays = (int)((m_nextItemLocation + (m_maxReadChunkBytes - 1)) / m_maxReadChunkBytes);
Contract.Assert(contentArrays > 0);
m_content = new byte[contentArrays][];
var bytesRemaining = m_nextItemLocation;
for (int i = 0; i < m_content.Length; i++)
{
var chunkSize = (int)Math.Min(bytesRemaining, m_maxReadChunkBytes);
m_content[i] = m_reader.ReadBytes(chunkSize);
bytesRemaining -= chunkSize;
}
Contract.Assert(bytesRemaining == 0);
// read out the metadata
Contract.Assert(m_reader.BaseStream.Position == m_nextItemLocation);
int count = 0;
// If the file combiner is empty, the end of the stream may have been reached.
if (m_reader.BaseStream.Position < m_reader.BaseStream.Length)
{
count = m_reader.ReadInt32Compact();
}
Contract.Assume(count >= 0);
m_fileLocations = new FileLocation[count];
long lastOffset = 0;
for (int i = 0; i < count; i++)
{
FileLocation fileLocation = FileLocation.Deserialize(m_reader);
if (fileLocation.Offset < lastOffset)
{
throw new BuildXLException("File location offsets should be increasing");
}
lastOffset = fileLocation.Offset;
m_fileLocations[i] = fileLocation;
// If the same path is encountered more than once, always overwrite with the most recently added one
m_filesByPath.AddOrUpdate(fileLocation.Path, i, (oldPath, oldInt) => i);
}
// Initialize the writer and return success
m_writer = new BuildXLWriter(false, m_file, true, false);
m_stats.BeginCount = count;
m_stats.InitializationTimeMs = (int)sw.ElapsedMilliseconds;
}
catch (Exception ex)
{
if (File.Exists(m_path))
{
// Only log the warning if the file previously existed. Otherwise we just failed to open it which
// isn't an error case
#pragma warning disable EPC12 // Suspicious exception handling: only Message property is observed in exception block.
Tracing.Logger.Log.FileCombinerFailedToInitialize(m_loggingContext, m_usage.ToString(), ex.Message);
#pragma warning restore EPC12 // Suspicious exception handling: only Message property is observed in exception block.
}
TryCreateClean();
}
}
