Handling errors

A broken file does not stop the scan

A repository often contains files that a scanner cannot read: a malformed JSON file, a template, a file locked by another process. When a file cannot be opened or read, or a scanner throws while scanning it, the remaining scanners are skipped for that file and the scan continues with the next file. The dependencies reported from the file before the failure are kept.

Get notified of the failures

Set ScannerOptions.OnFileScanFailed to receive the path of the file and the exception:

var options = new ScannerOptions
{
    // Number of parallel scanning tasks (default: 16)
    DegreeOfParallelism = 8,

    // Recurse into subdirectories (default: true)
    RecurseSubdirectories = true,

    // Filter files to scan (FileSystemEntry is in System.IO.Enumeration)
    ShouldScanFilePredicate = (ref FileSystemEntry entry) => !entry.FileName.StartsWith('.'),

    // Filter directories to recurse into
    ShouldRecursePredicate = (ref FileSystemEntry entry) => entry.FileName is not ("node_modules" or "bin"),

    // Called when a file cannot be read or parsed. The file is skipped and the scan continues.
    OnFileScanFailed = (filePath, exception) => Console.Error.WriteLine($"Cannot scan {filePath}: {exception.Message}"),
};

var dependencies = await DependencyScanner.ScanDirectoryAsync(
    @"C:\MyProject",
    options,
    cancellationToken);

The callback can be called concurrently from several threads, as files are scanned in parallel.

Stop at the first failure

An exception thrown by OnFileScanFailed stops the scan, and the scan method throws it. Use it to fail fast:

var options = new ScannerOptions
{
    OnFileScanFailed = (filePath, exception) => throw new InvalidOperationException($"Cannot scan '{filePath}'", exception),
};

What stops a scan

ScanFileAsync, ScanFilesAsync and ScanDirectoryAsync behave the same way, and ScanFileAsync returns the dependencies found before the failure. The ScanFileAsync overloads that scan content held in memory take no options, so they skip a failure silently.