/// <summary>
/// Runs an external process asynchronously, providing callbacks to
/// capture binary data from the standard error and standard output streams.
/// The callbacks contain a reference to the process so you can respond to output or
/// error streams by writing to the process' input stream.
/// The exit code (return value) will be -1 for forceful termination of the process.
/// </summary>
/// <param name="filename">The filename.</param>
/// <param name="arguments">The arguments.</param>
/// <param name="onOutputData">The on output data.</param>
/// <param name="onErrorData">The on error data.</param>
/// <param name="syncEvents">if set to <c>true</c> the next data callback will wait until the current one completes.</param>
/// <param name="cancellationToken">The cancellation token.</param>
/// <returns>Value type will be -1 for forceful termination of the process.</returns>
/// <example>
/// The following example illustrates how to run an external process using the
/// <see cref="RunProcessAsync(string, string, ProcessDataReceivedCallback, ProcessDataReceivedCallback, bool, CancellationToken)"/>
/// method.
/// <code>
/// class Example
/// {
/// using System.Diagnostics;
/// using System.Text;
/// using System.Threading.Tasks;
/// using Swan;
///
/// static async Task Main()
/// {
/// // Execute a process asynchronously
/// var data = await ProcessRunner
/// .RunProcessAsync("dotnet", "--help", Print, Print);
///
/// // flush all messages
/// Terminal.Flush();
/// }
///
/// // a callback to print both output or errors
/// static void Print(byte[] data, Process proc) =>
/// Encoding.GetEncoding(0).GetString(data).WriteLine();
/// }
/// </code>
/// </example>
public static Task <int> RunProcessAsync(
string filename,
string arguments,
ProcessDataReceivedCallback onOutputData,
ProcessDataReceivedCallback onErrorData,
bool syncEvents = true,
CancellationToken cancellationToken = default)
=> RunProcessAsync(
filename,
arguments,
null,
onOutputData,
onErrorData,
Definitions.CurrentAnsiEncoding,
syncEvents,
cancellationToken);
/// <summary>
/// Copies the stream asynchronously.
/// </summary>
/// <param name="process">The process.</param>
/// <param name="baseStream">The source stream.</param>
/// <param name="onDataCallback">The on data callback.</param>
/// <param name="syncEvents">if set to <c>true</c> [synchronize events].</param>
/// <param name="ct">The cancellation token.</param>
/// <returns>Total copies stream.</returns>
private static Task <ulong> CopyStreamAsync(
Process process,
Stream baseStream,
ProcessDataReceivedCallback onDataCallback,
bool syncEvents,
CancellationToken ct)
{
return(Task.Factory.StartNew(async() =>
{
// define some state variables
var swapBuffer = new byte[2048]; // the buffer to copy data from one stream to the next
ulong totalCount = 0; // the total amount of bytes read
var hasExited = false;
while (ct.IsCancellationRequested == false)
{
try
{
// Check if process is no longer valid
// if this condition holds, simply read the last bits of data available.
int readCount; // the bytes read in any given event
if (process.HasExited || process.WaitForExit(1))
{
while (true)
{
try
{
readCount = await baseStream.ReadAsync(swapBuffer, 0, swapBuffer.Length, ct);
if (readCount > 0)
{
totalCount += (ulong)readCount;
onDataCallback?.Invoke(swapBuffer.Skip(0).Take(readCount).ToArray(), process);
}
else
{
hasExited = true;
break;
}
}
catch
{
hasExited = true;
break;
}
}
}
if (hasExited)
{
break;
}
// Try reading from the stream. < 0 means no read occurred.
readCount = await baseStream.ReadAsync(swapBuffer, 0, swapBuffer.Length, ct);
// When no read is done, we need to let is rest for a bit
if (readCount <= 0)
{
await Task.Delay(1, ct); // do not hog CPU cycles doing nothing.
continue;
}
totalCount += (ulong)readCount;
if (onDataCallback == null)
{
continue;
}
// Create the buffer to pass to the callback
var eventBuffer = swapBuffer.Skip(0).Take(readCount).ToArray();
// Create the data processing callback invocation
var eventTask =
Task.Factory.StartNew(() => { onDataCallback.Invoke(eventBuffer, process); }, ct);
// wait for the event to process before the next read occurs
if (syncEvents)
{
eventTask.Wait(ct);
}
}
catch
{
break;
}
}
return totalCount;
}, ct).Unwrap());
}
/// <summary>
/// Runs an external process asynchronously, providing callbacks to
/// capture binary data from the standard error and standard output streams.
/// The callbacks contain a reference to the process so you can respond to output or
/// error streams by writing to the process' input stream.
/// The exit code (return value) will be -1 for forceful termination of the process.
/// </summary>
/// <param name="filename">The filename.</param>
/// <param name="arguments">The arguments.</param>
/// <param name="workingDirectory">The working directory.</param>
/// <param name="onOutputData">The on output data.</param>
/// <param name="onErrorData">The on error data.</param>
/// <param name="encoding">The encoding.</param>
/// <param name="syncEvents">if set to <c>true</c> the next data callback will wait until the current one completes.</param>
/// <param name="ct">The cancellation token.</param>
/// <returns>
/// Value type will be -1 for forceful termination of the process.
/// </returns>
public static Task <int> RunProcessAsync(
string filename,
string arguments,
string workingDirectory,
ProcessDataReceivedCallback onOutputData,
ProcessDataReceivedCallback onErrorData,
Encoding encoding,
bool syncEvents = true,
CancellationToken ct = default)
{
if (filename == null)
{
throw new ArgumentNullException(nameof(filename));
}
return(Task.Factory.StartNew(() =>
{
// Setup the process and its corresponding start info
var process = new Process
{
EnableRaisingEvents = false,
StartInfo = new ProcessStartInfo
{
Arguments = arguments,
CreateNoWindow = true,
FileName = filename,
RedirectStandardError = true,
StandardErrorEncoding = encoding,
RedirectStandardOutput = true,
StandardOutputEncoding = encoding,
UseShellExecute = false,
#if NET452
WindowStyle = ProcessWindowStyle.Hidden,
#endif
},
};
if (!string.IsNullOrWhiteSpace(workingDirectory))
{
process.StartInfo.WorkingDirectory = workingDirectory;
}
// Launch the process and discard any buffered data for standard error and standard output
process.Start();
process.StandardError.DiscardBufferedData();
process.StandardOutput.DiscardBufferedData();
// Launch the asynchronous stream reading tasks
var readTasks = new Task[2];
readTasks[0] = CopyStreamAsync(
process,
process.StandardOutput.BaseStream,
onOutputData,
syncEvents,
ct);
readTasks[1] = CopyStreamAsync(
process,
process.StandardError.BaseStream,
onErrorData,
syncEvents,
ct);
try
{
// Wait for all tasks to complete
Task.WaitAll(readTasks, ct);
}
catch (TaskCanceledException)
{
// ignore
}
finally
{
// Wait for the process to exit
while (ct.IsCancellationRequested == false)
{
if (process.HasExited || process.WaitForExit(5))
{
break;
}
}
// Forcefully kill the process if it do not exit
try
{
if (process.HasExited == false)
{
process.Kill();
}
}
catch
{
// swallow
}
}
try
{
// Retrieve and return the exit code.
// -1 signals error
return process.HasExited ? process.ExitCode : -1;
}
catch
{
return -1;
}
}, ct));
}
