private bool IsExternalProcessAlive()
{
lock (this.acquisitionLock)
{
if (this.isHeldInternally)
{
if (this.lockHolder != null)
{
throw new InvalidOperationException("Inconsistent GVFSLock state with external holder " + this.lockHolder.ToString());
}
return(false);
}
if (this.lockHolder == null)
{
return(false);
}
Process process;
if (ProcessHelper.TryGetProcess(this.lockHolder.PID, out process) &&
string.Equals(this.lockHolder.OriginalCommand, ProcessHelper.GetCommandLine(process)))
{
return(true);
}
this.ClearHolder();
return(false);
}
}
/// <summary>
/// Allows external callers (non-GVFS) to acquire the lock.
/// </summary>
/// <param name="requester">The data for the external acquisition request.</param>
/// <param name="holder">
/// The current holder of the lock if the acquisition fails, or
/// the input request if it succeeds.
/// </param>
/// <returns>True if the lock was acquired, false otherwise.</returns>
public bool TryAcquireLock(
NamedPipeMessages.AcquireLock.Data requester,
out NamedPipeMessages.AcquireLock.Data holder)
{
EventMetadata metadata = new EventMetadata();
EventLevel eventLevel = EventLevel.Verbose;
metadata.Add("LockRequest", requester.ToString());
try
{
lock (this.acquisitionLock)
{
if (this.isHeldInternally)
{
holder = null;
metadata.Add("CurrentLockHolder", "GVFS");
metadata.Add("Result", "Denied");
return(false);
}
if (this.IsExternalProcessAlive() &&
this.lockHolder.PID != requester.PID)
{
holder = this.lockHolder;
metadata.Add("CurrentLockHolder", this.lockHolder.ToString());
metadata.Add("Result", "Denied");
return(false);
}
metadata.Add("Result", "Accepted");
eventLevel = EventLevel.Informational;
Process process;
if (ProcessHelper.TryGetProcess(requester.PID, out process) &&
string.Equals(requester.OriginalCommand, ProcessHelper.GetCommandLine(process)))
{
this.lockHolder = requester;
holder = requester;
return(true);
}
else
{
// Process is no longer running so let it
// succeed since the process non-existence
// signals the lock release.
holder = null;
return(true);
}
}
}
finally
{
this.tracer.RelatedEvent(eventLevel, "TryAcquireLockExternal", metadata);
}
}
