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Function `std.process.tryWait`

A non-blocking version of wait.


						
				Tuple!(bool,"terminated",int,"status") tryWait
				(
				

				  Pid pid
				

				) @safe;

If the process associated with pid has already terminated, tryWait has the exact same effect as wait. In this case, it returns a tuple where the terminated field is set to true and the status field has the same interpretation as the return value of wait.

If the process has not yet terminated, this function differs from wait in that does not wait for this to happen, but instead returns immediately. The terminated field of the returned tuple will then be set to false, while the status field will always be 0 (zero). wait or tryWait should then be called again on the same Pid at some later time; not only to get the exit code, but also to avoid the process becoming a "zombie" when it finally terminates. (See wait for details).

Returns

An Tuple!(bool, "terminated", int, "status").

Throws

ProcessException on failure or on attempt to wait for detached process.

Example

auto pid = spawnProcess("dmd myapp.d");
scope(exit) wait(pid);
...
auto dmd = tryWait(pid);
if (dmd.terminated)
{
    if (dmd.status == 0) writeln("Compilation succeeded!");
    else writeln("Compilation failed");
}
else writeln("Still compiling...");
...

Note that in this example, the first wait call will have no effect if the process has already terminated by the time tryWait is called. In the opposite case, however, the scope statement ensures that we always wait for the process if it hasn't terminated by the time we reach the end of the scope.

Authors

Lars Tandle Kyllingstad, Steven Schveighoffer, Vladimir Panteleev

License

Boost License 1.0.