This module allows you to turn a regular Ceylon program into a daemonized version. On each connection, the daemon will accept command line arguments, a working directory, and standard input. It will then set up the environment for the program, and launch it. Afterwards, the program’s output and result are sent over the connection again. A simple client that just communicates with the daemon can then be used in place of the original program, eliminating VM startup time and taking advantage of VM optimizations for long-running programs. One example client may be found in the client/ directory of the source code repository of this module; if you wish to implement your own client, please consult the detailed protocol description in the makeDaemonizeProgramInstance documentation.

import com.example.program { program=run }
import de.lucaswerkmeister.ceylond.daemonizeProgram { daemonizeProgram }

shared void run() => daemonizeProgram { program; fd = 3; };

The following mechanisms are trapped/replaced and may be used by the program:

• standard input, output and error (but note that all standard input must be provided before the program starts)
• process.exit
• process.arguments, including named arguments
• uncaught exceptions from the run function

The working directory of the daemon process remains unchanged, but a small handler may be [[registered|makeDaemonizeProgramInstance.argumentsMap]] to adapt paths in process.arguments as needed.

The following mechanisms are not trapped/replaced and should not be used by the program:

• process.propertyValue
• process.environmentVariableValue
• any backend-specific mechanism

Logging

This module provides a custom version of the core module’s [[de.lucaswerkmeister.ceylond.core::writeSystemdLog]] that does not interfere with trapped standard error: see writeSystemdLog.