mm::core::SingleInstanceLock Class Reference

RAII holder of the process-wide single-instance lock. More...

#include <platform.h>

Public Member Functions
	SingleInstanceLock ()=default
	SingleInstanceLock (SingleInstanceLock &&other) noexcept
SingleInstanceLock &	operator= (SingleInstanceLock &&other) noexcept
	SingleInstanceLock (const SingleInstanceLock &)=delete
SingleInstanceLock &	operator= (const SingleInstanceLock &)=delete
	~SingleInstanceLock ()

Friends
std::expected< SingleInstanceLock, std::string >	acquireSingleInstanceLock ()
	Acquire the process-wide lock that permits only one running Motion Master.

Detailed Description

RAII holder of the process-wide single-instance lock.

Owns an OS handle whose lifetime is the lock: an flock'd file descriptor on Linux/macOS, a named mutex on Windows. The OS releases the lock automatically when the process exits for any reason — normal return, crash, or SIGKILL — so there is never a stale lock to clean up (unlike a PID file). Move-only; destroy it (or move-assign over it) to release the lock early.

Constructor & Destructor Documentation

SingleInstanceLock() [1/3]

mm::core::SingleInstanceLock::SingleInstanceLock ( )

default

SingleInstanceLock() [2/3]

mm::core::SingleInstanceLock::SingleInstanceLock ( SingleInstanceLock &&  other )

noexcept

SingleInstanceLock() [3/3]

mm::core::SingleInstanceLock::SingleInstanceLock ( const SingleInstanceLock &  )

delete

~SingleInstanceLock()

mm::core::SingleInstanceLock::~SingleInstanceLock

(

)

Member Function Documentation

operator=() [1/2]

SingleInstanceLock & mm::core::SingleInstanceLock::operator= ( const SingleInstanceLock &  )

delete

operator=() [2/2]

SingleInstanceLock & mm::core::SingleInstanceLock::operator= ( SingleInstanceLock &&  other )

noexcept

Friends And Related Symbol Documentation

acquireSingleInstanceLock

std::expected< SingleInstanceLock, std::string > acquireSingleInstanceLock ( )

friend

Acquire the process-wide lock that permits only one running Motion Master.

Non-blocking. Returns the held lock when no other instance holds it; fails when one already does. The lock guards the whole process — acquired before the EtherCAT NIC is claimed and before the servers bind — so a second master can never drive the same bus alongside the first. The exclusive port bind is only a backstop: it fires too late (the NIC is already claimed by then) and misses instances configured on different ports, so the lock, not the port, is the real guard.

• Linux/macOS: flock(LOCK_EX|LOCK_NB) on <temp_dir>/motion-master.lock (machine-wide).
• Windows: a named mutex in the session-local namespace (per interactive session — a standard user cannot create objects in the machine-global namespace).

  Returns

  The held lock on success; an error string describing the conflict on failure.

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The documentation for this class was generated from the following files:

• libs/core/platform.h
• libs/core/platform.cc