sigqueuepidt

Sigqueuepidt is a typedef used in some C and C++ codebases to denote the type of a process identifier (PID) in the context of queued signal delivery. It is not a standard POSIX type; rather, it is an implementation- or project-specific alias intended to improve code readability and portability when working with signal queuing APIs.

Common pattern and rationale

- Purpose: By introducing sigqueuepidt, developers can clearly indicate that a variable represents a target process ID for a queued signal, separate from general integers or other identifiers.

- Underlying type: In many codebases, sigqueuepidt aliases the standard pid_t (the POSIX type for PIDs). Some projects may map it to a platform-specific type if PIDs differ across environments.

- Benefits: Helps enforce a consistent abstraction for PIDs used in signal queuing code, facilitates type checking, and makes future changes to the underlying PID type easier.

Related concepts

- POSIX signal APIs: The standard interfaces for delivering signals with data include sigqueue and related mechanisms, where a PID is required as a target.

- pid_t and sigval: pid_t represents process IDs, while sigval carries data associated with a queued signal. Sigqueuepidt typically sits at the intersection of these concepts as a named PID type.

- Portability considerations: Because sigqueuepidt is not standardized, its definition and usage are specific to a codebase. If portability is needed, projects often typedef pid_t directly or wrap it in a clear alias.

Example usage (conceptual)

typedef pid_t sigqueuepidt;

void send_signal(sigqueuepidt pid, int signo, union sigval val);

See also

- pid_t

- sigqueue

- sigval

- POSIX signal APIs