Crate prock 

Fast, low-overhead CPU statistics for process trees.

This crate provides multiple approaches for measuring CPU usage:

1. Snapshot-based: Get raw CPU time at a point in time
2. Delta-based: Track changes between two snapshots
3. Cumulative: Track total CPU from a baseline (good for short-lived processes)

All approaches use direct syscalls for minimal overhead (~1-5µs per process).

Structs

AllStats

Combined stats from reading multiple /proc files.

CpuTime

CPU time for a process (user + system time in nanoseconds).

CumulativeTracker

Approach 3: Cumulative tracker.

DeltaTracker

Approach 2: Delta-based tracker.

DiskIo

Disk I/O statistics for a process.

LivenessInfo

Liveness information for a process, retrieved in a single syscall.

ProcessInfo

Info about a single process from a full system scan.

ProcessStats

Statistics for a single process.

TreeStats

Statistics for a process tree (process + all descendants).

Functions

build_children_map

Build a HashMap of pid -> children from a full process scan.

build_parent_map

Build a HashMap of pid -> parent pid for ALL processes on the system.

collect_descendants_from_map

Collect all descendant PIDs from a children map (built from full scan).

collect_tree_pids

Collect all PIDs in a process tree (BFS traversal).

get_all_stats

Get all stats (CPU, memory, disk I/O) by reading multiple /proc files.

get_children

Get direct child PIDs of a process.

get_cpu_time

Get CPU time for a process by reading /proc/[pid]/stat.

get_cpu_time_with_children

Get CPU time for a process INCLUDING time from waited-for (exited) children.

get_disk_io

Get disk I/O statistics for a process.

get_liveness_info

Get liveness information for a process in a single file read.

get_memory

Get memory usage (resident set size) for a process in bytes.

get_memory_virtual

Get virtual memory size for a process in bytes.

get_ppid

Get parent PID of a process.

get_process_comm

Get the kernel’s internal command name for a process.

get_process_environ

Get environment variables for a process.

get_process_path

Get the full executable path for a process.

get_start_time

Get process start time as seconds since Unix epoch.

get_tty

Get the controlling TTY device name for a process (like ps -o tty=).

is_descendant_of

Check if child_pid is a descendant of parent_pid using pre-built map.

list_all_pids

List all PIDs on the system.

scan_all_processes

Scan all processes on the system and return their info.

snapshot_process

Approach 1: Snapshot-based measurement.

snapshot_tree

Snapshot an entire process tree.

snapshot_tree_from_scan

Get stats for a process tree using the full scan approach.

Type Aliases

CpuPercent

CPU usage as a percentage (0.0 - 100.0+ for multi-core).