#!/bin/bash
# guest_sampler.sh TAG — runs INSIDE the Felhom guest. Every 5 s, one line per running container:
#   ts  name  mem_current  anon  inactive_file  shmem  cpu_usage_usec
# read straight from the container's cgroup v2 files (no docker stats: cheaper, and exact).
# Stops when /root/sizing/stop-TAG exists. Read-only: it writes only its own TSV.
TAG=${1:?tag}; D=/root/sizing; mkdir -p "$D"; OUT="$D/guest-$TAG.tsv"; rm -f "$D/stop-$TAG"
echo -e "ts\tname\tmem_current\tanon\tinactive_file\tshmem\tcpu_usage_usec" > "$OUT"
declare -A NAME; last=0
while [ ! -e "$D/stop-$TAG" ]; do
  now=$(date +%s)
  if (( now - last >= 30 )); then          # refresh the id->name map every 30 s
    NAME=(); while read -r id n; do NAME[$id]=$n; done < <(docker ps --no-trunc --format '{{.ID}} {{.Names}}')
    last=$now
  fi
  for id in "${!NAME[@]}"; do
    cg=/sys/fs/cgroup/system.slice/docker-$id.scope
    [ -r "$cg/memory.current" ] || continue
    cur=$(<"$cg/memory.current")
    read -r anon inf shm < <(awk '$1=="anon"{a=$2} $1=="inactive_file"{i=$2} $1=="shmem"{s=$2} END{print a,i,s}' "$cg/memory.stat")
    cpu=$(awk '$1=="usage_usec"{print $2}' "$cg/cpu.stat")
    echo -e "$now\t${NAME[$id]}\t$cur\t$anon\t$inf\t$shm\t$cpu"
  done >> "$OUT"
  sleep 5
done