#!/usr/bin/env bash
# spdk-target.sh — LONG-LIVED nvmf_tgt entrypoint.
#
# Starts the NVMe-oF target ONCE and keeps it up for the container's entire life.
# It is RELEASE-AGNOSTIC: rootfs versions are added/removed ONLINE via
# spdk-release.sh (JSON-RPC) without ever restarting this process, so a new build
# never drops running hosts' NVMe/TCP root connections (docs/TODO.md #6). This is
# the key difference from the legacy serving/spdk-setup.sh, which configured a
# single version at start and thus required a connection-dropping restart to
# change versions.
#
# On (re)start it reconciles: every release staged under $RELEASES_DIR is added,
# so a serving-host reboot restores all currently-served versions automatically.
set -euo pipefail

RELEASES_DIR="${RELEASES_DIR:-/releases}"
CPUMASK="${SPDK_CPUMASK:-0x1}"
TADDR="${TARGET_ADDR:-0.0.0.0}"
TPORT="${TARGET_PORT:-4420}"
HUGEPAGES="${HUGEPAGES:-1024}"
DISCOVERY_NQN="nqn.2014-08.org.nvmexpress.discovery"
# Readiness stamp for the container healthcheck. Written ONLY after the transport
# is up and releases are reconciled; removed on (re)start + exit. A file check is
# instant and python-free — the right probe for a box where SPDK busy-polls its
# (often single) reactor core and a python rpc.py healthcheck would starve/time
# out. Lives on the shared /run/spdk volume so it's cleared per container start.
READY_FILE="${READY_FILE:-/var/run/spdk/ready}"

TGT=$(command -v nvmf_tgt || echo /usr/libexec/spdk/spdk/build/bin/nvmf_tgt)
RPC=$(command -v rpc.py   || echo /usr/libexec/spdk/scripts/rpc.py)
RELEASE_CTL=$(command -v spdk-release || echo /usr/local/bin/spdk-release)
# Optional explicit RPC socket. Set it (compose does, on a shared volume) so a
# SEPARATE loader container can reach this target's JSON-RPC and add/remove
# versions online. Empty -> nvmf_tgt's default socket (single-container case).
RPC_SOCK="${RPC_SOCK:-}"
rpc() { if [ -n "$RPC_SOCK" ]; then "$RPC" -s "$RPC_SOCK" "$@"; else "$RPC" "$@"; fi; }
[ -n "$RPC_SOCK" ] && mkdir -p "$(dirname "$RPC_SOCK")"
mkdir -p "$(dirname "$READY_FILE")"
rm -f "$READY_FILE"   # clear any stale readiness from a previous container start

# Ensure hugepages exist — DPDK needs them. vm.nr_hugepages isn't namespaced, so
# a privileged container writes the host value; re-applied after a host reboot
# (the container restarts). Best-effort: allocation can fail on a fragmented
# host, in which case set vm.nr_hugepages on the host via /etc/sysctl.d.
if [ -w /proc/sys/vm/nr_hugepages ]; then
    cur=$(cat /proc/sys/vm/nr_hugepages 2>/dev/null || echo 0)
    if [ "${cur:-0}" -lt "$HUGEPAGES" ]; then
        echo "==> allocating $HUGEPAGES hugepages (was ${cur:-0})"
        echo "$HUGEPAGES" > /proc/sys/vm/nr_hugepages 2>/dev/null || true
    fi
fi
free=$(awk '/HugePages_Free/{print $2}' /proc/meminfo 2>/dev/null || echo 0)
[ "${free:-0}" -gt 0 ] || echo "WARNING: no free hugepages — SPDK will fail; allocate vm.nr_hugepages on the host." >&2

echo "==> starting LONG-LIVED nvmf_tgt (cpumask ${CPUMASK})${RPC_SOCK:+ rpc-sock $RPC_SOCK}"
TGT_ARGS=(-m "$CPUMASK")
[ -n "$RPC_SOCK" ] && TGT_ARGS+=(-r "$RPC_SOCK")
"$TGT" "${TGT_ARGS[@]}" &
TGT_PID=$!
# A TERM/INT here stops the target and DROPS EVERY connection — only on container
# stop, never for a version change. Make the intent loud.
trap 'echo "==> stopping nvmf_tgt — this drops ALL host root connections" >&2; rm -f "$READY_FILE"; kill "$TGT_PID" 2>/dev/null || true' TERM INT
trap 'rm -f "$READY_FILE"; kill "$TGT_PID" 2>/dev/null || true' EXIT

# Wait for the RPC socket.
for _ in $(seq 1 30); do
    rpc framework_get_config >/dev/null 2>&1 && break
    sleep 1
done

echo "==> creating TCP transport"
rpc nvmf_create_transport -t TCP -u 16384 -m 8 -c 8192 \
    || echo "WARNING: nvmf_create_transport failed (already present?)" >&2

echo "==> registering discovery listener ${TADDR}:${TPORT}"
rpc nvmf_subsystem_add_listener "$DISCOVERY_NQN" -t tcp -a "$TADDR" -s "$TPORT" >/dev/null 2>&1 || true

# Bootstrap convenience: if a single OCI artifact image is mounted at /artifacts
# (the simple one-version `docker compose up` flow) and that version isn't yet
# staged under $RELEASES_DIR, stage it so the long-lived target serves it too.
#
# COPY, never symlink: /artifacts is a version-pinned image volume that CHANGES
# when IMAGE_VERSION changes, so a symlink into it would silently re-point an
# already-staged release dir at the new version's data on the next bump. Each
# release dir must hold its own immutable copy. Self-heal: re-copy if the staged
# verity.json differs from the mounted artifact (repairs a dir left stale/symlinked
# by an older build).
if [ -s /artifacts/verity.json ] && [ -n "${IMAGE_VERSION:-}" ]; then
    seed="$RELEASES_DIR/$IMAGE_VERSION"
    if [ ! -s "$seed/verity.json" ] || ! cmp -s /artifacts/verity.json "$seed/verity.json"; then
        echo "==> seeding bootstrap release $IMAGE_VERSION from /artifacts (copy)"
        mkdir -p "$seed"
        cp -f /artifacts/rootfs.erofs /artifacts/rootfs.hash /artifacts/verity.json "$seed/" \
            || echo "WARNING: failed to seed $IMAGE_VERSION from /artifacts" >&2
    fi
fi

echo "==> reconciling releases under $RELEASES_DIR"
RELEASES_DIR="$RELEASES_DIR" TARGET_ADDR="$TADDR" TARGET_PORT="$TPORT" RPC_SOCK="$RPC_SOCK" \
    bash "$RELEASE_CTL" reconcile || echo "WARNING: reconcile reported errors" >&2

# Signal readiness for the healthcheck — transport is up and releases reconciled.
: > "$READY_FILE"

echo "==> nvmf_tgt up; releases served online. Add/remove versions with:"
echo "      docker compose exec ${NVMEOF_SVC:-nvmeof} spdk-release {add|remove|list} <version>"
echo "    or host-side: serving/spdk/spdk-ctl.sh {load|unload|list} <version>"
wait "$TGT_PID"