#!/usr/bin/env bash
# Scoped Values (JEP 506, final since JDK 25) vs ThreadLocal. StructuredTaskScope (JEP 505) is
# still PREVIEW on JDK 25 -- every file here that touches it needs --enable-preview --release 25.
#   ./scripts/scoped-values.sh -> docs/output/99-basics.txt 99-inheritance.txt
#                                  99-memory-heap-delta.txt 99-histogram-scopedvalue.txt
#                                  99-histogram-threadlocal.txt
set -uo pipefail
source "$(dirname "$0")/env.sh"
S="$ROOT/scoped-values/src"; B="$ROOT/build/scoped-values"; rm -rf "$B"; mkdir -p "$B"

# ScopedValuesBasics.java needs no preview flag (JEP 506 is final); the other three touch
# StructuredTaskScope and need --enable-preview.
"$JDK25/bin/javac" -d "$B" "$S/Check.java" "$S/ScopedValuesBasics.java" 2>&1 | grep -v -E '^(Note:|$)' || true
"$JDK25/bin/javac" --enable-preview --release 25 -Xlint:-preview -d "$B" "$S"/*.java 2>&1 | grep -v -E '^(Note:|$)' || true

{ echo "\$ java ScopedValuesBasics      (JDK 25, no preview flag -- JEP 506 is final)"
  "$JDK25/bin/java" -cp "$B" ScopedValuesBasics 2>&1; echo "exit=${PIPESTATUS[0]}"
} > "$OUT/99-basics.txt" 2>&1

{ echo "\$ java --enable-preview InheritanceRequiresStructuredTaskScope      (JDK 25)"
  "$JDK25/bin/java" --enable-preview -cp "$B" InheritanceRequiresStructuredTaskScope 2>&1; echo "exit=${PIPESTATUS[0]}"
} > "$OUT/99-inheritance.txt" 2>&1

{ echo "\$ java --enable-preview -Xmx6g ScopedValueVsThreadLocalMemory 500000      (JDK 25)"
  "$JDK25/bin/java" --enable-preview -Xmx6g -cp "$B" ScopedValueVsThreadLocalMemory 500000 2>&1; echo "exit=${PIPESTATUS[0]}"
} > "$OUT/99-memory-heap-delta.txt" 2>&1

# Precise version: park N=100000 subtasks holding 5 bound values each, then ask the JVM itself
# (jcmd GC.class_histogram) how many objects of each class actually exist while they're all alive.
histogram() {
  local mode="$1" outfile="$2"
  rm -f "$B/probe.log"
  "$JDK25/bin/java" --enable-preview -Xmx3g -cp "$B" MemoryFootprintProbe "$mode" 100000 > "$B/probe.log" 2>&1 &
  local pid=$!
  for _ in $(seq 1 60); do grep -q "READY $mode" "$B/probe.log" 2>/dev/null && break; sleep 1; done
  {
    echo "\$ jcmd <pid> GC.class_histogram      (100000 subtasks parked, mode=$mode, JDK 25)"
    "$JDK25/bin/jcmd" "$pid" GC.class_histogram 2>&1 \
      | grep -E 'ThreadLocal|VirtualThread |SubtaskImpl|Carrier|ScopedValue|StackChunk|^Total' \
      | grep -v CarrierThread
  } > "$OUT/$outfile" 2>&1
  kill -9 "$pid" 2>/dev/null
  wait "$pid" 2>/dev/null
}

histogram sv 99-histogram-scopedvalue.txt
histogram tl 99-histogram-threadlocal.txt

scrub() { sed -i -E "s#$ROOT#<repo>#g" "$@"; }
scrub "$OUT"/99-*.txt

echo "wrote $OUT/99-*.txt"