feat: add gperftools mise script

Cargo.toml

@@ -316,7 +316,7 @@ panic = "unwind"
 
 [profile.profiling]
 inherits = "dev"
-opt-level = 0
+opt-level = 1
 debug = true
 split-debuginfo = "unpacked"
 panic = "abort"

build.rs

@@ -11,6 +11,7 @@ use std::{
 
 fn main() {
     // Only needed when profiling Forest with `gperftools`. This might not work on all platforms.
+    println!("cargo:rerun-if-env-changed=FOREST_PROFILING_GPERFTOOLS_BUILD");
     if is_env_truthy("FOREST_PROFILING_GPERFTOOLS_BUILD") {
         println!("cargo:rustc-link-lib=tcmalloc");
     }

mise-tasks/gperf/heap.sh

@@ -0,0 +1,39 @@
+#!/bin/bash
+#MISE description="Build and heap-profile a Forest binary with gperftools. Usage: mise run gperf:heap <bin> [-- <bin-args...>]. Dumps to /tmp/gperfheap.<bin>.prof.*"
+
+set -euo pipefail
+
+if [ $# -lt 1 ]; then
+    echo "usage: mise run gperf:heap <bin> [-- <bin-args...>]" >&2
+    exit 2
+fi
+
+bin="$1"
+shift
+# Strip the `--` separator if mise forwarded it.
+if [ "${1-}" = "--" ]; then
+    shift
+fi
+
+# `FOREST_PROFILING_GPERFTOOLS_BUILD` toggles `cargo:rustc-link-lib=tcmalloc` in
+# build.rs — without it, the binary won't be linked against gperftools and
+# `HEAPPROFILE` is inert.
+# `--message-format=json-render-diagnostics` reports the built executable path
+# on stdout (respecting any `CARGO_TARGET_DIR` / `[build] target-dir` override);
+# diagnostics still render on stderr.
+exe=$(
+    FOREST_PROFILING_GPERFTOOLS_BUILD=1 cargo build \
+        --no-default-features --features system-alloc --profile=profiling \
+        --bin "$bin" --message-format=json-render-diagnostics |
+        sed -n 's/.*"executable":"\([^"]*\)".*/\1/p' |
+        tail -1
+)
+if [ -z "$exe" ]; then
+    echo "could not locate built executable for $bin" >&2
+    exit 1
+fi
+
+ulimit -n 8192
+HEAPPROFILE_USE_PID=t \
+HEAPPROFILE="/tmp/gperfheap.${bin}.prof" \
+    "$exe" "$@"