snapshot of https://github.com/nats-io/nats-server.git (main, 2026-09-15; blobs > 131072B omitted)

server/pse/pse_freebsd_sysctl.go

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+// Copyright 2015-2025 The NATS Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// There are two FreeBSD implementations; one which uses cgo and should build
+// locally on any FreeBSD, and this one which uses sysctl but needs us to know
+// the offset constants for the fields we care about.
+//
+// The advantage of this one is that without cgo, it is much easier to
+// cross-compile to a target.  The official releases are all built with
+// cross-compilation.
+//
+// We've switched the other implementation to include '_cgo' in the filename,
+// to show that it's not the default.  This isn't an os or arch build tag,
+// so we have to use explicit build-tags within.
+// If lacking CGO support and targeting an unsupported arch, then before the
+// change you would have a compile failure for not being able to cross-compile.
+// After the change, you have a compile failure for not having the symbols
+// because no source file satisfies them.
+// Thus we are no worse off, and it's now much easier to extend support for
+// non-CGO to new architectures, just by editing this file.
+//
+// To generate for other architectures:
+//   1. Copy `freebsd.txt` to have a .c filename on a box running the target
+//      architecture, compile and run it.
+//   2. Update the init() function below to include a case for this architecture
+//   3. Update the build-tags in this file.
+
+//go:build !cgo && freebsd && (amd64 || arm64)
+
+package pse
+
+import (
+	"encoding/binary"
+	"runtime"
+	"syscall"
+
+	"golang.org/x/sys/unix"
+)
+
+// On FreeBSD, to get proc information we read it out of the kernel using a
+// binary sysctl.  The endianness of integers is thus explicitly "host", rather
+// than little or big endian.
+var nativeEndian = binary.LittleEndian
+
+var pageshift int // derived from getpagesize(3) in init() below
+
+var (
+	// These are populated in the init function, based on the current architecture.
+	// (It's less file-count explosion than having one small file for each
+	// FreeBSD architecture).
+	KIP_OFF_size   int
+	KIP_OFF_rssize int
+	KIP_OFF_pctcpu int
+)
+
+func init() {
+	switch runtime.GOARCH {
+	// These are the values which come from compiling and running
+	// freebsd.txt as a C program.
+	// Most recently validated: 2025-04 with FreeBSD 14.2R in AWS.
+	case "amd64":
+		KIP_OFF_size = 256
+		KIP_OFF_rssize = 264
+		KIP_OFF_pctcpu = 308
+	case "arm64":
+		KIP_OFF_size = 256
+		KIP_OFF_rssize = 264
+		KIP_OFF_pctcpu = 308
+	default:
+		panic("code bug: server/pse FreeBSD support missing case for '" + runtime.GOARCH + "' but build-tags allowed us to build anyway?")
+	}
+
+	// To get the physical page size, the C library checks two places:
+	//   process ELF auxiliary info, AT_PAGESZ
+	//   as a fallback, the hw.pagesize sysctl
+	// In looking closely, I found that the Go runtime support is handling
+	// this for us, and exposing that as syscall.Getpagesize, having checked
+	// both in the same ways, at process start, so a call to that should return
+	// a memory value without even a syscall bounce.
+	pagesize := syscall.Getpagesize()
+	pageshift = 0
+	for pagesize > 1 {
+		pageshift += 1
+		pagesize >>= 1
+	}
+}
+
+func ProcUsage(pcpu *float64, rss, vss *int64) error {
+	rawdata, err := unix.SysctlRaw("kern.proc.pid", unix.Getpid())
+	if err != nil {
+		return err
+	}
+
+	r_vss_bytes := nativeEndian.Uint32(rawdata[KIP_OFF_size:])
+	r_rss_pages := nativeEndian.Uint32(rawdata[KIP_OFF_rssize:])
+	rss_bytes := r_rss_pages << pageshift
+
+	// In C: fixpt_t ki_pctcpu
+	// Doc: %cpu for process during ki_swtime
+	// fixpt_t is __uint32_t
+	// usr.bin/top uses pctdouble to convert to a double (float64)
+	// define pctdouble(p) ((double)(p) / FIXED_PCTCPU)
+	// FIXED_PCTCPU is _usually_ FSCALE (some architectures are special)
+	// <sys/param.h> has:
+	//   #define FSHIFT  11              /* bits to right of fixed binary point */
+	//   #define FSCALE  (1<<FSHIFT)
+	r_pcpu := nativeEndian.Uint32(rawdata[KIP_OFF_pctcpu:])
+	f_pcpu := float64(r_pcpu) / float64(2048)
+
+	*rss = int64(rss_bytes)
+	*vss = int64(r_vss_bytes)
+	*pcpu = f_pcpu
+
+	return nil
+}