Establish native micro runtime checkpoint

1 files changed, 43 insertions, 0 deletions

diff --git a/prototypes/connections/measure-peak-rss.c b/prototypes/connections/measure-peak-rss.c
new file mode 100644
index 0000000..1fe2e0b
--- /dev/null
+++ b/prototypes/connections/measure-peak-rss.c
@@ -0,0 +1,43 @@
+#ifdef __APPLE__
+#define _DARWIN_C_SOURCE
+#else
+#define _DEFAULT_SOURCE
+#endif
+#include <fcntl.h>
+#include <stdio.h>
+#include <sys/resource.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+/* Test helper: fork from a small native process so the interpreter's pre-exec
+ * RSS cannot become the measured child's peak. Not shipped. */
+int main(int argc, char **argv) {
+    if (argc < 2) return 2;
+    pid_t child = fork();
+    if (child < 0) return 2;
+    if (!child) {
+        int null = open("/dev/null", O_WRONLY);
+        if (null < 0 || dup2(null, STDOUT_FILENO) < 0 ||
+            dup2(null, STDERR_FILENO) < 0) _exit(127);
+        close(null);
+        execvp(argv[1], argv + 1);
+        _exit(127);
+    }
+    struct rusage usage;
+    int status;
+    if (wait4(child, &status, 0, &usage) < 0) return 2;
+    if (!WIFEXITED(status)) return 2;
+    if (usage.ru_maxrss < 0) return 2;
+#ifdef __APPLE__
+    /* XNU reports ru_maxrss in bytes; Linux reports KiB. */
+    long peak_kib = usage.ru_maxrss / 1024 + (usage.ru_maxrss % 1024 != 0);
+    const char *raw_unit = "bytes";
+#else
+    long peak_kib = usage.ru_maxrss;
+    const char *raw_unit = "KiB";
+#endif
+    printf("{\"exit_code\":%d,\"max_rss_kib\":%ld,"
+           "\"raw_max_rss\":%ld,\"raw_unit\":\"%s\"}\n",
+           WEXITSTATUS(status), peak_kib, usage.ru_maxrss, raw_unit);
+    return 0;
+}