test: add tests for $SYSTEMD_MEMPOOL=

This adds tests for b4f607433c and
205c085bc3 (#9792).

src/test/meson.build

@@ -399,6 +399,10 @@ tests += [
          [],
          []],
 
+        [['src/test/test-set-disable-mempool.c'],
+         [],
+         [threads]],
+
         [['src/test/test-bitmap.c'],
          [],
          []],

src/test/test-set-disable-mempool.c

@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <pthread.h>
+
+#include "process-util.h"
+#include "set.h"
+#include "tests.h"
+
+#define NUM 100
+
+static void* thread(void *p) {
+        Set **s = p;
+
+        assert_se(s);
+        assert_se(*s);
+
+        assert_se(!is_main_thread());
+        assert_se(set_size(*s) == NUM);
+        *s = set_free(*s);
+
+        return NULL;
+}
+
+static void test_one(const char *val) {
+        pthread_t t;
+        int x[NUM] = {};
+        unsigned i;
+        Set *s;
+
+        log_info("Testing with SYSTEMD_MEMPOOL=%s", val);
+        assert_se(setenv("SYSTEMD_MEMPOOL", val, true) == 0);
+        assert_se(is_main_thread());
+
+        assert_se(s = set_new(NULL));
+        for (i = 0; i < NUM; i++)
+                assert_se(set_put(s, &x[i]));
+
+        assert_se(pthread_create(&t, NULL, thread, &s) == 0);
+        assert_se(pthread_join(t, NULL) == 0);
+
+        assert_se(!s);
+}
+
+int main(int argc, char *argv[]) {
+        test_setup_logging(LOG_DEBUG);
+
+        test_one("0");
+        /* The value $SYSTEMD_MEMPOOL= is cached. So the following
+         * test should also succeed. */
+        test_one("1");
+
+        return 0;
+}