lightningd: try harder to ensure uniqueness in --dev-save-plugin-io names.

Incorporate a time: this covers the restart case as well.  And make it time_mono(),
which doesn't get overridden when we override normal wall time.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Author: rustyrussell

lightningd/plugin.c

@@ -2622,16 +2622,24 @@ static void dev_save_plugin_io(struct plugins *plugins,
 			       const char *buf, size_t len)
 {
 	static size_t counter;
+	static u64 starttime;
 	const char *file;
 	int fd;
 
 	if (!plugins->dev_save_io)
 		return;
 
+	/* If we reexec, we still want unique names */
+	if (!starttime) {
+		struct timemono start = time_mono();
+		starttime = start.ts.tv_sec * 1000000 + start.ts.tv_nsec / 1000;
+	}
+
 	file = path_join(tmpctx, plugins->dev_save_io,
-			 take(tal_fmt(NULL, "%s-%s-%u-%zu",
+			 take(tal_fmt(NULL, "%s-%s-%u-%"PRIu64"-%zu",
 				      type, name,
 				      (unsigned int)getpid(),
+				      starttime,
 				      counter++)));
 	fd = open(file, O_CREAT|O_EXCL|O_WRONLY, 0600);
 	if (fd < 0 || !write_all(fd, buf, len))

tests/test_misc.py

@@ -3692,8 +3692,6 @@ def test_version_reexec(node_factory, bitcoind):
     # We use a file to tell our openingd wrapper where the real one is
     with open(os.path.join(l1.daemon.lightning_dir, TEST_NETWORK, "openingd-real"), 'w') as f:
         f.write(os.path.abspath('lightningd/lightning_openingd'))
-    # Internal restart doesn't work well with --dev-save-plugin-io
-    del l1.daemon.opts['dev-save-plugin-io']
     l1.start()
     # This is a "version" message
     verfile = os.path.join(l1.daemon.lightning_dir, TEST_NETWORK, "openingd-version")
@@ -4569,11 +4567,7 @@ def test_setconfig_changed(node_factory, bitcoind):
 
 @unittest.skipIf(os.getenv('TEST_DB_PROVIDER', 'sqlite3') != 'sqlite3', "deletes database, which is assumed sqlite3")
 def test_recover_command(node_factory, bitcoind):
-    l1 = node_factory.get_node(start=False)
-    # Internal restart doesn't work well with --dev-save-plugin-io
-    del l1.daemon.opts['dev-save-plugin-io']
-    l1.start()
-    l2 = node_factory.get_node()
+    l1, l2 = node_factory.get_nodes(2)
 
     l1oldid = l1.info['id']