src: add --title command line argument, trace event

doc/api/cli.md

@@ -271,6 +271,13 @@ added: v0.11.14
 
 Throw errors for deprecations.
 
+### `--title=title`
+<!-- YAML
+added: REPLACEME
+-->
+
+Set `process.title` on startup.
+
 ### `--tls-cipher-list=list`
 <!-- YAML
 added: v4.0.0
@@ -532,6 +539,7 @@ Node options that are allowed are:
 - `--redirect-warnings`
 - `--require`, `-r`
 - `--throw-deprecation`
+- `--title`
 - `--tls-cipher-list`
 - `--trace-deprecation`
 - `--trace-event-categories`

doc/node.1

@@ -164,6 +164,9 @@ instead of printing to stderr.
 .It Fl -throw-deprecation
 Throw errors for deprecations.
 .
+.It Fl -title Ns = Ns Ar title
+Specify process.title on startup.
+.
 .It Fl -tls-cipher-list Ns = Ns Ar list
 Specify an alternative default TLS cipher list.
 Requires Node.js to be built with crypto support. (Default)

src/node.cc

@@ -273,6 +273,8 @@ std::string config_warning_file;  // NOLINT(runtime/string)
 // that is used by lib/internal/bootstrap/node.js
 bool config_expose_internals = false;
 
+std::string config_process_title;  // NOLINT(runtime/string)
+
 bool v8_initialized = false;
 
 bool linux_at_secure = false;
@@ -1655,6 +1657,8 @@ static void ProcessTitleSetter(Local<Name> property,
                                Local<Value> value,
                                const PropertyCallbackInfo<void>& info) {
   node::Utf8Value title(info.GetIsolate(), value);
+  TRACE_EVENT_METADATA1("__metadata", "process_name", "name",
+                        TRACE_STR_COPY(*title));
   uv_set_process_title(*title);
 }
 
@@ -2506,6 +2510,7 @@ static void PrintHelp() {
          "                             write warnings to file instead of\n"
          "                             stderr\n"
          "  --throw-deprecation        throw an exception on deprecations\n"
+         "  --title=title              the process title to use on start up\n"
 #if HAVE_OPENSSL
          "  --tls-cipher-list=val      use an alternative default TLS cipher "
          "list\n"
@@ -2643,6 +2648,7 @@ static void CheckIfAllowedInEnv(const char* exe, bool is_env,
     "--redirect-warnings",
     "--require",
     "--throw-deprecation",
+    "--title",
     "--tls-cipher-list",
     "--trace-deprecation",
     "--trace-event-categories",
@@ -2813,6 +2819,8 @@ static void ParseArgs(int* argc,
     } else if (strncmp(arg, "--security-revert=", 18) == 0) {
       const char* cve = arg + 18;
       Revert(cve);
+    } else if (strncmp(arg, "--title=", 8) == 0) {
+      config_process_title = arg + 8;
     } else if (strcmp(arg, "--preserve-symlinks") == 0) {
       config_preserve_symlinks = true;
     } else if (strcmp(arg, "--preserve-symlinks-main") == 0) {
@@ -3304,6 +3312,10 @@ void Init(int* argc,
 
   ProcessArgv(argc, argv, exec_argc, exec_argv);
 
+  // Set the process.title immediately after processing argv if --title is set.
+  if (!config_process_title.empty())
+    uv_set_process_title(config_process_title.c_str());
+
 #if defined(NODE_HAVE_I18N_SUPPORT)
   // If the parameter isn't given, use the env variable.
   if (icu_data_dir.empty())
@@ -3528,6 +3540,13 @@ inline int Start(Isolate* isolate, IsolateData* isolate_data,
   Environment env(isolate_data, context, v8_platform.GetTracingAgent());
   env.Start(argc, argv, exec_argc, exec_argv, v8_is_profiling);
 
+  char name_buffer[512];
+  if (uv_get_process_title(name_buffer, sizeof(name_buffer)) == 0) {
+    // Only emit the metadata event if the title can be retrieved successfully.
+    // Ignore it otherwise.
+    TRACE_EVENT_METADATA1("__metadata", "process_name", "name",
+                          TRACE_STR_COPY(name_buffer));
+  }
   TRACE_EVENT_METADATA1("__metadata", "version", "node", NODE_VERSION_STRING);
   TRACE_EVENT_METADATA1("__metadata", "thread_name", "name",
                         "JavaScriptMainThread");

test/parallel/test-process-title-cli.js

@@ -0,0 +1,13 @@
+// Flags: --title=foo
+'use strict';
+
+const common = require('../common');
+
+if (common.isSunOS)
+  common.skip(`Unsupported platform [${process.platform}]`);
+
+const assert = require('assert');
+
+// Verifies that the --title=foo command line flag set the process
+// title on startup.
+assert.strictEqual(process.title, 'foo');

test/parallel/test-trace-events-metadata.js

@@ -8,7 +8,8 @@ if (!common.isMainThread)
   common.skip('process.chdir is not available in Workers');
 
 const CODE =
-  'setTimeout(() => { for (var i = 0; i < 100000; i++) { "test" + i } }, 1)';
+  'setTimeout(() => { for (var i = 0; i < 100000; i++) { "test" + i } }, 1);' +
+  'process.title = "foo"';
 const FILE_NAME = 'node_trace.1.log';
 
 const tmpdir = require('../common/tmpdir');
@@ -17,6 +18,7 @@ process.chdir(tmpdir.path);
 
 const proc = cp.spawn(process.execPath,
                       [ '--trace-event-categories', 'node.perf.usertiming',
+                        '--title=bar',
                         '-e', CODE ]);
 proc.once('exit', common.mustCall(() => {
   assert(common.fileExists(FILE_NAME));
@@ -32,5 +34,14 @@ proc.once('exit', common.mustCall(() => {
     assert(traces.some((trace) =>
       trace.cat === '__metadata' && trace.name === 'version' &&
         trace.args.node === process.versions.node));
+    if (!common.isSunOS) {
+      // Changing process.title is currently unsupported on SunOS/SmartOS
+      assert(traces.some((trace) =>
+        trace.cat === '__metadata' && trace.name === 'process_name' &&
+          trace.args.name === 'foo'));
+      assert(traces.some((trace) =>
+        trace.cat === '__metadata' && trace.name === 'process_name' &&
+          trace.args.name === 'bar'));
+    }
   }));
 }));