Daemonize nebula-graphd (vesoft-inc#54)

etc/nebula-graphd.conf.default

@@ -1,3 +1,7 @@
+########## basics ##########
+# Whether run as a daemon process
+--daemonize=true
+
 ########## logging ##########
 # Directory to host logging files, which must already exist
 --log_dir=logs

src/common/process/ProcessUtils.cpp

@@ -63,6 +63,26 @@ Status ProcessUtils::makePidFile(const std::string &pidFile, uint32_t pid) {
 }
 
 
+Status ProcessUtils::daemonize(const std::string &pidFile) {
+    auto pid = ::fork();
+    if (pid == -1) {
+        return Status::Error("fork: %s", ::strerror(errno));
+    }
+    if (pid > 0) {  // parent process
+        ::exit(0);
+    }
+
+    // Make the child process as the session leader and detach with the controlling terminal
+    ::setsid();
+    // Set `/dev/null' as standard input
+    auto fd = ::open("/dev/null", O_RDWR);
+    ::dup2(fd, 0);
+    ::close(fd);
+
+    return makePidFile(pidFile);
+}
+
+
 StatusOr<std::string> ProcessUtils::getExePath(uint32_t pid) {
     if (pid == 0) {
         pid = ::getpid();

src/common/process/ProcessUtils.h

@@ -26,7 +26,14 @@ class ProcessUtils final {
      *      The pidFile contains a valid pid and no such process exists.
      */
     static Status isPidAvailable(const std::string &pidFile);
+    /**
+     * Write pid into file, create if not exist.
+     */
     static Status makePidFile(const std::string &path, uint32_t pid = 0);
+    /**
+     * Make current process a daemon and write the daemon's pid into pidFile
+     */
+    static Status daemonize(const std::string &pidFile);
     /**
      * Get the absolute path to the target process's executable.
      * Use the current process if pid == 0.

src/common/time/Duration.cpp

@@ -39,21 +39,28 @@ uint64_t calibrateTicksPerUSec() {
 }
 
 
+static void launchTickTockThread();
+
 volatile std::atomic<uint64_t> ticksPerUSec{
     []() -> uint64_t {
-        thread::NamedThread t("tick-tock",
-            []() {
-                while (true) {
-                    sleep(3);
-                    ticksPerUSec.store(calibrateTicksPerUSec());
-                }  // while
-            });
-        t.detach();
-
+        launchTickTockThread();
+        // re-launch tick-tock thread after forking
+        ::pthread_atfork(nullptr, nullptr, &launchTickTockThread);
         return calibrateTicksPerUSec();
     }()
 };
 
+void launchTickTockThread() {
+    thread::NamedThread t("tick-tock",
+        []() {
+            while (true) {
+                sleep(3);
+                ticksPerUSec.store(calibrateTicksPerUSec());
+            }  // while
+        });
+    t.detach();
+}
+
 }  // namespace detail
 
 

src/daemons/GraphDaemon.cpp

@@ -24,8 +24,31 @@ static std::unique_ptr<apache::thrift::ThriftServer> gServer;
 static void signalHandler(int sig);
 static Status setupSignalHandler();
 static Status setupLogging();
+static void printHelp(const char *prog);
+static void printVersion();
+
+DECLARE_string(flagfile);
 
 int main(int argc, char *argv[]) {
+    if (argc == 1) {
+        printHelp(argv[0]);
+        return EXIT_FAILURE;
+    }
+    if (argc == 2) {
+        if (::strcmp(argv[1], "-h") == 0) {
+            printHelp(argv[0]);
+            return EXIT_SUCCESS;
+        }
+        if (::strcmp(argv[1], "-v") == 0) {
+            printVersion();
+            return EXIT_SUCCESS;
+        }
+    }
+    if (FLAGS_flagfile.empty()) {
+        printHelp(argv[0]);
+        return EXIT_FAILURE;
+    }
+
     folly::init(&argc, &argv, true);
 
     // Setup logging
@@ -43,11 +66,19 @@ int main(int argc, char *argv[]) {
         return EXIT_FAILURE;
     }
 
-    // Write the current pid into the pid file
-    status = ProcessUtils::makePidFile(pidPath);
-    if (!status.ok()) {
-        LOG(ERROR) << status;
-        return EXIT_FAILURE;
+    if (FLAGS_daemonize) {
+        status = ProcessUtils::daemonize(pidPath);
+        if (!status.ok()) {
+            LOG(ERROR) << status;
+            return EXIT_FAILURE;
+        }
+    } else {
+        // Write the current pid into the pid file
+        status = ProcessUtils::makePidFile(pidPath);
+        if (!status.ok()) {
+            LOG(ERROR) << status;
+            return EXIT_FAILURE;
+        }
     }
 
     // Setup the signal handlers
@@ -123,6 +154,10 @@ void signalHandler(int sig) {
 
 
 Status setupLogging() {
+    if (!FLAGS_redirect_stdout) {
+        return Status::OK();
+    }
+
     auto dup = [] (const std::string &filename, FILE *stream) -> Status {
         auto path = FLAGS_log_dir + "/" + filename;
         auto fd = ::open(path.c_str(), O_WRONLY | O_APPEND | O_CREAT, 0644);
@@ -152,3 +187,15 @@ Status setupLogging() {
 
     return status;
 }
+
+
+void printHelp(const char *prog) {
+    fprintf(stderr, "%s -flagfile config_file\n", prog);
+    fprintf(stderr, "%s -h\n", prog);
+    fprintf(stderr, "%s -v\n", prog);
+}
+
+
+void printVersion() {
+    // TODO(dutor)
+}

src/graph/GraphFlags.cpp

@@ -21,3 +21,4 @@ DEFINE_string(pid_file, "nebula-graphd.pid", "File to hold the process id");
 DEFINE_bool(redirect_stdout, true, "Whether to redirect stdout and stderr to separate files");
 DEFINE_string(stdout_log_file, "graphd-stdout.log", "Destination filename of stdout");
 DEFINE_string(stderr_log_file, "graphd-stderr.log", "Destination filename of stderr");
+DEFINE_bool(daemonize, true, "Whether run as a daemon process");

src/graph/GraphFlags.h

@@ -23,6 +23,7 @@ DECLARE_string(pid_file);
 DECLARE_bool(redirect_stdout);
 DECLARE_string(stdout_log_file);
 DECLARE_string(stderr_log_file);
+DECLARE_bool(daemonize);
 
 
 #endif  // GRAPH_GRAPHFLAGS_H_