Function restartServer

src/server.cpp:3428–3494

Restart the server, executing the same executable that started this * instance, with the same arguments and configuration file. * * The function is designed to directly call execve() so that the new * server instance will retain the PID of the previous one. * * The list of flags, that may be bitwise ORed together, alter the * behavior of this function: * * RESTART_SERVER_NONE

 * On success the function does not return, because the process turns into
 * a different process. On error C_ERR is returned. */
int restartServer(int flags, mstime_t delay) {
    int j;

    /* Check if we still have accesses to the executable that started this
     * server instance. */
    if (access(cserver.executable,X_OK) == -1) {
        serverLog(LL_WARNING,"Can't restart: this process has no "
                             "permissions to execute %s", cserver.executable);
        return C_ERR;
    }

    /* Config rewriting. */
    if (flags & RESTART_SERVER_CONFIG_REWRITE &&
        cserver.configfile &&
        rewriteConfig(cserver.configfile, 0) == -1)
    {
        serverLog(LL_WARNING,"Can't restart: configuration rewrite process "
                             "failed");
        return C_ERR;
    }

    /* Perform a proper shutdown. */
    if (flags & RESTART_SERVER_GRACEFULLY &&
        prepareForShutdown(SHUTDOWN_NOFLAGS) != C_OK)
    {
        serverLog(LL_WARNING,"Can't restart: error preparing for shutdown");
        return C_ERR;
    }

    /* Close all file descriptors, with the exception of stdin, stdout, strerr
     * which are useful if we restart a Redis server which is not daemonized. */
    for (j = 3; j < (int)g_pserver->maxclients + 1024; j++) {
        /* Test the descriptor validity before closing it, otherwise
         * Valgrind issues a warning on close(). */
        if (fcntl(j,F_GETFD) != -1)
        {
            /* This user to just close() here, but sanitizers detected that as an FD race.
                The race doesn't matter since we're about to call exec() however we want
                to cut down on noise, so instead we ask the kernel to close when we call
                exec(), and only do it ourselves if that fails. */
            if (fcntl(j, F_SETFD, FD_CLOEXEC) == -1)
            {
                close(j);   // failed to set close on exec, close here
            }
        }
    }

    if (flags & RESTART_SERVER_GRACEFULLY) {
        if (g_pserver->m_pstorageFactory) {
            for (int idb = 0; idb < cserver.dbnum; ++idb) {
                g_pserver->db[idb]->storageProviderDelete();
            }
            delete g_pserver->metadataDb;
        }
    }

    /* Execute the server with the original command line. */
    if (delay) usleep(delay*1000);