8 #include <unordered_set>
13 #include "service-listener.h"
14 #include "service-constants.h"
17 * This header defines ServiceRecord, a data record maintaining information about a service,
18 * and ServiceSet, a set of interdependent service records. It also defines some associated
19 * types and exceptions.
23 * Services have both a current state and a desired state. The desired state can be
24 * either STARTED or STOPPED. The current state can also be STARTING or STOPPING.
25 * A service can be "pinned" in either the STARTED or STOPPED states to prevent it
26 * from leaving that state until it is unpinned.
28 * The total state is a combination of the two, current and desired:
29 * STOPPED/STOPPED : stopped and will remain stopped
30 * STOPPED/STARTED : stopped (pinned), must be unpinned to start
31 * STARTING/STARTED : starting, but not yet started. Dependencies may also be starting.
32 * STARTING/STOPPED : as above, but the service will be stopped again as soon as it has
34 * STARTED/STARTED : running and will continue running.
35 * STARTED/STOPPED : started (pinned), must be unpinned to stop
36 * STOPPING/STOPPED : stopping and will stop. Dependents may be stopping.
37 * STOPPING/STARTED : as above, but the service will be re-started again once it stops.
39 * A scripted service is in the STARTING/STOPPING states during the script execution.
40 * A process service is in the STOPPING state when it has been signalled to stop, and is
41 * in the STARTING state when waiting for dependencies to start or for the exec() call in
42 * the forked child to complete and return a status.
46 * Each service has a dependent-count ("required_by"). This starts at 0, adds 1 if the
47 * service has explicitly been started (i.e. "start_explicit" is true), and adds 1 for
48 * each dependent service which is not STOPPED (including dependents with a soft dependency).
49 * When required_by transitions to 0, the service is stopped (unless it is pinned). When
50 * require_by transitions from 0, the service is started (unless pinned).
52 * So, in general, the dependent-count determines the desired state (STARTED if the count
53 * is greater than 0, otherwise STOPPED). However, a service can be issued a stop-and-take
54 * down order (via `stop(true)'); this will first stop dependent services, which may restart
55 * and cancel the stop of the former service. Finally, a service can be force-stopped, which
56 * means that its stop process cannot be cancelled (though it may still be put in a desired
57 * state of STARTED, meaning it will start immediately upon stopping).
61 * A service may be "pinned" in either STARTED or STOPPED states (or even both). Once it
62 * reaches a pinned state, a service will not leave that state, though its desired state
63 * may still be set. (Note that pinning prevents, but never causes, state transition).
65 * The priority of the different state deciders is:
68 * - desired state (which is manipulated by require/release operations)
70 * So a forced stop cannot occur until the service is not pinned started, for instance.
77 // Not actually "onstart" commands:
78 bool no_sigterm : 1; // do not send SIGTERM
79 bool runs_on_console : 1; // run "in the foreground"
80 bool pass_cs_fd : 1; // pass this service a control socket connection via fd
82 OnstartFlags() noexcept : rw_ready(false), log_ready(false),
83 no_sigterm(false), runs_on_console(false), pass_cs_fd(false)
88 // Exception while loading a service
92 std::string serviceName;
93 const char *excDescription;
96 ServiceLoadExc(std::string serviceName) noexcept
97 : serviceName(serviceName)
102 class ServiceNotFound : public ServiceLoadExc
105 ServiceNotFound(std::string serviceName) noexcept
106 : ServiceLoadExc(serviceName)
108 excDescription = "Service description not found.";
112 class ServiceCyclicDependency : public ServiceLoadExc
115 ServiceCyclicDependency(std::string serviceName) noexcept
116 : ServiceLoadExc(serviceName)
118 excDescription = "Has cyclic dependency.";
122 class ServiceDescriptionExc : public ServiceLoadExc
125 std::string extraInfo;
127 ServiceDescriptionExc(std::string serviceName, std::string extraInfo) noexcept
128 : ServiceLoadExc(serviceName), extraInfo(extraInfo)
130 excDescription = extraInfo.c_str();
134 class ServiceRecord; // forward declaration
135 class ServiceSet; // forward declaration
137 /* Service dependency record */
140 ServiceRecord * from;
144 /* Whether the 'from' service is waiting for the 'to' service to start */
146 /* Whether the 'from' service is holding an acquire on the 'to' service */
149 ServiceDep(ServiceRecord * from, ServiceRecord * to) noexcept : from(from), to(to), waiting_on(false), holding_acq(false)
152 ServiceRecord * getFrom() noexcept
157 ServiceRecord * getTo() noexcept
163 // Given a string and a list of pairs of (start,end) indices for each argument in that string,
164 // store a null terminator for the argument. Return a `char *` vector containing the beginning
165 // of each argument and a trailing nullptr. (The returned array is invalidated if the string is later modified).
166 static std::vector<const char *> separate_args(std::string &s, std::list<std::pair<unsigned,unsigned>> &arg_indices)
168 std::vector<const char *> r;
169 r.reserve(arg_indices.size() + 1);
171 // First store nul terminator for each part:
172 for (auto index_pair : arg_indices) {
173 if (index_pair.second < s.length()) {
174 s[index_pair.second] = 0;
178 // Now we can get the C string (c_str) and store offsets into it:
179 const char * cstr = s.c_str();
180 for (auto index_pair : arg_indices) {
181 r.push_back(cstr + index_pair.first);
183 r.push_back(nullptr);
187 class ServiceChildWatcher : public EventLoop_t::ChildProcWatcher
190 ServiceRecord * service;
191 rearm childStatus(EventLoop_t &eloop, pid_t child, int status) noexcept;
193 ServiceChildWatcher(ServiceRecord * sr) noexcept : service(sr) { }
196 class ServiceIoWatcher : public EventLoop_t::FdWatcher
199 ServiceRecord * service;
200 rearm fdEvent(EventLoop_t &eloop, int fd, int flags) noexcept;
202 ServiceIoWatcher(ServiceRecord * sr) noexcept : service(sr) { }
207 friend class ServiceChildWatcher;
208 friend class ServiceIoWatcher;
210 typedef std::string string;
213 ServiceType service_type; /* ServiceType::DUMMY, PROCESS, SCRIPTED, INTERNAL */
214 ServiceState service_state = ServiceState::STOPPED; /* ServiceState::STOPPED, STARTING, STARTED, STOPPING */
215 ServiceState desired_state = ServiceState::STOPPED; /* ServiceState::STOPPED / STARTED */
217 string program_name; // storage for program/script and arguments
218 std::vector<const char *> exec_arg_parts; // pointer to each argument/part of the program_name, and nullptr
220 string stop_command; // storage for stop program/script and arguments
221 std::vector<const char *> stop_arg_parts; // pointer to each argument/part of the stop_command, and nullptr
225 OnstartFlags onstart_flags;
227 string logfile; // log file name, empty string specifies /dev/null
229 bool auto_restart : 1; // whether to restart this (process) if it dies unexpectedly
230 bool smooth_recovery : 1; // whether the service process can restart without bringing down service
232 bool pinned_stopped : 1;
233 bool pinned_started : 1;
234 bool waiting_for_deps : 1; // if STARTING, whether we are waiting for dependencies (inc console) to start
235 bool waiting_for_execstat : 1; // if we are waiting for exec status after fork()
236 bool doing_recovery : 1; // if we are currently recovering a BGPROCESS (restarting process, while
237 // holding STARTED service state)
238 bool start_explicit : 1; // whether we are are explictly required to be started
240 bool prop_require : 1; // require must be propagated
241 bool prop_release : 1; // release must be propagated
242 bool prop_failure : 1; // failure to start must be propagated
244 int required_by = 0; // number of dependents wanting this service to be started
246 typedef std::list<ServiceRecord *> sr_list;
247 typedef sr_list::iterator sr_iter;
249 // list of soft dependencies
250 typedef std::list<ServiceDep> softdep_list;
252 // list of soft dependents
253 typedef std::list<ServiceDep *> softdpt_list;
255 sr_list depends_on; // services this one depends on
256 sr_list dependents; // services depending on this one
257 softdep_list soft_deps; // services this one depends on via a soft dependency
258 softdpt_list soft_dpts; // services depending on this one via a soft dependency
260 // unsigned wait_count; /* if we are waiting for dependents/dependencies to
261 // start/stop, this is how many we're waiting for */
263 ServiceSet *service_set; // the set this service belongs to
265 std::unordered_set<ServiceListener *> listeners;
268 bool force_stop; // true if the service must actually stop. This is the
269 // case if for example the process dies; the service,
270 // and all its dependencies, MUST be stopped.
272 int term_signal = -1; // signal to use for process termination
274 string socket_path; // path to the socket for socket-activation service
275 int socket_perms; // socket permissions ("mode")
276 uid_t socket_uid = -1; // socket user id or -1
277 gid_t socket_gid = -1; // sockget group id or -1
279 // Implementation details
281 pid_t pid = -1; // PID of the process. If state is STARTING or STOPPING,
282 // this is PID of the service script; otherwise it is the
283 // PID of the process itself (process service).
284 int exit_status; // Exit status, if the process has exited (pid == -1).
285 int socket_fd = -1; // For socket-activation services, this is the file
286 // descriptor for the socket.
288 ServiceChildWatcher child_listener;
289 ServiceIoWatcher child_status_listener;
291 // Data for use by ServiceSet
294 // Next service (after this one) in the queue for the console. Intended to only be used by ServiceSet class.
295 ServiceRecord *next_for_console;
297 // Propagation and start/stop queues
298 ServiceRecord *next_in_prop_queue = nullptr;
299 ServiceRecord *next_in_stop_queue = nullptr;
304 // All dependents have stopped.
305 void allDepsStopped();
307 // Service has actually stopped (includes having all dependents
308 // reaching STOPPED state).
309 void stopped() noexcept;
311 // Service has successfully started
312 void started() noexcept;
314 // Service failed to start (only called when in STARTING state).
315 // dep_failed: whether failure is recorded due to a dependency failing
316 void failed_to_start(bool dep_failed = false) noexcept;
318 // For process services, start the process, return true on success
319 bool start_ps_process() noexcept;
320 bool start_ps_process(const std::vector<const char *> &args, bool on_console) noexcept;
322 void run_child_proc(const char * const *args, const char *logfile, bool on_console, int wpipefd,
325 // Callback from libev when a child process dies
326 static void process_child_callback(EventLoop_t *loop, ServiceChildWatcher *w,
327 int revents) noexcept;
329 void handle_exit_status() noexcept;
331 // A dependency has reached STARTED state
332 void dependencyStarted() noexcept;
334 void allDepsStarted(bool haveConsole = false) noexcept;
336 // Read the pid-file, return false on failure
337 bool read_pid_file() noexcept;
339 // Open the activation socket, return false on failure
340 bool open_socket() noexcept;
342 // Check whether dependencies have started, and optionally ask them to start
343 bool startCheckDependencies(bool do_start) noexcept;
345 // Whether a STARTING service can immediately transition to STOPPED (as opposed to
346 // having to wait for it reach STARTED and then go through STOPPING).
347 bool can_interrupt_start() noexcept
349 return waiting_for_deps;
352 // Whether a STOPPING service can immediately transition to STARTED.
353 bool can_interrupt_stop() noexcept
355 return waiting_for_deps && ! force_stop;
358 // Notify dependencies that we no longer need them,
359 // (if this is actually the case).
360 void notify_dependencies_stopped() noexcept;
362 // A dependent has reached STOPPED state
363 void dependentStopped() noexcept;
365 // check if all dependents have stopped
366 bool stopCheckDependents() noexcept;
368 // issue a stop to all dependents, return true if they are all already stopped
369 bool stopDependents() noexcept;
371 void require() noexcept;
372 void release() noexcept;
373 void release_dependencies() noexcept;
375 // Check if service is, fundamentally, stopped.
376 bool is_stopped() noexcept
378 return service_state == ServiceState::STOPPED
379 || (service_state == ServiceState::STARTING && waiting_for_deps);
382 void notifyListeners(ServiceEvent event) noexcept
384 for (auto l : listeners) {
385 l->serviceEvent(this, event);
389 // Queue to run on the console. 'acquiredConsole()' will be called when the console is available.
390 void queueForConsole() noexcept;
392 // Release console (console must be currently held by this service)
393 void releaseConsole() noexcept;
395 bool do_auto_restart() noexcept;
399 ServiceRecord(ServiceSet *set, string name)
400 : service_state(ServiceState::STOPPED), desired_state(ServiceState::STOPPED), auto_restart(false),
401 pinned_stopped(false), pinned_started(false), waiting_for_deps(false),
402 waiting_for_execstat(false), doing_recovery(false),
403 start_explicit(false), prop_require(false), prop_release(false), prop_failure(false),
404 force_stop(false), child_listener(this), child_status_listener(this)
408 service_type = ServiceType::DUMMY;
411 ServiceRecord(ServiceSet *set, string name, ServiceType service_type, string &&command, std::list<std::pair<unsigned,unsigned>> &command_offsets,
412 sr_list * pdepends_on, sr_list * pdepends_soft)
413 : ServiceRecord(set, name)
417 this->service_type = service_type;
418 this->depends_on = std::move(*pdepends_on);
420 program_name = command;
421 exec_arg_parts = separate_args(program_name, command_offsets);
423 for (sr_iter i = depends_on.begin(); i != depends_on.end(); ++i) {
424 (*i)->dependents.push_back(this);
428 auto b_iter = soft_deps.end();
429 for (sr_iter i = pdepends_soft->begin(); i != pdepends_soft->end(); ++i) {
430 b_iter = soft_deps.emplace(b_iter, this, *i);
431 (*i)->soft_dpts.push_back(&(*b_iter));
436 // TODO write a destructor
438 // begin transition from stopped to started state or vice versa depending on current and desired state
439 void execute_transition() noexcept;
441 void do_propagation() noexcept;
443 // Called on transition of desired state from stopped to started (or unpinned stop)
444 void do_start() noexcept;
446 // Called on transition of desired state from started to stopped (or unpinned start)
447 void do_stop() noexcept;
449 // Console is available.
450 void acquiredConsole() noexcept;
452 // Set the stop command and arguments (may throw std::bad_alloc)
453 void setStopCommand(std::string command, std::list<std::pair<unsigned,unsigned>> &stop_command_offsets)
455 stop_command = command;
456 stop_arg_parts = separate_args(stop_command, stop_command_offsets);
459 // Get the current service state.
460 ServiceState getState() noexcept
462 return service_state;
465 // Get the target (aka desired) state.
466 ServiceState getTargetState() noexcept
468 return desired_state;
471 // Set logfile, should be done before service is started
472 void setLogfile(string logfile)
474 this->logfile = logfile;
477 // Set whether this service should automatically restart when it dies
478 void setAutoRestart(bool auto_restart) noexcept
480 this->auto_restart = auto_restart;
483 void setSmoothRecovery(bool smooth_recovery) noexcept
485 this->smooth_recovery = smooth_recovery;
488 // Set "on start" flags (commands)
489 void setOnstartFlags(OnstartFlags flags) noexcept
491 this->onstart_flags = flags;
494 // Set an additional signal (other than SIGTERM) to be used to terminate the process
495 void setExtraTerminationSignal(int signo) noexcept
497 this->term_signal = signo;
500 void set_pid_file(string &&pid_file) noexcept
502 this->pid_file = pid_file;
505 void set_socket_details(string &&socket_path, int socket_perms, uid_t socket_uid, uid_t socket_gid) noexcept
507 this->socket_path = socket_path;
508 this->socket_perms = socket_perms;
509 this->socket_uid = socket_uid;
510 this->socket_gid = socket_gid;
513 const std::string &getServiceName() const noexcept { return service_name; }
514 ServiceState getState() const noexcept { return service_state; }
516 void start(bool activate = true) noexcept; // start the service
517 void stop(bool bring_down = true) noexcept; // stop the service
519 void forceStop() noexcept; // force-stop this service and all dependents
521 // Pin the service in "started" state (when it reaches the state)
522 void pinStart() noexcept
524 pinned_started = true;
527 // Pin the service in "stopped" state (when it reaches the state)
528 void pinStop() noexcept
530 pinned_stopped = true;
533 // Remove both "started" and "stopped" pins. If the service is currently pinned
534 // in either state but would naturally be in the opposite state, it will immediately
535 // commence starting/stopping.
536 void unpin() noexcept;
538 bool isDummy() noexcept
540 return service_type == ServiceType::DUMMY;
543 // Add a listener. A listener must only be added once. May throw std::bad_alloc.
544 void addListener(ServiceListener * listener)
546 listeners.insert(listener);
549 // Remove a listener.
550 void removeListener(ServiceListener * listener) noexcept
552 listeners.erase(listener);
557 * A ServiceSet, as the name suggests, manages a set of services.
559 * Other than the ability to find services by name, the service set manages various queues.
560 * One is the queue for processes wishing to acquire the console. There is also a set of
561 * processes that want to start, and another set of those that want to stop. These latter
562 * two "queues" (not really queues since their order is not important) are used to prevent too
563 * much recursion and to prevent service states from "bouncing" too rapidly.
565 * A service that wishes to start or stop puts itself on the start/stop queue; a service that
566 * needs to propagate changes to dependent services or dependencies puts itself on the
567 * propagation queue. Any operation that potentially manipulates the queues must be followed
568 * by a "process queues" order (processQueues() method).
570 * Note that processQueues always repeatedly processes both queues until they are empty. The
571 * process is finite because starting a service can never cause services to stop, unless they
572 * fail to start, which should cause them to stop semi-permanently.
577 std::list<ServiceRecord *> records;
578 const char *service_dir; // directory containing service descriptions
579 bool restart_enabled; // whether automatic restart is enabled (allowed)
581 ShutdownType shutdown_type = ShutdownType::CONTINUE; // Shutdown type, if stopping
583 ServiceRecord * console_queue_head = nullptr; // first record in console queue
584 ServiceRecord * console_queue_tail = nullptr; // last record in console queue
586 // Propagation and start/stop "queues" - list of services waiting for processing
587 ServiceRecord * first_prop_queue = nullptr;
588 ServiceRecord * first_stop_queue = nullptr;
592 // Load a service description, and dependencies, if there is no existing
593 // record for the given name.
595 // ServiceLoadException (or subclass) on problem with service description
596 // std::bad_alloc on out-of-memory condition
597 ServiceRecord *loadServiceRecord(const char *name);
602 ServiceSet(const char *service_dir)
604 this->service_dir = service_dir;
606 restart_enabled = true;
609 // Start the service with the given name. The named service will begin
610 // transition to the 'started' state.
612 // Throws a ServiceLoadException (or subclass) if the service description
613 // cannot be loaded or is invalid;
614 // Throws std::bad_alloc if out of memory.
615 void startService(const char *name);
617 // Locate an existing service record.
618 ServiceRecord *findService(const std::string &name) noexcept;
620 // Find a loaded service record, or load it if it is not loaded.
622 // ServiceLoadException (or subclass) on problem with service description
623 // std::bad_alloc on out-of-memory condition
624 ServiceRecord *loadService(const std::string &name)
626 ServiceRecord *record = findService(name);
627 if (record == nullptr) {
628 record = loadServiceRecord(name.c_str());
633 // Get the list of all loaded services.
634 const std::list<ServiceRecord *> &listServices()
639 // Stop the service with the given name. The named service will begin
640 // transition to the 'stopped' state.
641 void stopService(const std::string &name) noexcept;
643 // Add a service record to the state propogation queue
644 void addToPropQueue(ServiceRecord *service) noexcept
646 if (service->next_in_prop_queue == nullptr && first_prop_queue != service) {
647 service->next_in_prop_queue = first_prop_queue;
648 first_prop_queue = service;
652 // Add a service record to the start queue; called by service record
653 void addToStartQueue(ServiceRecord *service) noexcept
655 // The start/stop queue is actually one queue:
656 addToStopQueue(service);
659 // Add a service to the stop queue; called by service record
660 void addToStopQueue(ServiceRecord *service) noexcept
662 if (service->next_in_stop_queue == nullptr && first_stop_queue != service) {
663 service->next_in_stop_queue = first_stop_queue;
664 first_stop_queue = service;
668 // Process state propagation and start/stop queues, until they are empty.
669 // TODO remove the pointless parameter
670 void processQueues(bool ignoredparam = false) noexcept
672 while (first_stop_queue != nullptr || first_prop_queue != nullptr) {
673 while (first_prop_queue != nullptr) {
674 auto next = first_prop_queue;
675 first_prop_queue = next->next_in_prop_queue;
676 next->next_in_prop_queue = nullptr;
677 next->do_propagation();
679 while (first_stop_queue != nullptr) {
680 auto next = first_stop_queue;
681 first_stop_queue = next->next_in_stop_queue;
682 next->next_in_stop_queue = nullptr;
683 next->execute_transition();
688 // Set the console queue tail (returns previous tail)
689 ServiceRecord * consoleQueueTail(ServiceRecord * newTail) noexcept
691 auto prev_tail = console_queue_tail;
692 console_queue_tail = newTail;
693 newTail->next_for_console = nullptr;
695 console_queue_head = newTail;
696 enable_console_log(false);
699 prev_tail->next_for_console = newTail;
704 // Retrieve the current console queue head and remove it from the queue
705 ServiceRecord * pullConsoleQueue() noexcept
707 auto prev_head = console_queue_head;
709 prev_head->acquiredConsole();
710 console_queue_head = prev_head->next_for_console;
711 if (! console_queue_head) {
712 console_queue_tail = nullptr;
716 enable_console_log(true);
721 // Notification from service that it is active (state != STOPPED)
722 // Only to be called on the transition from inactive to active.
723 void service_active(ServiceRecord *) noexcept;
725 // Notification from service that it is inactive (STOPPED)
726 // Only to be called on the transition from active to inactive.
727 void service_inactive(ServiceRecord *) noexcept;
729 // Find out how many services are active (starting, running or stopping,
731 int count_active_services() noexcept
733 return active_services;
736 void stop_all_services(ShutdownType type = ShutdownType::HALT) noexcept
738 restart_enabled = false;
739 shutdown_type = type;
740 for (std::list<ServiceRecord *>::iterator i = records.begin(); i != records.end(); ++i) {
744 processQueues(false);
747 void set_auto_restart(bool restart) noexcept
749 restart_enabled = restart;
752 bool get_auto_restart() noexcept
754 return restart_enabled;
757 ShutdownType getShutdownType() noexcept
759 return shutdown_type;