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.
72 * Two-phase transition
73 * --------------------
74 * Transition between states occurs in two phases: propagation and execution. In the
75 * propagation phase, acquisition/release messages are processed, and desired state may be
76 * altered accordingly. Desired state of dependencies/dependents should not be examined in
77 * this phase, since it may change during the phase (i.e. its current value at any point
78 * may not reflect the true final value).
80 * In the execution phase, actions are taken to achieve the desired state. Actual state may
81 * transition according to the current and desired states.
88 // Not actually "onstart" commands:
89 bool no_sigterm : 1; // do not send SIGTERM
90 bool runs_on_console : 1; // run "in the foreground"
91 bool pass_cs_fd : 1; // pass this service a control socket connection via fd
93 OnstartFlags() noexcept : rw_ready(false), log_ready(false),
94 no_sigterm(false), runs_on_console(false), pass_cs_fd(false)
99 // Exception while loading a service
103 std::string serviceName;
104 const char *excDescription;
107 ServiceLoadExc(std::string serviceName, const char *desc) noexcept
108 : serviceName(serviceName), excDescription(desc)
113 class ServiceNotFound : public ServiceLoadExc
116 ServiceNotFound(std::string serviceName) noexcept
117 : ServiceLoadExc(serviceName, "Service description not found.")
122 class ServiceCyclicDependency : public ServiceLoadExc
125 ServiceCyclicDependency(std::string serviceName) noexcept
126 : ServiceLoadExc(serviceName, "Has cyclic dependency.")
131 class ServiceDescriptionExc : public ServiceLoadExc
134 ServiceDescriptionExc(std::string serviceName, std::string extraInfo) noexcept
135 : ServiceLoadExc(serviceName, extraInfo.c_str())
140 class ServiceRecord; // forward declaration
141 class ServiceSet; // forward declaration
143 /* Service dependency record */
146 ServiceRecord * from;
150 /* Whether the 'from' service is waiting for the 'to' service to start */
152 /* Whether the 'from' service is holding an acquire on the 'to' service */
155 ServiceDep(ServiceRecord * from, ServiceRecord * to) noexcept : from(from), to(to), waiting_on(false), holding_acq(false)
158 ServiceRecord * getFrom() noexcept
163 ServiceRecord * getTo() noexcept
169 // Given a string and a list of pairs of (start,end) indices for each argument in that string,
170 // store a null terminator for the argument. Return a `char *` vector containing the beginning
171 // of each argument and a trailing nullptr. (The returned array is invalidated if the string is later modified).
172 static std::vector<const char *> separate_args(std::string &s, std::list<std::pair<unsigned,unsigned>> &arg_indices)
174 std::vector<const char *> r;
175 r.reserve(arg_indices.size() + 1);
177 // First store nul terminator for each part:
178 for (auto index_pair : arg_indices) {
179 if (index_pair.second < s.length()) {
180 s[index_pair.second] = 0;
184 // Now we can get the C string (c_str) and store offsets into it:
185 const char * cstr = s.c_str();
186 for (auto index_pair : arg_indices) {
187 r.push_back(cstr + index_pair.first);
189 r.push_back(nullptr);
193 class ServiceChildWatcher : public EventLoop_t::child_proc_watcher_impl<ServiceChildWatcher>
196 ServiceRecord * service;
197 rearm child_status(EventLoop_t &eloop, pid_t child, int status) noexcept;
199 ServiceChildWatcher(ServiceRecord * sr) noexcept : service(sr) { }
202 class ServiceIoWatcher : public EventLoop_t::fd_watcher_impl<ServiceIoWatcher>
205 ServiceRecord * service;
206 rearm fd_event(EventLoop_t &eloop, int fd, int flags) noexcept;
208 ServiceIoWatcher(ServiceRecord * sr) noexcept : service(sr) { }
213 friend class ServiceChildWatcher;
214 friend class ServiceIoWatcher;
216 typedef std::string string;
219 ServiceType service_type; /* ServiceType::DUMMY, PROCESS, SCRIPTED, INTERNAL */
220 ServiceState service_state = ServiceState::STOPPED; /* ServiceState::STOPPED, STARTING, STARTED, STOPPING */
221 ServiceState desired_state = ServiceState::STOPPED; /* ServiceState::STOPPED / STARTED */
223 string program_name; // storage for program/script and arguments
224 std::vector<const char *> exec_arg_parts; // pointer to each argument/part of the program_name, and nullptr
226 string stop_command; // storage for stop program/script and arguments
227 std::vector<const char *> stop_arg_parts; // pointer to each argument/part of the stop_command, and nullptr
231 OnstartFlags onstart_flags;
233 string logfile; // log file name, empty string specifies /dev/null
235 bool auto_restart : 1; // whether to restart this (process) if it dies unexpectedly
236 bool smooth_recovery : 1; // whether the service process can restart without bringing down service
238 bool pinned_stopped : 1;
239 bool pinned_started : 1;
240 bool waiting_for_deps : 1; // if STARTING, whether we are waiting for dependencies (inc console) to start
241 bool waiting_for_execstat : 1; // if we are waiting for exec status after fork()
242 bool doing_recovery : 1; // if we are currently recovering a BGPROCESS (restarting process, while
243 // holding STARTED service state)
244 bool start_explicit : 1; // whether we are are explictly required to be started
246 bool prop_require : 1; // require must be propagated
247 bool prop_release : 1; // release must be propagated
248 bool prop_failure : 1; // failure to start must be propagated
250 int required_by = 0; // number of dependents wanting this service to be started
252 typedef std::list<ServiceRecord *> sr_list;
253 typedef sr_list::iterator sr_iter;
255 // list of soft dependencies
256 typedef std::list<ServiceDep> softdep_list;
258 // list of soft dependents
259 typedef std::list<ServiceDep *> softdpt_list;
261 sr_list depends_on; // services this one depends on
262 sr_list dependents; // services depending on this one
263 softdep_list soft_deps; // services this one depends on via a soft dependency
264 softdpt_list soft_dpts; // services depending on this one via a soft dependency
266 // unsigned wait_count; /* if we are waiting for dependents/dependencies to
267 // start/stop, this is how many we're waiting for */
269 ServiceSet *service_set; // the set this service belongs to
271 std::unordered_set<ServiceListener *> listeners;
274 bool force_stop; // true if the service must actually stop. This is the
275 // case if for example the process dies; the service,
276 // and all its dependencies, MUST be stopped.
278 int term_signal = -1; // signal to use for process termination
280 string socket_path; // path to the socket for socket-activation service
281 int socket_perms; // socket permissions ("mode")
282 uid_t socket_uid = -1; // socket user id or -1
283 gid_t socket_gid = -1; // sockget group id or -1
285 // Implementation details
287 pid_t pid = -1; // PID of the process. If state is STARTING or STOPPING,
288 // this is PID of the service script; otherwise it is the
289 // PID of the process itself (process service).
290 int exit_status; // Exit status, if the process has exited (pid == -1).
291 int socket_fd = -1; // For socket-activation services, this is the file
292 // descriptor for the socket.
294 ServiceChildWatcher child_listener;
295 ServiceIoWatcher child_status_listener;
297 // Data for use by ServiceSet
300 // Next service (after this one) in the queue for the console. Intended to only be used by ServiceSet class.
301 ServiceRecord *next_for_console;
303 // Propagation and start/stop queues
304 ServiceRecord *next_in_prop_queue = nullptr;
305 ServiceRecord *next_in_stop_queue = nullptr;
310 // All dependents have stopped.
311 void allDepsStopped();
313 // Service has actually stopped (includes having all dependents
314 // reaching STOPPED state).
315 void stopped() noexcept;
317 // Service has successfully started
318 void started() noexcept;
320 // Service failed to start (only called when in STARTING state).
321 // dep_failed: whether failure is recorded due to a dependency failing
322 void failed_to_start(bool dep_failed = false) noexcept;
324 // For process services, start the process, return true on success
325 bool start_ps_process() noexcept;
326 bool start_ps_process(const std::vector<const char *> &args, bool on_console) noexcept;
328 void run_child_proc(const char * const *args, const char *logfile, bool on_console, int wpipefd,
331 // Callback from libev when a child process dies
332 static void process_child_callback(EventLoop_t *loop, ServiceChildWatcher *w,
333 int revents) noexcept;
335 void handle_exit_status() noexcept;
337 // A dependency has reached STARTED state
338 void dependencyStarted() noexcept;
340 void allDepsStarted(bool haveConsole = false) noexcept;
342 // Read the pid-file, return false on failure
343 bool read_pid_file() noexcept;
345 // Open the activation socket, return false on failure
346 bool open_socket() noexcept;
348 // Check whether dependencies have started, and optionally ask them to start
349 bool startCheckDependencies(bool do_start) noexcept;
351 // Whether a STARTING service can immediately transition to STOPPED (as opposed to
352 // having to wait for it reach STARTED and then go through STOPPING).
353 bool can_interrupt_start() noexcept
355 return waiting_for_deps;
358 // Whether a STOPPING service can immediately transition to STARTED.
359 bool can_interrupt_stop() noexcept
361 return waiting_for_deps && ! force_stop;
364 // A dependent has reached STOPPED state
365 void dependentStopped() noexcept;
367 // check if all dependents have stopped
368 bool stopCheckDependents() noexcept;
370 // issue a stop to all dependents, return true if they are all already stopped
371 bool stopDependents() noexcept;
373 void require() noexcept;
374 void release() noexcept;
375 void release_dependencies() noexcept;
377 // Check if service is, fundamentally, stopped.
378 bool is_stopped() noexcept
380 return service_state == ServiceState::STOPPED
381 || (service_state == ServiceState::STARTING && waiting_for_deps);
384 void notifyListeners(ServiceEvent event) noexcept
386 for (auto l : listeners) {
387 l->serviceEvent(this, event);
391 // Queue to run on the console. 'acquiredConsole()' will be called when the console is available.
392 void queueForConsole() noexcept;
394 // Release console (console must be currently held by this service)
395 void releaseConsole() noexcept;
397 bool do_auto_restart() noexcept;
401 ServiceRecord(ServiceSet *set, string name)
402 : service_state(ServiceState::STOPPED), desired_state(ServiceState::STOPPED), auto_restart(false),
403 pinned_stopped(false), pinned_started(false), waiting_for_deps(false),
404 waiting_for_execstat(false), doing_recovery(false),
405 start_explicit(false), prop_require(false), prop_release(false), prop_failure(false),
406 force_stop(false), child_listener(this), child_status_listener(this)
410 service_type = ServiceType::DUMMY;
413 ServiceRecord(ServiceSet *set, string name, ServiceType service_type, string &&command, std::list<std::pair<unsigned,unsigned>> &command_offsets,
414 sr_list * pdepends_on, sr_list * pdepends_soft)
415 : ServiceRecord(set, name)
419 this->service_type = service_type;
420 this->depends_on = std::move(*pdepends_on);
422 program_name = command;
423 exec_arg_parts = separate_args(program_name, command_offsets);
425 for (sr_iter i = depends_on.begin(); i != depends_on.end(); ++i) {
426 (*i)->dependents.push_back(this);
430 auto b_iter = soft_deps.end();
431 for (sr_iter i = pdepends_soft->begin(); i != pdepends_soft->end(); ++i) {
432 b_iter = soft_deps.emplace(b_iter, this, *i);
433 (*i)->soft_dpts.push_back(&(*b_iter));
438 // TODO write a destructor
440 // begin transition from stopped to started state or vice versa depending on current and desired state
441 void execute_transition() noexcept;
443 void do_propagation() noexcept;
445 // Called on transition of desired state from stopped to started (or unpinned stop)
446 void do_start() noexcept;
448 // Called on transition of desired state from started to stopped (or unpinned start)
449 void do_stop() noexcept;
451 // Console is available.
452 void acquiredConsole() noexcept;
454 // Set the stop command and arguments (may throw std::bad_alloc)
455 void setStopCommand(std::string command, std::list<std::pair<unsigned,unsigned>> &stop_command_offsets)
457 stop_command = command;
458 stop_arg_parts = separate_args(stop_command, stop_command_offsets);
461 // Get the current service state.
462 ServiceState getState() noexcept
464 return service_state;
467 // Get the target (aka desired) state.
468 ServiceState getTargetState() noexcept
470 return desired_state;
473 // Set logfile, should be done before service is started
474 void setLogfile(string logfile)
476 this->logfile = logfile;
479 // Set whether this service should automatically restart when it dies
480 void setAutoRestart(bool auto_restart) noexcept
482 this->auto_restart = auto_restart;
485 void setSmoothRecovery(bool smooth_recovery) noexcept
487 this->smooth_recovery = smooth_recovery;
490 // Set "on start" flags (commands)
491 void setOnstartFlags(OnstartFlags flags) noexcept
493 this->onstart_flags = flags;
496 // Set an additional signal (other than SIGTERM) to be used to terminate the process
497 void setExtraTerminationSignal(int signo) noexcept
499 this->term_signal = signo;
502 void set_pid_file(string &&pid_file) noexcept
504 this->pid_file = pid_file;
507 void set_socket_details(string &&socket_path, int socket_perms, uid_t socket_uid, uid_t socket_gid) noexcept
509 this->socket_path = socket_path;
510 this->socket_perms = socket_perms;
511 this->socket_uid = socket_uid;
512 this->socket_gid = socket_gid;
515 const std::string &getServiceName() const noexcept { return service_name; }
516 ServiceState getState() const noexcept { return service_state; }
518 void start(bool activate = true) noexcept; // start the service
519 void stop(bool bring_down = true) noexcept; // stop the service
521 void forceStop() noexcept; // force-stop this service and all dependents
523 // Pin the service in "started" state (when it reaches the state)
524 void pinStart() noexcept
526 pinned_started = true;
529 // Pin the service in "stopped" state (when it reaches the state)
530 void pinStop() noexcept
532 pinned_stopped = true;
535 // Remove both "started" and "stopped" pins. If the service is currently pinned
536 // in either state but would naturally be in the opposite state, it will immediately
537 // commence starting/stopping.
538 void unpin() noexcept;
540 bool isDummy() noexcept
542 return service_type == ServiceType::DUMMY;
545 // Add a listener. A listener must only be added once. May throw std::bad_alloc.
546 void addListener(ServiceListener * listener)
548 listeners.insert(listener);
551 // Remove a listener.
552 void removeListener(ServiceListener * listener) noexcept
554 listeners.erase(listener);
559 * A ServiceSet, as the name suggests, manages a set of services.
561 * Other than the ability to find services by name, the service set manages various queues.
562 * One is the queue for processes wishing to acquire the console. There is also a set of
563 * processes that want to start, and another set of those that want to stop. These latter
564 * two "queues" (not really queues since their order is not important) are used to prevent too
565 * much recursion and to prevent service states from "bouncing" too rapidly.
567 * A service that wishes to start or stop puts itself on the start/stop queue; a service that
568 * needs to propagate changes to dependent services or dependencies puts itself on the
569 * propagation queue. Any operation that potentially manipulates the queues must be followed
570 * by a "process queues" order (processQueues() method).
572 * Note that processQueues always repeatedly processes both queues until they are empty. The
573 * process is finite because starting a service can never cause services to stop, unless they
574 * fail to start, which should cause them to stop semi-permanently.
579 std::list<ServiceRecord *> records;
580 const char *service_dir; // directory containing service descriptions
581 bool restart_enabled; // whether automatic restart is enabled (allowed)
583 ShutdownType shutdown_type = ShutdownType::CONTINUE; // Shutdown type, if stopping
585 ServiceRecord * console_queue_head = nullptr; // first record in console queue
586 ServiceRecord * console_queue_tail = nullptr; // last record in console queue
588 // Propagation and start/stop "queues" - list of services waiting for processing
589 ServiceRecord * first_prop_queue = nullptr;
590 ServiceRecord * first_stop_queue = nullptr;
594 // Load a service description, and dependencies, if there is no existing
595 // record for the given name.
597 // ServiceLoadException (or subclass) on problem with service description
598 // std::bad_alloc on out-of-memory condition
599 ServiceRecord *loadServiceRecord(const char *name);
604 ServiceSet(const char *service_dir)
606 this->service_dir = service_dir;
608 restart_enabled = true;
611 // Start the service with the given name. The named service will begin
612 // transition to the 'started' state.
614 // Throws a ServiceLoadException (or subclass) if the service description
615 // cannot be loaded or is invalid;
616 // Throws std::bad_alloc if out of memory.
617 void startService(const char *name);
619 // Locate an existing service record.
620 ServiceRecord *find_service(const std::string &name) noexcept;
622 // Find a loaded service record, or load it if it is not loaded.
624 // ServiceLoadException (or subclass) on problem with service description
625 // std::bad_alloc on out-of-memory condition
626 ServiceRecord *loadService(const std::string &name)
628 ServiceRecord *record = find_service(name);
629 if (record == nullptr) {
630 record = loadServiceRecord(name.c_str());
635 // Get the list of all loaded services.
636 const std::list<ServiceRecord *> &listServices()
641 // Stop the service with the given name. The named service will begin
642 // transition to the 'stopped' state.
643 void stopService(const std::string &name) noexcept;
645 // Add a service record to the state propogation queue
646 void addToPropQueue(ServiceRecord *service) noexcept
648 if (service->next_in_prop_queue == nullptr && first_prop_queue != service) {
649 service->next_in_prop_queue = first_prop_queue;
650 first_prop_queue = service;
654 // Add a service record to the start queue; called by service record
655 void addToStartQueue(ServiceRecord *service) noexcept
657 // The start/stop queue is actually one queue:
658 addToStopQueue(service);
661 // Add a service to the stop queue; called by service record
662 void addToStopQueue(ServiceRecord *service) noexcept
664 if (service->next_in_stop_queue == nullptr && first_stop_queue != service) {
665 service->next_in_stop_queue = first_stop_queue;
666 first_stop_queue = service;
670 // Process state propagation and start/stop queues, until they are empty.
671 // TODO remove the pointless parameter
672 void processQueues(bool ignoredparam = false) noexcept
674 while (first_stop_queue != nullptr || first_prop_queue != nullptr) {
675 while (first_prop_queue != nullptr) {
676 auto next = first_prop_queue;
677 first_prop_queue = next->next_in_prop_queue;
678 next->next_in_prop_queue = nullptr;
679 next->do_propagation();
681 while (first_stop_queue != nullptr) {
682 auto next = first_stop_queue;
683 first_stop_queue = next->next_in_stop_queue;
684 next->next_in_stop_queue = nullptr;
685 next->execute_transition();
690 // Set the console queue tail (returns previous tail)
691 ServiceRecord * append_console_queue(ServiceRecord * newTail) noexcept
693 auto prev_tail = console_queue_tail;
694 console_queue_tail = newTail;
695 newTail->next_for_console = nullptr;
697 console_queue_head = newTail;
698 enable_console_log(false);
701 prev_tail->next_for_console = newTail;
706 // Retrieve the current console queue head and remove it from the queue
707 ServiceRecord * pullConsoleQueue() noexcept
709 auto prev_head = console_queue_head;
711 prev_head->acquiredConsole();
712 console_queue_head = prev_head->next_for_console;
713 if (! console_queue_head) {
714 console_queue_tail = nullptr;
718 enable_console_log(true);
723 // Notification from service that it is active (state != STOPPED)
724 // Only to be called on the transition from inactive to active.
725 void service_active(ServiceRecord *) noexcept;
727 // Notification from service that it is inactive (STOPPED)
728 // Only to be called on the transition from active to inactive.
729 void service_inactive(ServiceRecord *) noexcept;
731 // Find out how many services are active (starting, running or stopping,
733 int count_active_services() noexcept
735 return active_services;
738 void stop_all_services(ShutdownType type = ShutdownType::HALT) noexcept
740 restart_enabled = false;
741 shutdown_type = type;
742 for (std::list<ServiceRecord *>::iterator i = records.begin(); i != records.end(); ++i) {
746 processQueues(false);
749 void set_auto_restart(bool restart) noexcept
751 restart_enabled = restart;
754 bool get_auto_restart() noexcept
756 return restart_enabled;
759 ShutdownType getShutdownType() noexcept
761 return shutdown_type;