Kea 2.7.4
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Implements a finite state machine. More...
#include <state_model.h>
Public Member Functions | |
StateModel () | |
Constructor. | |
virtual | ~StateModel () |
Destructor. | |
bool | didModelFail () const |
Returns whether or not the model failed. | |
void | endModel () |
Conducts a normal transition to the end of the model. | |
std::string | getContextStr () const |
Convenience method which returns a string rendition of the current state and next event. | |
unsigned int | getCurrState () const |
Fetches the model's current state. | |
std::string | getEventLabel (const int event) const |
Fetches the label associated with an event value. | |
unsigned int | getLastEvent () const |
Fetches the model's last event. | |
unsigned int | getNextEvent () const |
Fetches the model's next event. | |
std::string | getPrevContextStr () const |
Convenience method which returns a string rendition of the previous state and last event. | |
unsigned int | getPrevState () const |
Fetches the model's previous state. | |
std::string | getStateLabel (const int state) const |
Fetches the label associated with an state value. | |
bool | isModelDone () const |
Returns whether or not the model has finished execution. | |
bool | isModelNew () const |
Returns whether or not the model is new. | |
bool | isModelPaused () const |
Returns whether or not the model is paused. | |
bool | isModelRunning () const |
Returns whether or not the model is running. | |
bool | isModelWaiting () const |
Returns whether or not the model is waiting. | |
void | nopStateHandler () |
An empty state handler. | |
virtual void | runModel (unsigned int event) |
Processes events through the state model. | |
void | startModel (const int start_state) |
Begins execution of the model. | |
void | unpauseModel () |
Unpauses state model. | |
Static Public Attributes | |
static const int | END_EVT = 2 |
Event issued to end the model execution. | |
static const int | END_ST = 1 |
Final state, all the state model has reached its conclusion. | |
static const int | FAIL_EVT = 3 |
Event issued to abort the model execution. | |
static const int | NEW_ST = 0 |
State that a state model is in immediately after construction. | |
static const int | NOP_EVT = 0 |
Signifies that no event has occurred. | |
static const int | SM_DERIVED_EVENT_MIN = 11 |
Value at which custom events in a derived class should begin. | |
static const int | SM_DERIVED_STATE_MIN = 11 |
Value at which custom states in a derived class should begin. | |
static const int | START_EVT = 1 |
Event issued to start the model execution. | |
Protected Member Functions | |
void | abortModel (const std::string &explanation) |
Aborts model execution. | |
void | defineEvent (unsigned int value, const std::string &label) |
Adds an event value and associated label to the set of events. | |
virtual void | defineEvents () |
Populates the set of events. | |
void | defineState (unsigned int value, const std::string &label, StateHandler handler, const StatePausing &state_pausing=STATE_PAUSE_NEVER) |
Adds an state value and associated label to the set of states. | |
virtual void | defineStates () |
Populates the set of states. | |
bool | doOnEntry () |
Checks if on entry flag is true. | |
bool | doOnExit () |
Checks if on exit flag is true. | |
const EventPtr & | getEvent (unsigned int value) |
Fetches the event referred to by value. | |
const StatePtr | getState (unsigned int value) |
Fetches the state referred to by value. | |
const StatePtr | getStateInternal (unsigned int value) |
Fetches the state referred to by value. | |
void | initDictionaries () |
Initializes the event and state dictionaries. | |
virtual void | onModelFailure (const std::string &explanation) |
Handler for fatal model execution errors. | |
void | postNextEvent (unsigned int event) |
Sets the next event to the given event value. | |
void | setState (unsigned int state) |
Sets the current state to the given state value. | |
void | transition (unsigned int state, unsigned int event) |
Sets up the model to transition into given state with a given event. | |
virtual void | verifyEvents () |
Validates the contents of the set of events. | |
virtual void | verifyStates () |
Validates the contents of the set of states. | |
Implements a finite state machine.
StateModel is an abstract class that provides the structure and mechanics of a basic finite state machine.
The state model implementation used is a very basic approach. The model uses numeric constants to identify events and states, and maintains dictionaries of defined events and states. Event and state definitions include a text label for logging purposes. Additionally, each state definition includes a state handler. State handlers are methods which implement the actions that need to occur when the model is "in" a given state. The implementation provides methods to add entries to and verify the contents of both dictionaries.
During model execution, the following context is tracked:
When invoked, a state handler determines what it should do based upon the next event including what the next state and event should be. In other words the state transition knowledge is distributed among the state handlers rather than encapsulated in some form of state transition table.
Events "posted" from within the state handlers are "internally" triggered events. Events "posted" from outside the state model, such as through the invocation of a callback are "externally" triggered.
StateModel defines two states:
and the following events:
Derivations add their own states and events appropriate for their state model. Note that NEW_ST and END_ST do not support handlers. No work can be done (events consumed) prior to starting the model nor can work be done once the model has ended.
Model execution consists of iteratively invoking the state handler indicated by the current state which should consume the next event. As the handlers post events and/or change the state, the model is traversed. The loop stops whenever the model cannot continue without an externally triggered event or when it has reached its final state. In the case of the former, the loop may be re-entered upon arrival of the external event.
This loop is implemented in the runModel method. This method accepts an event as argument which it "posts" as the next event. It then retrieves the handler for the current state from the handler map and invokes it. runModel repeats this process until either a NOP_EVT posts or the state changes to END_ST. In other words each invocation of runModel causes the model to be traversed from the current state until it must wait or ends.
Re-entering the "loop" upon the occurrence of an external event is done by invoking runModel with the appropriate event. As before, runModel will loop until either the NOP_EVT occurs or until the model reaches its end.
A StateModel (derivation) is in the NEW_ST when constructed and remains there until it has been "started". Starting the model is done by invoking the startModel method which accepts a state as a parameter. This parameter specifies the "start" state and it becomes the current state. The first task undertaken by startModel is to initialize and verify the the event and state dictionaries. The following virtual methods are provided for this:
The concept behind the verify methods is to provide an initial sanity check of the dictionaries. This should help avoid using undefined event or state values accidentally.
These methods are intended to be implemented by each "layer" in a StateModel derivation hierarchy. This allows each layer to define additional events and states.
Once the dictionaries have been properly initialized, the startModel method invokes runModel with an event of START_EVT. From this point forward and until the model reaches the END_ST or fails, it is considered to be "running". If the model encounters a NOP_EVT then it is "running" and "waiting". If the model reaches END_ST with an END_EVT it is considered "done". If the model fails (END_ST with a FAILED_EVT) it is considered "done" and "failed". There are several boolean status methods which may be used to check these conditions. Once the model has been started, defining new events or new states is illegal. It is possible to call startModel only once.
To progress from one state to the another, state handlers invoke use the method, transition. This method accepts a state and an event as parameters. These values become the current state and the next event respectively. This has the effect of entering the given state having posted the given event. The postEvent method may be used to post a new event to the current state.
Bringing the model to a normal end is done by invoking the endModel method which transitions the model to END_ST with END_EVT. Bringing the model to an abnormal end is done via the abortModel method, which transitions the model to END_ST with FAILED_EVT.
The model can be paused in the selected states. The states in which the state model should pause (always or only once) are determined within the StateModel::defineStates
method. The state handlers can check whether the state machine is paused or not by calling StateModel::isModelPaused
and act accordingy. Typically, the state handler would simply post the NOP_EVT
when it finds that the state model is paused. The model remains paused until StateModel::unpauseModel
is called.
Definition at line 274 of file state_model.h.
isc::util::StateModel::StateModel | ( | ) |
Constructor.
Definition at line 89 of file state_model.cc.
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Destructor.
Definition at line 96 of file state_model.cc.
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Aborts model execution.
This method posts a FAILED_EVT and sets the current state to END_ST. It is called internally when a model violation occurs. Violations are any sort of inconsistency such as attempting to reference an invalid state, or if the next event is not valid for the current state, or a state handler throws an uncaught exception.
explanation | is text detailing the reason for aborting. |
Definition at line 282 of file state_model.cc.
References END_ST, FAIL_EVT, getContextStr(), onModelFailure(), and transition().
Referenced by isc::http::HttpMessageParserBase::parseEndedHandler(), isc::config::JSONFeed::poll(), isc::http::HttpMessageParserBase::poll(), and runModel().
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Adds an event value and associated label to the set of events.
This method is called in a thread safe context from defineEvents.
value | is the numeric value of the event |
label | is the text label of the event used in log messages and exceptions. |
StateModelError | if the model has already been started, if the value is already defined, or if the label is empty. |
Definition at line 170 of file state_model.cc.
References isc::util::LabeledValueSet::add(), isc_throw, and isc::Exception::what().
Referenced by isc::d2::CheckExistsAddTransaction::defineEvents(), isc::d2::NameAddTransaction::defineEvents(), isc::d2::SimpleAddTransaction::defineEvents(), isc::d2::SimpleAddWithoutDHCIDTransaction::defineEvents(), isc::d2::NameChangeTransaction::defineEvents(), defineEvents(), and isc::http::HttpMessageParserBase::defineEvents().
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Populates the set of events.
This method is used to construct the set of valid events. Each class within a StateModel derivation hierarchy uses this method to add any events it defines to the set. Each derivation's implementation must also call its superclass's implementation. This allows each class within the hierarchy to make contributions to the set of defined events. Implementations use the method, defineEvent(), to add event definitions. An example of the derivation's implementation follows:
This method is called in a thread safe context from initDictionaries.
Reimplemented in isc::d2::CheckExistsAddTransaction, isc::d2::CheckExistsRemoveTransaction, isc::d2::NameAddTransaction, isc::d2::NameRemoveTransaction, isc::d2::SimpleAddTransaction, isc::d2::SimpleAddWithoutDHCIDTransaction, isc::d2::SimpleRemoveTransaction, isc::d2::SimpleRemoveWithoutDHCIDTransaction, isc::d2::NameChangeTransaction, and isc::http::HttpMessageParserBase.
Definition at line 229 of file state_model.cc.
References defineEvent(), END_EVT, FAIL_EVT, NOP_EVT, and START_EVT.
Referenced by isc::d2::NameChangeTransaction::defineEvents(), isc::http::HttpMessageParserBase::defineEvents(), and initDictionaries().
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Adds an state value and associated label to the set of states.
This method is called in a thread safe context from defineStates.
value | is the numeric value of the state |
label | is the text label of the state used in log messages and exceptions. |
handler | is the bound instance method which implements the state's actions. |
state_pausing | pausing mode selected for the given state. The default value is STATE_PAUSE_NEVER . |
StateModelError | if the model has already been started, if the value is already defined, or if the label is empty. |
Definition at line 196 of file state_model.cc.
References isc::util::StateSet::add(), isc_throw, and isc::Exception::what().
Referenced by isc::d2::CheckExistsAddTransaction::defineStates(), isc::d2::CheckExistsRemoveTransaction::defineStates(), isc::d2::NameAddTransaction::defineStates(), isc::d2::NameRemoveTransaction::defineStates(), isc::d2::SimpleAddTransaction::defineStates(), isc::d2::SimpleAddWithoutDHCIDTransaction::defineStates(), isc::d2::SimpleRemoveTransaction::defineStates(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::defineStates(), defineStates(), and isc::http::HttpMessageParserBase::defineStates().
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protectedvirtual |
Populates the set of states.
This method is used to construct the set of valid states. Each class within a StateModel derivation hierarchy uses this method to add any states it defines to the set. Each derivation's implementation must also call its superclass's implementation. This allows each class within the hierarchy to make contributions to the set of defined states. Implementations use the method, defineState(), to add state definitions. An example of the derivation's implementation follows:
This method is called in a thread safe context from initDictionaries.
Reimplemented in isc::d2::CheckExistsAddTransaction, isc::d2::CheckExistsRemoveTransaction, isc::d2::NameAddTransaction, isc::d2::NameRemoveTransaction, isc::d2::SimpleAddTransaction, isc::d2::SimpleAddWithoutDHCIDTransaction, isc::d2::SimpleRemoveTransaction, isc::d2::SimpleRemoveWithoutDHCIDTransaction, isc::d2::NameChangeTransaction, and isc::http::HttpMessageParserBase.
Definition at line 245 of file state_model.cc.
References defineState(), END_ST, NEW_ST, and nopStateHandler().
Referenced by isc::d2::NameChangeTransaction::defineStates(), isc::http::HttpMessageParserBase::defineStates(), and initDictionaries().
bool isc::util::StateModel::didModelFail | ( | ) | const |
Returns whether or not the model failed.
Definition at line 409 of file state_model.cc.
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Checks if on entry flag is true.
This method acts as a one-shot test of whether or not the model is transitioning into a new state. It returns true if the on-entry flag is true upon entering this method and will set the flag false prior to exit. It may be used within state handlers to perform steps that should only occur upon entry into the state.
Definition at line 339 of file state_model.cc.
Referenced by isc::d2::CheckExistsAddTransaction::addingFwdAddrsHandler(), isc::d2::NameAddTransaction::addingFwdAddrsHandler(), isc::d2::CheckExistsRemoveTransaction::removingFwdAddrsHandler(), isc::d2::NameRemoveTransaction::removingFwdAddrsHandler(), isc::d2::CheckExistsRemoveTransaction::removingFwdRRsHandler(), isc::d2::NameRemoveTransaction::removingFwdRRsHandler(), isc::d2::SimpleRemoveTransaction::removingFwdRRsHandler(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::removingFwdRRsHandler(), isc::d2::CheckExistsRemoveTransaction::removingRevPtrsHandler(), isc::d2::NameRemoveTransaction::removingRevPtrsHandler(), isc::d2::SimpleRemoveTransaction::removingRevPtrsHandler(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::removingRevPtrsHandler(), isc::d2::CheckExistsAddTransaction::replacingFwdAddrsHandler(), isc::d2::NameAddTransaction::replacingFwdAddrsHandler(), isc::d2::SimpleAddTransaction::replacingFwdAddrsHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::replacingFwdAddrsHandler(), isc::d2::CheckExistsAddTransaction::replacingRevPtrsHandler(), isc::d2::NameAddTransaction::replacingRevPtrsHandler(), isc::d2::SimpleAddTransaction::replacingRevPtrsHandler(), and isc::d2::SimpleAddWithoutDHCIDTransaction::replacingRevPtrsHandler().
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Checks if on exit flag is true.
This method acts as a one-shot test of whether or not the model is transitioning out of the current state. It returns true if the on-exit flag is true upon entering this method and will set the flag false prior to exiting. It may be used within state handlers to perform steps that should only occur upon exiting out of the current state.
Definition at line 347 of file state_model.cc.
void isc::util::StateModel::endModel | ( | ) |
Conducts a normal transition to the end of the model.
This method posts an END_EVT and sets the current state to END_ST. It should be called by any state handler in the model from which an exit leads to the model end. In other words, if the transition out of a particular state is to the end of the model, that state's handler should call endModel.
Definition at line 271 of file state_model.cc.
References END_EVT, END_ST, and transition().
Referenced by isc::d2::CheckExistsAddTransaction::processAddFailedHandler(), isc::d2::NameAddTransaction::processAddFailedHandler(), isc::d2::SimpleAddTransaction::processAddFailedHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::processAddFailedHandler(), isc::d2::CheckExistsAddTransaction::processAddOkHandler(), isc::d2::NameAddTransaction::processAddOkHandler(), isc::d2::SimpleAddTransaction::processAddOkHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::processAddOkHandler(), isc::d2::CheckExistsRemoveTransaction::processRemoveFailedHandler(), isc::d2::NameRemoveTransaction::processRemoveFailedHandler(), isc::d2::SimpleRemoveTransaction::processRemoveFailedHandler(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::processRemoveFailedHandler(), isc::d2::CheckExistsRemoveTransaction::processRemoveOkHandler(), isc::d2::NameRemoveTransaction::processRemoveOkHandler(), isc::d2::SimpleRemoveTransaction::processRemoveOkHandler(), and isc::d2::SimpleRemoveWithoutDHCIDTransaction::processRemoveOkHandler().
std::string isc::util::StateModel::getContextStr | ( | ) | const |
Convenience method which returns a string rendition of the current state and next event.
The string will be of the form:
current state: [ {state} {label} ] next event: [ {event} {label} ]
Definition at line 443 of file state_model.cc.
Referenced by abortModel(), isc::d2::CheckExistsAddTransaction::addingFwdAddrsHandler(), isc::d2::NameAddTransaction::addingFwdAddrsHandler(), isc::http::HttpMessageParserBase::parseFailure(), isc::d2::CheckExistsAddTransaction::processAddFailedHandler(), isc::d2::NameAddTransaction::processAddFailedHandler(), isc::d2::SimpleAddTransaction::processAddFailedHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::processAddFailedHandler(), isc::d2::CheckExistsAddTransaction::processAddOkHandler(), isc::d2::NameAddTransaction::processAddOkHandler(), isc::d2::SimpleAddTransaction::processAddOkHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::processAddOkHandler(), isc::d2::CheckExistsRemoveTransaction::processRemoveFailedHandler(), isc::d2::NameRemoveTransaction::processRemoveFailedHandler(), isc::d2::SimpleRemoveTransaction::processRemoveFailedHandler(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::processRemoveFailedHandler(), isc::d2::CheckExistsRemoveTransaction::processRemoveOkHandler(), isc::d2::NameRemoveTransaction::processRemoveOkHandler(), isc::d2::SimpleRemoveTransaction::processRemoveOkHandler(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::processRemoveOkHandler(), isc::d2::CheckExistsAddTransaction::readyHandler(), isc::d2::CheckExistsRemoveTransaction::readyHandler(), isc::d2::NameAddTransaction::readyHandler(), isc::d2::NameRemoveTransaction::readyHandler(), isc::d2::SimpleAddTransaction::readyHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::readyHandler(), isc::d2::SimpleRemoveTransaction::readyHandler(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::readyHandler(), isc::d2::CheckExistsRemoveTransaction::removingFwdAddrsHandler(), isc::d2::NameRemoveTransaction::removingFwdAddrsHandler(), isc::d2::CheckExistsRemoveTransaction::removingFwdRRsHandler(), isc::d2::NameRemoveTransaction::removingFwdRRsHandler(), isc::d2::SimpleRemoveTransaction::removingFwdRRsHandler(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::removingFwdRRsHandler(), isc::d2::CheckExistsRemoveTransaction::removingRevPtrsHandler(), isc::d2::NameRemoveTransaction::removingRevPtrsHandler(), isc::d2::SimpleRemoveTransaction::removingRevPtrsHandler(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::removingRevPtrsHandler(), isc::d2::CheckExistsAddTransaction::replacingFwdAddrsHandler(), isc::d2::NameAddTransaction::replacingFwdAddrsHandler(), isc::d2::SimpleAddTransaction::replacingFwdAddrsHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::replacingFwdAddrsHandler(), isc::d2::CheckExistsAddTransaction::replacingRevPtrsHandler(), isc::d2::NameAddTransaction::replacingRevPtrsHandler(), isc::d2::SimpleAddTransaction::replacingRevPtrsHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::replacingRevPtrsHandler(), isc::d2::CheckExistsAddTransaction::selectingFwdServerHandler(), isc::d2::CheckExistsRemoveTransaction::selectingFwdServerHandler(), isc::d2::NameAddTransaction::selectingFwdServerHandler(), isc::d2::NameRemoveTransaction::selectingFwdServerHandler(), isc::d2::SimpleAddTransaction::selectingFwdServerHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::selectingFwdServerHandler(), isc::d2::SimpleRemoveTransaction::selectingFwdServerHandler(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::selectingFwdServerHandler(), isc::d2::CheckExistsAddTransaction::selectingRevServerHandler(), isc::d2::CheckExistsRemoveTransaction::selectingRevServerHandler(), isc::d2::NameAddTransaction::selectingRevServerHandler(), isc::d2::NameRemoveTransaction::selectingRevServerHandler(), isc::d2::SimpleAddTransaction::selectingRevServerHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::selectingRevServerHandler(), isc::d2::SimpleRemoveTransaction::selectingRevServerHandler(), and isc::d2::SimpleRemoveWithoutDHCIDTransaction::selectingRevServerHandler().
unsigned int isc::util::StateModel::getCurrState | ( | ) | const |
Fetches the model's current state.
This returns the model's notion of the current state. It is the state whose handler will be executed on the next iteration of the run loop.
Definition at line 355 of file state_model.cc.
Referenced by isc::ha::HAService::adjustNetworkState(), isc::ha::HAService::conditionalLogPausedState(), isc::config::JSONFeed::poll(), isc::http::HttpMessageParserBase::poll(), isc::config::JSONFeed::postBuffer(), isc::http::HttpMessageParserBase::postBuffer(), isc::d2::NameChangeTransaction::retryTransition(), and isc::ha::HAService::verboseTransition().
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Fetches the event referred to by value.
This method is called in a thread safe context from verifyEvents.
value | is the numeric value of the event desired. |
StateModelError | if the event is not defined. |
Definition at line 186 of file state_model.cc.
References isc::util::LabeledValueSet::get(), isc_throw, and isc::util::LabeledValueSet::isDefined().
Referenced by isc::d2::CheckExistsAddTransaction::verifyEvents(), isc::d2::NameAddTransaction::verifyEvents(), isc::d2::SimpleAddTransaction::verifyEvents(), isc::d2::SimpleAddWithoutDHCIDTransaction::verifyEvents(), isc::d2::NameChangeTransaction::verifyEvents(), verifyEvents(), and isc::http::HttpMessageParserBase::verifyEvents().
std::string isc::util::StateModel::getEventLabel | ( | const int | event | ) | const |
Fetches the label associated with an event value.
event | is the numeric event value for which the label is desired. |
Definition at line 432 of file state_model.cc.
Referenced by isc::http::HttpMessageParserBase::invalidEventError(), and isc::d2::NameChangeTransaction::transactionOutcomeString().
unsigned int isc::util::StateModel::getLastEvent | ( | ) | const |
Fetches the model's last event.
Definition at line 367 of file state_model.cc.
Referenced by isc::config::JSONFeed::feedOk(), isc::http::HttpMessageParserBase::httpParseOk(), and isc::ha::HAService::isMaintenanceCanceled().
unsigned int isc::util::StateModel::getNextEvent | ( | ) | const |
Fetches the model's next event.
This returns the model's notion of the next event. It is the event that will be passed into the current state's handler on the next iteration of the run loop.
Definition at line 373 of file state_model.cc.
Referenced by isc::d2::CheckExistsAddTransaction::addingFwdAddrsHandler(), isc::d2::NameAddTransaction::addingFwdAddrsHandler(), isc::config::JSONFeed::feedOk(), isc::http::HttpMessageParserBase::getNextFromBuffer(), isc::http::HttpMessageParserBase::httpParseOk(), isc::config::JSONFeed::needData(), isc::http::HttpMessageParserBase::needData(), isc::http::HttpMessageParserBase::parseEndedHandler(), isc::config::JSONFeed::poll(), isc::http::HttpMessageParserBase::poll(), isc::config::JSONFeed::postBuffer(), isc::http::HttpMessageParserBase::postBuffer(), isc::d2::CheckExistsAddTransaction::processAddFailedHandler(), isc::d2::NameAddTransaction::processAddFailedHandler(), isc::d2::SimpleAddTransaction::processAddFailedHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::processAddFailedHandler(), isc::d2::CheckExistsAddTransaction::processAddOkHandler(), isc::d2::NameAddTransaction::processAddOkHandler(), isc::d2::SimpleAddTransaction::processAddOkHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::processAddOkHandler(), isc::d2::CheckExistsRemoveTransaction::processRemoveFailedHandler(), isc::d2::NameRemoveTransaction::processRemoveFailedHandler(), isc::d2::SimpleRemoveTransaction::processRemoveFailedHandler(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::processRemoveFailedHandler(), isc::d2::CheckExistsRemoveTransaction::processRemoveOkHandler(), isc::d2::NameRemoveTransaction::processRemoveOkHandler(), isc::d2::SimpleRemoveTransaction::processRemoveOkHandler(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::processRemoveOkHandler(), isc::d2::CheckExistsAddTransaction::readyHandler(), isc::d2::CheckExistsRemoveTransaction::readyHandler(), isc::d2::NameAddTransaction::readyHandler(), isc::d2::NameRemoveTransaction::readyHandler(), isc::d2::SimpleAddTransaction::readyHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::readyHandler(), isc::d2::SimpleRemoveTransaction::readyHandler(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::readyHandler(), isc::d2::CheckExistsRemoveTransaction::removingFwdAddrsHandler(), isc::d2::NameRemoveTransaction::removingFwdAddrsHandler(), isc::d2::CheckExistsRemoveTransaction::removingFwdRRsHandler(), isc::d2::NameRemoveTransaction::removingFwdRRsHandler(), isc::d2::SimpleRemoveTransaction::removingFwdRRsHandler(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::removingFwdRRsHandler(), isc::d2::CheckExistsRemoveTransaction::removingRevPtrsHandler(), isc::d2::NameRemoveTransaction::removingRevPtrsHandler(), isc::d2::SimpleRemoveTransaction::removingRevPtrsHandler(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::removingRevPtrsHandler(), isc::d2::CheckExistsAddTransaction::replacingFwdAddrsHandler(), isc::d2::NameAddTransaction::replacingFwdAddrsHandler(), isc::d2::SimpleAddTransaction::replacingFwdAddrsHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::replacingFwdAddrsHandler(), isc::d2::CheckExistsAddTransaction::replacingRevPtrsHandler(), isc::d2::NameAddTransaction::replacingRevPtrsHandler(), isc::d2::SimpleAddTransaction::replacingRevPtrsHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::replacingRevPtrsHandler(), runModel(), isc::d2::CheckExistsAddTransaction::selectingFwdServerHandler(), isc::d2::CheckExistsRemoveTransaction::selectingFwdServerHandler(), isc::d2::NameAddTransaction::selectingFwdServerHandler(), isc::d2::NameRemoveTransaction::selectingFwdServerHandler(), isc::d2::SimpleAddTransaction::selectingFwdServerHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::selectingFwdServerHandler(), isc::d2::SimpleRemoveTransaction::selectingFwdServerHandler(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::selectingFwdServerHandler(), isc::d2::CheckExistsAddTransaction::selectingRevServerHandler(), isc::d2::CheckExistsRemoveTransaction::selectingRevServerHandler(), isc::d2::NameAddTransaction::selectingRevServerHandler(), isc::d2::NameRemoveTransaction::selectingRevServerHandler(), isc::d2::SimpleAddTransaction::selectingRevServerHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::selectingRevServerHandler(), isc::d2::SimpleRemoveTransaction::selectingRevServerHandler(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::selectingRevServerHandler(), isc::http::HttpMessageParserBase::stateWithMultiReadHandler(), isc::http::HttpMessageParserBase::stateWithReadHandler(), isc::d2::NameChangeTransaction::transactionOutcomeString(), and isc::ha::HAService::verboseTransition().
std::string isc::util::StateModel::getPrevContextStr | ( | ) | const |
Convenience method which returns a string rendition of the previous state and last event.
The string will be of the form:
previous state: [ {state} {label} ] last event: [ {event} {label} ]
Definition at line 454 of file state_model.cc.
unsigned int isc::util::StateModel::getPrevState | ( | ) | const |
Fetches the model's previous state.
Definition at line 361 of file state_model.cc.
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Fetches the state referred to by value.
value | is the numeric value of the state desired. |
StateModelError | if the state is not defined. |
Definition at line 213 of file state_model.cc.
References getStateInternal().
Referenced by isc::config::JSONFeed::poll(), isc::http::HttpMessageParserBase::poll(), and runModel().
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Fetches the state referred to by value.
This method should be called in a thread safe context.
value | is the numeric value of the state desired. |
StateModelError | if the state is not defined. |
Definition at line 219 of file state_model.cc.
References isc::util::StateSet::getState(), isc_throw, and isc::util::LabeledValueSet::isDefined().
Referenced by getState(), isc::d2::CheckExistsAddTransaction::verifyStates(), isc::d2::CheckExistsRemoveTransaction::verifyStates(), isc::d2::NameAddTransaction::verifyStates(), isc::d2::NameRemoveTransaction::verifyStates(), isc::d2::SimpleAddTransaction::verifyStates(), isc::d2::SimpleAddWithoutDHCIDTransaction::verifyStates(), isc::d2::SimpleRemoveTransaction::verifyStates(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::verifyStates(), isc::d2::NameChangeTransaction::verifyStates(), and verifyStates().
std::string isc::util::StateModel::getStateLabel | ( | const int | state | ) | const |
Fetches the label associated with an state value.
state | is the numeric state value for which the label is desired. |
Definition at line 421 of file state_model.cc.
Referenced by isc::ha::HAService::adjustNetworkState(), and isc::ha::HAService::verboseTransition().
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Initializes the event and state dictionaries.
This method invokes the define and verify methods for both events and states to initialize their respective dictionaries. This method can be called only once to initialize the state model.
StateModelError | or others indirectly, as this method calls dictionary define and verify methods. |
Definition at line 144 of file state_model.cc.
References defineEvents(), defineStates(), isc_throw, verifyEvents(), verifyStates(), and isc::Exception::what().
Referenced by isc::config::JSONFeed::initModel(), isc::http::HttpRequestParser::initModel(), isc::http::HttpResponseParser::initModel(), and startModel().
bool isc::util::StateModel::isModelDone | ( | ) | const |
Returns whether or not the model has finished execution.
Definition at line 403 of file state_model.cc.
References END_ST.
Referenced by isc::config::JSONFeed::poll(), isc::http::HttpMessageParserBase::poll(), and runModel().
bool isc::util::StateModel::isModelNew | ( | ) | const |
Returns whether or not the model is new.
Definition at line 379 of file state_model.cc.
bool isc::util::StateModel::isModelPaused | ( | ) | const |
Returns whether or not the model is paused.
Definition at line 415 of file state_model.cc.
Referenced by isc::ha::HAService::conditionalLogPausedState(), and isc::ha::HAService::unpause().
bool isc::util::StateModel::isModelRunning | ( | ) | const |
Returns whether or not the model is running.
Definition at line 390 of file state_model.cc.
bool isc::util::StateModel::isModelWaiting | ( | ) | const |
Returns whether or not the model is waiting.
Definition at line 396 of file state_model.cc.
void isc::util::StateModel::nopStateHandler | ( | ) |
An empty state handler.
This method is primarily used to permit special states, NEW_ST and END_ST to be included in the state dictionary. Currently it is an empty method.
Definition at line 140 of file state_model.cc.
Referenced by defineStates().
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Handler for fatal model execution errors.
This method is called when an unexpected error renders during model execution, such as a state handler throwing an exception. It provides derivations an opportunity to act accordingly by setting the appropriate status or taking other remedial action. This allows the model execution loop to remain exception safe. This default implementation does nothing.
explanation | text detailing the error and state machine context |
Reimplemented in isc::d2::NameChangeTransaction, and isc::http::HttpMessageParserBase.
Definition at line 259 of file state_model.cc.
Referenced by abortModel().
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Sets the next event to the given event value.
This updates the model's notion of the next event and is the event that will be passed into the current state's handler on the next iteration of the run loop.
event | the numeric event value to post as the next event. |
StateModelError | if the event is undefined |
Definition at line 320 of file state_model.cc.
Referenced by isc::http::HttpMessageParserBase::getNextFromBuffer(), isc::config::JSONFeed::initModel(), isc::http::HttpRequestParser::initModel(), isc::http::HttpResponseParser::initModel(), runModel(), and isc::d2::NameChangeTransaction::sendUpdate().
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Processes events through the state model.
This method implements the state model "execution loop". It uses the given event as the next event to process and begins invoking the state handler for the current state. As described above, the invoked state handler consumes the next event and then determines the next event and the current state as required to implement the business logic. The method continues to loop until the next event posted is NOP_EVT or the model ends.
Any exception thrown during the loop is caught, logged, and the model is aborted with a FAIL_EVT. The derivation's state model is expected to account for any possible errors so any that escape are treated as unrecoverable.
event | is the next event to process |
This method is guaranteed not to throw.
If the dictionaries aren't built bail out.
Definition at line 112 of file state_model.cc.
References abortModel(), getNextEvent(), getState(), isModelDone(), NOP_EVT, and postNextEvent().
Referenced by isc::ha::HAService::asyncSendLeaseUpdate(), isc::d2::NameChangeTransaction::operator()(), and startModel().
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Sets the current state to the given state value.
This updates the model's notion of the current state and is the state whose handler will be executed on the next iteration of the run loop. This is intended primarily for internal use and testing. It is unlikely that transitioning to a new state without a new event is of much use.
state | the new value to assign to the current state. |
StateModelError | if the state is invalid. |
Definition at line 291 of file state_model.cc.
Referenced by isc::config::JSONFeed::initModel(), isc::http::HttpRequestParser::initModel(), isc::http::HttpResponseParser::initModel(), and startModel().
void isc::util::StateModel::startModel | ( | const int | start_state | ) |
Begins execution of the model.
This method invokes initDictionaries method to initialize the event and state dictionaries and then starts the model execution setting the current state to the given start state, and the event to START_EVT. This method can be called only once to start the state model.
start_state | is the state in which to begin execution. |
StateModelError | or others indirectly, as this method calls dictionary define and verify methods. |
Definition at line 100 of file state_model.cc.
References initDictionaries(), runModel(), setState(), and START_EVT.
Referenced by isc::ha::HAService::HAService(), and isc::d2::NameChangeTransaction::startTransaction().
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Sets up the model to transition into given state with a given event.
This updates the model's notion of the current state and the next event to process. State handlers use this method to move from one state to the next.
state | the new value to assign to the current state. |
event | the new value to assign to the next event. |
StateModelError | if the state is invalid. |
Definition at line 264 of file state_model.cc.
Referenced by abortModel(), isc::d2::CheckExistsAddTransaction::addingFwdAddrsHandler(), isc::d2::NameAddTransaction::addingFwdAddrsHandler(), endModel(), isc::http::HttpMessageParserBase::parseEndedHandler(), isc::http::HttpMessageParserBase::parseFailure(), isc::config::JSONFeed::postBuffer(), isc::http::HttpMessageParserBase::postBuffer(), isc::d2::CheckExistsAddTransaction::readyHandler(), isc::d2::CheckExistsRemoveTransaction::readyHandler(), isc::d2::NameAddTransaction::readyHandler(), isc::d2::NameRemoveTransaction::readyHandler(), isc::d2::SimpleAddTransaction::readyHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::readyHandler(), isc::d2::SimpleRemoveTransaction::readyHandler(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::readyHandler(), isc::d2::CheckExistsRemoveTransaction::removingFwdAddrsHandler(), isc::d2::NameRemoveTransaction::removingFwdAddrsHandler(), isc::d2::CheckExistsRemoveTransaction::removingFwdRRsHandler(), isc::d2::NameRemoveTransaction::removingFwdRRsHandler(), isc::d2::SimpleRemoveTransaction::removingFwdRRsHandler(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::removingFwdRRsHandler(), isc::d2::CheckExistsRemoveTransaction::removingRevPtrsHandler(), isc::d2::NameRemoveTransaction::removingRevPtrsHandler(), isc::d2::SimpleRemoveTransaction::removingRevPtrsHandler(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::removingRevPtrsHandler(), isc::d2::CheckExistsAddTransaction::replacingFwdAddrsHandler(), isc::d2::NameAddTransaction::replacingFwdAddrsHandler(), isc::d2::SimpleAddTransaction::replacingFwdAddrsHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::replacingFwdAddrsHandler(), isc::d2::CheckExistsAddTransaction::replacingRevPtrsHandler(), isc::d2::NameAddTransaction::replacingRevPtrsHandler(), isc::d2::SimpleAddTransaction::replacingRevPtrsHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::replacingRevPtrsHandler(), isc::d2::NameChangeTransaction::retryTransition(), isc::d2::CheckExistsAddTransaction::selectingFwdServerHandler(), isc::d2::CheckExistsRemoveTransaction::selectingFwdServerHandler(), isc::d2::NameAddTransaction::selectingFwdServerHandler(), isc::d2::NameRemoveTransaction::selectingFwdServerHandler(), isc::d2::SimpleAddTransaction::selectingFwdServerHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::selectingFwdServerHandler(), isc::d2::SimpleRemoveTransaction::selectingFwdServerHandler(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::selectingFwdServerHandler(), isc::d2::CheckExistsAddTransaction::selectingRevServerHandler(), isc::d2::CheckExistsRemoveTransaction::selectingRevServerHandler(), isc::d2::NameAddTransaction::selectingRevServerHandler(), isc::d2::NameRemoveTransaction::selectingRevServerHandler(), isc::d2::SimpleAddTransaction::selectingRevServerHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::selectingRevServerHandler(), isc::d2::SimpleRemoveTransaction::selectingRevServerHandler(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::selectingRevServerHandler(), isc::d2::NameChangeTransaction::sendUpdate(), and isc::ha::HAService::verboseTransition().
void isc::util::StateModel::unpauseModel | ( | ) |
Unpauses state model.
Definition at line 276 of file state_model.cc.
Referenced by isc::ha::HAService::unpause().
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Validates the contents of the set of events.
This method is invoked immediately after the defineEvents method and is used to verify that all the required events are defined. If the event set is determined to be invalid this method should throw a StateModelError. As with the defineEvents method, each class within a StateModel derivation hierarchy must supply an implementation which calls its superclass's implementation as well as verifying any events added by the derivation. Validating an event is accomplished by simply attempting to fetch an event by its value from the event set. An example of the derivation's implementation follows:
This method is called in a thread safe context from initDictionaries.
Reimplemented in isc::d2::CheckExistsAddTransaction, isc::d2::CheckExistsRemoveTransaction, isc::d2::NameAddTransaction, isc::d2::NameRemoveTransaction, isc::d2::SimpleAddTransaction, isc::d2::SimpleAddWithoutDHCIDTransaction, isc::d2::SimpleRemoveTransaction, isc::d2::SimpleRemoveWithoutDHCIDTransaction, isc::d2::NameChangeTransaction, and isc::http::HttpMessageParserBase.
Definition at line 237 of file state_model.cc.
References END_EVT, FAIL_EVT, getEvent(), NOP_EVT, and START_EVT.
Referenced by initDictionaries(), isc::d2::NameChangeTransaction::verifyEvents(), and isc::http::HttpMessageParserBase::verifyEvents().
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Validates the contents of the set of states.
This method is invoked immediately after the defineStates method and is used to verify that all the required states are defined. If the state set is determined to be invalid this method should throw a StateModelError. As with the defineStates method, each class within a StateModel derivation hierarchy must supply an implementation which calls its superclass's implementation as well as verifying any states added by the derivation. Validating an state is accomplished by simply attempting to fetch the state by its value from the state set. An example of the derivation's implementation follows:
This method is called in a thread safe context from initDictionaries.
Reimplemented in isc::d2::CheckExistsAddTransaction, isc::d2::CheckExistsRemoveTransaction, isc::d2::NameAddTransaction, isc::d2::NameRemoveTransaction, isc::d2::SimpleAddTransaction, isc::d2::SimpleAddWithoutDHCIDTransaction, isc::d2::SimpleRemoveTransaction, isc::d2::SimpleRemoveWithoutDHCIDTransaction, and isc::d2::NameChangeTransaction.
Definition at line 253 of file state_model.cc.
References END_ST, getStateInternal(), and NEW_ST.
Referenced by initDictionaries(), and isc::d2::NameChangeTransaction::verifyStates().
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Event issued to end the model execution.
Definition at line 298 of file state_model.h.
Referenced by defineEvents(), endModel(), isc::config::JSONFeed::feedOk(), isc::http::HttpMessageParserBase::httpParseOk(), isc::http::HttpMessageParserBase::parseEndedHandler(), and verifyEvents().
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Final state, all the state model has reached its conclusion.
Definition at line 282 of file state_model.h.
Referenced by abortModel(), defineStates(), didModelFail(), endModel(), isModelDone(), isModelRunning(), isModelWaiting(), isc::http::HttpMessageParserBase::parseEndedHandler(), and verifyStates().
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Event issued to abort the model execution.
Definition at line 301 of file state_model.h.
Referenced by abortModel(), defineEvents(), didModelFail(), and verifyEvents().
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State that a state model is in immediately after construction.
Definition at line 279 of file state_model.h.
Referenced by defineStates(), isModelRunning(), isModelWaiting(), and verifyStates().
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Signifies that no event has occurred.
This is event used to interrupt the event loop to allow waiting for an IO event or when there is no more work to be done.
Definition at line 292 of file state_model.h.
Referenced by defineEvents(), isModelWaiting(), isc::config::JSONFeed::poll(), isc::http::HttpMessageParserBase::poll(), runModel(), isc::d2::NameChangeTransaction::sendUpdate(), and verifyEvents().
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Value at which custom events in a derived class should begin.
Definition at line 304 of file state_model.h.
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Value at which custom states in a derived class should begin.
Definition at line 285 of file state_model.h.
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Event issued to start the model execution.
Definition at line 295 of file state_model.h.
Referenced by defineEvents(), isc::config::JSONFeed::initModel(), isc::http::HttpRequestParser::initModel(), isc::http::HttpResponseParser::initModel(), isc::config::JSONFeed::needData(), isc::http::HttpMessageParserBase::needData(), isc::d2::CheckExistsAddTransaction::readyHandler(), isc::d2::CheckExistsRemoveTransaction::readyHandler(), isc::d2::NameAddTransaction::readyHandler(), isc::d2::NameRemoveTransaction::readyHandler(), isc::d2::SimpleAddTransaction::readyHandler(), isc::d2::SimpleAddWithoutDHCIDTransaction::readyHandler(), isc::d2::SimpleRemoveTransaction::readyHandler(), isc::d2::SimpleRemoveWithoutDHCIDTransaction::readyHandler(), startModel(), and verifyEvents().