btf::Semaphore Class Reference

Class for Semaphore (SEM) Events (see BTF Specification Chapter 2.3.7). More...

#include <semaphore.h>

Public Types
enum class	Events {   assigned , decrement , free , full ,   increment , lock , lock_used , overfull ,   queued , released , requestsemaphore , unlock ,   unlock_full , used , waiting , unknown }
	Possible types of Semaphore events. More...
enum class	States {   free , full , overfull , used ,   unknown }
	Possible types of Process states. More...

Public Member Functions
	Semaphore (States state=States::unknown)
	Constructor of the class Semaphore. More...
ErrorCodes	doStateTransition (Events ev)
	Transitions the current state depending on the event. More...

Static Public Member Functions
static std::string	eventToString (Events ev)
	Converts the enum Events into string. More...
static Events	stringToEvent (const std::string &str)
	Converts a string into the enum Events. More...

Detailed Description

Class for Semaphore (SEM) Events (see BTF Specification Chapter 2.3.7).

If more than one process is able to access a common resource, it might be necessary to
restrict the maximum amount of accesses in order to protect this resource from race conditions.
Therefore, the operating system provides the possibility to use a semaphore (SEM) (e.g. spinlock).

Member Enumeration Documentation

Events

enum btf::Semaphore::Events

strong

Possible types of Semaphore events.

Enumerator
assigned	The assigned event indicates that a process (source) gets assigned to a semaphore (target) and does not have to wait for assignment.
decrement	The decrement event indicates that a process (source) has released a semaphore (target) and now decrements its counter.
free	The free event indicates that a semaphore (source and target) reaches 0 assigned users and was not full before.
full	The full event indicates that a semaphore (source and target) gets released by a user and reaches its maximum amount of assignable semaphore users. In this case, no requesting user has to wait anymore.
increment	The increment event indicates that a process (source) has requested a semaphore (target) and now increments its counter.
lock	The lock event indicates that a semaphore (source and target) is requested by a user and reaches its maximum amount of assignable semaphore users and had no user assigned before.
lock_used	The lock_used event indicates that a semaphore (source and target) is requested by an additional user and reaches its maximum amount of assignable semaphore users.
overfull	The overfull event indicates that a semaphore (source and target) is requested by a user and has more simultaneous accesses as assignable. Therefore, at least one requesting user has to wait.
queued	The queued event indicates that a process (source) has requested a semaphore (target) and this request is queued to be either assigned or waiting later on.
released	The released event indicates that a process (source) that is assigned to a semaphore (target) releases this semaphore.
requestsemaphore	The requestsemaphore event indicates that a process (source) requests a semaphore (target).
unlock	The unlock event indicates that a semaphore (source and target) reaches 0 assigned users and was full before.
unlock_full	The unlock_full event indicates that a semaphore (source and target) which is released by a user, still has other users assigned and was full before.
used	The used event indicates that a semaphore (source and target) is requested and has user sassigned. The amount of assigned semaphore users is afterwards still less than the maximum amount of assignable semaphore users.
waiting	The waiting event indicates that a process (source) requests a semaphore (target). The semaphore has already reached the maximum amount of assignable semaphore users. Therefore, the request has to wait.
unknown	Default value.

States

enum btf::Semaphore::States

strong

Possible types of Process states.

Enumerator
free	Semaphore has no assigned users.
full	Semaphore has assigned requests and has reached its maximum amount of simultaneous accesses.
overfull	Semaphore is locked and at least one request is waiting for the semaphore.
used	Semaphore has assigned requests and is still able to handle at least one request.
unknown	Default state.

Constructor & Destructor Documentation

Semaphore()

btf::Semaphore::Semaphore

(

States

state = States::unknown

)

Constructor of the class Semaphore.

Member Function Documentation

doStateTransition()

ErrorCodes btf::Semaphore::doStateTransition

(

Events

ev

)

Transitions the current state depending on the event.

Parameters

[in]

ev

Events enum that triggered the state transition.

Returns

ErrorCodes enum.

eventToString()

std::string btf::Semaphore::eventToString ( Events  ev )

static

Converts the enum Events into string.

Parameters

[in]

ev

Events enum that will be converted.

Returns

String if Events type is valid, else a fatal error is triggered.

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stringToEvent()

Semaphore::Events btf::Semaphore::stringToEvent ( const std::string &  str )

static

Converts a string into the enum Events.

Parameters

[in]

str

String that will be converted.

Returns

Events enum.

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The documentation for this class was generated from the following files:

• src/libBtf/include/btf/semaphore.h
• src/libBtf/src/semaphore.cpp