Semaphore class is used to allow threads to synchronize access to a resource. The
UaSemaphore class provides a general counting semaphore. A semaphore is a generalization of a mutex. While a mutex can only be locked once, it's possible to acquire a semaphore multiple times. Semaphores are typically used to protect a certain number of identical resources. A typical application of semaphores is for controlling access to a circular buffer shared by a producer thread and a consumer thread. It is not possible to create plane copies of this Class. It is not possible to use the default constructor.
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#include <uasemaphore.h>
List of all members.
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Public Member Functions |
| | UaSemaphore (OpcUa_UInt32 initalValue, OpcUa_UInt32 maxRange) |
| | ~UaSemaphore () |
| OpcUa_StatusCode | wait () |
| OpcUa_StatusCode | timedWait (OpcUa_UInt32 msecTimeout) |
| OpcUa_StatusCode | post (OpcUa_UInt32 releaseCount) |
Detailed Description
Semaphore class is used to allow threads to synchronize access to a resource. The
UaSemaphore class provides a general counting semaphore. A semaphore is a generalization of a mutex. While a mutex can only be locked once, it's possible to acquire a semaphore multiple times. Semaphores are typically used to protect a certain number of identical resources. A typical application of semaphores is for controlling access to a circular buffer shared by a producer thread and a consumer thread. It is not possible to create plane copies of this Class. It is not possible to use the default constructor.
Constructor & Destructor Documentation
| UaSemaphore::UaSemaphore |
( |
OpcUa_UInt32 |
initalValue, |
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OpcUa_UInt32 |
maxRange | |
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) |
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Construction Constructs a UaSemaphore object that allows threads to synchronize access to a resource.
- Parameters:
-
| initalValue | Specifies an initial count for the semaphore object. This value must be greater than or equal to zero and less than or equal to maxCount. The state of a semaphore is signaled when its count is greater than zero and nonsignaled when it is zero. |
| maxRange | Specifies the maximum count for the semaphore object. This value must be greater than zero. |
| UaSemaphore::~UaSemaphore |
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) |
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Member Function Documentation
| OpcUa_StatusCode UaSemaphore::wait |
( |
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) |
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Wait until the Semaphore is in signaled state. This function will block the current thread until the Semaphore is in signaled state.
- See also:
- post()
- Returns:
- OpcUa_Good if the Semaphore is in signaled state, OpcUa_GoodNonCriticalTimeout if the Semaphore is in nonsignaled stte and the wait reached a timeout, OpcUa_BadInternalError if an error occurred in the wait function
| OpcUa_StatusCode UaSemaphore::timedWait |
( |
OpcUa_UInt32 |
msecTimeout |
) |
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Wait until the Semaphore is in signaled state. This function will block the current thread until the Semaphore is in signaled state or the passed timeout elapsed.
- See also:
- post()
- Parameters:
-
| msecTimeout | Timeout in milliseconds. |
- Returns:
- OpcUa_Good if the Semaphore is in signaled state, OpcUa_GoodNonCriticalTimeout if the Semaphore is in nonsignaled stte and the wait reached the passed timeout, OpcUa_BadInternalError if an error occurred in the wait function
| OpcUa_StatusCode UaSemaphore::post |
( |
OpcUa_UInt32 |
releaseCount |
) |
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Increases the count of the specified semaphore object by a specified amount.
- See also:
- wait()
- Parameters:
-
| releaseCount | Specifies the amount by which the current count of the semaphore object is to be increased. |
- Returns:
- OpcUa_Good if the post function succeeded, OpcUa_BadInvalidArgument if the specified count was less than 1, OpcUa_BadInternalError if an error occurred in the post function
The documentation for this class was generated from the following files:
- src/uabase/uabasecpp/uasemaphore.h
- src/uabase/uabasecpp/uasemaphore.cpp
