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Chapter 8. openETCS Domain Framework 8.6.2. Data Flow Implementation Most of the functionality of CFunctionBlock elements is simple to implement, like mathematical operations, but also the implementation of braking curves is mainly a transfer of a mathematical / physical model to C++ code. More crucial for the correct operation of any data flow is the execution in equidistant time points, which will be discussed here. Section 8.4 demonstrated that the cycles are generated in the CEVCState class by an own thread for each independent data flow. Those threads are implemented in the following method: void CEVCStateMachine : : CEVCState : : DataFlowThread ( const unsigned int& i I n d e x ) throw ( ) ; Since for each independent CDataFlow object an additional thread of this method is started, iIndex determines for which CDataFlow object in m_CurrentDataFlow the thread is responsible. In the implementation, the m_CurrentDataFlow aggregation is declared as : : s t d : : v e c t o r < CDataFlow∗ > m_CurrentDataFlow ; Creating threads according to C++11 is done by using the ::std::thread class [7, Ch. 30]. Hence, all data flow threads are created and started by the lines of code in Listing D.1 in Appendix D. These are located in the definition of the following method: void CEVCStateMachine : : CEVCState : : S t a r t ( ) throw ( : : oETCS : : DF : : E r r o r : : CException ) Since the CEVCStateMachine::CEVCState::Start() method should be blocking and should only return if all threads are terminated, the ::std::thread::join() method is used, which blocks until the corresponding thread has been terminated in Listing D.2. While this is mainly an object-oriented and platform independent way of starting a group of worker-thread, the thread-method implementation is more complex and therefore of more interest. The execution of the related CDataFlow object at equidistant time points must be implemented, which is done in corresponding CEVCState method: void CEVCStateMachine : : CEVCState : : DataFlowThread ( const unsigned int & i I n d e x ) throw ( ) Furthermore, all m_Threads must be synchronised in that way that the execution of each thread should start for every k at the same time point t = kT s (see (7.1)). This problem is related to real-time scheduling [77, pp. 457-504]. Although this is very difficult to realise in real technical systems, the time difference between the execution start points should be minimised. Figure 8.20 sketches a sample execution in the time domain for two unsynchronised threads. Besides that the second thread always starts the execution with a delay ∆t i , those delays also differ: ∆t 1 ≠ ∆t 2 ≠ ∆t 3 ≠ . . . . As already discussed in Section 7.6, this can lead to an undefined behaviour of the data flows in the time domain. The ideal sample execution for two threads is shown in Figure 8.21 The execution is implemented as a loop that calculates for each execution cycle k the consumed time and puts the thread for the remaining time to the next execution time point (k + 1)T s to sleep. The corresponding C++ source code can be found in Listing D.3 in Appendix D. At the very first execution of the while-loop, the time point of the execution start is measured once (Line 21) by the ::std::chrono::high_resolution_clock::now() method, which is 150
8.6. Implementation execution thread 2 ∆t 0 ∆t 1 ∆t 2 . . . 0 t thread 1 0 T s 2T s . . . t Figure 8.20.: Temporal execution of two unsynchronised data flow threads with a constant sample time T s execution thread 2 . . . 0 t thread 1 0 T s 2T s . . . t Figure 8.21.: Ideal temporal execution of two synchronised data flow threads with a constant sample time T s 151
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Open Source Software for Train Cont
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Datum des Promotionskolloquiums: 21
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Acknowledgments I would like to tha
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Abstract This document describes th
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Contents 3.3.3. Rascal . . . . . .
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Contents 8.4. Behavioural Design .
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Contents D.3. Domain Framework Mode
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List of Figures 6.4. Simple CORBA u
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List of Figures 10.27. General read
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Chapter 1. Introduction Railway Con
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Chapter 1. Introduction MontiCore M
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Chapter 1. Introduction ERTMS Forma
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Part I. Background 9
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Chapter 2. Concepts for Safe Railwa
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Chapter 3. Domain-Specific Modellin
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4The GOPPRR Meta Meta Model - An Ex
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4.1. Concrete Syntax Description Fo
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4.2. GOPPRR C++ Abstract Syntax Mod
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4.2. GOPPRR C++ Abstract Syntax Mod
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4.5. The Object Constraint Language
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4.5. The Object Constraint Language
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4.6. Tool Chain where artefacts are
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4.7. Conclusion External Artefacts
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Part II. Dependability 55
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Chapter 5. Verification and Validat
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6Security in Open Source Software A
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6.1. Memory Management Open Meta Me
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6.2. Hardware Virtualisation a fixe
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6.2. Hardware Virtualisation in a v
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6.2. Hardware Virtualisation Again,
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6.2. Hardware Virtualisation the fa
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Part III. openETCS Case Study 77
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Chapter 7. openETCS Meta Model far
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Chapter 7. openETCS Meta Model gEVC
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Chapter 7. openETCS Meta Model gEVC
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Chapter 7. openETCS Meta Model gMai
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Chapter 7. openETCS Meta Model Outp
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Chapter 7. openETCS Meta Model thei
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Chapter 7. openETCS Meta Model gSub
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Chapter 7. openETCS Meta Model The
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Chapter 10. openETCS Model Current
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Chapter 10. openETCS Model The purp
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Chapter 10. openETCS Model 10.3.3.
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Chapter 10. openETCS Model be expla
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Chapter 10. openETCS Model 10.4.4.
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11 openETCS Simulation Generally, a
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11.2. Platform Specific Model for t
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11.3. Simulation Model Figure 11.6.
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11.3. Simulation Model 11.3.2. CDMI
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11.3. Simulation Model sets the Boo
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11.3. Simulation Model Entering_Dri
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11.3. Simulation Model The states o
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11.3. Simulation Model Figure 11.13
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11.6. Conclusion about warnings, fa
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Chapter 12. Conclusion and Outlook
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Part IV. Appendix 241
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Appendix A. GOPPRR to MOF Transform
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Appendix B. openETCS Meta Model Con
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DopenETCS Domain Framework D.1. Dom
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D.2. Domain Framework Source Code 8
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D.3. Domain Framework Model 32 m_pT
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Appendix E. openETCS Generator 39 <
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Appendix E. openETCS Generator 200
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Appendix E. openETCS Generator 46 4
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FMetaEdit+ Generators F.1. GOPPRR X
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GopenETCS Unit Testing G.1. Unit Te
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Appendix H. openETCS Simulation 14
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Glossary ANTLR ANother Tool for Lan
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Glossary EVC An European Vital Comp
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Glossary OEM An original equipment
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Glossary XML The Extensible Markup
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Bibliography [12] “EN 50128 - Rai
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Bibliography [39] ——, ““Ope
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Bibliography [69] T. J. Parr and R.
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Index Artefact, 51 Automatic train
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Index Linux, 149 Memory management,
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