217 lines
8.9 KiB
Text
217 lines
8.9 KiB
Text
The DiVinE 2 model checker
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[http://web.archive.org/web/20120723095042/http://divine.fi.muni.cz/index.html]
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used to have a specification language called DVE, for modelling
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processes synchonizing through channels
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[http://web.archive.org/web/20120723095115/http://divine.fi.muni.cz/language.html].
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A lot of models can be found in the BEEM database at
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http://paradise.fi.muni.cz/beem/
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The LTSmin group [https://ltsmin.utwente.nl/] patched
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DiVinE and to compile models as dynamic libraries. This dynamic
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library provides a very simple C interface (no C++) and extra
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information about state variables (name, type, possible values).
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They also distribute SpinS, a compiler for PROMELA models generating
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dynamic libraries with the same interface.
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Spot uses this interface so you will need to install their version of
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these tools to use Spot with DVE or PROMELA models.
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The source code for our interface is in spot/ltsmin/ and generates a
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separate library, libspotltsmin.so, that has to be linked in addition
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to libspot.so. The current directory contains some testing code based
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on a toy modelchecker built upon the above interface: using it require
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an installation of DiVinE or SpinS (preferably both for testing
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purpose).
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Installation of DiVinE
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======================
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Use the following commands to compile and install the patched version
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of DiVinE.
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git clone https://gitlab.lrde.epita.fr/spot/divine-ltsmin-deb
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cd divine-ltsmin-deb
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mkdir _build && cd _build
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cmake .. -DMURPHI=OFF -DHOARD=OFF -DGUI=OFF -DRX_PATH= -DCMAKE_INSTALL_PREFIX=$HOME/usr
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make
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make install
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The CMAKE_INSTALL_PREFIX variable is the equivalent of the --prefix
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option of configure scripts. If you decide to install in $HOME/usr
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like I do, make sure that $HOME/usr/bin is in your PATH. If you omit
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the CMAKE_INSTALL_PREFIX setting, it will default to /usr/local.
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If you are using MacOS, you must add option -DHOARD=OF to the cmake
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command line in order to make it compile without errors. Also,
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DiVinE 2 only compiles with the GNU std C++ library; as a consequence,
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you must provide the option -DCMAKE_CXX_FLAGS="-stdlib=libstdc++" to
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the cmake command line.
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The above git repository is our own copy of the LTSmin fork of Divine,
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that we patched to generate Debian packages for amd64. If you use
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our Debian repository [https://spot.lrde.epita.fr/install.html#Debian]
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you can actually install this version of divine with just:
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apt-get install divine-ltsmin
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After installation, you can check that compilation works by running
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the following command on any DVE model. It should create a file
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model.dve2C (which is a dynamic library).
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divine compile --ltsmin model.dve
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Installation of SpinS
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======================
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The extended version of SpinJa is called SpinS and should be included
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with LTSmin. You can download LTSmin from their website
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[http://ltsmin.utwente.nl/] and install it following the INSTALL
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instructions.
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To compile a promela model, simply run the following command:
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spins model.pm
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It should create a dynamic library called model.pm.spins in the
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current directory.
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Usage with Spot
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===============
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The function load_dve2() defined in dve2.hh in this directory will
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accept either a model or its compiled version as file argument. In
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the former case, it will call "divine compile --ltsmin model.dve" or
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"spins model.pm" depending on the file extension, only if a compiled
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model with the corresponding file extension (.dve2C or .spins) does
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not exist or is older. Then it will load the compiled model
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dynamically.
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load_dve2() also requires a set of atomic propositions that should
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be observed in the model. These are usually the atomic propositions
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that occur in the formula to verify, but it might be a larger set.
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There are two kinds of atomic propositions, those that refer to the
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state of a process, and those that compare the value of a variable.
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Let's have some example on an excerpt of the beem-peterson.4.dve
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model included in this directory:
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byte pos[4];
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byte step[4];
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process P_0 {
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byte j=0, k=0;
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state NCS, CS, wait ,q2,q3;
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init NCS;
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trans
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NCS -> wait { effect j = 1; },
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wait -> q2 { guard j < 4; effect pos[0] = j;},
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q2 -> q3 { effect step[j-1] = 0, k = 0; },
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q3 -> q3 { guard k < 4 && (k == 0 || pos[k] < j); effect k = k+1;},
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q3 -> wait { guard step[j-1] != 0 || k == 4; effect j = j+1;},
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wait -> CS { guard j == 4; },
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CS -> NCS { effect pos[0] = 0;};
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}
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The following atomic propositions could be used in LTL formula:
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P_0.CS Process P_0 is in state CS.
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"pos[3] < 3" Global variable pos[3] is less than 3.
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"P_0.j >= 2" Process P_0's variable j is greater or equal to 2.
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P_0.j This is equivalent to "P_0.j != 0".
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Comparison operators available are "<", ">", ">=", "<=", "==", and
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"!=". The left operand should always be a variable and the right
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operand should always be a number, so you cannot write something
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like "P_0.j <= P_0.i".
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Because the LTL parser knows nothing about the details of the
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languages we interface with, every atomic proposition that cannot be
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expressed using only alphanumeric characters (plus `_' and `.')
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should be enclosed in double quote.
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Caveat: "P_0.j >= 2" and " P_0.j>=2" (watch the spaces!) are
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considered to be two distinct atomic propositions with the same
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semantics.
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Examples
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========
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Using the modelcheck program built into this directory, we can verify
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that the critical section is accessed infinitely often by some
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processes using:
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% ./modelcheck beem-peterson.4.dve '!GF(P_0.CS|P_1.CS|P_2.CS|P_3.CS)'
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2239039 unique states visited
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0 strongly connected components in search stack
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11449204 transitions explored
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1024245 items max in DFS search stack
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no accepting run found
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Process P_0 can starve, waiting to enter in critical section:
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% ./modelcheck beem-peterson.4.dve '!G(P_0.wait -> F P_0.CS)'
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2190 unique states visited
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34 strongly connected components in search stack
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4896 transitions explored
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83 items max in DFS search stack
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an accepting run exists (use -C to print it)
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Variable pos[1] is not always < 3 (this formula makes no sense, it
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is just to demonstrate the use of double quote).
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% ./modelcheck beem-peterson.4.dve '!G("pos[1] < 3")'
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130 unique states visited
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61 strongly connected components in search stack
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132 transitions explored
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130 items max in DFS search stack
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an accepting run exists (use -C to print it)
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Two state-compression techniques have been implemented as experiments.
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Prefer the -Z option if your model use only non-negative value less
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than 2^28, it is way faster than -z (which will work for all values).
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Activating state compression will often reduce runtime. Compare:
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% ./modelcheck -T beem-peterson.4.dve '!GF(P_0.CS|P_1.CS|P_2.CS|P_3.CS)'
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2239039 unique states visited
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0 strongly connected components in search stack
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11449204 transitions explored
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1024245 items max in DFS search stack
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122102 pages allocated for emptiness check
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no accepting run found
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| user time | sys. time | total |
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name | ticks % | ticks % | ticks % | n
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-------------------------------------------------------------------------------
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loading dve2 | 0 0.0 | 0 0.0 | 0 0.0 | 1
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parsing formula | 0 0.0 | 0 0.0 | 0 0.0 | 1
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reducing A_f w/ SCC | 0 0.0 | 0 0.0 | 0 0.0 | 1
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running emptiness chec | 1222 100.0 | 18 100.0 | 1240 100.0 | 1
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translating formula | 0 0.0 | 0 0.0 | 0 0.0 | 1
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-------------------------------------------------------------------------------
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TOTAL | 1222 100.0 | 18 100.0 | 1240 100.0 |
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% ./modelcheck -T -Z beem-peterson.4.dve '!GF(P_0.CS|P_1.CS|P_2.CS|P_3.CS)'
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2239039 unique states visited
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0 strongly connected components in search stack
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11449204 transitions explored
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1024245 items max in DFS search stack
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78580 pages allocated for emptiness check
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no accepting run found
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| user time | sys. time | total |
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name | ticks % | ticks % | ticks % | n
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-------------------------------------------------------------------------------
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loading dve2 | 0 0.0 | 0 0.0 | 0 0.0 | 1
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parsing formula | 0 0.0 | 0 0.0 | 0 0.0 | 1
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reducing A_f w/ SCC | 0 0.0 | 0 0.0 | 0 0.0 | 1
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running emptiness chec | 1051 100.0 | 10 100.0 | 1061 100.0 | 1
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translating formula | 0 0.0 | 0 0.0 | 0 0.0 | 1
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-------------------------------------------------------------------------------
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TOTAL | 1051 100.0 | 10 100.0 | 1061 100.0 |
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It's a 15% speedup in this case, be the improvement can be more
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important on larger models.
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