`mebos` works similarly as `flow`, but in contrast to `flow`, `mebos`
only creates the deck in the common code path whilst the
'EclipseState' and the other higher-level parser objects are always
created internally by the vanguard. this approach avoids code
duplication and the worst effects of parser API creep.
to avoid having to compile non-trivial compile units multiple times,
the actual code of the variants is moved into `ebos_$VARIANT.{hh,cc}`
files and the respective compile units are each put into a small
static library whilst the main function of said libraries are invoked
by either the multiplexed or the respective specialized simulator's
`main()`. This is also somewhat similar of how `flow` works, with the
difference that `mebos` uses the blackoil variant to determine the
parameters it needs to know for parsing the deck instead of
introducing a "fake" type tag for this. The rationale is to reduce
compile time compared to the "fake type tag" approach and -- to a
lesser extend -- avoid unnecessary copy-and-pasting of code. In
particular, this means that for the vast majority of cases, only one
place needs changed in the code for all `ebos` variants if, for
example, the parser API requires further objects in the future.
for some reason, this yields quite different results for norne than
the default variant, e.g. when comparing PRESSURE, we get
```
> compareECL -k PRESSURE -t UNRST ebos/NORNE_ATW2013 ebos_altidx/NORNE_ATW2013 1 1e-4
Comparing 'ebos/NORNE_ATW2013' to 'ebos_altidx/NORNE_ATW2013'.
Comparing PRESSURE...
Occurrence in first file = 9
Occurrence in second file = 9
Value index = 0
(first value, second value) = (254.195, 253.191)
Program threw an exception: [/home/and/src/opm-common/build-cmake/fake-src/examples/test_util/EclRegressionTest.cpp:161] Deviations exceed tolerances.
The absolute deviation is 1.00311, and the tolerance limit is 1.
The relative deviation is 0.00394624, and the tolerance limit is 0.0001.
```
IMO this is a bug, but the reasons for it are currently unknown.
this simply excludes the disabled simulators from `make all` while
`make flow` will continue to work even if the cmake variable
`BUILD_FLOW` was set to `OFF`. This requires a small patch for
opm-common.
these variants should cover most of the common use cases. That said,
there are no plans to provide simulators for combinations of blackoil
extensions or a "multiplexing" simulator like `flow`: If someone is
interested in e.g., an oil-water simulator with polymer and energy
enabled, a separate self-compiled executable should be added locally.
for some reason, libraries produced for a module are not linked to the
executables of the module by the default build system. so far this did
not matter for `ebos` but with this PR, it starts using stuff from
`libopmsimulators`...
so far, the actual specializations of the simulator were compiled into
the `libopmsimulators` library and the build of the glue code
(`flow.cpp`) thus needed to be deferred until the library was fully
built. Since the compilation of the glue code requires a full property
hierarchy for handling command line parameters, this arrangement
significantly increases the build time for systems with a sufficient
number of parallel build processes. ("sufficient" here means 8 or more
threads, i.e., a quadcore system with hyperthreading is sufficient
provided that it has enough main memory.)
the new approach is not to include these objects in
`libopmsimulators`, but to directly deal with them in the `flow`
binary. this allows all of them and the glue code to be compiled in
parallel.
compilation time on my machine before this change:
```
> touch ../opm/autodiff/BlackoilModelEbos.hpp; time make -j32 flow 2> /dev/null
Scanning dependencies of target opmsimulators
[ 2%] Building CXX object CMakeFiles/opmsimulators.dir/opm/simulators/flow_ebos_gasoil.cpp.o
[ 2%] Building CXX object CMakeFiles/opmsimulators.dir/opm/simulators/flow_ebos_oilwater.cpp.o
[ 2%] Building CXX object CMakeFiles/opmsimulators.dir/opm/simulators/flow_ebos_blackoil.cpp.o
[ 2%] Building CXX object CMakeFiles/opmsimulators.dir/opm/simulators/flow_ebos_solvent.cpp.o
[ 4%] Building CXX object CMakeFiles/opmsimulators.dir/opm/simulators/flow_ebos_polymer.cpp.o
[ 6%] Building CXX object CMakeFiles/opmsimulators.dir/opm/simulators/flow_ebos_energy.cpp.o
[ 6%] Building CXX object CMakeFiles/opmsimulators.dir/opm/simulators/flow_ebos_oilwater_polymer.cpp.o
[ 6%] Linking CXX static library lib/libopmsimulators.a
[ 97%] Built target opmsimulators
Scanning dependencies of target flow
[100%] Building CXX object CMakeFiles/flow.dir/examples/flow.cpp.o
[100%] Linking CXX executable bin/flow
[100%] Built target flow
real 1m45.692s
user 8m47.195s
sys 0m11.533s
```
after:
```
> touch ../opm/autodiff/BlackoilModelEbos.hpp; time make -j32 flow 2> /dev/null
[ 91%] Built target opmsimulators
Scanning dependencies of target flow
[ 93%] Building CXX object CMakeFiles/flow.dir/flow/flow.cpp.o
[ 95%] Building CXX object CMakeFiles/flow.dir/flow/flow_ebos_gasoil.cpp.o
[ 97%] Building CXX object CMakeFiles/flow.dir/flow/flow_ebos_oilwater_polymer.cpp.o
[100%] Building CXX object CMakeFiles/flow.dir/flow/flow_ebos_polymer.cpp.o
[100%] Building CXX object CMakeFiles/flow.dir/flow/flow_ebos_oilwater.cpp.o
[100%] Building CXX object CMakeFiles/flow.dir/flow/flow_ebos_solvent.cpp.o
[100%] Building CXX object CMakeFiles/flow.dir/flow/flow_ebos_blackoil.cpp.o
[100%] Building CXX object CMakeFiles/flow.dir/flow/flow_ebos_energy.cpp.o
[100%] Linking CXX executable bin/flow
[100%] Built target flow
real 1m21.597s
user 8m49.476s
sys 0m10.973s
```
(this corresponds to a ~20% reduction of the time spend on waiting for
the compiler.)
