[issue1076] Replace OSI with our own interface to LP/MIP solvers

For LP/MIP users: so far, we used the open solver interface OSI to communicate
with MIP and LP solvers. We now replaced this with our own interface to have
more direct control and fewer external dependencies. We now support CPLEX
22.11 and SoPlex from their current main branch (released versions <= 6.0.3 are
incompatible with C++-20). We dropped command line options for CLP and Gurobi
in the process: CLP has much worse performance than SoPlex which is also open
source, while Gurobi was never practically possible to compile with, as we did
not have a CMake find script for it. Performance with CPLEX increased in MIP
configurations and stayed roughly the same in LP configurations. Performance
with SoPlex increased for potential heuristics and decreased slightly in other
configurations.

src/cmake_modules/FindCplex.cmake

@@ -136,44 +136,46 @@ find_library(CPLEX_LIBRARY_DEBUG
     ${CPLEX_LIBRARY_PATH_SUFFIX_DEBUG}
 )
 
-# Parse CPLEX version.
-file(STRINGS ${CPLEX_INCLUDE_DIRS}/cpxconst.h CPLEX_VERSION_STR
-     REGEX "#define[ ]+CPX_VERSION[ ]+[0-9]+")
-string(REGEX MATCH "[0-9]+" CPLEX_VERSION_STR ${CPLEX_VERSION_STR})
-if(CPLEX_VERSION_STR)
-  math(EXPR CPLEX_VERSION_MAJOR "${CPLEX_VERSION_STR} / 1000000")
-  math(EXPR CPLEX_VERSION_MINOR "${CPLEX_VERSION_STR} / 10000 % 100")
-  math(EXPR CPLEX_VERSION_SUBMINOR "${CPLEX_VERSION_STR} / 100 % 100")
-  set(CPLEX_VERSION
-      "${CPLEX_VERSION_MAJOR}.${CPLEX_VERSION_MINOR}.${CPLEX_VERSION_SUBMINOR}")
-endif()
+if(CPLEX_INCLUDE_DIRS)
+    # Parse CPLEX version.
+    file(STRINGS ${CPLEX_INCLUDE_DIRS}/cpxconst.h CPLEX_VERSION_STR
+         REGEX "#define[ ]+CPX_VERSION[ ]+[0-9]+")
+    string(REGEX MATCH "[0-9]+" CPLEX_VERSION_STR ${CPLEX_VERSION_STR})
+    if(CPLEX_VERSION_STR)
+      math(EXPR CPLEX_VERSION_MAJOR "${CPLEX_VERSION_STR} / 1000000")
+      math(EXPR CPLEX_VERSION_MINOR "${CPLEX_VERSION_STR} / 10000 % 100")
+      math(EXPR CPLEX_VERSION_SUBMINOR "${CPLEX_VERSION_STR} / 100 % 100")
+      set(CPLEX_VERSION
+          "${CPLEX_VERSION_MAJOR}.${CPLEX_VERSION_MINOR}.${CPLEX_VERSION_SUBMINOR}")
+    endif()
+
+    if(CPLEX_LIBRARY_RELEASE OR CPLEX_LIBRARY_DEBUG)
+        find_package(Threads REQUIRED)
 
-if(CPLEX_LIBRARY_RELEASE OR CPLEX_LIBRARY_DEBUG)
-    find_package(Threads REQUIRED)
+        set(CPLEX_LIBRARIES_COMMON ${CMAKE_THREAD_LIBS_INIT})
+        if(NOT (${CPLEX_VERSION} VERSION_LESS "12.8"))
+            set(CPLEX_LIBRARIES_COMMON ${CPLEX_LIBRARIES_COMMON} ${CMAKE_DL_LIBS})
+        endif()
 
-    set(CPLEX_LIBRARIES_COMMON ${CMAKE_THREAD_LIBS_INIT})
-    if(NOT (${CPLEX_VERSION} VERSION_LESS "12.8"))
-        set(CPLEX_LIBRARIES_COMMON ${CPLEX_LIBRARIES_COMMON} ${CMAKE_DL_LIBS})
+        set(CPLEX_LIBRARIES
+            optimized ${CPLEX_LIBRARY_RELEASE} ${CPLEX_LIBRARIES_COMMON}
+            debug ${CPLEX_LIBRARY_DEBUG} ${CPLEX_LIBRARIES_COMMON}
+        )
     endif()
 
-    set(CPLEX_LIBRARIES
-        optimized ${CPLEX_LIBRARY_RELEASE} ${CPLEX_LIBRARIES_COMMON}
-        debug ${CPLEX_LIBRARY_DEBUG} ${CPLEX_LIBRARIES_COMMON}
+    # HACK: there must be a better way to find the dll file.
+    find_path(CPLEX_RUNTIME_LIBRARY_PATH
+        NAMES
+        cplex1262.dll
+        HINTS
+        ${CPLEX_HINT_PATHS_RELEASE}
+        ${CPLEX_HINT_PATHS_DEBUG}
+        PATH_SUFFIXES
+        ${CPLEX_RUNTIME_LIBRARY_HINT}
     )
-endif()
-
-# HACK: there must be a better way to find the dll file.
-find_path(CPLEX_RUNTIME_LIBRARY_PATH
-    NAMES
-    cplex1262.dll
-    HINTS
-    ${CPLEX_HINT_PATHS_RELEASE}
-    ${CPLEX_HINT_PATHS_DEBUG}
-    PATH_SUFFIXES
-    ${CPLEX_RUNTIME_LIBRARY_HINT}
-)
-if(CPLEX_RUNTIME_LIBRARY_PATH)
-    set(CPLEX_RUNTIME_LIBRARY "${CPLEX_RUNTIME_LIBRARY_PATH}/cplex1262.dll")
+    if(CPLEX_RUNTIME_LIBRARY_PATH)
+        set(CPLEX_RUNTIME_LIBRARY "${CPLEX_RUNTIME_LIBRARY_PATH}/cplex1262.dll")
+    endif()
 endif()
 
 # Check if everything was found and set CPLEX_FOUND.

src/cmake_modules/FindSoplex.cmake → src/cmake_modules/FindSoPlex.cmake

@@ -68,7 +68,7 @@ endif()
 # Check if everything was found and set SOPLEX_FOUND.
 include(FindPackageHandleStandardArgs)
 find_package_handle_standard_args(
-    soplex
+    SoPlex
     REQUIRED_VARS SOPLEX_INCLUDE_DIRS SOPLEX_LIBRARIES
 )
 

src/search/CMakeLists.txt

@@ -57,41 +57,45 @@ option(
   TRUE)
 
 if(PLUGIN_LP_SOLVER_ENABLED AND USE_LP)
-    find_package(OSI OPTIONAL_COMPONENTS Cpx Clp Grb Spx)
-    if(OSI_FOUND AND (OSI_Cpx_FOUND OR OSI_Clp_FOUND OR OSI_Grb_FOUND OR OSI_Spx_FOUND))
-        if(USE_GLIBCXX_DEBUG)
-            message(
-                FATAL_ERROR
-                "To prevent incompatibilities, the option USE_GLIBCXX_DEBUG is "
-                "not supported when an LP solver is used. See issue982 for details.")
+    add_definitions("-D USE_LP")
+
+    find_package(Cplex)
+    if(CPLEX_FOUND)
+        add_definitions("-D HAS_CPLEX")
+        include_directories(${CPLEX_INCLUDE_DIRS})
+        target_link_libraries(downward ${CPLEX_LIBRARIES})
+        if(CPLEX_RUNTIME_LIBRARY)
+            add_custom_command(TARGET downward POST_BUILD
+                COMMAND ${CMAKE_COMMAND} -E copy
+                ${CPLEX_RUNTIME_LIBRARY}
+                $<TARGET_FILE_DIR:downward>
+            )
         endif()
-        foreach(SOLVER Cpx Clp Grb Spx)
-            if(OSI_${SOLVER}_FOUND)
-                string(TOUPPER ${SOLVER} TMP_SOLVER_UPPER_CASE)
-                mark_as_advanced(TMP_SOLVER_UPPER_CASE)
-                add_definitions("-D COIN_HAS_${TMP_SOLVER_UPPER_CASE}")
-                include_directories(${OSI_${SOLVER}_INCLUDE_DIRS})
-                target_link_libraries(downward ${OSI_${SOLVER}_LIBRARIES})
-            endif()
-        endforeach()
-
-        # Note that basic OSI libs must be added after (!) all OSI solver libs.
-        add_definitions("-D USE_LP")
-        include_directories(${OSI_INCLUDE_DIRS})
-        target_link_libraries(downward ${OSI_LIBRARIES})
+    endif()
 
+    find_package(SoPlex)
+    if (SOPLEX_FOUND)
+        add_definitions("-D HAS_SOPLEX")
+        include_directories(${SOPLEX_INCLUDE_DIRS})
+        target_link_libraries(downward ${SOPLEX_LIBRARIES})
         find_package(ZLIB REQUIRED)
         if(ZLIB_FOUND)
             include_directories(${ZLIB_INCLUDE_DIRS})
             target_link_libraries(downward ${ZLIB_LIBRARIES})
         endif()
+        find_library(GMP_LIBRARY gmp REQUIRED)
+        if(GMP_LIBRARY)
+            target_link_libraries(downward ${GMP_LIBRARY})
+        endif()
     endif()
 
-    if(OSI_Cpx_FOUND AND CPLEX_RUNTIME_LIBRARY)
-        add_custom_command(TARGET downward POST_BUILD
-            COMMAND ${CMAKE_COMMAND} -E copy
-            ${CPLEX_RUNTIME_LIBRARY}
-            $<TARGET_FILE_DIR:downward>
-        )
+    if(CPLEX_FOUND OR SOPLEX_FOUND)
+        if(USE_GLIBCXX_DEBUG)
+            message(
+                FATAL_ERROR
+                "To prevent incompatibilities, the option USE_GLIBCXX_DEBUG is "
+                "not supported when an LP solver is used. See issue982 for details.")
+        endif()
     endif()
+
 endif()

src/search/DownwardFiles.cmake

@@ -476,8 +476,11 @@ fast_downward_plugin(
     NAME LP_SOLVER
     HELP "Interface to an LP solver"
     SOURCES
+        lp/cplex_solver_interface
         lp/lp_internals
         lp/lp_solver
+        lp/solver_interface
+        lp/soplex_solver_interface
     DEPENDS NAMED_VECTOR
     DEPENDENCY_ONLY
 )