Global variables
This article is about planned development or proposed functionality. Comments welcome.
We would like to get rid of the current use of global variables in ASCEND, so that we can start to think about using ASCEND in multithreaded and/or embedded ways. This page will report any cases of global variables that we have found, and perhaps some discussion about how we can best eliminate them. Not all cases will be the same.
Ways for removing global variables
A number of options exist:
- keeping them. This is appropriate in a very limited set of situations, such as for data that has been loaded from a configuration file when the program started.
- groupin them into a top-level data structure. We imagine structures like "library", "simulation" and "system" could be created that could hold most global variables.
- passing them. Where global variables have been used as a convenience to avoid having to expand function parameter lists, we can just change to passing them as parameters.
- converting them to #defines. May be appropriate for certain constants.
- converting them to thread-local variables (may need to assess implication for embedded applications)
- adding mutex constraints (so that they can only be accessed once at a time)
- migrating them to another code layer, eg into the GUI (this has already been done in some cases)
Global variables in libascend.so
The main place where global variables are a problem for ASCEND is in libascend, our core library include the ASCEND parser/compiler and evaluation routines, but hopefully excluding the solvers.
Below is a list of globals generated using GNU nm.
john@thunder:~/ascend$ nm libascend.so | grep -i " [DdGgSsBb] " 001828a0 b AllowedContents 00926420 b BracesNestLevel 0092889c b CmpEv 0092641c b CommentNestLevel 00180be0 d DimNames 00927ac8 b EvaluatingSets 00926548 b FundamentalTypeList 00928528 b GlobalUniversalTable 00927c14 b InterfaceNotify 00927c0c b InterfacePtrATS 00927c10 b InterfacePtrDelete 00928790 b L.6247 0092879c b L.6717 0092bca0 b LibraryHashTable 00927ac4 b ListMode 00926424 b MatchedBackslash 00927a64 b MinusOne 00927a84 b One 001820c0 b RecycledContents 001818e0 b RecycledList 00926428 b RequireIndex 00926460 b RequireStack 009286e0 B Solv_C_CheckHalt_Flag 00927aa4 b Three 00927a94 b Two 001816a0 d VpTable 009300dc b X 00927a74 b Zero 0017fcc0 d __CTOR_END__ 0017fcbc d __CTOR_LIST__ 0017fcc8 d __DTOR_END__ 0017fcc4 d __DTOR_LIST__ 0017fccc d __JCR_END__ 0017fccc d __JCR_LIST__ 00180a20 d __dso_handle 00181811 d blockend 001817fc d blockmagic 001814fc D calc_ok 00181500 d calc_print_errors 00928338 b cap.11161 009286d8 b cap.7377 00181520 d commands 001818a0 b completed.6625 009300e0 b conopt_fptrs 00927a54 b constants_inited 001817d0 d csdata 00183088 b dcps.2434 00926488 b default_library_path.7912 0092648c b default_solvers_path.7911 0018167c d defaultintegrators.6720 00927a60 b deriv_store.5961 00926564 b done.4160 00183090 b dref.2433 00927c80 b ds.3670 00927d60 b ds.4078 00928540 b ds.4252 00928060 b ds.4837 00928140 b ds.5578 001818a4 b dtor_idx.6627 009287c8 b elt.4095 009287cc b elt.4148 00926430 b errcount.6732 009263a4 b errcount.8155 00181670 d errname.6760 00928384 b error_statement_sym.4928 00928800 b exception_buffer 009287e0 b exception_status 00180a24 d f_first 00180a28 d f_fpe_top_of_stack 00926364 b f_fpe_traps 00180a2c d f_int_top_of_stack 00926368 b f_int_traps 001830e0 b f_mem_rec 001830c8 b f_memory_allocated 001830c4 b f_memory_length 001830c0 b f_memory_log_file 009242e0 b f_panic_callback_func 001830cc b f_peak_memory_usage 00180a30 d f_seg_top_of_stack 0092636c b f_seg_traps 00925300 b g_Asc_printVtables 00927acc b g_DeclarativeContext 00181320 d g_DefinitionErrorMessages 00927abc b g_EvaluationContext 00927ac0 b g_EvaluationForTable 00927ab8 b g_ExtVariablesTable 00927ab4 b g_ExternalFuncLibrary 00928018 b g_ExternalNodeStamps 00180e60 d g_abs_f 001812b0 D g_alt_ending 00926490 b g_ammarking 00180f20 d g_arccos_f 001810a0 d g_arccosh_f 00180ee0 d g_arcsin_f 00181060 d g_arcsinh_f 00180f60 d g_arctan_f 001810e0 d g_arctanh_f 00926494 b g_array_child_pool 00928444 b g_array_desc_count 00928448 b g_array_desc_list 0018309c b g_ascend_dllist 009264c0 b g_atom_bytes 009263b0 b g_atom_dim_ptr 0092bc50 b g_b_inst 0018187c d g_ba_elimdata 0092bc6c b g_ba_inst 0092863c b g_bad_rel_in_list 0092bc7c b g_bc_inst 00928434 b g_big_strings 00928438 b g_big_strings_cnt 00928640 b g_blockmethod 00180a60 d g_bt_data 00926398 b g_callargs 0092864c b g_case_number 00928030 b g_cbbccount 0092802c b g_cbbdcount 00181160 d g_cbrt_f 001812ec D g_check_dimensions_noisy 00926514 b g_clique_list 00181208 D g_compiler_counter 00928360 B g_compiler_timing 00180a34 D g_compiler_warnings 0092649c b g_cons 009263a0 b g_constant_type 009279d4 b g_copy_numnodes 00180d60 d g_cos_f 00180fe0 d g_cosh_f 00181120 d g_cube_f 00927f54 b g_current_module 0092bc48 b g_cursim 00926544 b g_def_child_bit_list 00926540 b g_def_child_desc_ptr 0092653c b g_def_child_list_ptr 009263b4 b g_default_dim_ptr 009263b8 b g_default_double 009263c0 b g_default_long 00928b4c b g_default_symbol 009263a8 b g_defaulted 00926534 b g_diagf 009263ac b g_dim_ptr 0092ac38 B g_dimen_list 0092ac30 b g_dimensionless 009286b4 b g_dis_tag 009284c0 b g_drt_depth 00927c28 b g_dummy_type 0092ac40 b g_dump_ht 0092bc40 b g_dump_inst_count 0092bc44 b g_dump_type_count 00926384 b g_end_identifier 001830a0 b g_env_list 00925340 b g_error_reporter_cache 00925328 b g_error_reporter_callback 00925320 b g_error_reporter_tree 00925324 b g_error_reporter_tree_current 00180c20 d g_exp_f 00927a50 b g_exprs_pool 00927c34 b g_externalmodel_type 009264fc b g_extra_parents 00926500 b g_extra_parents_sum 009264f8 b g_extra_paths 009288a0 b g_foreign_code_call_env 00927ad0 b g_forvar_recycle_list 00927ad4 b g_forvarfile 009289e0 B g_fpe_env 00927ad8 b g_free_store 001811a0 d g_func_list 00926370 b g_header_linenum 00180ea0 d g_hold_f 0092bc5c b g_i_inst 0092bc74 b g_ia_inst 0092bc60 b g_ic_inst 0017fce0 d g_instancetypenames 0018120c d g_instantiate_relns 00928a80 B g_int_env 001814f8 d g_iscomplete 0092844c b g_it_dummy_enum 00181310 d g_it_dummy_int 00927c00 b g_iteration 009284a8 b g_lcl_head 009284b8 b g_lcl_length 009284b4 b g_lcl_pivot 009284b0 b g_lcl_recycle 009284ac b g_lcl_tail 009284bc b g_lclrecycle_length 00181740 D g_linsolqr_timing 001818c0 b g_list_head_pool 00180c60 d g_ln_f 00180c08 D g_lnm_epsilon 00180ca0 d g_lnm_f 00180ce0 d g_log10_f 00927e40 b g_log_shortbuf 00927d54 b g_logrel_stack 00927c24 b g_logrel_type 00927f44 b g_logrelation_bvar_list 00927f48 b g_logrelation_satrel_list 00927f50 b g_logterm_pool 00181288 d g_logterm_ptrs 00927e34 b g_logwritfp 0092bc54 b g_lrel_inst 0092650c b g_maximum_children 009264f4 b g_maximum_parents 00926520 b g_maximum_relations 00926508 b g_minimum_children 009264f0 b g_minimum_parents 0092651c b g_minimum_relations 00926560 b g_missing 0092bc88 b g_mod_inst 009264b8 b g_model_bytes 00928000 b g_model_definition_methods 00926388 b g_model_parameters 00927f5c b g_module_list 00181220 d g_mpi_message 009287c4 b g_mtx_debug_redirect 0018185c d g_mtx_null_col_vector_data 0018181c d g_mtx_null_index_data 0018183c d g_mtx_null_mark_data 0018186c d g_mtx_null_row_vector_data 0018182c d g_mtx_null_sum_data 0018184c d g_mtx_null_vector_data 009301b4 b g_mtxerr 00927f6c b g_name_pool 009279e0 b g_names_needed 00927a58 b g_new_var_list 0092639c b g_notelist 00927f70 b g_notes_data_base 009264e8 b g_num_array_instances 009264dc b g_num_atom_children 009264bc b g_num_atom_instances 009264b0 b g_num_complex_instances 009264d8 b g_num_constant_all 009264cc b g_num_constant_bool 009264d0 b g_num_constant_int 009264c8 b g_num_constant_real 009264d4 b g_num_constant_sym 009264b4 b g_num_model_instances 00927f64 b g_num_names_cur 00927f68 b g_num_names_max 009264e0 b g_num_relation_instances 009264ec b g_num_unsel_instances 009284a4 b g_number 00927f90 b g_numlist_head_pool 00924300 b g_panic_outfile 00926390 b g_parameter_reduction 0092638c b g_parameter_wheres 0018130c d g_parse_count 00180a38 d g_parse_relns 009284c4 B g_parser_warnings 00927f9c b g_pending_count 00927fa0 b g_pending_list 00927fa4 b g_pending_list_end 00927fa8 b g_pending_pool 0092cca0 B g_plot_type 00927f94 b g_ppe_pool 001811fc d g_proc 00926378 b g_proc_name 00928004 b g_procframe_stop 00928008 b g_proto_count 0092ccc0 b g_proto_ht 0092bc94 b g_r_inst 0092bc78 b g_ra_inst 0092bc64 b g_rc_inst 00927a00 b g_recycle_expreval_stacks 00927f84 b g_recycled_npl 00926380 b g_refines_name 0092bc84 b g_rel_inst 00928040 b g_rel_stack 00928044 b g_rel_stack_pool 009264e4 b g_relation_guts 0092652c b g_relation_terms 00927c20 b g_relation_type 00928014 b g_relation_var_list 00928010 B g_relative_inst 00928618 b g_reuse 009286c4 b g_reuse 0092bc58 b g_s_inst 0092bc80 b g_sa_inst 0092bc90 b g_sc_inst 0092800c B g_search_inst 00928940 B g_seg_env 00928354 b g_set_pool 00927c30 b g_set_type 00928358 b g_sets_pool 00928220 b g_shortbuf 001812f4 d g_show_statement_detail 00927f4c b g_simplify_logrelations 001812cc D g_simplify_relations 0092835c B g_simulation_list 00180d20 d g_sin_f 00180fa0 d g_sinh_f 00927f60 b g_sldestroy 0092877c b g_solver_binary_type 009286c0 b g_solver_dis_type 00928778 b g_solver_int_type 00928780 b g_solver_semi_type 00928774 b g_solver_var_type 00180de0 d g_sqr_f 00180e20 d g_sqrt_f 00928414 b g_statio_flowtypenames 001812f8 d g_statio_label 009283a0 b g_statio_stattypenames 00928380 b g_statio_suppressions 00927b00 b g_string_buffer 00927f58 b g_string_modules_processed 00928428 b g_string_space 00927fc0 b g_strings 00928624 b g_strings 009286b8 b g_strings 009286d0 b g_strings 009286d4 b g_strings 00928758 b g_strings 00926498 b g_suppressions 0092bc8c b g_sym_inst 0092bc4c b g_syma_inst 00928430 b g_symbol_collisions 0092842c b g_symbol_size 0092dcc0 b g_symbol_table 00928614 b g_symbol_values_list 00927c40 b g_symbols 00928460 b g_symbols 009287ac b g_symbols 0092bc68 b g_symc_inst 00180da0 d g_tan_f 00181020 d g_tanh_f 0092843c b g_temporary_var_list 00928440 b g_temporary_var_recycle 0092801c b g_term_pool 001812d0 d g_term_ptrs 009284c8 b g_tlibs_depth 0092ab80 b g_token_counts 00926530 b g_total_array_children 00926510 b g_total_children 00926504 b g_total_parents 00926528 b g_total_reals_in_rels 00926524 b g_total_relations 00926518 b g_total_variables 009264c4 b g_tree_bytes 0092ac34 b g_trig_dimen 00927c04 b g_trychildexpansion_errmessage 009264ac b g_type_count_list 0092637c b g_type_name 00926394 b g_typeargs 00927c08 b g_unasscon_count 00928500 b g_unit_base_name 009284f0 b g_unit_explain_error_strings 00927adc b g_units_alloc 009284ec b g_units_collisions 001814c0 d g_units_errors.4640 0092f0e0 B g_units_hash_table 0092ecc0 b g_units_id_space 009263c4 b g_units_ptr 009284e8 b g_units_size 009284e0 b g_units_str 009284e4 b g_units_str_len 00927f98 b g_unresolved_count 00926374 b g_untrapped_error 00181204 D g_use_copyanon 0092852c b g_value_pool 00928754 b g_var_tag 0092bc70 b g_when_inst 00927c2c b g_when_type 0092ac3c b g_wild_dimen 0092642c b g_workbuf 00180a44 d g_workbuf_len.6555 00928214 b g_writfp 00928348 b glob_done 00927f40 b glob_lrel 00928340 b glob_rel 00928344 b glob_varnum 009279d0 b global_command_list 00928530 b global_visit_num 009287bc b hhrowlist.6528 00183074 b i.2578 00926354 b i.2755 00927ae0 b importhandler_library 00927ae4 b importhandler_sharedpointers 00926538 b init.5484 00928794 b init.6246 009287a0 b init.6716 0092878c b inst 009287c0 b last_value_matrix 00928798 b lastsolver.6445 00928330 b lhscap.9848 009287b8 b listlen.6529 00928784 b loaded.3887 00180ba0 d metadata.4158 001817e0 d mtxmagic 00928700 b name.6123 00928660 b name.6164 00181744 d names.4315 00181760 d names.4320 0018307c b newsize.2576 0092635c b newsize.2753 00181504 d nextid.6241 001812c8 d nostr.4857 00181688 d nrels.7185 0018168c d nrels.7199 009286fc b nuldev.5971 00181690 d nvars.7213 00183080 b oldsize.2575 00926360 b oldsize.2752 001817f2 d permmagic 00928648 b poly.3808 00928350 b poly.3924 00928644 b poly_cap.3809 0092834c b poly_cap.3925 00927a5c b previous_store.5962 0092833c b ptr.11160 009286dc b ptr.7376 00183078 b punt.2577 00926358 b punt.2754 00183098 b ref.2432 00928334 b rel.9847 009287a4 b reported_already.8633 009287a8 b reported_already.8653 00926580 b result.4159 009286e4 b rfilter.7742 0092832c b rhscap.9849 001817c0 d rsdata 001812f0 d safe_print_errors 0017fda0 d slv_reg 00928320 b soln_list.9691 00926418 b start_line 00928534 b stopnum.3912 00181508 d suppress_rel_flag.6780 00928788 b sys 001812a4 d unk.4785 00925304 b use_xterm_color.2533 009286ec b vfilter.7802 009286f4 b vfilter.7892 00928020 b warnexpt.5603 00928028 b warnexpt.5731 00928024 b warnfdiff.5732 009263f4 b yy_buffer_stack 009263f0 b yy_buffer_stack_max 009263ec b yy_buffer_stack_top 009263f8 b yy_c_buf_p 0092643c b yy_did_buffer_switch_on_eof 00926448 b yy_full_lp 00926440 b yy_full_match 0092644c b yy_full_state 00926434 b yy_hold_char 009263fc b yy_init 00180a40 d yy_line 0092640c b yy_looking_for_trail_begin 00926444 b yy_lp 00926410 b yy_more_offset 00926438 b yy_n_chars 00926414 b yy_prev_more_offset 00926400 b yy_start 00926404 b yy_state_buf 00926408 b yy_state_ptr 0092ab64 b yytext_ptr 009263e8 b zz__flex_debug 00928b50 b zz_char 009263e0 b zz_in 0092ab60 b zz_leng 00180a3c d zz_lineno 00928b20 b zz_lval 00928b54 b zz_nerrs 009263e4 b zz_out 00928b60 b zz_text john@thunder:~/ascend$
Static variables
Another place where quasi-global variables can occur is as static variables within functions. It needs to be assessed whether the above listing includes those types of variables.