feat(api/ml): release runtime lock on some long-running functions

scripts/update_api.py

@@ -1328,6 +1328,13 @@ def mk_ml(ml_src_dir, ml_output_dir):
 
     mk_z3native_stubs_c(ml_src_dir, ml_output_dir)
 
+z3_long_funs = frozenset([
+    'Z3_solver_check',
+    'Z3_solver_check_assumptions',
+    'Z3_simplify',
+    'Z3_simplify_ex',
+    ])
+
 def mk_z3native_stubs_c(ml_src_dir, ml_output_dir): # C interface
     ml_wrapperf = os.path.join(ml_output_dir, 'z3native_stubs.c')
     ml_wrapper = open(ml_wrapperf, 'w')
@@ -1491,6 +1498,10 @@ def mk_z3native_stubs_c(ml_src_dir, ml_output_dir): # C interface
                 ml_wrapper.write('  assert(_iter == Val_emptylist);\n\n')
             i = i + 1
 
+        release_caml_gc= name in z3_long_funs
+        if release_caml_gc:
+            ml_wrapper.write('\n  caml_release_runtime_system();\n')
+
         ml_wrapper.write('\n  /* invoke Z3 function */\n  ')
         if result != VOID:
             ts = type2str(result)
@@ -1499,6 +1510,7 @@ def mk_z3native_stubs_c(ml_src_dir, ml_output_dir): # C interface
             else:
                 ml_wrapper.write('z3rv = ')
 
+
         # invoke procedure
         ml_wrapper.write('%s(' % name)
         i = 0
@@ -1516,6 +1528,9 @@ def mk_z3native_stubs_c(ml_src_dir, ml_output_dir): # C interface
             i = i + 1
         ml_wrapper.write(');\n')
 
+        if release_caml_gc:
+            ml_wrapper.write('\n  caml_acquire_runtime_system();\n')
+
         if have_context and name not in Unwrapped:
             ml_wrapper.write('  ec = Z3_get_error_code(ctx_p->ctx);\n')
             ml_wrapper.write('  if (ec != Z3_OK) {\n')

src/api/ml/META.in

@@ -1,7 +1,7 @@
 # META file for the "z3" package:
 version = "@VERSION@"
 description = "Z3 Theorem Prover (OCaml API)"
-requires = "num"
+requires = "num threads"
 archive(byte) = "z3ml.cma"
 archive(native) = "z3ml.cmxa"
 archive(byte,plugin) = "z3ml.cma"

src/api/ml/z3native_stubs.c.pre

@@ -11,6 +11,7 @@ extern "C" {
 #include <caml/alloc.h>
 #include <caml/fail.h>
 #include <caml/callback.h>
+#include <caml/threads.h>
 
 #ifdef Custom_tag
 #include <caml/custom.h>