cleanup cancelation logic

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/muz/base/dl_context.cpp

@@ -230,8 +230,7 @@ namespace datalog {
         m_enable_bind_variables(true),
         m_last_status(OK),
         m_last_answer(m),
-        m_engine_type(LAST_ENGINE),
-        m_cancel(false) {
+        m_engine_type(LAST_ENGINE) {
         re.set_context(this);
         updt_params(pa);
     }
@@ -751,15 +750,16 @@ namespace datalog {
     }
 
 
+#if 0
     void context::cancel() {
         m_cancel = true;
         m_last_status = CANCELED;
         m_transf.cancel();
         if (m_engine) m_engine->cancel();
     }
+#endif
 
     void context::cleanup() {
-        m_cancel = false;
         m_last_status = OK;
         if (m_engine) m_engine->cleanup();
     }

src/muz/base/dl_context.h

@@ -487,11 +487,13 @@ namespace datalog {
         //
         // -----------------------------------
 
-        void cancel();
-        bool canceled() const { return m_cancel; }
+        bool canceled() {
+            if (m.limit().inc()) return true;
+            m_last_status = CANCELED;
+            return false;
+        }
 
         void cleanup();
-        void reset_cancel() { cleanup(); }
 
         /**
            \brief check if query 'q' is satisfied under asserted rules and background.

src/muz/base/hnf.cpp

@@ -74,7 +74,6 @@ class hnf::imp {
 
     ast_manager&          m;
     bool                  m_produce_proofs;
-    volatile bool         m_cancel;
     expr_ref_vector       m_todo;
     proof_ref_vector      m_proofs;
     expr_ref_vector       m_refs;
@@ -96,7 +95,6 @@ public:
     imp(ast_manager & m):
         m(m),
         m_produce_proofs(false),
-        m_cancel(false),
         m_todo(m),
         m_proofs(m),
         m_refs(m), 
@@ -156,7 +154,7 @@ public:
         m_todo.push_back(n);
         m_proofs.push_back(p);
         m_produce_proofs = p != 0;
-        while (!m_todo.empty() && !m_cancel) {
+        while (!m_todo.empty() && checkpoint()) {
             fml = m_todo.back();
             pr = m_proofs.back();
             m_todo.pop_back();
@@ -174,8 +172,8 @@ public:
               });
     }
 
-    void set_cancel(bool f) {
-        m_cancel = f;
+    bool checkpoint() {
+        return m.limit().inc();
     }
 
     void set_name(symbol const& n) {
@@ -192,7 +190,6 @@ public:
     }
 
     void reset() {
-        m_cancel = false;
         m_todo.reset();
         m_proofs.reset();
         m_refs.reset();
@@ -524,9 +521,6 @@ void hnf::operator()(expr * n, proof* p, expr_ref_vector & rs, proof_ref_vector&
           );
 }
 
-void hnf::set_cancel(bool f) {
-    m_imp->set_cancel(f);
-}
 
 void hnf::set_name(symbol const& n) {
     m_imp->set_name(n);

src/muz/base/hnf.h

@@ -43,9 +43,6 @@ class hnf {
                     proof_ref_vector& ps               // [OUT] proofs of rs
                     );
 
-    void cancel() { set_cancel(true); }
-    void reset_cancel() { set_cancel(false); }
-    void set_cancel(bool f);
     void set_name(symbol const& name);    
     void reset();
     func_decl_ref_vector const& get_fresh_predicates();