From 86afbe06e0c5e93206de33c54e1924630ca19aeb Mon Sep 17 00:00:00 2001
From: kevin <kevin@larke.org>
Date: Wed, 19 Mar 2025 16:34:02 -0400
Subject: [PATCH] cwFlowTypes.h/cpp, cwFlowNet.cpp : Initial implementation of
 proc_t.modVarMapA[]. This functionality however is not yet enabled.

---
 cwFlowNet.cpp   | 10 ++++----
 cwFlowTypes.cpp | 62 +++++++++++++++++++++++++++++++++++++++++++++++++
 cwFlowTypes.h   |  9 +++++++
 3 files changed, 77 insertions(+), 4 deletions(-)

diff --git a/cwFlowNet.cpp b/cwFlowNet.cpp
index b384f5a..9e76a66 100644
--- a/cwFlowNet.cpp
+++ b/cwFlowNet.cpp
@@ -1337,10 +1337,12 @@ namespace cw
       if( max_vid != kInvalidId )
       {
         // create the variable map array
-        proc->varMapChN = max_chIdx + 1;
-        proc->varMapIdN = max_vid + 1;
-        proc->varMapN   = proc->varMapIdN * proc->varMapChN;
-        proc->varMapA   = mem::allocZ<variable_t*>( proc->varMapN );
+        proc->varMapChN    = max_chIdx + 1;
+        proc->varMapIdN    = max_vid + 1;
+        proc->varMapN      = proc->varMapIdN * proc->varMapChN;
+        proc->varMapA      = mem::allocZ<variable_t*>( proc->varMapN );
+        proc->modVarMapN   = proc->varMapN;
+        proc->modVarMapA   = mem::allocZ<variable_t*>( proc->modVarMapN );
 
         // assign each variable to a location in the map
         for(variable_t* var=proc->varL; var!=nullptr; var=var->var_link)
diff --git a/cwFlowTypes.cpp b/cwFlowTypes.cpp
index 5c31854..d17056a 100644
--- a/cwFlowTypes.cpp
+++ b/cwFlowTypes.cpp
@@ -157,6 +157,67 @@ namespace cw
     }
 
 
+    // Incr the var->modN value and put the var pointer in var->proc->modVarMapA[]
+    // where it will be picked up by a later call to _mod-var_map_dispatch().
+    // This function runs in a multi-thread context.
+    rc_t _mod_var_map_update( variable_t* var )
+    {
+      // if the var is in already modVarMapA[] then there is nothing to do
+      // (use acquire to prevent rd/wr from moving before this op)
+      if( var->modN.load(std::memory_order_acquire) > 0 )
+        return kOkRC;
+      
+      // reserve a slot in proc->modVarMapA[]
+      // (use acquire to prevent rd/wr from moving before this op)
+      if( var->proc->modVarMapFullCnt.fetch_add(1,std::memory_order_acquire) >= var->proc->modVarMapN )
+        return kBufTooSmallRC;
+
+      
+      // Get the next empty slot in proc->modVarMapA[]
+      // (use acquire to prevent rd/wr from moving before this op)
+      unsigned idx = var->proc->modVarMapHeadIdx.fetch_add(1,std::memory_order_acquire) % var->proc->modVarMapN;      
+
+      var->proc->modVarMapA[ idx ] = var;
+
+      // mark the var as in the list
+      var->modN.fetch_add(1,std::memory_order_release);
+
+      return kOkRC;
+    }
+
+    // Call proc->proc_desc->value() on every var in the proc->modVarMapA[].
+    // This function is called inside proc->proc_desc->exec().
+    rc_t _mod_var_map_dispatch( proc_t* proc, bool callback_fl )
+    {
+      // get the count of variables to be updated
+      unsigned n = proc->modVarMapFullCnt.load( std::memory_order_acquire );
+
+      if( n )
+      {
+        if( callback_fl )
+        {
+          for(unsigned i=0; i<n; ++i)
+          {
+            // get a pointer to the var that has been marked as modified
+            variable_t* var = proc->modVarMapA[ proc->modVarMapTailIdx ];
+
+            // callback to inform the proc that the var has changed
+            proc->class_desc->members->value( var->proc, var );
+
+            // mark this var as having been removed from the modVarMapA[]
+            var->modN.store(0,std::memory_order_relaxed );
+
+            // increment modVarMapA[]'s tail index
+            proc->modVarMapTailIdx = (proc->modVarMapTailIdx + 1) % proc->modVarMapN;        
+          }
+        }
+        
+        // decrement the count of elemnts in the modVarMapA[]
+        proc->modVarMapFullCnt.fetch_sub(n, std::memory_order_release );
+      }
+
+      return kOkRC;
+    }
     
     // 'argTypeFlag' is the type (tflag) of 'val'.
     template< typename T >    
@@ -950,6 +1011,7 @@ void cw::flow::proc_destroy( proc_t* proc )
       
   mem::release(proc->label);
   mem::release(proc->varMapA);
+  mem::release(proc->modVarMapA);
   mem::release(proc);
 }
 
diff --git a/cwFlowTypes.h b/cwFlowTypes.h
index 60f9ee6..36642f0 100644
--- a/cwFlowTypes.h
+++ b/cwFlowTypes.h
@@ -114,6 +114,9 @@ namespace cw
 
       ui_var_t*            ui_var;       // this variables UI description
       std::atomic<struct variable_str*> ui_var_link; // UI update var link based on flow_t ui_var_head;
+
+      std::atomic<unsigned> modN; // count of modifactions made to this variable during this cycl
+      
     } variable_t;
 
 
@@ -147,6 +150,12 @@ namespace cw
       unsigned        varMapN;       // varMapN = varMapIdN * varMapChN 
       variable_t**    varMapA;       // varMapA[ varMapN ] = allows fast lookup from ('vid','chIdx) to variable
 
+      variable_t**          modVarMapA;       // modVarMapA[ modVarMapN ]
+      unsigned              modVarMapN;       // modVarMapN == varMapN
+      unsigned              modVarMapTailIdx; // index of next full slot in varMapA[]
+      std::atomic<unsigned> modVarMapFullCnt; // count of elements in modVarMapA[]
+      std::atomic<unsigned> modVarMapHeadIdx; // index of next empty slot in varMapA[]
+
       // For 'poly' proc's 'internal_net' is a list linked by network_t.poly_link.
       struct network_str*  internal_net;
       unsigned             internal_net_cnt; // count of hetergenous networks contained in the internal_net linked list.