nodestack: limit the number of future values per read

Not tested very thoroughly, but it seems to limit the future values set
as intended.

diff --git a/nodestack.cc b/nodestack.cc
index 743cb864452589f615d937220fe9440bf8bad093..f73d4cf4a154e264ed93a32f250c6a0f6dfaa11a 100644 (file)
--- a/nodestack.cc
+++ b/nodestack.cc
@@ -192,8 +192,13 @@ bool Node::misc_empty() {
 
 
 /**
- * Adds a value from a weakly ordered future write to backtrack to.
+ * Adds a value from a weakly ordered future write to backtrack to. This
+ * operation may "fail" if the future value is already set (with a later
+ * expiration), or if the futurevalues set has reached its maximum.
+ * @see model_params.maxfuturevalues
+ *
  * @param value is the value to backtrack to.
+ * @return True if the future value was successully added; false otherwise
  */
 bool Node::add_future_value(uint64_t value, modelclock_t expiration) {
        int suitableindex=-1;
@@ -211,7 +216,12 @@ bool Node::add_future_value(uint64_t value, modelclock_t expiration) {
                future_values[suitableindex].expiration=expiration;
                return true;
        }
-       struct future_value newfv={value, expiration};
+
+       if (model->params.maxfuturevalues > 0 &&
+                       (int)future_values.size() >= model->params.maxfuturevalues)
+               return false;
+
+       struct future_value newfv = {value, expiration};
        future_values.push_back(newfv);
        return true;
 }