CustomIntegrator avoids extra force computations when UpdateContextState doesn't change them

openmmapi/include/openmm/internal/AndersenThermostatImpl.h

@@ -52,7 +52,7 @@ public:
     const AndersenThermostat& getOwner() const {
         return owner;
     }
-    void updateContextState(ContextImpl& context);
+    void updateContextState(ContextImpl& context, bool& forcesInvalid);
     double calcForcesAndEnergy(ContextImpl& context, bool includeForces, bool includeEnergy, int groups) {
         // This force doesn't apply forces to particles.
         return 0.0;

openmmapi/include/openmm/internal/CMAPTorsionForceImpl.h

@@ -52,7 +52,7 @@ public:
     const CMAPTorsionForce& getOwner() const {
         return owner;
     }
-    void updateContextState(ContextImpl& context) {
+    void updateContextState(ContextImpl& context, bool& forcesInvalid) {
         // This force field doesn't update the state directly.
     }
     double calcForcesAndEnergy(ContextImpl& context, bool includeForces, bool includeEnergy, int groups);

openmmapi/include/openmm/internal/CMMotionRemoverImpl.h

@@ -49,7 +49,7 @@ public:
     const CMMotionRemover& getOwner() const {
         return owner;
     }
-    void updateContextState(ContextImpl& context);
+    void updateContextState(ContextImpl& context, bool& forcesInvalid);
     double calcForcesAndEnergy(ContextImpl& context, bool includeForces, bool includeEnergy, int groups) {
         // This force doesn't apply forces to particles.
         return 0.0;

openmmapi/include/openmm/internal/ContextImpl.h

@@ -210,8 +210,11 @@ public:
     /**
      * This should be called at the start of each time step.  It calls updateContextState() on each
      * ForceImpl in the system, allowing them to modify the values of state variables.
+     * 
+     * @return true if the state was modified in any way that would cause the forces on particles
+     * to change, false otherwise
      */
-    void updateContextState();
+    bool updateContextState();
     /**
      * Get the list of ForceImpls belonging to this ContextImpl.
      */

openmmapi/include/openmm/internal/CustomAngleForceImpl.h

@@ -53,7 +53,7 @@ public:
     const CustomAngleForce& getOwner() const {
         return owner;
     }
-    void updateContextState(ContextImpl& context) {
+    void updateContextState(ContextImpl& context, bool& forcesInvalid) {
         // This force field doesn't update the state directly.
     }
     double calcForcesAndEnergy(ContextImpl& context, bool includeForces, bool includeEnergy, int groups);

openmmapi/include/openmm/internal/CustomBondForceImpl.h

@@ -53,7 +53,7 @@ public:
     const CustomBondForce& getOwner() const {
         return owner;
     }
-    void updateContextState(ContextImpl& context) {
+    void updateContextState(ContextImpl& context, bool& forcesInvalid) {
         // This force field doesn't update the state directly.
     }
     double calcForcesAndEnergy(ContextImpl& context, bool includeForces, bool includeEnergy, int groups);

openmmapi/include/openmm/internal/CustomCVForceImpl.h

@@ -56,7 +56,7 @@ public:
     const CustomCVForce& getOwner() const {
         return owner;
     }
-    void updateContextState(ContextImpl& context) {
+    void updateContextState(ContextImpl& context, bool& forcesInvalid) {
         // This force field doesn't update the state directly.
     }
     double calcForcesAndEnergy(ContextImpl& context, bool includeForces, bool includeEnergy, int groups);

openmmapi/include/openmm/internal/CustomCentroidBondForceImpl.h

@@ -58,7 +58,7 @@ public:
     const CustomCentroidBondForce& getOwner() const {
         return owner;
     }
-    void updateContextState(ContextImpl& context) {
+    void updateContextState(ContextImpl& context, bool& forcesInvalid) {
         // This force field doesn't update the state directly.
     }
     double calcForcesAndEnergy(ContextImpl& context, bool includeForces, bool includeEnergy, int groups);

openmmapi/include/openmm/internal/CustomCompoundBondForceImpl.h

@@ -57,7 +57,7 @@ public:
     const CustomCompoundBondForce& getOwner() const {
         return owner;
     }
-    void updateContextState(ContextImpl& context) {
+    void updateContextState(ContextImpl& context, bool& forcesInvalid) {
         // This force field doesn't update the state directly.
     }
     double calcForcesAndEnergy(ContextImpl& context, bool includeForces, bool includeEnergy, int groups);

openmmapi/include/openmm/internal/CustomExternalForceImpl.h

@@ -53,7 +53,7 @@ public:
     const CustomExternalForce& getOwner() const {
         return owner;
     }
-    void updateContextState(ContextImpl& context) {
+    void updateContextState(ContextImpl& context, bool& forcesInvalid) {
         // This force field doesn't update the state directly.
     }
     double calcForcesAndEnergy(ContextImpl& context, bool includeForces, bool includeEnergy, int groups);

openmmapi/include/openmm/internal/CustomGBForceImpl.h

@@ -53,7 +53,7 @@ public:
     const CustomGBForce& getOwner() const {
         return owner;
     }
-    void updateContextState(ContextImpl& context) {
+    void updateContextState(ContextImpl& context, bool& forcesInvalid) {
         // This force field doesn't update the state directly.
     }
     double calcForcesAndEnergy(ContextImpl& context, bool includeForces, bool includeEnergy, int groups);

openmmapi/include/openmm/internal/CustomHbondForceImpl.h

@@ -57,7 +57,7 @@ public:
     const CustomHbondForce& getOwner() const {
         return owner;
     }
-    void updateContextState(ContextImpl& context) {
+    void updateContextState(ContextImpl& context, bool& forcesInvalid) {
         // This force field doesn't update the state directly.
     }
     double calcForcesAndEnergy(ContextImpl& context, bool includeForces, bool includeEnergy, int groups);

openmmapi/include/openmm/internal/CustomManyParticleForceImpl.h

@@ -57,7 +57,7 @@ public:
     const CustomManyParticleForce& getOwner() const {
         return owner;
     }
-    void updateContextState(ContextImpl& context) {
+    void updateContextState(ContextImpl& context, bool& forcesInvalid) {
         // This force field doesn't update the state directly.
     }
     double calcForcesAndEnergy(ContextImpl& context, bool includeForces, bool includeEnergy, int groups);

openmmapi/include/openmm/internal/CustomNonbondedForceImpl.h

@@ -54,7 +54,7 @@ public:
     const CustomNonbondedForce& getOwner() const {
         return owner;
     }
-    void updateContextState(ContextImpl& context) {
+    void updateContextState(ContextImpl& context, bool& forcesInvalid) {
         // This force field doesn't update the state directly.
     }
     double calcForcesAndEnergy(ContextImpl& context, bool includeForces, bool includeEnergy, int groups);

openmmapi/include/openmm/internal/CustomTorsionForceImpl.h

@@ -53,7 +53,7 @@ public:
     const CustomTorsionForce& getOwner() const {
         return owner;
     }
-    void updateContextState(ContextImpl& context) {
+    void updateContextState(ContextImpl& context, bool& forcesInvalid) {
         // This force field doesn't update the state directly.
     }
     double calcForcesAndEnergy(ContextImpl& context, bool includeForces, bool includeEnergy, int groups);

openmmapi/include/openmm/internal/ForceImpl.h

@@ -73,9 +73,16 @@ public:
      * to modify the state variables (positions, velocities, and parameters) stored in the
      * Context in arbitrary ways before integration is performed.
      * 
-     * @param context     the context in which the system is being simulated
+     * @param context        the context in which the system is being simulated
+     * @param forcesInvalid  if the state was modified in any way that might cause previously
+     *                       calculated forces to no longer be valid (such as modifying
+     *                       positions or parameters), the method should set this to true.
+     */
+    virtual void updateContextState(ContextImpl& context, bool& forcesInvalid);
+    /**
+     * @deprecated This version exists for backward compatibility.  Subclasses should implement the other version instead.
      */
-    virtual void updateContextState(ContextImpl& context) = 0;
+    virtual void updateContextState(ContextImpl& context);
     /**
      * Calculate the force on each particle generated by this ForceImpl and/or this ForceImpl's
      * contribution to the potential energy of the system.

openmmapi/include/openmm/internal/GBSAOBCForceImpl.h

@@ -50,7 +50,7 @@ public:
     const GBSAOBCForce& getOwner() const {
         return owner;
     }
-    void updateContextState(ContextImpl& context) {
+    void updateContextState(ContextImpl& context, bool& forcesInvalid) {
         // This force field doesn't update the state directly.
     }
     double calcForcesAndEnergy(ContextImpl& context, bool includeForces, bool includeEnergy, int groups);

openmmapi/include/openmm/internal/HarmonicAngleForceImpl.h

@@ -53,7 +53,7 @@ public:
     const HarmonicAngleForce& getOwner() const {
         return owner;
     }
-    void updateContextState(ContextImpl& context) {
+    void updateContextState(ContextImpl& context, bool& forcesInvalid) {
         // This force field doesn't update the state directly.
     }
     double calcForcesAndEnergy(ContextImpl& context, bool includeForces, bool includeEnergy, int groups);

openmmapi/include/openmm/internal/HarmonicBondForceImpl.h

@@ -53,7 +53,7 @@ public:
     const HarmonicBondForce& getOwner() const {
         return owner;
     }
-    void updateContextState(ContextImpl& context) {
+    void updateContextState(ContextImpl& context, bool& forcesInvalid) {
         // This force field doesn't update the state directly.
     }
     double calcForcesAndEnergy(ContextImpl& context, bool includeForces, bool includeEnergy, int groups);

openmmapi/include/openmm/internal/MonteCarloBarostatImpl.h

@@ -51,7 +51,7 @@ public:
     const MonteCarloBarostat& getOwner() const {
         return owner;
     }
-    void updateContextState(ContextImpl& context);
+    void updateContextState(ContextImpl& context, bool& forcesInvalid);
     double calcForcesAndEnergy(ContextImpl& context, bool includeForces, bool includeEnergy, int groups) {
         // This force doesn't apply forces to particles.
         return 0.0;