Bullet 2 threading refactor: moved parallel-for calls into core libs

src/BulletDynamics/Dynamics/btDiscreteDynamicsWorldMt.h

@@ -18,24 +18,116 @@ subject to the following restrictions:
 #define BT_DISCRETE_DYNAMICS_WORLD_MT_H
 
 #include "btDiscreteDynamicsWorld.h"
+#include "btSimulationIslandManagerMt.h"
+#include "BulletDynamics/ConstraintSolver/btConstraintSolver.h"
 
 struct InplaceSolverIslandCallbackMt;
 
+///
+/// btConstraintSolverPoolMt - masquerades as a constraint solver, but really it is a threadsafe pool of them.
+///
+///  Each solver in the pool is protected by a mutex.  When solveGroup is called from a thread,
+///  the pool looks for a solver that isn't being used by another thread, locks it, and dispatches the
+///  call to the solver.
+///  So long as there are at least as many solvers as there are hardware threads, it should never need to
+///  spin wait.
+///
+class btConstraintSolverPoolMt : public btConstraintSolver
+{
+public:
+    // create the solvers for me
+    explicit btConstraintSolverPoolMt( int numSolvers );
+
+    // pass in fully constructed solvers (destructor will delete them)
+    btConstraintSolverPoolMt( btConstraintSolver** solvers, int numSolvers );
+
+    virtual ~btConstraintSolverPoolMt();
+
+    ///solve a group of constraints
+    virtual btScalar solveGroup( btCollisionObject** bodies,
+        int numBodies,
+        btPersistentManifold** manifolds,
+        int numManifolds,
+        btTypedConstraint** constraints,
+        int numConstraints,
+        const btContactSolverInfo& info,
+        btIDebugDraw* debugDrawer,
+        btDispatcher* dispatcher
+    ) BT_OVERRIDE;
+
+    virtual	void reset() BT_OVERRIDE;
+    virtual btConstraintSolverType getSolverType() const BT_OVERRIDE { return m_solverType; }
+
+private:
+    const static size_t kCacheLineSize = 128;
+    struct ThreadSolver
+    {
+        btConstraintSolver* solver;
+        btSpinMutex mutex;
+        char _cachelinePadding[ kCacheLineSize - sizeof( btSpinMutex ) - sizeof( void* ) ];  // keep mutexes from sharing a cache line
+    };
+    btAlignedObjectArray<ThreadSolver> m_solvers;
+    btConstraintSolverType m_solverType;
+
+    ThreadSolver* getAndLockThreadSolver();
+    void init( btConstraintSolver** solvers, int numSolvers );
+};
+
+
+
 ///
 /// btDiscreteDynamicsWorldMt -- a version of DiscreteDynamicsWorld with some minor changes to support
 ///                              solving simulation islands on multiple threads.
 ///
+///  Should function exactly like btDiscreteDynamicsWorld.
+///  Also 3 methods that iterate over all of the rigidbodies can run in parallel:
+///     - predictUnconstraintMotion
+///     - integrateTransforms
+///     - createPredictiveContacts
+///
 ATTRIBUTE_ALIGNED16(class) btDiscreteDynamicsWorldMt : public btDiscreteDynamicsWorld
 {
 protected:
     InplaceSolverIslandCallbackMt* m_solverIslandCallbackMt;
 
-    virtual void	solveConstraints(btContactSolverInfo& solverInfo);
+    virtual void solveConstraints(btContactSolverInfo& solverInfo) BT_OVERRIDE;
+
+    virtual void predictUnconstraintMotion( btScalar timeStep ) BT_OVERRIDE;
+
+    struct UpdaterCreatePredictiveContacts : public btIParallelForBody
+    {
+        btScalar timeStep;
+        btRigidBody** rigidBodies;
+        btDiscreteDynamicsWorldMt* world;
+
+        void forLoop( int iBegin, int iEnd ) const BT_OVERRIDE
+        {
+            world->createPredictiveContactsInternal( &rigidBodies[ iBegin ], iEnd - iBegin, timeStep );
+        }
+    };
+    virtual void createPredictiveContacts( btScalar timeStep ) BT_OVERRIDE;
+
+    struct UpdaterIntegrateTransforms : public btIParallelForBody
+    {
+        btScalar timeStep;
+        btRigidBody** rigidBodies;
+        btDiscreteDynamicsWorldMt* world;
+
+        void forLoop( int iBegin, int iEnd ) const BT_OVERRIDE
+        {
+            world->integrateTransformsInternal( &rigidBodies[ iBegin ], iEnd - iBegin, timeStep );
+        }
+    };
+    virtual void integrateTransforms( btScalar timeStep ) BT_OVERRIDE;
 
 public:
 	BT_DECLARE_ALIGNED_ALLOCATOR();
 
-	btDiscreteDynamicsWorldMt(btDispatcher* dispatcher,btBroadphaseInterface* pairCache,btConstraintSolver* constraintSolver,btCollisionConfiguration* collisionConfiguration);
+	btDiscreteDynamicsWorldMt(btDispatcher* dispatcher,
+        btBroadphaseInterface* pairCache,
+        btConstraintSolverPoolMt* constraintSolver,   // Note this should be a solver-pool for multi-threading
+        btCollisionConfiguration* collisionConfiguration
+    );
 	virtual ~btDiscreteDynamicsWorldMt();
 };