make iffHardDisk thread safe

Sample/Aggregate/InterferenceFunctionHardDisk.cpp

@@ -82,16 +82,19 @@ double InterferenceFunctionHardDisk::density() const
 
 double InterferenceFunctionHardDisk::iff_without_dw(const kvector_t q) const
 {
-    double qx = q.x();
-    double qy = q.y();
-    m_q = 2.0 * std::sqrt(qx * qx + qy * qy) * m_radius;
-    m_packing = packingRatio();
-    m_c_zero = Czero(m_packing);
-    m_s2 = S2(m_packing);
-    double c_q =
+    const double qx = q.x();
+    const double qy = q.y();
+    const double q2r = 2.0 * std::sqrt(qx * qx + qy * qy) * m_radius;
+    const double packing = packingRatio();
+    const double c_zero = Czero(packing);
+    const double s2 = S2(packing);
+    const double c_q =
         2.0 * M_PI
-        * RealIntegrator().integrate([&](double x) -> double { return integrand(x); }, 0.0, 1.0);
-    double rho = 4.0 * m_packing / M_PI;
+        * RealIntegrator().integrate([=](double x) -> double {
+            double cx = c_zero * (1.0 + 4.0 * packing * (W2(x / 2.0) - 1.0) + s2 * x);
+            return x * cx * Math::Bessel::J0(q2r * x);
+        }, 0.0, 1.0);
+    const double rho = 4.0 * packing / M_PI;
     return 1.0 / (1.0 - rho * c_q);
 }
 
@@ -99,9 +102,3 @@ double InterferenceFunctionHardDisk::packingRatio() const
 {
     return M_PI * m_radius * m_radius * m_density;
 }
-
-double InterferenceFunctionHardDisk::integrand(double x) const
-{
-    double cx = m_c_zero * (1.0 + 4.0 * m_packing * (W2(x / 2.0) - 1.0) + m_s2 * x);
-    return x * cx * Math::Bessel::J0(m_q * x);
-}

Sample/Aggregate/InterferenceFunctionHardDisk.h

@@ -41,12 +41,9 @@ public:
 private:
     double iff_without_dw(const kvector_t q) const override;
     double packingRatio() const;
-    double integrand(double x) const;
 
     double m_radius;
     double m_density;
-
-    mutable double m_q, m_c_zero, m_s2, m_packing;
 };
 
 #endif // BORNAGAIN_SAMPLE_AGGREGATE_INTERFERENCEFUNCTIONHARDDISK_H