fftw_lock: add test for new fftw_lock

test/CMakeLists.txt

@@ -36,6 +36,17 @@ add_test(
   COMMAND testutils
   WORKING_DIRECTORY ${CMAKE_BINARY_DIR})
 
+if(NOT FINUFFT_USE_DUCC0)
+  add_executable(fftw_lock_test fftw_lock_test.cpp)
+  target_compile_features(fftw_lock_test PRIVATE cxx_std_17)
+  finufft_link_test(fftw_lock_test)
+
+  add_test(
+    NAME run_fftw_lock_test
+    COMMAND fftw_lock_test
+    WORKING_DIRECTORY ${CMAKE_BINARY_DIR})
+endif()
+
 # Add ctest definitions that run at both precisions...
 function(add_tests_with_prec PREC REQ_TOL CHECK_TOL SUFFIX)
   # All of the following should be run at OMP_NUM_THREADS=4 or something small,

test/fftw_lock_test.cpp

@@ -0,0 +1,56 @@
+#include <complex>
+#include <mutex>
+#include <vector>
+
+#include <fftw3.h>
+#include <finufft.h>
+#include <omp.h>
+
+constexpr int N = 65384;
+
+void locker(void *lck) { reinterpret_cast<std::mutex *>(lck)->lock(); }
+void unlocker(void *lck) { reinterpret_cast<std::mutex *>(lck)->unlock(); }
+
+int main() {
+  int64_t Ns[3]; // guru describes mode array by vector [N1,N2..]
+  Ns[0] = N;
+  std::mutex lck;
+
+  finufft_opts opts;
+  finufft_default_opts(&opts);
+  opts.nthreads        = 1;
+  opts.debug           = 0;
+  opts.fftw_lock_fun   = locker;
+  opts.fftw_unlock_fun = unlocker;
+  opts.fftw_lock_data  = reinterpret_cast<void *>(&lck);
+
+  // random nonuniform points (x) and complex strengths (c)...
+  std::vector<std::complex<double>> c(N);
+
+  omp_set_num_threads(8);
+
+  // init FFTW threads
+  fftw_init_threads();
+
+// FFTW and FINUFFT execution using OpenMP parallelization
+#pragma omp parallel for
+  for (int j = 0; j < 100; ++j) {
+    // allocate output array for FFTW...
+    std::vector<std::complex<double>> F1(N);
+
+    // FFTW plan
+    lck.lock();
+    fftw_plan_with_nthreads(1);
+    fftw_plan plan = fftw_plan_dft_1d(N, reinterpret_cast<fftw_complex *>(c.data()),
+                                      reinterpret_cast<fftw_complex *>(F1.data()),
+                                      FFTW_FORWARD, FFTW_ESTIMATE);
+    fftw_destroy_plan(plan);
+    lck.unlock();
+
+    // FINUFFT plan
+    finufft_plan nufftplan;
+    finufft_makeplan(1, 1, Ns, 1, 1, 1e-6, &nufftplan, &opts);
+    finufft_destroy(nufftplan);
+  }
+  return 0;
+}