[mlpack-git] master: Removes numThreadsUsed variable, changes how maxThreads is initialized (6152527)

[gitdub at mlpack.org]

Repository : https://github.com/mlpack/mlpack
On branch  : master
Link       : https://github.com/mlpack/mlpack/compare/34cf8d94f79c9a72ff4199676033b060cd039fcd...425324bf7fb7c86c85d10a909d8a59d4f69b7164

>---------------------------------------------------------------

commit 6152527d44f3d30ef529f8cfcbd6bf300e29ceb3
Author: Yannis Mentekidis <mentekid at gmail.com>
Date:   Mon Jun 27 11:01:30 2016 +0100

    Removes numThreadsUsed variable, changes how maxThreads is initialized


>---------------------------------------------------------------

6152527d44f3d30ef529f8cfcbd6bf300e29ceb3
 src/mlpack/methods/lsh/lsh_search_impl.hpp | 70 +++++++++++++++++-------------
 1 file changed, 39 insertions(+), 31 deletions(-)

diff --git a/src/mlpack/methods/lsh/lsh_search_impl.hpp b/src/mlpack/methods/lsh/lsh_search_impl.hpp
index a81fa55..6ec13d8 100644
--- a/src/mlpack/methods/lsh/lsh_search_impl.hpp
+++ b/src/mlpack/methods/lsh/lsh_search_impl.hpp
@@ -9,20 +9,9 @@
 
 #include <mlpack/core.hpp>
 
-using std::cout; using std::endl; //TODO: remove
-
 namespace mlpack {
 namespace neighbor {
 
-// Simple small function to set threads to 1 if OpenMP is not used
-inline size_t DefineMaxThreads()
-{
-  #ifdef _OPENMP
-    return omp_get_max_threads();
-  #else
-    return 1;
-  #endif
-}
 
 // Construct the object with random tables
 template<typename SortPolicy>
@@ -40,10 +29,14 @@ LSHSearch(const arma::mat& referenceSet,
   hashWidth(hashWidthIn),
   secondHashSize(secondHashSize),
   bucketSize(bucketSize),
-  distanceEvaluations(0),
-  maxThreads(DefineMaxThreads()),
-  numThreadsUsed(1)
+  distanceEvaluations(0)
 {
+
+  #ifdef _OPENMP
+    maxThreads = omp_get_max_threads();
+  #else
+    maxThreads = 1;
+  #endif
   // Pass work to training function.
   Train(referenceSet, numProj, numTables, hashWidthIn, secondHashSize,
       bucketSize);
@@ -64,10 +57,13 @@ LSHSearch(const arma::mat& referenceSet,
   hashWidth(hashWidthIn),
   secondHashSize(secondHashSize),
   bucketSize(bucketSize),
-  distanceEvaluations(0),
-  maxThreads(omp_get_max_threads()),
-  numThreadsUsed(1)
+  distanceEvaluations(0)
 {
+  #ifdef _OPENMP
+    maxThreads = omp_get_max_threads();
+  #else
+    maxThreads = 1;
+  #endif
   // Pass work to training function
   Train(referenceSet, numProj, numTables, hashWidthIn, secondHashSize,
       bucketSize, projections);
@@ -83,11 +79,14 @@ LSHSearch<SortPolicy>::LSHSearch() :
     hashWidth(0),
     secondHashSize(99901),
     bucketSize(500),
-    distanceEvaluations(0),
-    maxThreads(omp_get_max_threads()),
-    numThreadsUsed(1)
+    distanceEvaluations(0)
 {
-  // Nothing to do.
+  // Only define maxThreads. Nothing else to do.
+  #ifdef _OPENMP
+    maxThreads = omp_get_max_threads();
+  #else
+    maxThreads = 1;
+  #endif
 }
 
 // Destructor.
@@ -445,10 +444,15 @@ void LSHSearch<SortPolicy>::ReturnIndicesFromTable(
       }
     }
 
-    // Only keep reference points found in at least one bucket.
-    // TODO: maybe write parallel implementation of this?
-    referenceIndices = arma::find(refPointsConsidered > 0);
-    return;
+    // Only keep reference points found in at least one bucket. If OpenMP is
+    // found, do it in parallel
+    #ifdef _OPENMP
+      referenceIndices = arma::find(refPointsConsidered > 0);
+      return;
+    #else
+      referenceIndices = OmpFind(refPointsConsideredSmall);
+      return;
+    #endif
   }
   else
   {
@@ -491,10 +495,14 @@ void LSHSearch<SortPolicy>::ReturnIndicesFromTable(
       }
     }
 
-    // Only keep unique candidates.
-    // TODO: again main bottleneck is here. Parallelize?
-    referenceIndices = arma::unique(refPointsConsideredSmall);
-    return;
+    // Only keep unique candidates. If OpenMP is found, do it in parallel.
+    #ifdef _OPENMP
+      referenceIndices = arma::unique(refPointsConsideredSmall);
+      return;
+    #else
+      referenceIndices = OmpUnique(refPointsConsideredSmall);
+      return;
+    #endif
   }
 }
 
@@ -611,8 +619,8 @@ Search(const size_t k,
     ReturnIndicesFromTable(referenceSet->col(i), refIndices, numTablesToSearch);
 
     // An informative book-keeping for the number of neighbor candidates
-    // returned on average.
-    // Make atomic to avoid race conditions when multiple threads are running
+    // returned on average. Make atomic to avoid race conditions when multiple
+    // threads are running.
     #pragma omp atomic
     avgIndicesReturned += refIndices.n_elem;