ENH: Random numbers - cachedRandom - updated to use the re-entrant random interface

src/OpenFOAM/primitives/random/cachedRandom/cachedRandom.C

@@ -3,7 +3,7 @@
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
     \\  /    A nd           | Copyright (C) 2011-2015 OpenFOAM Foundation
-     \\/     M anipulation  |
+     \\/     M anipulation  | Copyright (C) 2017 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -31,88 +31,38 @@ License
 
 Foam::scalar Foam::cachedRandom::scalar01()
 {
-    if (sampleI_ < 0)
-    {
-        return osRandomDouble();
-    }
-
-    if (sampleI_ == samples_.size() - 1)
-    {
-        scalar s = samples_[sampleI_];
-        sampleI_ = 0;
-        return s;
-    }
-    else
-    {
-        scalar s = samples_[sampleI_];
-        sampleI_++;
-        return s;
-    }
+    return osRandomDouble(buffer_);
 }
 
 
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
-Foam::cachedRandom::cachedRandom(const label seed, const label count)
+Foam::cachedRandom::cachedRandom(const label seed)
 :
-    seed_(1),
-    samples_(0),
-    sampleI_(-1),
+    buffer_(osRandomBufferSize()),
+    seed_(seed),
     hasGaussSample_(false),
     gaussSample_(0)
 {
-    if (seed > 1)
-    {
-        seed_ = seed;
-    }
-
-    // Initialise samples
-    osRandomSeed(seed_);
-
-    // Samples will be cached if count > 0
-    if (count > 0)
-    {
-        samples_.setSize(count);
-        forAll(samples_, i)
-        {
-            samples_[i] = osRandomDouble();
-        }
-
-        sampleI_ = 0;
-    }
+    // Initialise the random number generator
+    osRandomSeed(seed_, buffer_);
 }
 
 
 Foam::cachedRandom::cachedRandom(const cachedRandom& cr, const bool reset)
 :
+    buffer_(cr.buffer_),
     seed_(cr.seed_),
-    samples_(cr.samples_),
-    sampleI_(cr.sampleI_),
     hasGaussSample_(cr.hasGaussSample_),
     gaussSample_(cr.gaussSample_)
 {
-    //if (sampleI_ == -1)
-    //{
-    //    WarningInFunction
-    //        << "Copy constructor called, but samples not being cached. "
-    //        << "This may lead to non-repeatable behaviour" << endl;
-    //
-    //}
-
     if (reset)
     {
         hasGaussSample_ = false;
         gaussSample_ = 0;
 
-        if (samples_.size())
-        {
-            sampleI_ = 0;
-        }
-        else
-        {
-            // Re-initialise the samples
-            osRandomSeed(seed_);
-        }
+        // Re-initialise the samples
+        osRandomSeed(seed_, buffer_);
     }
 }
 
@@ -125,6 +75,13 @@ Foam::cachedRandom::~cachedRandom()
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
+void Foam::cachedRandom::reset(const label seed)
+{
+    seed_ = seed;
+    osRandomSeed(seed_, buffer_);
+}
+
+
 template<>
 Foam::scalar Foam::cachedRandom::sample01()
 {

src/OpenFOAM/primitives/random/cachedRandom/cachedRandom.H

@@ -3,7 +3,7 @@
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
     \\  /    A nd           | Copyright (C) 2011-2015 OpenFOAM Foundation
-     \\/     M anipulation  |
+     \\/     M anipulation  | Copyright (C) 2017 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -27,15 +27,6 @@ Class
 Description
     Random number generator.
 
-    Pre-computes and caches samples on construction, so that when sample01()
-    is called, the function simply returns the next (pre-computed) sample. On
-    reaching the last sample, the sample sequence is repeated.
-
-    Constructed using a seed and sample count. If the supplied count is
-    negative, no caching is performed, and a new sample is generated on each
-    call to sample01().
-
-    Note: the copy constructor cannot be used if count = -1.
 
 SourceFiles
     cachedRandomI.H
@@ -65,15 +56,12 @@ class cachedRandom
 {
     // Private data
 
+        //- Buffer used by re-entrant random number generator
+        List<char> buffer_;
+
         //- Initial random number seed
         label seed_;
 
-        //- List of scalar samples
-        scalarList samples_;
-
-        //- Current sample marker
-        label sampleI_;
-
         //- Indicator, which tells if there is a stored gaussian sample
         bool hasGaussSample_;
 
@@ -92,7 +80,7 @@ public:
     // Constructors
 
         //- Construct given seed and sample count
-        cachedRandom(const label seed, const label count);
+        cachedRandom(const label seed = 123456);
 
         //- Copy constructor with optional reset of sampleI
         cachedRandom(const cachedRandom& cr, const bool reset = false);
@@ -109,18 +97,7 @@ public:
             //- Return const access to the initial random number seed
             inline label seed() const;
 
-            //- Return const access to the list of samples
-            inline const scalarList& samples() const;
-
-            //- Return the current sample marker
-            inline label sampleI() const;
-
-
-        // Manipulation
-
-            //- Return non-const access to the sample marker
-            inline label& sampleI();
-
+            void reset(const label seed);
 
         // Evaluation
 

src/OpenFOAM/primitives/random/cachedRandom/cachedRandomI.H

@@ -33,22 +33,4 @@ inline Foam::label Foam::cachedRandom::seed() const
 }
 
 
-inline const Foam::scalarList& Foam::cachedRandom::samples() const
-{
-    return samples_;
-}
-
-
-inline Foam::label Foam::cachedRandom::sampleI() const
-{
-    return sampleI_;
-}
-
-
-inline Foam::label& Foam::cachedRandom::sampleI()
-{
-    return sampleI_;
-}
-
-
 // ************************************************************************* //