make straus cached mode thread safe, and add tests for it

src/ringct/bulletproofs.cc

@@ -61,6 +61,7 @@ static constexpr size_t maxM = 16;
 static rct::key Hi[maxN*maxM], Gi[maxN*maxM];
 static ge_p3 Hi_p3[maxN*maxM], Gi_p3[maxN*maxM];
 static ge_dsmp Gprecomp[maxN*maxM], Hprecomp[maxN*maxM];
+static std::shared_ptr<straus_cached_data> HiGi_cache;
 static const rct::key TWO = { {0x02, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00 , 0x00, 0x00, 0x00,0x00  } };
 static const rct::keyV oneN = vector_dup(rct::identity(), maxN);
 static const rct::keyV twoN = vector_powers(TWO, maxN);
@@ -70,7 +71,7 @@ static boost::mutex init_mutex;
 static inline rct::key multiexp(const std::vector<MultiexpData> &data, bool HiGi)
 {
   if (HiGi || data.size() < 1000)
-    return straus(data, HiGi);
+    return straus(data, HiGi ? HiGi_cache: NULL);
   else
     return bos_coster_heap_conv_robust(data);
 }
@@ -116,6 +117,7 @@ static void init_exponents()
   static bool init_done = false;
   if (init_done)
     return;
+  std::vector<MultiexpData> data;
   for (size_t i = 0; i < maxN*maxM; ++i)
   {
     Hi[i] = get_exponent(rct::H, i * 2);
@@ -124,8 +126,13 @@ static void init_exponents()
     Gi[i] = get_exponent(rct::H, i * 2 + 1);
     rct::precomp(Gprecomp[i], Gi[i]);
     CHECK_AND_ASSERT_THROW_MES(ge_frombytes_vartime(&Gi_p3[i], Gi[i].bytes) == 0, "ge_frombytes_vartime failed");
+
+    data.push_back({rct::zero(), Gi[i]});
+    data.push_back({rct::zero(), Hi[i]});
   }
-  MINFO("cache size: " << (sizeof(Hi)+sizeof(Hprecomp)+sizeof(Hi_p3))*2/1024 << " kB");
+  HiGi_cache = straus_init_cache(data);
+  size_t cache_size = (sizeof(Hi)+sizeof(Hprecomp)+sizeof(Hi_p3))*2 + straus_get_cache_size(HiGi_cache);
+  MINFO("cache size: " << cache_size/1024 << " kB");
   init_done = true;
 }
 

src/ringct/multiexp.cc

@@ -259,15 +259,58 @@ rct::key bos_coster_heap_conv_robust(std::vector<MultiexpData> data)
   return res;
 }
 
-rct::key straus(const std::vector<MultiexpData> &data, bool HiGi)
+struct straus_cached_data
+{
+  std::vector<std::vector<ge_cached>> multiples;
+};
+
+static constexpr unsigned int STRAUS_C = 4;
+
+std::shared_ptr<straus_cached_data> straus_init_cache(const std::vector<MultiexpData> &data)
+{
+  MULTIEXP_PERF(PERF_TIMER_START_UNIT(multiples, 1000000));
+  ge_cached cached;
+  ge_p1p1 p1;
+  ge_p3 p3;
+  std::shared_ptr<straus_cached_data> cache(new straus_cached_data());
+
+  cache->multiples.resize(1<<STRAUS_C);
+  size_t offset = cache->multiples[1].size();
+  cache->multiples[1].resize(std::max(offset, data.size()));
+  for (size_t i = offset; i < data.size(); ++i)
+    ge_p3_to_cached(&cache->multiples[1][i], &data[i].point);
+  for (size_t i=2;i<1<<STRAUS_C;++i)
+    cache->multiples[i].resize(std::max(offset, data.size()));
+  for (size_t j=offset;j<data.size();++j)
+  {
+    for (size_t i=2;i<1<<STRAUS_C;++i)
+    {
+      ge_add(&p1, &data[j].point, &cache->multiples[i-1][j]);
+      ge_p1p1_to_p3(&p3, &p1);
+      ge_p3_to_cached(&cache->multiples[i][j], &p3);
+    }
+  }
+  MULTIEXP_PERF(PERF_TIMER_STOP(multiples));
+
+  return cache;
+}
+
+size_t straus_get_cache_size(const std::shared_ptr<straus_cached_data> &cache)
+{
+  size_t sz = 0;
+  for (const auto &e0: cache->multiples)
+    sz += e0.size() * sizeof(ge_p3);
+  return sz;
+}
+
+rct::key straus(const std::vector<MultiexpData> &data, const std::shared_ptr<straus_cached_data> &cache)
 {
   MULTIEXP_PERF(PERF_TIMER_UNIT(straus, 1000000));
+  bool HiGi = cache != NULL;
 
   MULTIEXP_PERF(PERF_TIMER_START_UNIT(setup, 1000000));
-  static constexpr unsigned int c = 4;
-  static constexpr unsigned int mask = (1<<c)-1;
-  static std::vector<std::vector<ge_cached>> HiGi_multiples;
-  std::vector<std::vector<ge_cached>> local_multiples, &multiples = HiGi ? HiGi_multiples : local_multiples;
+  static constexpr unsigned int mask = (1<<STRAUS_C)-1;
+  std::shared_ptr<straus_cached_data> local_cache = cache == NULL ? straus_init_cache(data) : cache;
   ge_cached cached;
   ge_p1p1 p1;
   ge_p3 p3;
@@ -276,25 +319,6 @@ rct::key straus(const std::vector<MultiexpData> &data, bool HiGi)
   for (size_t i = 0; i < data.size(); ++i)
     skip[i] = data[i].scalar == rct::zero() || !memcmp(&data[i].point, &ge_p3_identity, sizeof(ge_p3));
 
-  MULTIEXP_PERF(PERF_TIMER_START_UNIT(multiples, 1000000));
-  multiples.resize(1<<c);
-  size_t offset = multiples[1].size();
-  multiples[1].resize(std::max(offset, data.size()));
-  for (size_t i = offset; i < data.size(); ++i)
-    ge_p3_to_cached(&multiples[1][i], &data[i].point);
-  for (size_t i=2;i<1<<c;++i)
-    multiples[i].resize(std::max(offset, data.size()));
-  for (size_t j=offset;j<data.size();++j)
-  {
-    for (size_t i=2;i<1<<c;++i)
-    {
-      ge_add(&p1, &data[j].point, &multiples[i-1][j]);
-      ge_p1p1_to_p3(&p3, &p1);
-      ge_p3_to_cached(&multiples[i][j], &p3);
-    }
-  }
-  MULTIEXP_PERF(PERF_TIMER_STOP(multiples));
-
   MULTIEXP_PERF(PERF_TIMER_START_UNIT(digits, 1000000));
   std::vector<std::vector<uint8_t>> digits;
   digits.resize(data.size());
@@ -305,7 +329,7 @@ rct::key straus(const std::vector<MultiexpData> &data, bool HiGi)
     memcpy(bytes33,  data[j].scalar.bytes, 32);
     bytes33[32] = 0;
 #if 1
-    static_assert(c == 4, "optimized version needs c == 4");
+    static_assert(STRAUS_C == 4, "optimized version needs STRAUS_C == 4");
     const unsigned char *bytes = bytes33;
     unsigned int i;
     for (i = 0; i < 256; i += 8, bytes++)
@@ -339,22 +363,22 @@ rct::key straus(const std::vector<MultiexpData> &data, bool HiGi)
       maxscalar = data[i].scalar;
   size_t i = 0;
   while (i < 256 && !(maxscalar < pow2(i)))
-    i += c;
+    i += STRAUS_C;
   MULTIEXP_PERF(PERF_TIMER_STOP(setup));
 
   ge_p3 res_p3 = ge_p3_identity;
-  if (!(i < c))
+  if (!(i < STRAUS_C))
     goto skipfirst;
-  while (!(i < c))
+  while (!(i < STRAUS_C))
   {
-    for (size_t j = 0; j < c; ++j)
+    for (size_t j = 0; j < STRAUS_C; ++j)
     {
       ge_p3_to_cached(&cached, &res_p3);
       ge_add(&p1, &res_p3, &cached);
       ge_p1p1_to_p3(&res_p3, &p1);
     }
 skipfirst:
-    i -= c;
+    i -= STRAUS_C;
     for (size_t j = 0; j < data.size(); ++j)
     {
       if (skip[j])
@@ -362,7 +386,7 @@ skipfirst:
       int digit = digits[j][i];
       if (digit)
       {
-        ge_add(&p1, &res_p3, &multiples[digit][j]);
+        ge_add(&p1, &res_p3, &local_cache->multiples[digit][j]);
         ge_p1p1_to_p3(&res_p3, &p1);
       }
     }

src/ringct/multiexp.h

@@ -36,6 +36,7 @@
 #include <vector>
 #include "crypto/crypto.h"
 #include "rctTypes.h"
+#include "misc_log_ex.h"
 
 namespace rct
 {
@@ -52,9 +53,13 @@ struct MultiexpData {
   }
 };
 
+struct straus_cached_data;
+
 rct::key bos_coster_heap_conv(std::vector<MultiexpData> data);
 rct::key bos_coster_heap_conv_robust(std::vector<MultiexpData> data);
-rct::key straus(const std::vector<MultiexpData> &data, bool HiGi = false);
+std::shared_ptr<straus_cached_data> straus_init_cache(const std::vector<MultiexpData> &data);
+size_t straus_get_cache_size(const std::shared_ptr<straus_cached_data> &cache);
+rct::key straus(const std::vector<MultiexpData> &data, const std::shared_ptr<straus_cached_data> &cache = NULL);
 
 }
 

tests/performance_tests/main.cpp

@@ -221,6 +221,13 @@ int main(int argc, char** argv)
   TEST_PERFORMANCE2(filter, verbose, test_multiexp, multiexp_straus, 1024);
   TEST_PERFORMANCE2(filter, verbose, test_multiexp, multiexp_straus, 4096);
 
+  TEST_PERFORMANCE2(filter, verbose, test_multiexp, multiexp_straus_cached, 2);
+  TEST_PERFORMANCE2(filter, verbose, test_multiexp, multiexp_straus_cached, 8);
+  TEST_PERFORMANCE2(filter, verbose, test_multiexp, multiexp_straus_cached, 16);
+  TEST_PERFORMANCE2(filter, verbose, test_multiexp, multiexp_straus_cached, 256);
+  TEST_PERFORMANCE2(filter, verbose, test_multiexp, multiexp_straus_cached, 1024);
+  TEST_PERFORMANCE2(filter, verbose, test_multiexp, multiexp_straus_cached, 4096);
+
   std::cout << "Tests finished. Elapsed time: " << timer.elapsed_ms() / 1000 << " sec" << std::endl;
 
   return 0;

tests/performance_tests/multiexp.h

@@ -38,6 +38,7 @@ enum test_multiexp_algorithm
 {
   multiexp_bos_coster,
   multiexp_straus,
+  multiexp_straus_cached,
 };
 
 template<test_multiexp_algorithm algorithm, size_t npoints>
@@ -59,6 +60,7 @@ public:
       rct::key kn = rct::scalarmultKey(point, data[n].scalar);
       res = rct::addKeys(res, kn);
     }
+    cache = rct::straus_init_cache(data);
     return true;
   }
 
@@ -69,7 +71,9 @@ public:
       case multiexp_bos_coster:
         return res == bos_coster_heap_conv_robust(data);
       case multiexp_straus:
-        return res == straus(data, false);
+        return res == straus(data);
+      case multiexp_straus_cached:
+        return res == straus(data, cache);
       default:
         return false;
     }
@@ -77,5 +81,6 @@ public:
 
 private:
   std::vector<rct::MultiexpData> data;
+  std::shared_ptr<rct::straus_cached_data> cache;
   rct::key res;
 };

tests/unit_tests/CMakeLists.txt

@@ -58,6 +58,7 @@ set(unit_tests_sources
   mlocker.cpp
   mnemonics.cpp
   mul_div.cpp
+  multiexp.cpp
   multisig.cpp
   parse_amount.cpp
   random.cpp

tests/unit_tests/multiexp.cpp

@@ -0,0 +1,149 @@
+// Copyright (c) 2018, The Monero Project
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+// 
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+// 
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+// 
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "gtest/gtest.h"
+
+#include "crypto/crypto.h"
+#include "ringct/rctOps.h"
+#include "ringct/multiexp.h"
+
+static const rct::key TESTSCALAR = rct::H;
+static const rct::key TESTPOINT = rct::scalarmultBase(rct::H);
+
+static rct::key basic(const std::vector<rct::MultiexpData> &data)
+{
+  ge_p3 res_p3 = ge_p3_identity;
+  for (const auto &d: data)
+  {
+    ge_cached cached;
+    ge_p3 p3;
+    ge_p1p1 p1;
+    ge_scalarmult_p3(&p3, d.scalar.bytes, &d.point);
+    ge_p3_to_cached(&cached, &p3);
+    ge_add(&p1, &res_p3, &cached);
+    ge_p1p1_to_p3(&res_p3, &p1);
+  }
+  rct::key res;
+  ge_p3_tobytes(res.bytes, &res_p3);
+  return res;
+}
+
+static ge_p3 get_p3(const rct::key &point)
+{
+  ge_p3 p3;
+  EXPECT_TRUE(ge_frombytes_vartime(&p3, point.bytes) == 0);
+  return p3;
+}
+
+TEST(multiexp, bos_coster_empty)
+{
+  std::vector<rct::MultiexpData> data;
+  data.push_back({rct::zero(), get_p3(rct::identity())});
+  ASSERT_TRUE(basic(data) == bos_coster_heap_conv_robust(data));
+}
+
+TEST(multiexp, straus_empty)
+{
+  std::vector<rct::MultiexpData> data;
+  data.push_back({rct::zero(), get_p3(rct::identity())});
+  ASSERT_TRUE(basic(data) == straus(data));
+}
+
+TEST(multiexp, bos_coster_only_zeroes)
+{
+  std::vector<rct::MultiexpData> data;
+  for (int n = 0; n < 16; ++n)
+    data.push_back({rct::zero(), get_p3(TESTPOINT)});
+  ASSERT_TRUE(basic(data) == bos_coster_heap_conv_robust(data));
+}
+
+TEST(multiexp, straus_only_zeroes)
+{
+  std::vector<rct::MultiexpData> data;
+  for (int n = 0; n < 16; ++n)
+    data.push_back({rct::zero(), get_p3(TESTPOINT)});
+  ASSERT_TRUE(basic(data) == straus(data));
+}
+
+TEST(multiexp, bos_coster_only_identities)
+{
+  std::vector<rct::MultiexpData> data;
+  for (int n = 0; n < 16; ++n)
+    data.push_back({TESTSCALAR, get_p3(rct::identity())});
+  ASSERT_TRUE(basic(data) == bos_coster_heap_conv_robust(data));
+}
+
+TEST(multiexp, straus_only_identities)
+{
+  std::vector<rct::MultiexpData> data;
+  for (int n = 0; n < 16; ++n)
+    data.push_back({TESTSCALAR, get_p3(rct::identity())});
+  ASSERT_TRUE(basic(data) == straus(data));
+}
+
+TEST(multiexp, bos_coster_random)
+{
+  std::vector<rct::MultiexpData> data;
+  for (int n = 0; n < 32; ++n)
+  {
+    data.push_back({rct::skGen(), get_p3(rct::scalarmultBase(rct::skGen()))});
+    ASSERT_TRUE(basic(data) == bos_coster_heap_conv_robust(data));
+  }
+}
+
+TEST(multiexp, straus_random)
+{
+  std::vector<rct::MultiexpData> data;
+  for (int n = 0; n < 32; ++n)
+  {
+    data.push_back({rct::skGen(), get_p3(rct::scalarmultBase(rct::skGen()))});
+    ASSERT_TRUE(basic(data) == straus(data));
+  }
+}
+
+TEST(multiexp, straus_cached)
+{
+  static constexpr size_t N = 256;
+  std::vector<rct::MultiexpData> P(N);
+  for (size_t n = 0; n < N; ++n)
+  {
+    P[n].scalar = rct::zero();
+    ASSERT_TRUE(ge_frombytes_vartime(&P[n].point, rct::scalarmultBase(rct::skGen()).bytes) == 0);
+  }
+  std::shared_ptr<rct::straus_cached_data> cache = rct::straus_init_cache(P);
+  for (size_t n = 0; n < N/16; ++n)
+  {
+    std::vector<rct::MultiexpData> data;
+    size_t sz = 1 + crypto::rand<size_t>() % (N-1);
+    for (size_t s = 0; s < sz; ++s)
+    {
+      data.push_back({rct::skGen(), P[s].point});
+    }
+    ASSERT_TRUE(basic(data) == straus(data, cache));
+  }
+}