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

1 files changed, 52 insertions, 28 deletions

diff --git a/src/ringct/multiexp.cc b/src/ringct/multiexp.cc
index 7ed9672f2..4f16bd588 100644
--- a/src/ringct/multiexp.cc
+++ b/src/ringct/multiexp.cc
@@ -259,42 +259,66 @@ 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
 {
-  MULTIEXP_PERF(PERF_TIMER_UNIT(straus, 1000000));
+  std::vector<std::vector<ge_cached>> multiples;
+};
 
-  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 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());
 
-  std::vector<uint8_t> skip(data.size());
-  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()));
+  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(&multiples[1][i], &data[i].point);
-  for (size_t i=2;i<1<<c;++i)
-    multiples[i].resize(std::max(offset, data.size()));
+    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<<c;++i)
+    for (size_t i=2;i<1<<STRAUS_C;++i)
     {
-      ge_add(&p1, &data[j].point, &multiples[i-1][j]);
+      ge_add(&p1, &data[j].point, &cache->multiples[i-1][j]);
       ge_p1p1_to_p3(&p3, &p1);
-      ge_p3_to_cached(&multiples[i][j], &p3);
+      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 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;
+
+  std::vector<uint8_t> skip(data.size());
+  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(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);
       }
     }