Add thin Minisketch wrapper to pick best implementation

Author: sipa

src/Makefile.am

@@ -167,6 +167,7 @@ BITCOIN_CORE_H = \
   memusage.h \
   merkleblock.h \
   miner.h \
+  minisketchwrapper.h \
   net.h \
   net_permissions.h \
   net_processing.h \
@@ -334,6 +335,7 @@ libbitcoin_server_a_SOURCES = \
   init.cpp \
   mapport.cpp \
   miner.cpp \
+  minisketchwrapper.cpp \
   net.cpp \
   net_processing.cpp \
   node/blockstorage.cpp \

src/minisketchwrapper.cpp

@@ -0,0 +1,77 @@
+// Copyright (c) 2021 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <minisketchwrapper.h>
+
+#include <logging.h>
+#include <util/time.h>
+
+#include <minisketch.h>
+
+#include <algorithm>
+#include <cstddef>
+#include <cstdint>
+#include <optional>
+#include <utility>
+#include <vector>
+
+namespace {
+
+static constexpr uint32_t BITS = 32;
+
+uint32_t FindBestImplementation()
+{
+    std::optional<std::pair<int64_t, uint32_t>> best;
+
+    uint32_t max_impl = Minisketch::MaxImplementation();
+    for (uint32_t impl = 0; impl <= max_impl; ++impl) {
+        std::vector<int64_t> benches;
+        uint64_t offset = 0;
+        /* Run a little benchmark with capacity 32, adding 184 entries, and decoding 11 of them once. */
+        for (int b = 0; b < 11; ++b) {
+            if (!Minisketch::ImplementationSupported(BITS, impl)) break;
+            Minisketch sketch(BITS, impl, 32);
+            auto start = GetTimeMicros();
+            for (uint64_t e = 0; e < 100; ++e) {
+                sketch.Add(e*1337 + b*13337 + offset);
+            }
+            for (uint64_t e = 0; e < 84; ++e) {
+                sketch.Add(e*1337 + b*13337 + offset);
+            }
+            offset += (*sketch.Decode(32))[0];
+            auto stop = GetTimeMicros();
+            benches.push_back(stop - start);
+        }
+        /* Remember which implementation has the best median benchmark time. */
+        if (!benches.empty()) {
+            std::sort(benches.begin(), benches.end());
+            if (!best || best->first > benches[5]) {
+                best = std::make_pair(benches[5], impl);
+            }
+        }
+    }
+    assert(best.has_value());
+    LogPrintf("Using Minisketch implementation number %i\n", best->second);
+    return best->second;
+}
+
+uint32_t Minisketch32Implementation()
+{
+    // Fast compute-once idiom.
+    static uint32_t best = FindBestImplementation();
+    return best;
+}
+
+} // namespace
+
+
+Minisketch MakeMinisketch32(size_t capacity)
+{
+    return Minisketch(BITS, Minisketch32Implementation(), capacity);
+}
+
+Minisketch MakeMinisketch32FP(size_t max_elements, uint32_t fpbits)
+{
+    return Minisketch::CreateFP(BITS, Minisketch32Implementation(), max_elements, fpbits);
+}

src/minisketchwrapper.h

@@ -0,0 +1,17 @@
+// Copyright (c) 2021 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_MINISKETCHWRAPPER_H
+#define BITCOIN_MINISKETCHWRAPPER_H
+
+#include <minisketch.h>
+#include <cstddef>
+#include <cstdint>
+
+/** Wrapper around Minisketch::Minisketch(32, implementation, capacity). */
+Minisketch MakeMinisketch32(size_t capacity);
+/** Wrapper around Minisketch::CreateFP. */
+Minisketch MakeMinisketch32FP(size_t max_elements, uint32_t fpbits);
+
+#endif // BITCOIN_DBWRAPPER_H

src/test/minisketch_tests.cpp

@@ -3,6 +3,7 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <minisketch.h>
+#include <minisketchwrapper.h>
 #include <random.h>
 #include <test/util/setup_common.h>
 
@@ -24,13 +25,13 @@ BOOST_AUTO_TEST_CASE(minisketch_test)
         uint32_t start_b = start_a + a_not_b;
         uint32_t end_b = start_b + both + b_not_a;
 
-        Minisketch sketch_a(32, 0, 10);
+        Minisketch sketch_a = MakeMinisketch32(10);
         for (uint32_t a = start_a; a < end_a; ++a) sketch_a.Add(a);
-        Minisketch sketch_b(32, 0, 10);
+        Minisketch sketch_b = MakeMinisketch32(10);
         for (uint32_t b = start_b; b < end_b; ++b) sketch_b.Add(b);
 
-        Minisketch sketch_ar(32, 0, 10);
-        Minisketch sketch_br(32, 0, 10);
+        Minisketch sketch_ar = MakeMinisketch32(10);
+        Minisketch sketch_br = MakeMinisketch32(10);
         sketch_ar.Deserialize(sketch_a.Serialize());
         sketch_br.Deserialize(sketch_b.Serialize());