Problem: radix tree needs benchmarks and improvements (#3290)

* Problem: radix tree needs benchmarks and improvements

Solution: add a benchmark and make suggested improvements

CMakeLists.txt

@@ -1209,6 +1209,15 @@ if(BUILD_SHARED)
           COMPONENT PerfTools)
       endif()
     endforeach()
+
+    if(BUILD_STATIC)
+      add_executable(benchmark_radix_tree perf/benchmark_radix_tree.cpp)
+      target_link_libraries(benchmark_radix_tree libzmq-static)
+      target_include_directories(benchmark_radix_tree
+        PUBLIC
+        "${CMAKE_SOURCE_DIR}/src")
+    endif()
+
   endif()
 elseif(WITH_PERF_TOOL)
   message(FATAL_ERROR "Shared library disabled - perf-tools unavailable.")

Makefile.am

@@ -372,6 +372,17 @@ perf_inproc_lat_SOURCES = perf/inproc_lat.cpp
 
 perf_inproc_thr_LDADD = src/libzmq.la
 perf_inproc_thr_SOURCES = perf/inproc_thr.cpp
+
+if ENABLE_STATIC
+noinst_PROGRAMS += \
+	perf/benchmark_radix_tree
+
+perf_benchmark_radix_tree_DEPENDENCIES = src/libzmq.la
+perf_benchmark_radix_tree_CPPFLAGS = -I$(top_srcdir)/src
+perf_benchmark_radix_tree_LDADD = $(top_builddir)/src/.libs/libzmq.a \
+	${src_libzmq_la_LIBADD}
+perf_benchmark_radix_tree_SOURCES = perf/benchmark_radix_tree.cpp
+endif
 endif
 
 if ENABLE_CURVE_KEYGEN

perf/benchmark_radix_tree.cpp

+/*
+    Copyright (c) 2018 Contributors as noted in the AUTHORS file
+
+    This file is part of libzmq, the ZeroMQ core engine in C++.
+
+    libzmq is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License (LGPL) as published
+    by the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    As a special exception, the Contributors give you permission to link
+    this library with independent modules to produce an executable,
+    regardless of the license terms of these independent modules, and to
+    copy and distribute the resulting executable under terms of your choice,
+    provided that you also meet, for each linked independent module, the
+    terms and conditions of the license of that module. An independent
+    module is a module which is not derived from or based on this library.
+    If you modify this library, you must extend this exception to your
+    version of the library.
+
+    libzmq is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+    License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#if __cplusplus >= 201103L
+
+#include "radix_tree.hpp"
+#include "trie.hpp"
+
+#include <chrono>
+#include <cstddef>
+#include <cstdio>
+#include <random>
+#include <vector>
+
+const std::size_t nkeys = 10000;
+const std::size_t nqueries = 100000;
+const std::size_t warmup_runs = 10;
+const std::size_t samples = 10;
+const std::size_t key_length = 20;
+const char *chars = "abcdefghijklmnopqrstuvwxyz0123456789";
+const int chars_len = 36;
+
+template <class T>
+void benchmark_lookup (T &t,
+                       std::vector<unsigned char *> &input_set,
+                       std::vector<unsigned char *> &queries)
+{
+    std::puts ("Starting warmup...");
+    for (std::size_t run = 0; run < warmup_runs; ++run) {
+        for (auto &query : queries)
+            t.check (query, key_length);
+    }
+
+    std::puts ("Collecting samples...");
+    std::vector<double> samples_vec;
+    samples_vec.reserve (samples);
+    for (std::size_t run = 0; run < samples; ++run) {
+        auto start = std::chrono::high_resolution_clock::now ();
+        for (auto &query : queries)
+            t.check (query, key_length);
+        auto end = std::chrono::high_resolution_clock::now ();
+        samples_vec.push_back (
+          std::chrono::duration_cast<std::chrono::milliseconds> ((end - start))
+            .count ());
+    }
+
+    for (const auto &sample : samples_vec)
+        std::printf ("%.2lf\n", sample);
+}
+
+int main ()
+{
+    // Generate input set.
+    std::minstd_rand rng (123456789);
+    std::vector<unsigned char *> input_set;
+    std::vector<unsigned char *> queries;
+    input_set.reserve (nkeys);
+    queries.reserve (nqueries);
+
+    for (std::size_t i = 0; i < nkeys; ++i) {
+        unsigned char *key = new unsigned char[key_length];
+        for (std::size_t j = 0; j < key_length; j++)
+            key[j] = static_cast<unsigned char> (chars[rng () % chars_len]);
+        input_set.emplace_back (key);
+    }
+    for (std::size_t i = 0; i < nqueries; ++i)
+        queries.push_back (input_set[rng () % nkeys]);
+
+    // Initialize both data structures.
+    //
+    // Keeping initialization out of the benchmarking function helps
+    // heaptrack detect peak memory consumption of the radix tree.
+    zmq::trie_t trie;
+    zmq::radix_tree radix_tree;
+    for (auto &key : input_set) {
+        trie.add (key, key_length);
+        radix_tree.add (key, key_length);
+    }
+
+    // Create a benchmark.
+    std::puts ("[trie]");
+    benchmark_lookup (trie, input_set, queries);
+
+    std::puts ("[radix_tree]");
+    benchmark_lookup (radix_tree, input_set, queries);
+
+    for (auto &op : input_set)
+        delete[] op;
+}
+
+#else
+
+int main ()
+{
+}
+
+#endif

src/radix_tree.cpp

@@ -210,9 +210,9 @@ match_result::match_result (size_t i,
 {
 }
 
-inline match_result zmq::radix_tree::match (const unsigned char *key,
-                                            size_t size,
-                                            bool check = false) const
+match_result zmq::radix_tree::match (const unsigned char *key,
+                                     size_t size,
+                                     bool check = false) const
 {
     zmq_assert (key);
 
@@ -553,26 +553,3 @@ size_t zmq::radix_tree::size () const
 {
     return size_;
 }
-
-static void visit_child (node child_node, size_t level)
-{
-    zmq_assert (level > 0);
-
-    for (size_t i = 0; i < 4 * (level - 1) + level; ++i)
-        putchar (' ');
-    printf ("`-> ");
-    for (uint32_t i = 0; i < child_node.prefix_length (); ++i)
-        printf ("%c", child_node.prefix ()[i]);
-    if (child_node.refcount () > 0)
-        printf (" [*]");
-    printf ("\n");
-    for (uint32_t i = 0; i < child_node.edgecount (); ++i)
-        visit_child (child_node.node_at (i), level + 1);
-}
-
-void zmq::radix_tree::print ()
-{
-    puts ("[root]");
-    for (uint32_t i = 0; i < root_.edgecount (); ++i)
-        visit_child (root_.node_at (i), 1);
-}

src/radix_tree.hpp

@@ -133,11 +133,10 @@ class radix_tree
     void apply (void (*func) (unsigned char *data_, size_t size_, void *arg_),
                 void *arg);
 
-    void print ();
     size_t size () const;
 
   private:
-    match_result
+    inline match_result
     match (const unsigned char *key, size_t size, bool check) const;
 
     node root_;

unittests/unittest_radix_tree.cpp

@@ -256,26 +256,6 @@ void test_apply ()
     delete vec;
 }
 
-void test_print ()
-{
-    zmq::radix_tree tree;
-
-    // Adapted from the example on wikipedia.
-    std::vector<std::string> keys;
-    keys.push_back ("tester");
-    keys.push_back ("water");
-    keys.push_back ("slow");
-    keys.push_back ("slower");
-    keys.push_back ("test");
-    keys.push_back ("team");
-    keys.push_back ("toast");
-
-    for (size_t i = 0; i < keys.size (); ++i)
-        tree_add (tree, keys[i]);
-
-    tree.print ();
-}
-
 int main (void)
 {
     setup_test_environment ();
@@ -306,7 +286,5 @@ int main (void)
 
     RUN_TEST (test_apply);
 
-    RUN_TEST (test_print);
-
     return UNITY_END ();
 }