bench: add "priority level" to the benchmark framework

Will allow us to run certain benchmarks while skip
non-prioritized ones in 'make check'.

src/bench/bench.cpp

@@ -6,6 +6,7 @@
 
 #include <fs.h>
 #include <test/util/setup_common.h>
+#include <util/string.h>
 
 #include <chrono>
 #include <fstream>
@@ -43,15 +44,37 @@ void GenerateTemplateResults(const std::vector<ankerl::nanobench::Result>& bench
 
 namespace benchmark {
 
+// map a label to one or multiple priority levels
+std::map<std::string, uint8_t> map_label_priority = {
+    {"high", PriorityLevel::HIGH},
+    {"low", PriorityLevel::LOW},
+    {"all", 0xff}
+};
+
+std::string ListPriorities()
+{
+    using item_t = std::pair<std::string, uint8_t>;
+    auto sort_by_priority = [](item_t a, item_t b){ return a.second < b.second; };
+    std::set<item_t, decltype(sort_by_priority)> sorted_priorities(map_label_priority.begin(), map_label_priority.end(), sort_by_priority);
+    return Join(sorted_priorities, ',', [](const auto& entry){ return entry.first; });
+}
+
+uint8_t StringToPriority(const std::string& str)
+{
+    auto it = map_label_priority.find(str);
+    if (it == map_label_priority.end()) throw std::runtime_error(strprintf("Unknown priority level %s", str));
+    return it->second;
+}
+
 BenchRunner::BenchmarkMap& BenchRunner::benchmarks()
 {
-    static std::map<std::string, BenchFunction> benchmarks_map;
+    static BenchmarkMap benchmarks_map;
     return benchmarks_map;
 }
 
-BenchRunner::BenchRunner(std::string name, BenchFunction func)
+BenchRunner::BenchRunner(std::string name, BenchFunction func, PriorityLevel level)
 {
-    benchmarks().insert(std::make_pair(name, func));
+    benchmarks().insert(std::make_pair(name, std::make_pair(func, level)));
 }
 
 void BenchRunner::RunAll(const Args& args)
@@ -64,13 +87,19 @@ void BenchRunner::RunAll(const Args& args)
     }
 
     std::vector<ankerl::nanobench::Result> benchmarkResults;
-    for (const auto& p : benchmarks()) {
-        if (!std::regex_match(p.first, baseMatch, reFilter)) {
+    for (const auto& [name, bench_func] : benchmarks()) {
+        const auto& [func, priority_level] = bench_func;
+
+        if (!(priority_level & args.priority)) {
+            continue;
+        }
+
+        if (!std::regex_match(name, baseMatch, reFilter)) {
             continue;
         }
 
         if (args.is_list_only) {
-            std::cout << p.first << std::endl;
+            std::cout << name << std::endl;
             continue;
         }
 
@@ -78,7 +107,7 @@ void BenchRunner::RunAll(const Args& args)
         if (args.sanity_check) {
             bench.epochs(1).epochIterations(1);
         }
-        bench.name(p.first);
+        bench.name(name);
         if (args.min_time > 0ms) {
             // convert to nanos before dividing to reduce rounding errors
             std::chrono::nanoseconds min_time_ns = args.min_time;
@@ -86,11 +115,11 @@ void BenchRunner::RunAll(const Args& args)
         }
 
         if (args.asymptote.empty()) {
-            p.second(bench);
+            func(bench);
         } else {
             for (auto n : args.asymptote) {
                 bench.complexityN(n);
-                p.second(bench);
+                func(bench);
             }
             std::cout << bench.complexityBigO() << std::endl;
         }