Replace current benchmarking framework with nanobench

This replaces the current benchmarking framework with nanobench [1], an
MIT licensed single-header benchmarking library, of which I am the
autor. This has in my opinion several advantages, especially on Linux:

* fast: Running all benchmarks takes ~6 seconds instead of 4m13s on
  an Intel i7-8700 CPU @ 3.20GHz.

* accurate: I ran e.g. the benchmark for SipHash_32b 10 times and
  calculate standard deviation / mean = coefficient of variation:

  * 0.57% CV for old benchmarking framework
  * 0.20% CV for nanobench

  So the benchmark results with nanobench seem to vary less than with
  the old framework.

* It automatically determines runtime based on clock precision, no need
  to specify number of evaluations.

* measure instructions, cycles, branches, instructions per cycle,
  branch misses (only Linux, when performance counters are available)

* output in markdown table format.

* Warn about unstable environment (frequency scaling, turbo, ...)

* For better profiling, it is possible to set the environment variable
  NANOBENCH_ENDLESS to force endless running of a particular benchmark
  without the need to recompile. This makes it to e.g. run "perf top"
  and look at hotspots.

Here is an example copy & pasted from the terminal output:

|             ns/byte |              byte/s |    err% |        ins/byte |        cyc/byte |    IPC |       bra/byte |   miss% |     total | benchmark
|--------------------:|--------------------:|--------:|----------------:|----------------:|-------:|---------------:|--------:|----------:|:----------
|                2.52 |      396,529,415.94 |    0.6% |           25.42 |            8.02 |  3.169 |           0.06 |    0.0% |      0.03 | `bench/crypto_hash.cpp RIPEMD160`
|                1.87 |      535,161,444.83 |    0.3% |           21.36 |            5.95 |  3.589 |           0.06 |    0.0% |      0.02 | `bench/crypto_hash.cpp SHA1`
|                3.22 |      310,344,174.79 |    1.1% |           36.80 |           10.22 |  3.601 |           0.09 |    0.0% |      0.04 | `bench/crypto_hash.cpp SHA256`
|                2.01 |      496,375,796.23 |    0.0% |           18.72 |            6.43 |  2.911 |           0.01 |    1.0% |      0.00 | `bench/crypto_hash.cpp SHA256D64_1024`
|                7.23 |      138,263,519.35 |    0.1% |           82.66 |           23.11 |  3.577 |           1.63 |    0.1% |      0.00 | `bench/crypto_hash.cpp SHA256_32b`
|                3.04 |      328,780,166.40 |    0.3% |           35.82 |            9.69 |  3.696 |           0.03 |    0.0% |      0.03 | `bench/crypto_hash.cpp SHA512`

[1] https://github.com/martinus/nanobench

* Adds support for asymptotes

  This adds support to calculate asymptotic complexity of a benchmark.
  This is similar to #17375, but currently only one asymptote is
  supported, and I have added support in the benchmark `ComplexMemPool`
  as an example.

  Usage is e.g. like this:

  ```
  ./bench_bitcoin -filter=ComplexMemPool -asymptote=25,50,100,200,400,600,800
  ```

  This runs the benchmark `ComplexMemPool` several times but with
  different complexityN settings. The benchmark can extract that number
  and use it accordingly. Here, it's used for `childTxs`. The output is
  this:

  | complexityN |               ns/op |                op/s |    err% |          ins/op |          cyc/op |    IPC |     total | benchmark
  |------------:|--------------------:|--------------------:|--------:|----------------:|----------------:|-------:|----------:|:----------
  |          25 |        1,064,241.00 |              939.64 |    1.4% |    3,960,279.00 |    2,829,708.00 |  1.400 |      0.01 | `ComplexMemPool`
  |          50 |        1,579,530.00 |              633.10 |    1.0% |    6,231,810.00 |    4,412,674.00 |  1.412 |      0.02 | `ComplexMemPool`
  |         100 |        4,022,774.00 |              248.58 |    0.6% |   16,544,406.00 |   11,889,535.00 |  1.392 |      0.04 | `ComplexMemPool`
  |         200 |       15,390,986.00 |               64.97 |    0.2% |   63,904,254.00 |   47,731,705.00 |  1.339 |      0.17 | `ComplexMemPool`
  |         400 |       69,394,711.00 |               14.41 |    0.1% |  272,602,461.00 |  219,014,691.00 |  1.245 |      0.76 | `ComplexMemPool`
  |         600 |      168,977,165.00 |                5.92 |    0.1% |  639,108,082.00 |  535,316,887.00 |  1.194 |      1.86 | `ComplexMemPool`
  |         800 |      310,109,077.00 |                3.22 |    0.1% |1,149,134,246.00 |  984,620,812.00 |  1.167 |      3.41 | `ComplexMemPool`

  |   coefficient |   err% | complexity
  |--------------:|-------:|------------
  |   4.78486e-07 |   4.5% | O(n^2)
  |   6.38557e-10 |  21.7% | O(n^3)
  |   3.42338e-05 |  38.0% | O(n log n)
  |   0.000313914 |  46.9% | O(n)
  |     0.0129823 | 114.4% | O(log n)
  |     0.0815055 | 133.8% | O(1)

  The best fitting curve is O(n^2), so the algorithm seems to scale
  quadratic with `childTxs` in the range 25 to 800.

1 files changed, 24 insertions, 40 deletions

diff --git a/src/bench/bench_bitcoin.cpp b/src/bench/bench_bitcoin.cpp
index 1b75854210..981800c68e 100644
--- a/src/bench/bench_bitcoin.cpp
+++ b/src/bench/bench_bitcoin.cpp
@@ -9,26 +9,30 @@
 
 #include <memory>
 
-static const int64_t DEFAULT_BENCH_EVALUATIONS = 5;
 static const char* DEFAULT_BENCH_FILTER = ".*";
-static const char* DEFAULT_BENCH_SCALING = "1.0";
-static const char* DEFAULT_BENCH_PRINTER = "console";
-static const char* DEFAULT_PLOT_PLOTLYURL = "https://cdn.plot.ly/plotly-latest.min.js";
-static const int64_t DEFAULT_PLOT_WIDTH = 1024;
-static const int64_t DEFAULT_PLOT_HEIGHT = 768;
 
 static void SetupBenchArgs(ArgsManager& argsman)
 {
     SetupHelpOptions(argsman);
 
-    argsman.AddArg("-list", "List benchmarks without executing them. Can be combined with -scaling and -filter", ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
-    argsman.AddArg("-evals=<n>", strprintf("Number of measurement evaluations to perform. (default: %u)", DEFAULT_BENCH_EVALUATIONS), ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
+    argsman.AddArg("-list", "List benchmarks without executing them", ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     argsman.AddArg("-filter=<regex>", strprintf("Regular expression filter to select benchmark by name (default: %s)", DEFAULT_BENCH_FILTER), ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
-    argsman.AddArg("-scaling=<n>", strprintf("Scaling factor for benchmark's runtime (default: %u)", DEFAULT_BENCH_SCALING), ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
-    argsman.AddArg("-printer=(console|plot)", strprintf("Choose printer format. console: print data to console. plot: Print results as HTML graph (default: %s)", DEFAULT_BENCH_PRINTER), ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
-    argsman.AddArg("-plot-plotlyurl=<uri>", strprintf("URL to use for plotly.js (default: %s)", DEFAULT_PLOT_PLOTLYURL), ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
-    argsman.AddArg("-plot-width=<x>", strprintf("Plot width in pixel (default: %u)", DEFAULT_PLOT_WIDTH), ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
-    argsman.AddArg("-plot-height=<x>", strprintf("Plot height in pixel (default: %u)", DEFAULT_PLOT_HEIGHT), ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
+    argsman.AddArg("-asymptote=n1,n2,n3,...", strprintf("Test asymptotic growth of the runtime of an algorithm, if supported by the benchmark"), ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
+    argsman.AddArg("-output_csv=<output.csv>", "Generate CSV file with the most important benchmark results.", ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
+    argsman.AddArg("-output_json=<output.json>", "Generate JSON file with all benchmark results.", ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
+}
+
+// parses a comma separated list like "10,20,30,50"
+static std::vector<double> parseAsymptote(const std::string& str) {
+    std::stringstream ss(str);
+    std::vector<double> numbers;
+    double d;
+    char c;
+    while (ss >> d) {
+        numbers.push_back(d);
+        ss >> c;
+    }
+    return numbers;
 }
 
 int main(int argc, char** argv)
@@ -47,34 +51,14 @@ int main(int argc, char** argv)
         return EXIT_SUCCESS;
     }
 
-    int64_t evaluations = argsman.GetArg("-evals", DEFAULT_BENCH_EVALUATIONS);
-    std::string regex_filter = argsman.GetArg("-filter", DEFAULT_BENCH_FILTER);
-    std::string scaling_str = argsman.GetArg("-scaling", DEFAULT_BENCH_SCALING);
-    bool is_list_only = argsman.GetBoolArg("-list", false);
-
-    if (evaluations == 0) {
-        return EXIT_SUCCESS;
-    } else if (evaluations < 0) {
-        tfm::format(std::cerr, "Error parsing evaluations argument: %d\n", evaluations);
-        return EXIT_FAILURE;
-    }
-
-    double scaling_factor;
-    if (!ParseDouble(scaling_str, &scaling_factor)) {
-        tfm::format(std::cerr, "Error parsing scaling factor as double: %s\n", scaling_str);
-        return EXIT_FAILURE;
-    }
-
-    std::unique_ptr<benchmark::Printer> printer = MakeUnique<benchmark::ConsolePrinter>();
-    std::string printer_arg = argsman.GetArg("-printer", DEFAULT_BENCH_PRINTER);
-    if ("plot" == printer_arg) {
-        printer.reset(new benchmark::PlotlyPrinter(
-            argsman.GetArg("-plot-plotlyurl", DEFAULT_PLOT_PLOTLYURL),
-            argsman.GetArg("-plot-width", DEFAULT_PLOT_WIDTH),
-            argsman.GetArg("-plot-height", DEFAULT_PLOT_HEIGHT)));
-    }
+    benchmark::Args args;
+    args.regex_filter = argsman.GetArg("-filter", DEFAULT_BENCH_FILTER);
+    args.is_list_only = argsman.GetBoolArg("-list", false);
+    args.asymptote = parseAsymptote(argsman.GetArg("-asymptote", ""));
+    args.output_csv = argsman.GetArg("-output_csv", "");
+    args.output_json = argsman.GetArg("-output_json", "");
 
-    benchmark::BenchRunner::RunAll(*printer, evaluations, scaling_factor, regex_filter, is_list_only);
+    benchmark::BenchRunner::RunAll(args);
 
     return EXIT_SUCCESS;
 }