Adding a "get_corpus" benchmark. (#456)

* Adding a "get_corpus" benchmark.

* Improving portability.

Makefile

@@ -160,6 +160,10 @@ $(JSON_INCLUDE) $(SAJSON_INCLUDE) $(RAPIDJSON_INCLUDE) $(JSON11_INCLUDE) $(FASTJ
 parse: benchmark/parse.cpp benchmark/json_parser.h benchmark/event_counter.h benchmark/benchmarker.h $(HEADERS) $(LIBFILES)
 	$(CXX) $(CXXFLAGS) -o parse $(LIBFILES) benchmark/parse.cpp $(LIBFLAGS)
 
+get_corpus_benchmark: benchmark/get_corpus_benchmark.cpp  $(HEADERS) $(LIBFILES)
+	$(CXX) $(CXXFLAGS) -o get_corpus_benchmark $(LIBFILES) benchmark/get_corpus_benchmark.cpp $(LIBFLAGS)
+
+
 parse_stream: benchmark/parse_stream.cpp benchmark/json_parser.h benchmark/event_counter.h benchmark/benchmarker.h $(HEADERS) $(LIBFILES)
 	$(CXX) $(CXXFLAGS) -o parse_stream $(LIBFILES) benchmark/parse_stream.cpp $(LIBFLAGS)
 

benchmark/CMakeLists.txt

@@ -7,5 +7,6 @@ target_include_directories(${SIMDJSON_LIB_NAME}
 add_cpp_benchmark(parse)
 add_cpp_benchmark(statisticalmodel)
 add_cpp_benchmark(parse_stream)
+add_cpp_benchmark(get_corpus_benchmark)
 
 add_executable(perfdiff perfdiff.cpp)

benchmark/get_corpus_benchmark.cpp

@@ -0,0 +1,54 @@
+
+#include "simdjson/common_defs.h"
+#include "simdjson/jsonioutil.h"
+#include "simdjson/jsonparser.h"
+#include <chrono>
+#include <cstring>
+#include <iostream>
+
+never_inline
+double bench(std::string filename, simdjson::padded_string& p) {
+  std::chrono::time_point<std::chrono::steady_clock> start_clock =
+      std::chrono::steady_clock::now();
+  simdjson::get_corpus(filename).swap(p);
+  std::chrono::time_point<std::chrono::steady_clock> end_clock =
+      std::chrono::steady_clock::now();
+  std::chrono::duration<double> elapsed = end_clock - start_clock;
+  return (p.size() / (1024. * 1024 * 1024.)) / elapsed.count();
+}
+
+int main(int argc, char *argv[]) {
+  int optind = 1;
+  if (optind >= argc) {
+    std::cerr << "Reads document as far as possible. " << std::endl;
+    std::cerr << "Usage: " << argv[0] << " <jsonfile>" << std::endl;
+    exit(1);
+  }
+  const char *filename = argv[optind];
+  if (optind + 1 < argc) {
+    std::cerr << "warning: ignoring everything after " << argv[optind + 1]
+              << std::endl;
+  }
+  simdjson::padded_string p;
+  bench(filename, p); 
+  double meanval = 0;
+  double maxval = 0;
+  double minval = 10000;
+std::cout << "file size: "<<  (p.size() / (1024. * 1024 * 1024.)) << " GB" <<std::endl;
+  size_t times = p.size() > 1024*1024*1024 ? 5 : 50;
+  try {
+    for(size_t i = 0; i < times; i++) {
+      double tval = bench(filename, p);
+      if(maxval < tval) maxval = tval;
+      if(minval > tval) minval = tval;
+      meanval += tval;
+    }
+   } catch (const std::exception &) { // caught by reference to base
+    std::cerr << "Could not load the file " << filename << std::endl;
+    return EXIT_FAILURE;
+   }
+   std::cout << "average speed: " << meanval / times << " GB/s"<< std::endl;
+   std::cout << "min speed    : " << minval << " GB/s" << std::endl;
+   std::cout << "max speed    : " << maxval << " GB/s" << std::endl;
+   return EXIT_SUCCESS;
+}