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#ifdef _WIN32
#include <windows.h>
#include <sysinfoapi.h>
#else
#include <unistd.h>
#endif
#include "simdjson.h"
#include <cstdio>
#include <vector>
// Returns the default size of the page in bytes on this system.
long page_size() {
#ifdef _WIN32
SYSTEM_INFO sysInfo;
GetSystemInfo(&sysInfo);
long pagesize = sysInfo.dwPageSize;
#else
long pagesize = sysconf(_SC_PAGESIZE);
#endif
return pagesize;
}
// Returns true if the buffer + len + simdjson::SIMDJSON_PADDING crosses the
// page boundary.
bool need_allocation(const char *buf, size_t len) {
return ((reinterpret_cast<uintptr_t>(buf + len - 1) % page_size())
+ simdjson::SIMDJSON_PADDING >= static_cast<uintptr_t>(page_size()));
}
bool check_need_allocation() {
long ps = page_size();
std::vector<std::tuple<uintptr_t,size_t,bool>> test_cases = {
{2*ps, 5, false}, {2*ps, ps, true}, {2*ps, 100, false},
};
for(auto t : test_cases) {
uintptr_t buf = std::get<0>(t);
size_t len = std::get<1>(t);
bool expected = std::get<2>(t);
if(need_allocation(reinterpret_cast<const char *>(buf), len) != expected) {
return false;
}
}
return true;
}
simdjson::padded_string_view
get_padded_string_view(const char *buf, size_t len,
simdjson::padded_string &jsonbuffer) {
if (need_allocation(buf, len)) { // unlikely case
jsonbuffer = simdjson::padded_string(buf, len);
return jsonbuffer;
} else { // no reallcation needed (very likely)
return simdjson::padded_string_view(buf, len,
len + simdjson::SIMDJSON_PADDING);
}
}
int main() {
printf("page_size: %ld\n", page_size());
if(!check_need_allocation()) {
printf("Bug in the need_allocation function.\n");
return EXIT_FAILURE;
}
const char *jsonpoiner = R"(
{
"key": "value"
}
)";
size_t len = strlen(jsonpoiner);
simdjson::padded_string jsonbuffer; // only allocate if needed
simdjson::ondemand::parser parser;
simdjson::ondemand::document doc;
simdjson::error_code error =
parser.iterate(get_padded_string_view(jsonpoiner, len, jsonbuffer))
.get(doc);
if (error) {
printf("error: %s\n", simdjson::error_message(error));
return EXIT_FAILURE;
}
std::string_view value;
error = doc["key"].get_string().get(value);
if (error) {
return EXIT_FAILURE;
}
printf("Value: \"%.*s\"\n", (int)value.size(), value.data());
if (value != "value") {
return EXIT_FAILURE;
}
return EXIT_SUCCESS;
}
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