osrm-backend/third_party/libosmium/examples/osmium_location_cache_use.cpp

109 lines
3.5 KiB
C++

/*
EXAMPLE osmium_location_cache_use
This reads ways from an OSM file and writes out the way node locations
it got from a location cache generated with osmium_location_cache_create.
Warning: The locations cache file will get huge (>32GB) if you are using
the DenseFileArray index even if the input file is small, because
it depends on the *largest* node ID, not the number of nodes.
DEMONSTRATES USE OF:
* file input
* location indexes and the NodeLocationsForWays handler
* location indexes on disk
SIMPLER EXAMPLES you might want to understand first:
* osmium_read
* osmium_count
* osmium_road_length
LICENSE
The code in this example file is released into the Public Domain.
*/
#include <cerrno> // for errno
#include <cstdlib> // for std::exit
#include <cstring> // for strerror
#include <fcntl.h> // for open
#include <iostream> // for std::cout, std::cerr
#include <string> // for std::string
#include <sys/stat.h> // for open
#include <sys/types.h> // for open
#ifdef _WIN32
# include <io.h> // for _setmode
#endif
// Allow any format of input files (XML, PBF, ...)
#include <osmium/io/any_input.hpp>
// For the location index. There are different types of index implementation
// available. These implementations put the index on disk. See below.
#include <osmium/index/map/dense_file_array.hpp>
#include <osmium/index/map/sparse_file_array.hpp>
// For the NodeLocationForWays handler
#include <osmium/handler/node_locations_for_ways.hpp>
// For osmium::apply()
#include <osmium/visitor.hpp>
// Chose one of these two. "sparse" is best used for small and medium extracts,
// the "dense" index for large extracts or the whole planet.
using index_type = osmium::index::map::SparseFileArray<osmium::unsigned_object_id_type, osmium::Location>;
//using index_type = osmium::index::map::DenseFileArray<osmium::unsigned_object_id_type, osmium::Location>;
// The location handler always depends on the index type
using location_handler_type = osmium::handler::NodeLocationsForWays<index_type>;
// This handler only implements the way() function which prints out the way
// ID and all nodes IDs and locations in those ways.
struct MyHandler : public osmium::handler::Handler {
void way(const osmium::Way& way) {
std::cout << "way " << way.id() << "\n";
for (const auto& nr : way.nodes()) {
std::cout << " node " << nr.ref() << " " << nr.location() << "\n";
}
}
}; // struct MyHandler
int main(int argc, char* argv[]) {
if (argc != 3) {
std::cerr << "Usage: " << argv[0] << " OSM_FILE CACHE_FILE\n";
std::exit(1);
}
const std::string input_filename{argv[1]};
const std::string cache_filename{argv[2]};
// Construct Reader reading only ways
osmium::io::Reader reader{input_filename, osmium::osm_entity_bits::way};
// Initialize location index on disk using an existing file
const int fd = ::open(cache_filename.c_str(), O_RDWR);
if (fd == -1) {
std::cerr << "Can not open location cache file '" << cache_filename << "': " << std::strerror(errno) << "\n";
return 1;
}
#ifdef _WIN32
_setmode(fd, _O_BINARY);
#endif
index_type index{fd};
// The handler that adds node locations from the index to the ways.
location_handler_type location_handler{index};
// Feed all ways through the location handler and then our own handler.
MyHandler handler;
osmium::apply(reader, location_handler, handler);
// Explicitly close input so we get notified of any errors.
reader.close();
}