mxx::file interface

include/mxx/file.hpp

@@ -22,7 +22,6 @@
  * This is not a substitute for MPI_File functionality.
  * TODO:
  * - [ ] Implement proper MPI_File functions for parallel reading of files
- * - [ ] HDF5 ?
  */
 
 #ifndef MXX_FILE_HPP
@@ -78,6 +77,144 @@ class rangebuf: public std::streambuf {
  char* buf_;
 };
 
+
+struct file {
+protected:
+ MPI_File handle;
+ std::string filename;
+ bool isopen;
+
+
+ void clear() {
+ handle = MPI_FILE_NULL;
+ filename = "";
+ isopen = false;
+ }
+public:
+ file() : handle(MPI_FILE_NULL), filename(), isopen(false) {}
+
+ file(file&& o) : handle(o.handle), filename(o.filename), isopen(o.isopen) {
+ o.clear();
+ }
+
+ file(const std::string& filename) : handle(MPI_FILE_NULL), filename(filename), isopen(false) {}
+
+ file(const std::string& filename, int mode) : file(filename) {
+ open(mode);
+ }
+
+ void open(const std::string& filename, int mode) {
+ this->filename = filename;
+ MPI_File_open(MPI_COMM_SELF, filename.c_str(), mode, MPI_INFO_NULL, &handle);
+ this->isopen = true;
+ }
+
+ void open(int mode) {
+ open(this->filename, mode);
+ }
+
+ void close() {
+ if (isopen) {
+ MPI_File_close(&handle);
+ isopen = false;
+ handle = MPI_FILE_NULL;
+ }
+ }
+
+ static void delete_file(const std::string& filename) {
+ MPI_File_delete(filename.c_str(), MPI_INFO_NULL);
+ }
+
+
+ size_t get_size() {
+ MPI_Offset s;
+ MPI_File_get_size(handle, &s);
+ return s;
+ }
+
+ void set_size(size_t size) {
+ MPI_File_set_size(handle, size);
+ }
+
+ template <typename T>
+ void read_at(MPI_Offset offset, T* out, size_t count) {
+ mxx::datatype dt = mxx::get_datatype<T>().contiguous(count);
+ MPI_File_read_at(handle, offset, out, 1, dt.type(), MPI_STATUS_IGNORE);
+ }
+
+ template <typename T>
+ void write_at(MPI_Offset offset, T* data, size_t count) {
+ mxx::datatype dt = mxx::get_datatype<T>().contiguous(count);
+ MPI_File_write_at(handle, offset, data, 1, dt.type(), MPI_STATUS_IGNORE);
+ }
+
+ // TODO:
+
+ // iread_at
+ // iwrite_at
+ //
+ // read_at_all
+ // write_at_all
+ //
+ // iread_at_all
+ // iwrite_at_all
+ //
+ // read
+ // write
+ //
+ // read_all
+ // write_all
+ //
+ // iread
+ // iwrite
+ //
+ // iread_all
+ // iwrite_all
+ //
+ //
+ //
+ // seek_set
+ // seek_cur
+ // seek_end
+ //
+ // get_pos // `etype` units
+ // get_byte_offset
+ //
+ //
+ //
+
+ virtual ~file() {
+ close();
+ }
+};
+
+struct coll_file : public file {
+ const mxx::comm& comm;
+
+ coll_file(const std::string& filename, const mxx::comm& comm)
+ : file(filename), comm(comm) {}
+
+
+ template <typename T>
+ void read_ordered(size_t count, T* out) {
+ mxx::datatype dt = mxx::get_datatype<T>().contiguous(count);
+ MPI_File_read_ordered(handle, out, 1, dt.type(), MPI_STATUS_IGNORE);
+ }
+
+ // collective, blocking
+ // simple ordered write without a need for a file view
+ template <typename T>
+ void write_ordered(const T* buf, size_t count) {
+ mxx::datatype dt = mxx::get_datatype<T>().contiguous(count);
+ MPI_File_write_ordered(handle, const_cast<T*>(buf), 1, dt.type(), MPI_STATUS_IGNORE);
+ }
+
+ void open(int mode) {
+ MPI_File_open(comm, &filename[0], mode, MPI_INFO_NULL, &handle);
+ this->isopen = true;
+ }
+};
+
 std::string file_block_decompose(const char* filename, MPI_Comm comm = MPI_COMM_WORLD, std::size_t max_local_size = 0)
 {
  // TODO: handle error if file doesn't exist