/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Copyright by The HDF Group. * * Copyright by the Board of Trustees of the University of Illinois. * * All rights reserved. * * * * This file is part of HDF5. The full HDF5 copyright notice, including * * terms governing use, modification, and redistribution, is contained in * * the files COPYING and Copyright.html. COPYING can be found at the root * * of the source code distribution tree; Copyright.html can be found at the * * root level of an installed copy of the electronic HDF5 document set and * * is linked from the top-level documents page. It can also be found at * * http://hdfgroup.org/HDF5/doc/Copyright.html. If you do not have * * access to either file, you may request a copy from help@hdfgroup.org. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ /* * This program illustrates the usage of HDF5's implicit message sharing * feature, which can be used to save space when the same messages are * used many times in a file. * * This example creates a standard file using file creation property lists * to control which messages are shared. Messages that can be shared are * datatypes, dataspaces, attributes, fill values, and filter pipelines. * In this example, with messages sharing feature on, the file size is * reduced by 15%. * */ #include #include "hdf5.h" #define NUM_DATASETS 40 const char* DSETNAME[] = { "dataset0", "dataset1", "dataset2", "dataset3", "dataset4", "dataset5", "dataset6", "dataset7", "dataset8", "dataset9", "dataset10", "dataset11", "dataset12", "dataset13", "dataset14", "dataset15", "dataset16", "dataset17", "dataset18", "dataset19", "dataset20", "dataset21", "dataset22", "dataset23", "dataset24", "dataset25", "dataset26", "dataset27", "dataset28", "dataset29", "dataset30", "dataset31", "dataset32", "dataset33", "dataset34", "dataset35", "dataset36", "dataset37", "dataset38", "dataset39", NULL }; herr_t create_standard_file(const char *filename, hid_t fcpl); /*------------------------------------------------------------------------- * Function: main * * Purpose: Enables shared messages using File Creation Property Lists * and creates files using these settings. * *------------------------------------------------------------------------- */ int main(void) { hid_t fcpl_id; herr_t ret; /* Create a file creation property list */ fcpl_id = H5Pcreate(H5P_FILE_CREATE); if(fcpl_id < 0) goto error; /* Create a file without shared message. */ ret = create_standard_file("default_file.h5", fcpl_id); if(ret < 0) goto error; /* There are five kinds of messages that can be shared: datatypes, * dataspaces, attributes, fill values, and filter pipelines. * Shared messages are stored in up to five "indexes," this example * only uses one index. */ /* To begin with, use only one index. */ ret = H5Pset_shared_mesg_nindexes(fcpl_id, 1); if(ret < 0) goto error; /* Each index has a "minimum message size" for a message of that * type to be shared. Since sharing a message creates some overhead, * this is to prevent this overhead for very small messages when little * space would be saved by sharing them . * Let's set the message size to be 40. */ ret = H5Pset_shared_mesg_index(fcpl_id, 0, H5O_MESG_ALL_FLAG, 40); if(ret < 0) goto error; /* Each shared message index beins life as a simple list of messages * and becomes a B-tree when "too many" messages are written to it. * This keeps the indexes simple when only a few messages are shared, * but allows them to scale for many messages. * The first value is the maximum list size, the * second the minimum B-tree size. */ ret = H5Pset_shared_mesg_phase_change(fcpl_id, 30, 20); if(ret < 0) goto error; /* Now create a file with shared messages. */ ret = create_standard_file("one_index_file.h5", fcpl_id); if(ret < 0) goto error; /* Close the property list */ ret = H5Pclose(fcpl_id); if(ret < 0) goto error; return 0; error: return -1; } /*------------------------------------------------------------------------- * Function: create_standard_file * * Purpose: A helper functon for the example. Creates an HDF5 file * with many repeated messages using the file creation * property list FCPL. * * This function only uses datatypes and dataspaces. *------------------------------------------------------------------------- */ herr_t create_standard_file(const char *filename, hid_t fcpl_id) { /* First structure and dataset*/ typedef struct { int a; float b; } s1_t; typedef struct { int c; s1_t d; } s2_t; s2_t s2[10]; hid_t s1_tid,s2_tid; /* File datatype identifier */ hid_t file_id=-1; hsize_t dims[] = {10}; hid_t space_id=-1; hid_t dset_id=-1; int i,x; herr_t ret; /* Create the file */ file_id = H5Fcreate(filename, H5F_ACC_TRUNC, fcpl_id, H5P_DEFAULT); if(file_id < 0) goto error; /* Create the datatype we'll be using. Generally, sharing messages * is most useful when the message is complex and takes more space on * disk, so the type in this example will be an compound type rather than an atomic type. * However, any type can be shared. */ for( i=0;i<10;i++) { s2[i].c=i; s2[i].d.a=i+1; s2[i].d.b=i*0.6; } /* Create the data type. */ s1_tid = H5Tcreate (H5T_COMPOUND, sizeof(s1_t)); H5Tinsert(s1_tid, "inner_int", HOFFSET(s1_t, a), H5T_NATIVE_INT); H5Tinsert(s1_tid, "inner_float", HOFFSET(s1_t, b), H5T_NATIVE_FLOAT); s2_tid = H5Tcreate (H5T_COMPOUND, sizeof(s2_t)); H5Tinsert(s2_tid,"outer_int",HOFFSET(s2_t,c),H5T_NATIVE_INT); H5Tinsert(s2_tid,"outer_com",HOFFSET(s2_t,d),s1_tid); /* Create the dataspace we'll be using. */ space_id = H5Screate_simple(1, dims, NULL); if(space_id < 0) goto error; /* Begin using the messages many times. Do this by creating datasets * that use this datatype, dataspace. */ for(x = 0; x < NUM_DATASETS; ++x) { for( i=0;i<10;i++) { s2[i].c=i+x; s2[i].d.a=i+x+1; s2[i].d.b=(i+x)*0.6; } /* Create a dataset */ dset_id = H5Dcreate(file_id, DSETNAME[x], s2_tid, space_id, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT); if(dset_id < 0) goto error; ret = H5Dwrite(dset_id, s2_tid, H5S_ALL, H5S_ALL, H5P_DEFAULT, s2); } ret = H5Tclose(s1_tid); if(ret < 0) goto error; ret = H5Tclose(s2_tid); if(ret < 0) goto error; ret = H5Sclose(space_id); if(ret < 0) goto error; ret = H5Fclose(file_id); if(ret < 0) goto error; return 0; error: return -1; }