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90 lines
2.8 KiB
C
90 lines
2.8 KiB
C
/************************************************************
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This example shows how to use the external file cache.
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This file is intended for use with HDF5 Library version
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1.8.7 or newer
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************************************************************/
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#include "hdf5.h"
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#define FILENAME "h5efc.h5"
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#define EXT_FILE1 "h5efc1.h5"
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#define EXT_FILE2 "h5efc2.h5"
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#define EXT_FILE3 "h5efc3.h5"
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int
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main(void)
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{
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hid_t file1, file2, group, fapl; /* Handles */
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herr_t status;
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/*
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* Create file access property list and set it to allow caching of open
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* files visited through external links.
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*/
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fapl = H5Pcreate(H5P_FILE_ACCESS);
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status = H5Pset_elink_file_cache_size(fapl, 8);
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/*
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* Create a new file using the file access property list.
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*/
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file1 = H5Fcreate(FILENAME, H5F_ACC_TRUNC, H5P_DEFAULT, fapl);
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/*
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* Create files to serve as targets for external links.
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*/
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file2 = H5Fcreate(EXT_FILE1, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
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status = H5Fclose(file2);
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file2 = H5Fcreate(EXT_FILE2, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
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status = H5Fclose(file2);
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file2 = H5Fcreate(EXT_FILE3, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
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status = H5Fclose(file2);
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/*
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* Create external links to the target files.
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*/
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status = H5Lcreate_external(EXT_FILE1, "/", file1, "link_to_1", H5P_DEFAULT, H5P_DEFAULT);
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status = H5Lcreate_external(EXT_FILE2, "/", file1, "link_to_2", H5P_DEFAULT, H5P_DEFAULT);
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status = H5Lcreate_external(EXT_FILE3, "/", file1, "link_to_3", H5P_DEFAULT, H5P_DEFAULT);
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/*
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* Open and close the targets of all three external links (these will be the
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* root groups of the target files). The target files should be held open
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* by the root file's external file cache after traversal.
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*/
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group = H5Gopen(file1, "/link_to_1", H5P_DEFAULT);
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status = H5Gclose(group);
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group = H5Gopen(file1, "/link_to_2", H5P_DEFAULT);
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status = H5Gclose(group);
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group = H5Gopen(file1, "/link_to_3", H5P_DEFAULT);
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status = H5Gclose(group);
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/*
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* Open and close the targets of all three external links again. The target
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* files should already be held open by the root file's external file cache,
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* so the library will not actually have to issue an "open" system call.
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*/
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group = H5Gopen(file1, "/link_to_1", H5P_DEFAULT);
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status = H5Gclose(group);
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group = H5Gopen(file1, "/link_to_2", H5P_DEFAULT);
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status = H5Gclose(group);
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group = H5Gopen(file1, "/link_to_3", H5P_DEFAULT);
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status = H5Gclose(group);
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/*
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* Release the root file's external file cache. This will close all the
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* external link target files.
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*/
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status = H5Frelease_file_cache(file1);
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/*
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* Close and release resources.
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*/
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status = H5Pclose(fapl);
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status = H5Fclose(file1);
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return 0;
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}
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