diff options
Diffstat (limited to 'doxygen/dox/cookbook')
| -rw-r--r-- | doxygen/dox/cookbook/Accessibility.c | 48 | ||||
| -rw-r--r-- | doxygen/dox/cookbook/Accessibility.dox | 39 | ||||
| -rw-r--r-- | doxygen/dox/cookbook/Attributes.c | 61 | ||||
| -rw-r--r-- | doxygen/dox/cookbook/Attributes.dox | 38 | ||||
| -rw-r--r-- | doxygen/dox/cookbook/Files.c | 87 | ||||
| -rw-r--r-- | doxygen/dox/cookbook/Files.dox | 71 | ||||
| -rw-r--r-- | doxygen/dox/cookbook/Performance.dox | 21 |
7 files changed, 365 insertions, 0 deletions
diff --git a/doxygen/dox/cookbook/Accessibility.c b/doxygen/dox/cookbook/Accessibility.c new file mode 100644 index 0000000..f4cc905 --- /dev/null +++ b/doxygen/dox/cookbook/Accessibility.c @@ -0,0 +1,48 @@ +/* -*- c-file-style: "stroustrup" -*- */ + +#include "hdf5.h" + +#include <assert.h> +#include <stdio.h> +#include <stdlib.h> + +int +main(void) +{ + int ret_val = EXIT_SUCCESS; + + //! <!-- [set_libver_bounds] --> + { + __label__ fail_fapl, fail_file; + hid_t fapl, file, aspace, attr; + + if ((fapl = H5Pcreate(H5P_FILE_ACCESS)) < 0) { + ret_val = EXIT_FAILURE; + goto fail_fapl; + } +#if H5_VERSION_GE(1, 10, 0) + if (H5Pset_libver_bounds(fapl, H5F_LIBVER_V18, H5F_LIBVER_V18) < 0) { +#elif H5_VERSION_GE(1, 8, 0) + if (H5Pset_libver_bounds(fapl, H5F_LIBVER_LATEST, H5F_LIBVER_LATEST) < 0) { +#else +#error Only HDF5 1.8.x and later supported. +#endif + ret_val = EXIT_FAILURE; + goto fail_file; + } + if ((file = H5Fcreate("set_libver_bounds.h5", H5F_ACC_TRUNC, H5P_DEFAULT, fapl)) < 0) { + ret_val = EXIT_FAILURE; + goto fail_file; + } + + H5Fclose(file); +fail_file: + H5Pclose(fapl); +fail_fapl:; + } + //! <!-- [set_libver_bounds] --> + + assert(ret_val == EXIT_SUCCESS); + + return ret_val; +} diff --git a/doxygen/dox/cookbook/Accessibility.dox b/doxygen/dox/cookbook/Accessibility.dox new file mode 100644 index 0000000..f100283 --- /dev/null +++ b/doxygen/dox/cookbook/Accessibility.dox @@ -0,0 +1,39 @@ +/** \page Accessibility + +\section Accessibility + +\subsection CB_MaintainCompat Maintaining Compatibility with other HDF5 Library Versions + +\par Problem +You want to ensure that the HDF5 files you produce or modify are accessible by all +releavnt tools and applications + +\par Solution +For HDF5 items (objects, attributes, etc.) that you would like to +create in new or existing HDF5 files, ascertain the supported range of HDF5 +library versions as lower and upper bounds. When creating new or opening +existing HDF5 files, use a file access property list and configure the supported +range via the H5Pset_libver_bounds() function.\n +In the example below, we restrict HDF5 item creation to the HDF5 1.8.x family of +library versions. +\snippet{lineno} Accessibility.c set_libver_bounds + +\par Discussion +See RFC \ref_rfc20160105 for a detailed and comprehensive account of HDF5 +versioning (library, file format spec., etc.) and the H5Pset_libver_bounds() +function.\n +The default range #H5F_LIBVER_EARLIEST (low) - #H5F_LIBVER_LATEST (high) offers the +widest compatibility range, but may not be suitable for certain (feature-)use +cases.\n +The HDF5 library comes with a \Emph{forward-} and \Emph{backward-compatibility} +guarantee: This means that the latest version of the library can always read +HDF5 files created by a version realesed earlier (backward compatibility). +It also means that a given release of the library can read the contents of +HDF5 files created with later versions of the library as long as the files +do not contain features introduced in later versions (forward compatibility). + +\par See Also +See the recipe \ref CB_LargeAttributes for an example where we use HDF5 +compatibility settings to enable the creation of large HDF5 attributes. + +*/
\ No newline at end of file diff --git a/doxygen/dox/cookbook/Attributes.c b/doxygen/dox/cookbook/Attributes.c new file mode 100644 index 0000000..f4e894f --- /dev/null +++ b/doxygen/dox/cookbook/Attributes.c @@ -0,0 +1,61 @@ +/* -*- c-file-style: "stroustrup" -*- */ + +#include "hdf5.h" + +#include <assert.h> +#include <stdio.h> +#include <stdlib.h> + +int +main(void) +{ + int ret_val = EXIT_SUCCESS; + + //! <!-- [large_attribute] --> + { + __label__ fail_attr, fail_aspace, fail_fapl, fail_file; + hid_t fapl, file, aspace, attr; + + if ((fapl = H5Pcreate(H5P_FILE_ACCESS)) < 0) { + ret_val = EXIT_FAILURE; + goto fail_fapl; + } +#if H5_VERSION_GE(1, 10, 0) + if (H5Pset_libver_bounds(fapl, H5F_LIBVER_V18, H5F_LIBVER_LATEST) < 0) { +#elif H5_VERSION_GE(1, 8, 0) + if (H5Pset_libver_bounds(fapl, H5F_LIBVER_LATEST, H5F_LIBVER_LATEST) < 0) { +#else +#error Only HDF5 1.8.x and later supported. +#endif + ret_val = EXIT_FAILURE; + goto fail_file; + } + if ((file = H5Fcreate("large_attribute.h5", H5F_ACC_TRUNC, H5P_DEFAULT, fapl)) < 0) { + ret_val = EXIT_FAILURE; + goto fail_file; + } + + if ((aspace = H5Screate_simple(1, (hsize_t[]){1024 * 1024}, NULL)) < 0) { + ret_val = EXIT_FAILURE; + goto fail_aspace; + } + if ((attr = H5Acreate(file, "4MiB", H5T_IEEE_F32LE, aspace, H5P_DEFAULT, H5P_DEFAULT)) < 0) { + ret_val = EXIT_FAILURE; + goto fail_attr; + } + + H5Aclose(attr); +fail_attr: + H5Sclose(aspace); +fail_aspace: + H5Fclose(file); +fail_file: + H5Pclose(fapl); +fail_fapl:; + } + //! <!-- [large_attribute] --> + + assert(ret_val == EXIT_SUCCESS); + + return ret_val; +} diff --git a/doxygen/dox/cookbook/Attributes.dox b/doxygen/dox/cookbook/Attributes.dox new file mode 100644 index 0000000..68fd159 --- /dev/null +++ b/doxygen/dox/cookbook/Attributes.dox @@ -0,0 +1,38 @@ +/** \page Attributes + +\section Attributes + +\subsection CB_LargeAttributes Creating "Large" HDF5 Attributes + +\par Problem +You would like to use HDF5 attributes the size of whose values +exceeds a few dozen kilobytes + +\par Solution +A file format change in the HDF5 1.8.x family of library releases made it +possible to have attributes larger than about 64 KiB. Ensure that the lower +library version bound for new HDF5 item creation is at least 1.8.x, and create +larger attributes as usual.\n +In the example below, we create an attribute whose value occupies 4 MiB. + +\note This feature is only supported in HDF5 1.8.x+ + +\snippet{lineno} Attributes.c large_attribute + +\par Discussion +Large attributes are supported only in HDF5 versions 1.8.x and higher. +This has implications for the accessibility of your HDF5 files and +is your call.\n +Since there are no size limitations for large attributes, it might +seem tempting to mistake them for dataset stand-ins. This is not the +case, for at least two reasons: +1. Attributes decorate HDF5 objects, have their own local namespace, + and can't be link targets. +2. Attribute I/O treats the attribute value as atomic, i.e., there + is no support for partial I/O. A large attribute will always be + read or written in its entirety. + +\par See Also +See \ref CB_MaintainCompat for HDF5 compatibility implications. + + */
\ No newline at end of file diff --git a/doxygen/dox/cookbook/Files.c b/doxygen/dox/cookbook/Files.c new file mode 100644 index 0000000..b824933 --- /dev/null +++ b/doxygen/dox/cookbook/Files.c @@ -0,0 +1,87 @@ +/* -*- c-file-style: "stroustrup" -*- */ + +#include "hdf5.h" + +#include <assert.h> +#include <stdio.h> +#include <stdlib.h> + +int +main(void) +{ + int ret_val = EXIT_SUCCESS; + + //! <!-- [free_space] --> + { + __label__ fail_fcpl, fail_fapl, fail_file; + hid_t fcpl, fapl, file; + + if ((fcpl = H5Pcreate(H5P_FILE_CREATE)) < 0) { + ret_val = EXIT_FAILURE; + goto fail_fcpl; + } +#if H5_VERSION_GE(1, 10, 1) + if (H5Pset_file_space_strategy(fcpl, H5F_FSPACE_STRATEGY_FSM_AGGR, 1, 4096) < 0) { +#else +#error HDF5 1.10.1+ required +#endif + ret_val = EXIT_FAILURE; + goto fail_fapl; + } + + if ((fapl = H5Pcreate(H5P_FILE_ACCESS)) < 0) { + ret_val = EXIT_FAILURE; + goto fail_fapl; + } +#if H5_VERSION_GE(1, 10, 1) + if (H5Pset_libver_bounds(fapl, H5F_LIBVER_V110, H5F_LIBVER_LATEST) < 0) { +#else +#error HDF5 1.10.x+ required +#endif + ret_val = EXIT_FAILURE; + goto fail_file; + } + + if ((file = H5Fcreate("free_space.h5", H5F_ACC_TRUNC, fcpl, fapl)) < 0) { + ret_val = EXIT_FAILURE; + goto fail_file; + } + H5Fclose(file); + +fail_file: + H5Pclose(fapl); +fail_fapl: + H5Pclose(fcpl); +fail_fcpl:; + } + //! <!-- [free_space] --> + + //! <!-- [user_block] --> + { + __label__ fail_fcpl, fail_file; + hid_t fcpl, file; + + if ((fcpl = H5Pcreate(H5P_FILE_CREATE)) < 0) { + ret_val = EXIT_FAILURE; + goto fail_fcpl; + } + if (H5Pset_userblock(fcpl, 8192 * 1024) < 0) { + ret_val = EXIT_FAILURE; + goto fail_file; + } + if ((file = H5Fcreate("userblock.h5", H5F_ACC_TRUNC, fcpl, H5P_DEFAULT)) < 0) { + ret_val = EXIT_FAILURE; + goto fail_file; + } + H5Fclose(file); + +fail_file: + H5Pclose(fcpl); +fail_fcpl:; + } + //! <!-- [user_block] --> + + assert(ret_val == EXIT_SUCCESS); + + return ret_val; +} diff --git a/doxygen/dox/cookbook/Files.dox b/doxygen/dox/cookbook/Files.dox new file mode 100644 index 0000000..169d638 --- /dev/null +++ b/doxygen/dox/cookbook/Files.dox @@ -0,0 +1,71 @@ +/** \page Files + +\section Files + +\subsection CB_FreeSpace Tracking Free Space in HDF5 Files + +\par Problem +You sometimes delete objects in HDF5 files and don't have new content to use the +free space, but would like to reuse it in the future. + +\par Solution +At file creation time, set the file space management strategy and persistence of +free space tracking information via H5Pset_file_space_strategy(). + +\note This feature is only supported in HDF5 1.10.1+. + +\snippet{lineno} Files.c free_space + +\par Discussion +Free space tracking is supported only in HDF5 versions 1.10.x and higher. +This has implications for the accessibility of your HDF5 files and +should be considered carefully. If compatibility with previous versions of +HDF5 must be maintained, space reclamation via \Code{h5repack} might be an option.\n +The file space strategy #H5F_FSPACE_STRATEGY_FSM_AGGR is not the only option +that supports free-space tracking. #H5F_FSPACE_STRATEGY_PAGE is another option, +which adds paged allocation and is used most effectively with page buffering.\n +For an in-depth account of HDF5 file space management, paged-allocation, and +page buffering, see the following documents: +\li \ref_rfc20121024 +\li \ref_rfc20120523 +\li \ref_rfc20150709 + +\par See Also +See \ref CB_MaintainCompat for HDF5 compatibility implications. + + +\subsection CB_RemoveUnusedSpace Removing Unused Space from HDF5 Files + +\par Problem +Based on estimates or \Code{h5stat} output you know that a large portion +of an HDF5 file consists of free or unaccounted space, and you would like +to remove it. + + +\subsection CB_UserBlock Creating an HDF5 File User Block + +\par Problem +You would like to include certain ancillary, non-HDF5 content in an +HDF5 file such that it can be accessed without the HDF5 library. + +\par Solution +Use a file creation property list in which the user block size is set via +H5Pset_userblock(). In the example below, we create an 8 MiB user block. +\snippet{lineno} Files.c user_block + +\par Discussion +The user block begins at offset 0 and must be at least 512 bytes and a power +of 2. The HDF5 library ignores any content between the beginning of the +file and the end of the user block.\n +You can add or strip a user block to/from an existing HDF5 file with the +\Code{h5jam}/\Code{h5unjam} tool, respectively. +\warning +If you try to embed content into the user block for use by other applications, +pay close attention to how they handle space beyond the last used byte in the +user block or the user block in general. In the worst case, applications might +try to truncate the rest of the file and destroy the HDF5 portion of the file. + +\par See Also +References to related recipes + + */
\ No newline at end of file diff --git a/doxygen/dox/cookbook/Performance.dox b/doxygen/dox/cookbook/Performance.dox new file mode 100644 index 0000000..7ac3a18 --- /dev/null +++ b/doxygen/dox/cookbook/Performance.dox @@ -0,0 +1,21 @@ +/** \page Performance + +\section Performance + +\subsection CB_MDCPerf Assessing HDF5 Metadata Cache Performance + +\par Problem +You are trying to diagnose and improve the I/O performance of an application +and would like to understand if a simple metadata cache adjustment might +yield substantial performance gains + +\par Solution +The to-the-point solution, i.e., the solution w/o any background or explanation + +\par Discussion +A discussion of the fine points and variants of the solution + +\par See Also +References to related recipes + + */
\ No newline at end of file |