Last modified: 28 August 2015
Name: H5PLset_loading_state
Signature:
herr_t H5PLset_loading_state( int plugin_flags )

Purpose:
Control the loading of dynamic plugins.

Motivation:
The loading of external dynamic plugins can be controlled during runtime with an environment variable, HDF5_PLUGIN_PRELOAD. The environment variable can control the loading of dynamic filters at runtime, but it will disable it for all running programs that access that variable using the library.

H5PLset_loading_state controls the loading of external dynamic plugins during program execution.

Description:
H5PLset_loading_state uses one argument to enable or disable individual plugins.

The plugin_flags parameter is an encoded integer in which each bit controls a specific plugin or class of plugins. Bit positions allocated to date are listed in the “Plugin Type/Bit Position” table below.

A plugin bit set to 0 (zero) prevents the use of the dynamic plugin corresponding to that bit position. A plugin bit set to 1 (one) allows the use of that dynamic plugin.

All dynamic plugins can be enabled by setting plugin_flags to a negative value. A value of 0 (zero) will disable all dynamic plugins.

H5PLset_loading_state inspects the HDF5_PLUGIN_PRELOAD environment variable every time it is called. If the environment variable is set to the special :: string, all dynamic plugins will be disabled.

Note:
The classes of plugins subject to programmatic control are specified in the H5PL_type_t ENUM. Since only dynamically loaded filter plugins are currently subject to programmatic control, only one plugin type is defined:
     Plugin Type Bit Position
  H5PL_TYPE_FILTER     0
Additional values may be added to the H5PL_type_t ENUM as programmatic control is implemented for other plugin types.

Parameters:
int plugin_flags     IN: The list of dynamic plugin types to enable or disable.
A plugin bit set to 0 (zero) prevents use of that dynamic plugin.
A plugin bit set to 1 (one) enables use of that dynamic plugin.

Setting plugin_flags to a negative value enables all dynamic plugins.
Setting plugin_flags to 0 (zero) disables all dynamic plugins.

Returns:
Returns a non-negative value if successful; otherwise returns a negative value.

Example Usage: 
/* Disable plugin X: Requires user to negate the state 
 * with a 0 in bit position X and AND it with the result 
 * from an H5PLget_loading_state call. */

H5PLget_loading_state(&curr_setting);
int new_setting = curr_setting & ~H5PL_FILTER_PLUGIN ;
H5PLset_loading_state (new_setting);

Fortran90 Interface:
None.

See Also:
H5PLget_loading_state

“Dynamic Plugins in HDF5”

History:
Release     C
1.8.15 Function introduced in this release.