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kdbprivate.h(3elektra) Elektra kdbprivate.h(3elektra)

NAME

kdbprivate.h - Private declarations.

SYNOPSIS

#include <kdb.h>
#include <kdbconfig.h>
#include <kdbextension.h>
#include <kdbhelper.h>
#include <kdbmacros.h>
#include <kdbplugin.h>
#include <kdbproposal.h>
#include <kdbtypes.h>
#include <kdbglobal.h>
#include <limits.h>

Macros


#define KEYSET_SIZE 16
The minimal allocation size of a keyset inclusive NULL byte. #define NR_OF_PLUGINS 10
How many plugins can exist in an backend. #define COMMIT_PLUGIN 7
The index of the commit plugin. #define STORAGE_PLUGIN 5
The index of the storage plugin. #define RESOLVER_PLUGIN 0
The index of the resolver plugin. #define APPROXIMATE_NR_OF_BACKENDS 16
Trie optimization. #define MAX_LEN_INT 31
The maximum of how many characters an integer needs as decimal number. #define KDB_SYSTEM_ELEKTRA 'system/elektra'
Backend mounting information. #define test_bit(var, bit) ((var) & (bit))
Test a bit. #define set_bit(var, bit) ((var) |= (bit))
Set a bit. #define clear_bit(var, bit) ((var) &= ~(bit))
Clear a bit.

Enumerations


enum keyflag_t { KEY_FLAG_SYNC = 1, KEY_FLAG_RO_NAME = 1 << 1, KEY_FLAG_RO_VALUE = 1 << 2, KEY_FLAG_RO_META = 1 << 3 }
Key Flags. enum ksflag_t { KS_FLAG_SYNC = 1 }
Ks Flags. enum splitflag_t { SPLIT_FLAG_SYNC = 1, SPLIT_FLAG_CASCADING = 1 << 1 }

Functions


Split * splitNew (void)
Allocates a new split object. void splitDel (Split *keysets)
Delete a split object. void splitRemove (Split *split, size_t where)
Remove one part of split. ssize_t splitAppend (Split *split, Backend *backend, Key *parentKey, int syncbits)
Increases the size of split and appends a new empty keyset. int splitBuildup (Split *split, KDB *handle, Key *parentKey)
Walks through kdb->split and adds all backends below parentKey to split. void splitUpdateFileName (Split *split, KDB *handle, Key *key)
Update the (configuration) file name for the parent key. int splitAppoint (Split *split, KDB *handle, KeySet *ks)
Appoints all keys from ks to yet unsynced splits. int splitGet (Split *split, Key *warningKey, KDB *handle)
Does some work after getting of backends is finished. int splitMerge (Split *split, KeySet *dest)
Merges together all parts of split into dest. int splitDivide (Split *split, KDB *handle, KeySet *ks)
Splits up the keysets and search for a sync bit in every key. int splitSync (Split *split)
Add sync bits everywhere keys were removed/added. void splitPrepare (Split *split)
Prepares for kdbSet() mainloop afterwards. int splitUpdateSize (Split *split)
Also update sizes after kdbSet() to recognize multiple kdbSet() attempts. Backend * backendOpen (KeySet *elektra_config, KeySet *modules, Key *errorKey)
Builds a backend out of the configuration supplied from: Backend * backendOpenDefault (KeySet *modules, const char *file, Key *errorKey)
Opens a default backend using the plugin named KDB_RESOLVER and KDB_STORAGE. Backend * backendOpenModules (KeySet *modules, Key *errorKey)
Backend * backendOpenVersion (Key *errorKey)
Opens the internal version backend. int backendUpdateSize (Backend *backend, Key *parent, int size)
Update internal size in backend. Plugin * elektraPluginOpen (const char *backendname, KeySet *modules, KeySet *config, Key *errorKey)
Opens a plugin. int elektraProcessPlugin (Key *cur, int *pluginNumber, char **pluginName, char **referenceName, Key *errorKey)
int elektraProcessPlugins (Plugin **plugins, KeySet *modules, KeySet *referencePlugins, KeySet *config, KeySet *systemConfig, Key *errorKey)
Load a plugin. int trieClose (Trie *trie, Key *errorKey)
Closes the trie and all opened backends within. Backend * trieLookup (Trie *trie, const Key *key)
The Trie structure. Trie * trieInsert (Trie *trie, const char *name, Backend *value)
Insert into trie. int mountOpen (KDB *kdb, KeySet *config, KeySet *modules, Key *errorKey)
Creates a trie from a given configuration. int mountDefault (KDB *kdb, KeySet *modules, int inFallback, Key *errorKey)
Reopens the default backend and mounts the default backend if needed. int mountModules (KDB *kdb, KeySet *modules, Key *errorKey)
Mount all module configurations. int mountVersion (KDB *kdb, Key *errorKey)
Mount the version backend. int mountBackend (KDB *kdb, Backend *backend, Key *errorKey)
Mounts a backend into the trie. Key * mountGetMountpoint (KDB *handle, const Key *where)

Lookup a mountpoint in a handle for a specific key. " Backend * mountGetBackend (KDB *handle, const Key *key)
Lookup a backend handle for a specific key. Key * elektraKsPrev (KeySet *ks)
Returns the previous Key in a KeySet. Key * elektraKsPopAtCursor (KeySet *ks, cursor_t pos)
Pop key at given cursor position. int elektraKeyLock (Key *key, enum elektraLockOptions what)
Permanently locks a part of the key. ssize_t ksSearchInternal (const KeySet *ks, const Key *toAppend)

" ssize_t elektraMemcpy (Key **array1, Key **array2, size_t size)
Internal Methods for Elektra. ssize_t elektraMemmove (Key **array1, Key **array2, size_t size)
Copies the key array2 into where array1 points. int elektraValidateKeyName (const char *name, size_t size)
Validates whether the supplied keyname is valid. KeySet * elektraRenameKeys (KeySet *config, const char *name)
Takes the first key and cuts off this common part for all other keys, instead name will be prepended.

Detailed Description

Private declarations.

Copyright:

BSD License (see LICENSE.md or https://www.libelektra.org)

Macro Definition Documentation

#define clear_bit(var, bit) ((var) &= ~(bit))

Clear a bit.

See also:

set_bit()

#define KDB_SYSTEM_ELEKTRA 'system/elektra'

Backend mounting information. This key directory tells you where each backend is mounted to which mountpoint.

#define KEYSET_SIZE 16

The minimal allocation size of a keyset inclusive NULL byte. ksGetAlloc() will return one less because it says how much can actually be stored.

#define MAX_LEN_INT 31

The maximum of how many characters an integer needs as decimal number.

#define NR_OF_PLUGINS 10

How many plugins can exist in an backend.

#define set_bit(var, bit) ((var) |= (bit))

Set a bit.

See also:

clear_bit()

#define test_bit(var, bit) ((var) & (bit))

Test a bit.

See also:

set_bit(), clear_bit()

Enumeration Type Documentation

enum keyflag_t

Key Flags. Store a synchronizer state so that the Elektra knows if something has changed or not.

Enumerator

Key need sync. If name, value or metadata are changed this flag will be set, so that the backend will sync the key to database.
Read only flag for name. Key name is read only and not allowed to be changed. All attempts to change the name will lead to an error. Needed for metakeys and keys that are in a data structure that depends on name ordering.
Read only flag for value. Key value is read only and not allowed to be changed. All attempts to change the value will lead to an error. Needed for metakeys
Read only flag for meta. Key meta is read only and not allowed to be changed. All attempts to change the value will lead to an error. Needed for metakeys.

enum ksflag_t

Ks Flags. Store a synchronizer state so that the Elektra knows if something has changed or not.

Enumerator

KeySet need sync. If keys were popped from the Keyset this flag will be set, so that the backend will sync the keys to database.

enum splitflag_t

Enumerator

KeySet in Split need sync. Is there any key in there which need to be synced? If keys were popped from the Keyset this flag will be set, so that the backend will sync the keys to database.
Do we need relative checks? Is this a cascading backend?

Function Documentation

Backend* backendOpen (KeySet * elektraConfig, KeySet * modules, Key * errorKey)

Builds a backend out of the configuration supplied from:

system/elektra/mountpoints/<name>

The root key must be like the above example. You do not need to rewind the keyset. But every key must be below the root key.

The internal consistency will be checked in this function. If necessary parts are missing, like no plugins, they cant be loaded or similar 0 will be returned.

ksCut() is perfectly suitable for cutting out the configuration like needed.

Note:

The given KeySet will be deleted within the function, don't use it afterwards.

Parameters:

elektraConfig the configuration to work with. It is used to build up this backend.
modules used to load new modules or get references to existing one
errorKey the key where an error and warnings are added

Returns:

a pointer to a freshly allocated backend this could be the requested backend or a so called 'missing backend'.

Return values:

0 if out of memory

Backend* backendOpenDefault (KeySet * modules, const char * file, Key * errorKey)

Opens a default backend using the plugin named KDB_RESOLVER and KDB_STORAGE.

Parameters:

modules the modules to work with
errorKey the key to issue warnings and errors to

Returns:

the fresh allocated default backend or 0 if it failed

Backend* backendOpenModules (KeySet * modules, Key * errorKey)

Returns:

a backend which gives plugin configuration of the module which is currently point to.

Parameters:

modules the modules to work with
errorKey the key to issue warnings and errors to

Backend* backendOpenVersion (Key * errorKey)

Opens the internal version backend.

Parameters:

errorKey the key to issue warnings and errors to

Returns:

the fresh allocated default backend or 0 if it failed

int backendUpdateSize (Backend * backend, Key * parent, int size)

Update internal size in backend.

Parameters:

backend the backend to update
parent for parent
size to update (-1 default, 0 empty, >0 otherwise)

Precondition:

parent must be serializable namespace

Return values:

-1 if invalid parent (assert)
0 on success

int elektraKeyLock (Key * key, enum elektraLockOptions what)

Permanently locks a part of the key. This can be:

  • KEY_FLAG_LOCK_NAME to lock the name
  • KEY_FLAG_LOCK_VALUE to lock the value
  • KEY_FLAG_LOCK_META to lock the metadata

To unlock the key, duplicate it.

It is also possible to lock when the key is created with keyNew().

Some data structures need to lock the key (most likely its name), so that the ordering does not get confused.

Parameters:

key which name should be locked

See also:

keyNew(), keyDup(), ksAppendKey()

Return values:

>0 the bits that were successfully locked
0 if everything was locked before
-1 if it could not be locked (nullpointer)

Key* elektraKsPopAtCursor (KeySet * ks, cursor_t pos)

Pop key at given cursor position.

Parameters:

ks the keyset to pop key from
c where to pop

The internal cursor will be rewinded using ksRewind(). You can use ksGetCursor() and ksSetCursor() jump back to the previous position. e.g. to pop at current position within ksNext() loop:

cursor_t c = ksGetCursor(ks);
keyDel (ksPopAtCursor(ks, c));
ksSetCursor(ks, c);
ksPrev(ks); // to have correct key after next ksNext()

Warning:

do not use, will be superseded by external iterator API

Returns:

the popped key

Return values:

0 if ks is 0

Key* elektraKsPrev (KeySet * ks)

Returns the previous Key in a KeySet. KeySets have an internal cursor that can be reset with ksRewind(). Every time ksPrev() is called the cursor is decremented and the new current Key is returned.

You'll get a NULL pointer if the key before begin of the KeySet was reached.

Don't delete the key, use ksPop() if you want to delete it.

Returns:

the new current Key

See also:

ksRewind(), ksCurrent()

ssize_t elektraMemcpy (Key ** array1, Key ** array2, size_t size)

Internal Methods for Elektra. To use them:

#include <kdbinternal.h>

There are some areas where libraries have to reimplement some basic functions to archive support for non-standard systems, for testing purposes or to provide a little more convenience. Copies the key array2 into where array1 points. It copies size elements.

Overlapping is prohibited, use elektraMemmove() instead.

Parameters:

array1 the destination
array2 the source
size how many pointer to Keys to copy

Return values:

-1 on null pointers
0 if nothing was done

Returns:

size how many keys were copied

ssize_t elektraMemmove (Key ** array1, Key ** array2, size_t size)

Copies the key array2 into where array1 points. It copies size elements.

Overlapping is ok. If they do not overlap consider elektraMemcpy() instead.

Parameters:

array1 the destination
array2 the source
size how many pointer to Keys to copy

Return values:

-1 on null pointers
0 if nothing was done

Returns:

size how many keys were copied

Plugin* elektraPluginOpen (const char * name, KeySet * modules, KeySet * config, Key * errorKey)

Opens a plugin. The config will be used as is. So be sure to transfer ownership of the config to it, with e.g. ksDup(). elektraPluginClose() will delete the config.

Returns:

a pointer to a new created plugin or 0 on error

int elektraProcessPlugin (Key * cur, int * pluginNumber, char ** pluginName, char ** referenceName, Key * errorKey)

Return values:

1 and an allocated string of the pluginName if a new plugins should be created.
2 and an allocated string of the referenceName if an old plugin should be used
3 and both if a new plugin should be created and made available for later back referencing.
-1 on error

int elektraProcessPlugins (Plugin ** plugins, KeySet * modules, KeySet * referencePlugins, KeySet * config, KeySet * systemConfig, Key * errorKey)

Load a plugin. The array of plugins must be set to 0. Its length is NR_OF_PLUGINS.

systemConfig will only be used, not deleted.

Parameters:

config the config with the information how the plugins should be put together
systemConfig the shared (system) config for the plugins. Every plugin additional get this config.

Return values:

-1 on failure

KeySet* elektraRenameKeys (KeySet * config, const char * name)

Takes the first key and cuts off this common part for all other keys, instead name will be prepended.

Returns:

a new allocated keyset with keys in user namespace.

The first key is removed in the resulting keyset.

int elektraValidateKeyName (const char * name, size_t size)

Validates whether the supplied keyname is valid. The function looks for tangling escape characters in the end and for a minimum length.

Does not check for valid namespaces

Precondition:

size must be at least 2

Parameters:

name the key name that is to be checked
size a elektraStrLen of the key name

Return values:

true if the supplied keyname part is valid
false if its invalid

int mountBackend (KDB * kdb, Backend * backend, Key * errorKey)

Mounts a backend into the trie.

Precondition:

user must pass correctly allocated backend

Postcondition:

sets reference counter of backend

Warning:

in case of init and default backends, the reference counter needs to be modified after calling mountBackend.

Parameters:

kdb the handle to work with
backend the backend to mount
errorKey the key used to report warnings

Return values:

-1 on failure
1 on success

int mountDefault (KDB * kdb, KeySet * modules, int inFallback, Key * errorKey)

Reopens the default backend and mounts the default backend if needed.

Precondition:

Default Backend is closed. mountOpen was executed before.

Parameters:

kdb the handle to work with
modules the current list of loaded modules
errorKey the key used to report warnings

Return values:

-1 on error
0 on success

Backend* mountGetBackend (KDB * handle, const Key * key)

Lookup a backend handle for a specific key. The required canonical name is ensured by using a key as parameter, which will transform the key to canonical representation.

Will return handle when no more specific KDB could be found.

If key is 0 or invalid the default backend will be returned.

Parameters:

handle is the data structure, where the mounted directories are saved.
key the key, that should be looked up.

Returns:

the backend handle associated with the key

Key* mountGetMountpoint (KDB * handle, const Key * where)


Lookup a mountpoint in a handle for a specific key. Will return a key representing the mountpoint or null if there is no appropriate mountpoint e.g. its the root mountpoint.

Example:

Key * key = keyNew ("system/template");
KDB * handle = kdbOpen();
Key *mountpoint=0;
mountpoint=kdbGetMountpoint(handle, key);
printf("The backend I am using is %s mounted in %s0,


        keyValue(mountpoint),


        keyName(mountpoint));
kdbClose (handle);
keyDel (key);

Parameters:

handle is the data structure, where the mounted directories are saved.
where the key, that should be looked up.

Returns:

the mountpoint associated with the key

int mountModules (KDB * kdb, KeySet * modules, Key * errorKey)

Mount all module configurations.

Parameters:

kdb the handle to work with
modules the current list of loaded modules
errorKey the key used to report warnings

Return values:

-1 if not rootkey was found
0 otherwise

int mountOpen (KDB * kdb, KeySet * config, KeySet * modules, Key * errorKey)

Creates a trie from a given configuration. The config will be deleted within this function.

is not allowed to be executed before

Parameters:

kdb the handle to work with
modules the current list of loaded modules
config the configuration which should be used to build up the trie.
errorKey the key used to report warnings

Return values:

-1 on failure
0 on success

int mountVersion (KDB * kdb, Key * errorKey)

Mount the version backend.

Parameters:

kdb the handle to work with
errorKey the key used to report warnings

Return values:

0 on success

ssize_t splitAppend (Split * split, Backend * backend, Key * parentKey, int syncbits)

Increases the size of split and appends a new empty keyset. Initializes the element with the given parameters at size-1 to be used.

Will automatically resize split if needed.

Parameters:

split the split object to work with
backend the backend which should be appended
parentKey the parentKey which should be appended
syncbits the initial syncstate which should be appended

Return values:

-1 if no split is found

Returns:

the position of the new element: size-1

int splitAppoint (Split * split, KDB * handle, KeySet * ks)

Appoints all keys from ks to yet unsynced splits.

Precondition:

splitBuildup() need to be executed before.

Parameters:

split the split object to work with
handle to determine to which backend a key belongs
ks the keyset to appoint to split

Return values:

1 on success
-1 if no backend was found for a key

int splitBuildup (Split * split, KDB * kdb, Key * parentKey)

Walks through kdb->split and adds all backends below parentKey to split. Sets syncbits to 2 if it is a default or root backend (which needs splitting). The information is copied from kdb->split.

Precondition:

split needs to be empty, directly after creation with splitNew().

there needs to be a valid defaultBackend but its ok not to have a trie inside KDB.

parentKey must be a valid key! (could be implemented more generally, but that would require splitting up of keysets of the same backend)

Parameters:

split will get all backends appended
kdb the handle to get information about backends
parentKey the information below which key the backends are from interest

Return values:

1 always

void splitDel (Split * keysets)

Delete a split object. Will free all allocated resources of a split keyset.

Parameters:

keysets the split object to work with

int splitDivide (Split * split, KDB * handle, KeySet * ks)

Splits up the keysets and search for a sync bit in every key. It does not check if there were removed keys, see splitSync() for the next step.

It does not create new backends, this has to be done by buildup before.

Precondition:

splitBuildup() need to be executed before.

Parameters:

split the split object to work with
handle to get information where the individual keys belong
ks the keyset to divide

Return values:

0 if there were no sync bits
1 if there were sync bits
-1 if no backend was found for any key

int splitGet (Split * split, Key * warningKey, KDB * handle)

Does some work after getting of backends is finished.

  • Update sizes
  • Removal of wrong keys

Precondition:

splitAppoint() needs to be executed before.
  • check if keys are in correct backend
  • remove syncbits
  • update sizes in the backends

Parameters:

split the split object to work with
warningKey postcondition violations are reported here
handle the handle to preprocess the keys

Return values:

1 on success
-1 if no backend was found for a key or split->parents has invalid namespace

int splitMerge (Split * split, KeySet * dest)

Merges together all parts of split into dest.

Parameters:

split the split object to work with
dest the destination keyset where all keysets are appended.

Return values:

1 on success

Split* splitNew (void)

Allocates a new split object. Splits up a keyset into multiple keysets where each of them will passed to the correct kdbSet().

Initially the size is 0 and alloc is APPROXIMATE_NR_OF_BACKENDS.

Returns:

a fresh allocated split object

See also:

splitDel()

void splitPrepare (Split * split)

Prepares for kdbSet() mainloop afterwards. All splits which do not need sync are removed and a deep copy of the remaining keysets is done.

Parameters:

split the split object to work with

void splitRemove (Split * split, size_t where)

Remove one part of split.

Parameters:

split the split object to work with
where the position to cut away

Precondition:

where must be within the size of the split

Postcondition:

split will be removed

int splitSync (Split * split)

Add sync bits everywhere keys were removed/added.

  • checks if the size of a previous kdbGet() is unchanged.
  • checks if in correct state (kdbGet() needs to be executed before)

Only splitDivide() together with this function can really decide if sync is needed or not.

Precondition:

split needs to be processed with splitDivide() before.

Return values:

0 if kdbSet() is not needed
1 if kdbSet() is needed
-1 on wrong keys (also has assert, should not happen)
-2 wrong spec state: kdbGet() was not executed before
-3 wrong dir state: kdbGet() was not executed before
-4 wrong user state: kdbGet() was not executed before
-5 wrong system state: kdbGet() was not executed before

Precondition:

user/system was split before.

Parameters:

split the split object to work with

void splitUpdateFileName (Split * split, KDB * handle, Key * key)

Update the (configuration) file name for the parent key.

Parameters:

split the split to work with
handle the handle to work with
key the parentKey that should be updated (name must be correct)

int splitUpdateSize (Split * split)

Also update sizes after kdbSet() to recognize multiple kdbSet() attempts.

Warning:

cant use the same code with splitGet because there is no default split part for kdbSet().

int trieClose (Trie * trie, Key * errorKey)

Closes the trie and all opened backends within.

Parameters:

trie the trie to close
errorKey the key used to report warnings

Return values:

0 on success

Trie* trieInsert (Trie * trie, const char * name, Backend * value)

Insert into trie.

Parameters:

trie the trie to insert to (0 to create a new trie)
name the key's name to insert
value the value to insert

Return values:

trie on success

Backend* trieLookup (Trie * trie, const Key * key)

The Trie structure. Lookups a backend inside the trie.

Returns:

the backend if found

0 otherwise

Parameters:

trie the trie object to work with
key the name of this key will be looked up

Author

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