Enumerations¶

Functions¶

KeySet * ksNew (size_t alloc,...)
Allocate, initialize and return a new KeySet object. KeySet * ksVNew (size_t alloc, va_list va)
Allocate, initialize and return a new KeySet object. KeySet * ksDup (const KeySet *source)
Return a duplicate of a keyset. int ksCopy (KeySet *dest, const KeySet *source)
Copy a keyset. int ksDel (KeySet *ks)
A destructor for KeySet objects. int ksNeedSync (const KeySet *ks)
Checks if KeySet needs sync. ssize_t ksGetSize (const KeySet *ks)
Return the number of keys that ks contains. ssize_t ksAppendKey (KeySet *ks, Key *toAppend)
Appends a Key to the end of ks. ssize_t ksAppend (KeySet *ks, const KeySet *toAppend)
Append all toAppend contained keys to the end of the ks. KeySet * ksCut (KeySet *ks, const Key *cutpoint)
Cuts out a keyset at the cutpoint. Key * ksPop (KeySet *ks)
Remove and return the last key of ks. int ksRewind (KeySet *ks)
Rewinds the KeySet internal cursor. Key * ksNext (KeySet *ks)
Returns the next Key in a KeySet. Key * ksCurrent (const KeySet *ks)
Return the current Key. Key * ksHead (const KeySet *ks)
Return the first key in the KeySet. Key * ksTail (const KeySet *ks)
Return the last key in the KeySet. cursor_t ksGetCursor (const KeySet *ks)
Get the KeySet internal cursor. Key * ksAtCursor (KeySet *ks, cursor_t pos)
return key at given cursor position int ksSetCursor (KeySet *ks, cursor_t cursor)
Set the KeySet internal cursor. Key * ksLookup (KeySet *ks, Key *key, option_t options)
Look for a Key contained in ks that matches the name of the key. Key * ksLookupByName (KeySet *ks, const char *name, option_t options)
Convenience method to look for a Key contained in ks that matches name.

enum option_t¶

Options to change the default behavior of ksLookup() functions. These options can be ORed. That is the |-Operator in C.

See also:

Enumerator

KDB_O_NONE

No Option set.

See also:

KDB_O_DEL

Delete parentKey key in ksLookup().

See also:

KDB_O_POP

Pop Parent out of keyset key in ksLookup().

See also:

KDB_O_NODIR

Feature not available. TODO: remove for 1.0

KDB_O_DIRONLY

Feature not available. TODO: remove for 1.0

KDB_O_NOREMOVE

Feature not available. TODO: remove for 1.0

KDB_O_REMOVEONLY

Feature not available. TODO: remove for 1.0

KDB_O_INACTIVE

Feature not available. TODO: remove for 1.0

KDB_O_SYNC

Feature not available. TODO: remove for 1.0

KDB_O_SORT

Feature not available. TODO: remove for 1.0

KDB_O_NORECURSIVE

Feature not available. TODO: remove for 1.0

KDB_O_NOCASE

Ignore case. do not use without KDB_O_NOALL

TODO: remove for 1.0

See also:

KDB_O_WITHOWNER

Search with owner. The owner concept is deprecated, do not use.

TODO: remove for 1.0

See also:

KDB_O_NOALL

Linear search from start -> cursor to cursor -> end. TODO: remove for 1.0

See also:

ssize_t ksAppend (KeySet * ks, const KeySet * toAppend)¶

Append all toAppend contained keys to the end of the ks. toAppend KeySet will be left unchanged.

If a key is both in toAppend and ks, the Key in ks will be overridden.

Note:

Postcondition:

Returns:

Return values:

Parameters:

See also:

ssize_t ksAppendKey (KeySet * ks, Key * toAppend)¶

Appends a Key to the end of ks. Will take ownership of the key toAppend. That means ksDel(ks) will remove the key unless the key:

• was duplicated before inserting
• got its refcount incremented by keyIncRef() before inserting
• was also inserted into another keyset with ksAppendKey()

The reference counter of the key will be incremented to show this ownership, and thus toAppend is not const.

Note:

See also:

If the keyname already existed in the keyset, it will be replaced with the new key.

The KeySet internal cursor will be set to the new key.

It is save to directly append newly created keys:

KeySet *ks = ksNew(1, KS_END);
ksAppendKey(ks,


        keyNew("user/my/new/key", KEY_END));
ksDel(ks);
// key deleted, too!

If you want the key to outlive the keyset, make sure to do proper ref counting:

KeySet *ks = ksNew(1, KS_END);
Key *k = keyNew("user/ref/key", KEY_END);
keyIncRef(k);
ksAppendKey(ks, k);
ksDel(ks);
// now we still can work with the key k!
keyDecRef(k);
keyDel(k);

Or if you want to avoid aliasing at all, you can duplicate the key. But then key in the keyset has another identity:

KeySet *ks = ksNew(1, KS_END);
Key *k = keyNew("user/ref/key", KEY_END);
ksAppendKey(ks, keyDup(k));
ksDel(ks);
// now we still can work with the key k!
keyDel(k);

Returns:

Return values:

Parameters:

See also:

Key* ksAtCursor (KeySet * ks, cursor_t pos)¶

return key at given cursor position

Parameters:

Returns:

Return values:

int ksCopy (KeySet * dest, const KeySet * source)¶

Copy a keyset. Most often you may want a duplicate of a keyset, see ksDup() or append keys, see ksAppend(). But in some situations you need to copy a keyset to a existing keyset, for that this function exists.

You can also use it to clear a keyset when you pass a NULL pointer as source.

Note that all keys in dest will be deleted. Afterwards the content of the source will be added to the destination and the ksCurrent() is set properly in dest.

A flat copy is made, so the keys will not be duplicated, but there reference counter is updated, so both keysets need to be ksDel().

Note:

1 int f (KeySet *ks)
2 {
3         KeySet *c = ksNew (20, ..., KS_END);
4         // c receives keys
5         ksCopy (ks, c); // pass the keyset to the caller
6 
7         ksDel (c);
8 }       // caller needs to ksDel (ks)

Parameters:

Return values:

See also:

Key* ksCurrent (const KeySet * ks)¶

Return the current Key. The pointer is NULL if you reached the end or after ksRewind().

Note:

Parameters:

Returns:

Return values:

See also:

KeySet* ksCut (KeySet * ks, const Key * cutpoint)¶

Cuts out a keyset at the cutpoint. Searches for the cutpoint inside the KeySet ks. If found it cuts out everything which is below (see keyIsBelow()) this key. These keys will be missing in the keyset ks. Instead, they will be moved to the returned keyset. If cutpoint is not found an empty keyset is returned and ks is not changed.

The cursor will stay at the same key as it was before. If the cursor was inside the region of cut (moved) keys, the cursor will be set to the key before the cutpoint.

If you use ksCut() on a keyset you got from kdbGet() and plan to make a kdbSet() later, make sure that you keep all keys that should not be removed permanently. You have to keep the KeySet that was returned and the KeySet ks.

Example:

You have the keyset ks:

• system/mountpoint/interest
• system/mountpoint/interest/folder
• system/mountpoint/interest/folder/key1
• system/mountpoint/interest/folder/key2
• system/mountpoint/other/key1

When you use

     Key *parentKey = keyNew("system/mountpoint/interest", KEY_END);


        KDB *kdb = kdbOpen(parentKey);


        KeySet *ks = ksNew(0, KS_END);


        kdbGet(kdb, ks, parentKey);


        KeySet *returned = ksCut(ks, parentKey);


        kdbSet(kdb, ks, parentKey); // all keys below cutpoint are now removed


        kdbClose(kdb, parentKey);

Then in returned are:

• system/mountpoint/interest
• system/mountpoint/interest/folder
• system/mountpoint/interest/folder/key1
• system/mountpoint/interest/folder/key2

And in ks are:

•

system/mountpoint/other/key1

So kdbSet() permanently removes all keys below system/mountpoint/interest.

See also:

Returns:

Return values:

Parameters:

int ksDel (KeySet * ks)¶

A destructor for KeySet objects. Cleans all internal dynamic attributes, decrement all reference pointers to all keys and then keyDel() all contained Keys, and free()s the release the KeySet object memory (that was previously allocated by ksNew()).

Parameters:

Return values:

See also:

KeySet* ksDup (const KeySet * source)¶

Return a duplicate of a keyset. Objects created with ksDup() must be destroyed with ksDel().

Memory will be allocated as needed for dynamic properties, so you need to ksDel() the returned pointer.

A flat copy is made, so the keys will not be duplicated, but there reference counter is updated, so both keysets need ksDel().

Parameters:

Returns:

Return values:

See also:

cursor_t ksGetCursor (const KeySet * ks)¶

Get the KeySet internal cursor. Use it to get the cursor of the actual position.

Warning:

ssize_t ksGetSize (const KeySet * ks)¶

Return the number of keys that ks contains.

Parameters:

Returns:

Return values:

See also:

Key* ksHead (const KeySet * ks)¶

Return the first key in the KeySet. The KeySets cursor will not be effected.

If ksCurrent()==ksHead() you know you are on the first key.

Parameters:

Returns:

Return values:

See also:

Key* ksLookup (KeySet * ks, Key * key, option_t options)¶

Look for a Key contained in ks that matches the name of the key. ksLookup() is designed to let you work with entirely pre-loaded KeySets. The idea is to fully kdbGet() for your application root key and process it all at once with ksLookup().

This function is efficient by using binary search. Together with kdbGet() which can you load the whole configuration you can write very effective but short code for configuration:

This is the way programs should get their configuration and search after the values. It is guaranteed that more namespaces can be added easily and that all values can be set by admin and user. Furthermore, using the kdb-tool, it is possible to find out which value an application will find.

If found, ks internal cursor will be positioned in the matched key (also accessible by ksCurrent()), and a pointer to the Key is returned. If not found, ks internal cursor will not move, and a NULL pointer is returned.

Cascading is done if the first character is a /. This leads to search in all namespaces proc/, dir/, user/ and system/, but also correctly considers the specification (=metadata) in spec/:

• override/# will make sure that another key is considered before
• namespace/# will change the number and/or order in which the namespaces are searched
• fallback/# will search for other keys when the other possibilities up to now were not successful
• default to return the given value when not even fallback keys were found.

Note:

This process is very flexible, but it would be boring to follow all this links in the head to find out which key will be taken. So use kdb get -v to trace the keys.

KDB_O_POP

Note:

Warning:

The invalidation of cursors does not matter if you use multiple keysets, e.g. by using ksDup(). E.g., to separate ksLookup() with KDB_O_POP and ksAppendKey():

void f(KeySet *iterator, KeySet *lookup)
{


        KeySet *append = ksNew (ksGetSize(lookup), KS_END);


        Key *key;


        Key *current;


        ksRewind(iterator);


        while ((current=ksNext(iterator)))


        {


                key = ksLookup (lookup, current, KDB_O_POP);


                // do something...


                ksAppendKey(append, key); // now append it to append, not lookup!


                keyDel (key); // make sure to ALWAYS delete poped keys.


        }


        ksAppend(lookup, append);


        // now lookup needs to be sorted only once, append never


        ksDel (append);
}

This is also a nice example how a complete application with ksLookup() can look like.

KDB_O_DEL

KDB_O_NOALL (deprecated)

KDB_O_WITHOWNER (deprecated)

KDB_O_NOCASE (deprecated)

Parameters:

Returns:

Return values:

See also:

Key* ksLookupByName (KeySet * ks, const char * name, option_t options)¶

Convenience method to look for a Key contained in ks that matches name. ksLookupByName() is designed to let you work with entirely pre-loaded KeySets, so instead of kdbGetKey(), key by key, the idea is to fully kdbGetByName() for your application root key and process it all at once with ksLookupByName().

This function is very efficient by using binary search. Together with kdbGetByName() which can you load the whole configuration with only some communication to backends you can write very effective but short code for configuration.

If found, ks internal cursor will be positioned in the matched key (also accessible by ksCurrent()), and a pointer to the Key is returned. If not found, ks internal cursor will not move, and a NULL pointer is returned. If requested to pop the key, the cursor will be rewinded.

int ksNeedSync (const KeySet * ks)¶

Checks if KeySet needs sync. When keys are changed this is reflected into keyNeedSync().

But when keys are popped from a keyset this can't be seen by looking at the individual keys.

ksNeedSync() allows the backends to know if a key was popped from the keyset to know that this keyset needs to be written out.

Deprecated

Parameters:

Return values:

KeySet* ksNew (size_t alloc, ...)¶

Allocate, initialize and return a new KeySet object. Objects created with ksNew() must be destroyed with ksDel().

You can use a various long list of parameters to preload the keyset with a list of keys. Either your first and only parameter is 0 or your last parameter must be KEY_END.

So, terminate with ksNew(0, KS_END) or ksNew(20, ..., KS_END)

For most uses

1 KeySet *keys = ksNew(0, KS_END);
2 // work with it
3 ksDel (keys);

goes ok, the alloc size will be 16, defined in kdbprivate.h. The alloc size will be doubled whenever size reaches alloc size, so it also performs out large keysets.

But if you have any clue how large your keyset may be you should read the next statements.

If you want a keyset with length 15 (because you know of your application that you normally need about 12 up to 15 keys), use:

1 KeySet * keys = ksNew (15,
2         keyNew ("user/sw/app/fixedConfiguration/key01", KEY_SWITCH_VALUE, "value01", 0),
3         keyNew ("user/sw/app/fixedConfiguration/key02", KEY_SWITCH_VALUE, "value02", 0),
4         keyNew ("user/sw/app/fixedConfiguration/key03", KEY_SWITCH_VALUE, "value03", 0),
5         // ...
6         keyNew ("user/sw/app/fixedConfiguration/key15", KEY_SWITCH_VALUE, "value15", 0),
7         KS_END);
8 // work with it
9 ksDel (keys);

If you start having 3 keys, and your application needs approximately 200-500 keys, you can use:

1 KeySet * config = ksNew (500,
2         keyNew ("user/sw/app/fixedConfiguration/key1", KEY_SWITCH_VALUE, "value1", 0),
3         keyNew ("user/sw/app/fixedConfiguration/key2", KEY_SWITCH_VALUE, "value2", 0),
4         keyNew ("user/sw/app/fixedConfiguration/key3", KEY_SWITCH_VALUE, "value3", 0),
5         KS_END); // don't forget the KS_END at the end!
6 // work with it
7 ksDel (config);

Alloc size is 500, the size of the keyset will be 3 after ksNew. This means the keyset will reallocate when appending more than 497 keys.

The main benefit of taking a list of variant length parameters is to be able to have one C-Statement for any possible KeySet.

Postcondition:

See also:

Parameters:

Returns:

Return values:

Key* ksNext (KeySet * ks)¶

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

You'll get a NULL pointer if the key after the end of the KeySet was reached. On subsequent calls of ksNext() it will still return the NULL pointer.

The ks internal cursor will be changed, so it is not const.

Note:

Parameters:

Returns:

Return values:

See also:

Key* ksPop (KeySet * ks)¶

Remove and return the last key of ks. The reference counter will be decremented by one.

The KeySets cursor will not be effected if it did not point to the popped key.

Note:

1 ks1=ksNew(0, KS_END);
2 ks2=ksNew(0, KS_END);
3 
4 k1=keyNew("user/name", KEY_END); // ref counter 0
5 ksAppendKey(ks1, k1); // ref counter 1
6 ksAppendKey(ks2, k1); // ref counter 2
7 
8 k1=ksPop (ks1); // ref counter 1
9 k1=ksPop (ks2); // ref counter 0, like after keyNew()
10 
11 ksAppendKey(ks1, k1); // ref counter 1
12 
13 ksDel (ks1); // key is deleted too
14 ksDel (ks2);

Returns:

Return values:

Parameters:

See also:

int ksRewind (KeySet * ks)¶

Rewinds the KeySet internal cursor. Use it to set the cursor to the beginning of the KeySet. ksCurrent() will then always return NULL afterwards. So you want to ksNext() first.

1 ksRewind (ks);
2 while ((key = ksNext (ks))!=0) {}

Parameters:

Return values:

See also:

int ksSetCursor (KeySet * ks, cursor_t cursor)¶

Set the KeySet internal cursor. Use it to set the cursor to a stored position. ksCurrent() will then be the position which you got with.

Warning:

1 cursor_t cursor;
2 ..
3 // key now in any position here
4 cursor = ksGetCursor (ks);
5 while ((key = keyNextMeta (ks))!=0) {}
6 ksSetCursor (ks, cursor); // reset state
7 ksCurrent(ks); // in same position as before

An invalid cursor will set the keyset to its beginning like ksRewind(). When you set an invalid cursor ksCurrent() is 0 and ksNext() == ksHead().

Parameters:

Return values:

See also:

Key* ksTail (const KeySet * ks)¶

Return the last key in the KeySet. The KeySets cursor will not be effected.

If ksCurrent()==ksTail() you know you are on the last key. ksNext() will return a NULL pointer afterwards.

Parameters:

Returns:

Return values:

See also:

KeySet* ksVNew (size_t alloc, va_list va)¶

Allocate, initialize and return a new KeySet object. Objects created with ksNew() must be destroyed with ksDel().

You can use a various long list of parameters to preload the keyset with a list of keys. Either your first and only parameter is 0 or your last parameter must be KEY_END.

So, terminate with ksNew(0, KS_END) or ksNew(20, ..., KS_END)

For most uses

1 KeySet *keys = ksNew(0, KS_END);
2 // work with it
3 ksDel (keys);

goes ok, the alloc size will be 16, defined in kdbprivate.h. The alloc size will be doubled whenever size reaches alloc size, so it also performs out large keysets.

But if you have any clue how large your keyset may be you should read the next statements.

If you want a keyset with length 15 (because you know of your application that you normally need about 12 up to 15 keys), use:

1 KeySet * keys = ksNew (15,
2         keyNew ("user/sw/app/fixedConfiguration/key01", KEY_SWITCH_VALUE, "value01", 0),
3         keyNew ("user/sw/app/fixedConfiguration/key02", KEY_SWITCH_VALUE, "value02", 0),
4         keyNew ("user/sw/app/fixedConfiguration/key03", KEY_SWITCH_VALUE, "value03", 0),
5         // ...
6         keyNew ("user/sw/app/fixedConfiguration/key15", KEY_SWITCH_VALUE, "value15", 0),
7         KS_END);
8 // work with it
9 ksDel (keys);

If you start having 3 keys, and your application needs approximately 200-500 keys, you can use:

1 KeySet * config = ksNew (500,
2         keyNew ("user/sw/app/fixedConfiguration/key1", KEY_SWITCH_VALUE, "value1", 0),
3         keyNew ("user/sw/app/fixedConfiguration/key2", KEY_SWITCH_VALUE, "value2", 0),
4         keyNew ("user/sw/app/fixedConfiguration/key3", KEY_SWITCH_VALUE, "value3", 0),
5         KS_END); // don't forget the KS_END at the end!
6 // work with it
7 ksDel (config);

Alloc size is 500, the size of the keyset will be 3 after ksNew. This means the keyset will reallocate when appending more than 497 keys.

The main benefit of taking a list of variant length parameters is to be able to have one C-Statement for any possible KeySet.

Postcondition:

See also:

Parameters:

Returns:

Return values:

Precondition:

va the list of arguments

Parameters: