.TH "kdb::KDB" 3elektra "Sun May 29 2016" "Version 0.8.14" "Elektra" \" -*- nroff -*-
.ad l
.nh
.SH NAME
kdb::KDB \- Constructs a class \fBKDB\fP\&.  

.SH SYNOPSIS
.br
.PP
.PP
\fC#include <kdb\&.hpp>\fP
.SS "Public Member Functions"

.in +1c
.ti -1c
.RI "\fBKDB\fP ()"
.br
.RI "\fIConstructs a class \fBKDB\fP\&. \fP"
.ti -1c
.RI "\fBKDB\fP (\fBKey\fP &errorKey)"
.br
.RI "\fIConstructs a class \fBKDB\fP\&. \fP"
.ti -1c
.RI "\fB~KDB\fP ()  throw ()"
.br
.RI "\fIThe destructor closes the database\&. \fP"
.ti -1c
.RI "void \fBopen\fP (\fBKey\fP &errorKey)"
.br
.RI "\fIOpen the database\&. \fP"
.ti -1c
.RI "void \fBclose\fP (\fBKey\fP &errorKey)  throw ()"
.br
.RI "\fIOpen the database\&. \fP"
.ti -1c
.RI "int \fBget\fP (\fBKeySet\fP &returned, std::string const &keyname)"
.br
.RI "\fIGet all keys below keyname inside returned\&. \fP"
.ti -1c
.RI "int \fBget\fP (\fBKeySet\fP &returned, \fBKey\fP &parentKey)"
.br
.RI "\fIGet all keys below parentKey inside returned\&. \fP"
.ti -1c
.RI "int \fBset\fP (\fBKeySet\fP &returned, std::string const &keyname)"
.br
.RI "\fISet all keys below keyname\&. \fP"
.ti -1c
.RI "int \fBset\fP (\fBKeySet\fP &returned, \fBKey\fP &parentKey)"
.br
.RI "\fISet all keys below parentKey\&. \fP"
.in -1c
.SH "Detailed Description"
.PP 
Constructs a class \fBKDB\fP\&. 


.PP
\fBExceptions:\fP
.RS 4
\fIKDBException\fP if database could not be opened
.RE
.PP
Opens the session with the \fBKey\fP database\&. 
.PP
\fBPrecondition:\fP
.RS 4
errorKey must be a valid key, e\&.g\&. created with \fBkeyNew()\fP
.RE
.PP
The method will bootstrap itself the following way\&. The first step is to open the default backend\&. With it system/elektra/mountpoints will be loaded and all needed libraries and mountpoints will be determined\&. These libraries for backends will be loaded and with it the \fC\fBKDB\fP\fP datastructure will be initialized\&.
.PP
You must always call this method before retrieving or committing any keys to the database\&. In the end of the program, after using the key database, you must not forget to \fBkdbClose()\fP\&.
.PP
The pointer to the \fC\fBKDB\fP\fP structure returned will be initialized like described above, and it must be passed along on any kdb*() method your application calls\&.
.PP
Get a \fC\fBKDB\fP\fP handle for every thread using elektra\&. Don't share the handle across threads, and also not the pointer accessing it:
.PP
.PP
.nf
void thread1()
{
        Key *parent = keyNew("/app/part1", KEY_CASCADING_NAME, KEY_END);
        KDB * h = kdbOpen(parent);
        // fetch keys and work with them
        kdbClose(h, parent);
}
void thread2()
{
        Key *parent = keyNew("/app/part2", KEY_CASCADING_NAME, KEY_END);
        KDB * h = kdbOpen(parent);
        // fetch keys and work with them
        kdbClose(h, parent);
}
.fi
.PP
 You don't need \fBkdbOpen()\fP if you only want to manipulate plain in-memory \fBKey\fP or \fBKeySet\fP objects\&.
.PP
\fBPrecondition:\fP
.RS 4
errorKey must be a valid key, e\&.g\&. created with \fBkeyNew()\fP
.RE
.PP
\fBParameters:\fP
.RS 4
\fIerrorKey\fP the key which holds errors and warnings which were issued 
.RE
.PP
\fBSee also:\fP
.RS 4
\fBkdbGet()\fP, \fBkdbClose()\fP to end all affairs to the \fBKey\fP database\&. 
.RE
.PP
\fBReturn values:\fP
.RS 4
\fIhandle\fP on success 
.br
\fINULL\fP on failure
.RE
.PP
Access to the key database\&.
.PP
\fBInvariant:\fP
.RS 4
the object holds an valid connection to the key database or is empty 
.RE
.PP

.SH "Constructor & Destructor Documentation"
.PP 
.SS "kdb::KDB::KDB ()\fC [inline]\fP"

.PP
Constructs a class \fBKDB\fP\&. 
.PP
\fBExceptions:\fP
.RS 4
\fIKDBException\fP if database could not be opened
.RE
.PP
Opens the session with the \fBKey\fP database\&. 
.PP
\fBPrecondition:\fP
.RS 4
errorKey must be a valid key, e\&.g\&. created with \fBkeyNew()\fP
.RE
.PP
The method will bootstrap itself the following way\&. The first step is to open the default backend\&. With it system/elektra/mountpoints will be loaded and all needed libraries and mountpoints will be determined\&. These libraries for backends will be loaded and with it the \fC\fBKDB\fP\fP datastructure will be initialized\&.
.PP
You must always call this method before retrieving or committing any keys to the database\&. In the end of the program, after using the key database, you must not forget to \fBkdbClose()\fP\&.
.PP
The pointer to the \fC\fBKDB\fP\fP structure returned will be initialized like described above, and it must be passed along on any kdb*() method your application calls\&.
.PP
Get a \fC\fBKDB\fP\fP handle for every thread using elektra\&. Don't share the handle across threads, and also not the pointer accessing it:
.PP
.PP
.nf
void thread1()
{
        Key *parent = keyNew("/app/part1", KEY_CASCADING_NAME, KEY_END);
        KDB * h = kdbOpen(parent);
        // fetch keys and work with them
        kdbClose(h, parent);
}
void thread2()
{
        Key *parent = keyNew("/app/part2", KEY_CASCADING_NAME, KEY_END);
        KDB * h = kdbOpen(parent);
        // fetch keys and work with them
        kdbClose(h, parent);
}
.fi
.PP
 You don't need \fBkdbOpen()\fP if you only want to manipulate plain in-memory \fBKey\fP or \fBKeySet\fP objects\&.
.PP
\fBPrecondition:\fP
.RS 4
errorKey must be a valid key, e\&.g\&. created with \fBkeyNew()\fP
.RE
.PP
\fBParameters:\fP
.RS 4
\fIerrorKey\fP the key which holds errors and warnings which were issued 
.RE
.PP
\fBSee also:\fP
.RS 4
\fBkdbGet()\fP, \fBkdbClose()\fP to end all affairs to the \fBKey\fP database\&. 
.RE
.PP
\fBReturn values:\fP
.RS 4
\fIhandle\fP on success 
.br
\fINULL\fP on failure 
.RE
.PP

.SS "kdb::KDB::KDB (\fBKey\fP & errorKey)\fC [inline]\fP"

.PP
Constructs a class \fBKDB\fP\&. 
.PP
\fBParameters:\fP
.RS 4
\fIerrorKey\fP is useful if you want to get the warnings in the successful case, when no exception is thrown\&.
.RE
.PP
\fBExceptions:\fP
.RS 4
\fIKDBException\fP if database could not be opened
.RE
.PP
Opens the session with the \fBKey\fP database\&. 
.PP
\fBPrecondition:\fP
.RS 4
errorKey must be a valid key, e\&.g\&. created with \fBkeyNew()\fP
.RE
.PP
The method will bootstrap itself the following way\&. The first step is to open the default backend\&. With it system/elektra/mountpoints will be loaded and all needed libraries and mountpoints will be determined\&. These libraries for backends will be loaded and with it the \fC\fBKDB\fP\fP datastructure will be initialized\&.
.PP
You must always call this method before retrieving or committing any keys to the database\&. In the end of the program, after using the key database, you must not forget to \fBkdbClose()\fP\&.
.PP
The pointer to the \fC\fBKDB\fP\fP structure returned will be initialized like described above, and it must be passed along on any kdb*() method your application calls\&.
.PP
Get a \fC\fBKDB\fP\fP handle for every thread using elektra\&. Don't share the handle across threads, and also not the pointer accessing it:
.PP
.PP
.nf
void thread1()
{
        Key *parent = keyNew("/app/part1", KEY_CASCADING_NAME, KEY_END);
        KDB * h = kdbOpen(parent);
        // fetch keys and work with them
        kdbClose(h, parent);
}
void thread2()
{
        Key *parent = keyNew("/app/part2", KEY_CASCADING_NAME, KEY_END);
        KDB * h = kdbOpen(parent);
        // fetch keys and work with them
        kdbClose(h, parent);
}
.fi
.PP
 You don't need \fBkdbOpen()\fP if you only want to manipulate plain in-memory \fBKey\fP or \fBKeySet\fP objects\&.
.PP
\fBPrecondition:\fP
.RS 4
errorKey must be a valid key, e\&.g\&. created with \fBkeyNew()\fP
.RE
.PP
\fBParameters:\fP
.RS 4
\fIerrorKey\fP the key which holds errors and warnings which were issued 
.RE
.PP
\fBSee also:\fP
.RS 4
\fBkdbGet()\fP, \fBkdbClose()\fP to end all affairs to the \fBKey\fP database\&. 
.RE
.PP
\fBReturn values:\fP
.RS 4
\fIhandle\fP on success 
.br
\fINULL\fP on failure 
.RE
.PP

.SS "kdb::KDB::~KDB ()\fC [inline]\fP"

.PP
The destructor closes the database\&. Closes the session with the \fBKey\fP database\&. 
.PP
\fBPrecondition:\fP
.RS 4
The handle must be a valid handle as returned from \fBkdbOpen()\fP
.PP
errorKey must be a valid key, e\&.g\&. created with \fBkeyNew()\fP
.RE
.PP
This is the counterpart of \fBkdbOpen()\fP\&.
.PP
You must call this method when you finished your affairs with the key database\&. You can manipulate \fBKey\fP and \fBKeySet\fP objects also after \fBkdbClose()\fP, but you must not use any kdb*() call afterwards\&.
.PP
The \fChandle\fP parameter will be finalized and all resources associated to it will be freed\&. After a \fBkdbClose()\fP, the \fChandle\fP cannot be used anymore\&.
.PP
\fBParameters:\fP
.RS 4
\fIhandle\fP contains internal information of \fBopened \fP key database 
.br
\fIerrorKey\fP the key which holds error/warning information 
.RE
.PP
\fBReturn values:\fP
.RS 4
\fI0\fP on success 
.br
\fI-1\fP on NULL pointer 
.RE
.PP

.SH "Member Function Documentation"
.PP 
.SS "void kdb::KDB::close (\fBKey\fP & errorKey)\fC [inline]\fP"

.PP
Open the database\&. The return value does not matter because its only a null pointer check\&.
.PP
\fBParameters:\fP
.RS 4
\fIerrorKey\fP is useful if you want to get the warnings
.RE
.PP
Closes the session with the \fBKey\fP database\&. 
.PP
\fBPrecondition:\fP
.RS 4
The handle must be a valid handle as returned from \fBkdbOpen()\fP
.PP
errorKey must be a valid key, e\&.g\&. created with \fBkeyNew()\fP
.RE
.PP
This is the counterpart of \fBkdbOpen()\fP\&.
.PP
You must call this method when you finished your affairs with the key database\&. You can manipulate \fBKey\fP and \fBKeySet\fP objects also after \fBkdbClose()\fP, but you must not use any kdb*() call afterwards\&.
.PP
The \fChandle\fP parameter will be finalized and all resources associated to it will be freed\&. After a \fBkdbClose()\fP, the \fChandle\fP cannot be used anymore\&.
.PP
\fBParameters:\fP
.RS 4
\fIhandle\fP contains internal information of \fBopened \fP key database 
.br
\fIerrorKey\fP the key which holds error/warning information 
.RE
.PP
\fBReturn values:\fP
.RS 4
\fI0\fP on success 
.br
\fI-1\fP on NULL pointer 
.RE
.PP

.SS "int kdb::KDB::get (\fBKeySet\fP & returned, std::string const & keyname)\fC [inline]\fP"

.PP
Get all keys below keyname inside returned\&. Retrieve keys in an atomic and universal way\&. 
.PP
\fBPrecondition:\fP
.RS 4
The \fChandle\fP must be passed as returned from \fBkdbOpen()\fP
.PP
The \fCreturned\fP \fBKeySet\fP must be a valid \fBKeySet\fP, e\&.g\&. constructed with \fBksNew()\fP\&.
.PP
The \fCparentKey\fP \fBKey\fP must be a valid \fBKey\fP, e\&.g\&. constructed with \fBkeyNew()\fP\&.
.RE
.PP
If you pass NULL, which violates the preconditions, on any parameter \fBkdbGet()\fP will fail immediately without doing anything\&.
.PP
The \fCreturned\fP \fBKeySet\fP may already contain some keys, e\&.g\&. from previous \fBkdbGet()\fP calls\&. The new retrieved keys will be appended using \fBksAppendKey()\fP\&.
.PP
It will fully retrieve, at least, all keys under the \fCparentKey\fP folder, with all subfolders and their children\&.
.PP
\fBNote:\fP
.RS 4
\fBkdbGet()\fP might retrieve more keys then requested (that are not below parentKey)\&. These keys must be passed to calls of \fBkdbSet()\fP, otherwise they will be lost\&. This stems from the fact that the user has the only copy of the whole configuration and backends only write configuration that was passed to them\&. For example, if you \fBkdbGet()\fP 'system/mountpoint/interest' you will not only get all keys below system/mountpoint/interest, but also all keys below system/mountpoint (if system/mountpoint is a mountpoint as the name suggests, but system/mountpoint/interest is not a mountpoint)\&. Make sure to not touch or remove keys outside the keys of interest, because others may need them!
.RE
.PP
\fBExample:\fP
.RS 4
This example demonstrates the typical usecase within an application (without error handling)\&.
.RE
.PP
.PP
.nf
#include <kdb\&.h>
#include <stdio\&.h>

int main()
{
        KeySet *myConfig = ksNew(0, KS_END);
        Key *key = keyNew("/sw/MyApp", KEY_CASCADING_NAME, KEY_END);
        KDB *handle = kdbOpen(key);

        kdbGet(handle, myConfig, key);
        // to get an intention of proper error handling see kdbget_error\&.c

        keyDel (key);

        Key * result = ksLookupByName (myConfig,"/sw/MyApp/Tests/TestKey1", 0);

        const char * key_name = keyName(result);
        const char * key_value = keyString(result);
        const char * key_comment = keyString(keyGetMeta(result, "comment"));
        printf("key: %s value: %s comment: %s\n", key_name, key_value, key_comment);

        ksDel (myConfig); // delete the in-memory configuration


        // maybe you want kdbSet() myConfig here

        kdbClose(handle, 0); // no more affairs with the key database\&.
}
.fi
.PP
.PP
When a backend fails \fBkdbGet()\fP will return -1 with all error and warning information in the \fCparentKey\fP\&. The parameter \fCreturned\fP will not be changed\&.
.PP
\fBUpdates:\fP
.RS 4
In the first run of kdbGet all requested (or more) keys are retrieved\&. On subsequent calls only the keys are retrieved where something was changed inside the key database\&. The other keys stay unchanged in the keyset, even if they were manipulated\&.
.RE
.PP
It is your responsibility to save the original keyset if you need it afterwards\&.
.PP
If you want to get the same keyset again, you need to open a second handle to the key database using \fBkdbOpen()\fP\&.
.PP
\fBParameters:\fP
.RS 4
\fIhandle\fP contains internal information of \fBopened \fP key database 
.br
\fIparentKey\fP is used to add warnings and set an error information\&. Additionally, its name is an hint which keys should be retrieved (it is possible that more are retrieved)\&.
.IP "\(bu" 2
cascading keys (starting with /) will retrieve the same path in all namespaces
.IP "\(bu" 2
/ will retrieve all keys 
.PP
.br
\fIks\fP the (pre-initialized) \fBKeySet\fP returned with all keys found will not be changed on error or if no update is required 
.RE
.PP
\fBSee also:\fP
.RS 4
\fBksLookup()\fP, \fBksLookupByName()\fP for powerful lookups after the \fBKeySet\fP was retrieved 
.PP
\fBkdbOpen()\fP which needs to be called before 
.PP
\fBkdbSet()\fP to save the configuration afterwards and \fBkdbClose()\fP to finish affairs with the \fBKey\fP database\&. 
.RE
.PP
\fBReturn values:\fP
.RS 4
\fI1\fP if the keys were retrieved successfully 
.br
\fI0\fP if there was no update - no changes are made to the keyset then 
.br
\fI-1\fP on failure - no changes are made to the keyset then
.RE
.PP
.PP
.nf
#include <kdb\&.hpp>

#include <keyio\&.hpp>

using namespace kdb;

int main()
{
        KeySet config;
        KDB kdb;
        kdb\&.get(config, "/sw/MyApp");

        Key k = config\&.lookup("/sw/MyApp/mykey");
        if (k)
        {
                std::cout << k << " is " << k\&.get<int>() << std::endl;
        }
        else
        {
                std::cerr << "No key found" << std::endl;
                return 1;
        }
}
.fi
.PP
.PP
\fBParameters:\fP
.RS 4
\fIreturned\fP the keyset where the keys will be in 
.br
\fIkeyname\fP the root keyname which should be used to get keys below it
.RE
.PP
\fBReturn values:\fP
.RS 4
\fI0\fP if no key was updated 
.br
\fI1\fP if user or system keys were updated 
.br
\fI2\fP if user and system keys were updated
.RE
.PP
\fBExceptions:\fP
.RS 4
\fIKDBException\fP if there were problems with the database
.RE
.PP
\fBSee also:\fP
.RS 4
\fBKDB::get\fP (\fBKeySet\fP & returned, \fBKey\fP & parentKey) 
.RE
.PP

.SS "int kdb::KDB::get (\fBKeySet\fP & returned, \fBKey\fP & parentKey)\fC [inline]\fP"

.PP
Get all keys below parentKey inside returned\&. Retrieve keys in an atomic and universal way\&. 
.PP
\fBPrecondition:\fP
.RS 4
The \fChandle\fP must be passed as returned from \fBkdbOpen()\fP
.PP
The \fCreturned\fP \fBKeySet\fP must be a valid \fBKeySet\fP, e\&.g\&. constructed with \fBksNew()\fP\&.
.PP
The \fCparentKey\fP \fBKey\fP must be a valid \fBKey\fP, e\&.g\&. constructed with \fBkeyNew()\fP\&.
.RE
.PP
If you pass NULL, which violates the preconditions, on any parameter \fBkdbGet()\fP will fail immediately without doing anything\&.
.PP
The \fCreturned\fP \fBKeySet\fP may already contain some keys, e\&.g\&. from previous \fBkdbGet()\fP calls\&. The new retrieved keys will be appended using \fBksAppendKey()\fP\&.
.PP
It will fully retrieve, at least, all keys under the \fCparentKey\fP folder, with all subfolders and their children\&.
.PP
\fBNote:\fP
.RS 4
\fBkdbGet()\fP might retrieve more keys then requested (that are not below parentKey)\&. These keys must be passed to calls of \fBkdbSet()\fP, otherwise they will be lost\&. This stems from the fact that the user has the only copy of the whole configuration and backends only write configuration that was passed to them\&. For example, if you \fBkdbGet()\fP 'system/mountpoint/interest' you will not only get all keys below system/mountpoint/interest, but also all keys below system/mountpoint (if system/mountpoint is a mountpoint as the name suggests, but system/mountpoint/interest is not a mountpoint)\&. Make sure to not touch or remove keys outside the keys of interest, because others may need them!
.RE
.PP
\fBExample:\fP
.RS 4
This example demonstrates the typical usecase within an application (without error handling)\&.
.RE
.PP
.PP
.nf
#include <kdb\&.h>
#include <stdio\&.h>

int main()
{
        KeySet *myConfig = ksNew(0, KS_END);
        Key *key = keyNew("/sw/MyApp", KEY_CASCADING_NAME, KEY_END);
        KDB *handle = kdbOpen(key);

        kdbGet(handle, myConfig, key);
        // to get an intention of proper error handling see kdbget_error\&.c

        keyDel (key);

        Key * result = ksLookupByName (myConfig,"/sw/MyApp/Tests/TestKey1", 0);

        const char * key_name = keyName(result);
        const char * key_value = keyString(result);
        const char * key_comment = keyString(keyGetMeta(result, "comment"));
        printf("key: %s value: %s comment: %s\n", key_name, key_value, key_comment);

        ksDel (myConfig); // delete the in-memory configuration


        // maybe you want kdbSet() myConfig here

        kdbClose(handle, 0); // no more affairs with the key database\&.
}
.fi
.PP
.PP
When a backend fails \fBkdbGet()\fP will return -1 with all error and warning information in the \fCparentKey\fP\&. The parameter \fCreturned\fP will not be changed\&.
.PP
\fBUpdates:\fP
.RS 4
In the first run of kdbGet all requested (or more) keys are retrieved\&. On subsequent calls only the keys are retrieved where something was changed inside the key database\&. The other keys stay unchanged in the keyset, even if they were manipulated\&.
.RE
.PP
It is your responsibility to save the original keyset if you need it afterwards\&.
.PP
If you want to get the same keyset again, you need to open a second handle to the key database using \fBkdbOpen()\fP\&.
.PP
\fBParameters:\fP
.RS 4
\fIhandle\fP contains internal information of \fBopened \fP key database 
.br
\fIparentKey\fP is used to add warnings and set an error information\&. Additionally, its name is an hint which keys should be retrieved (it is possible that more are retrieved)\&.
.IP "\(bu" 2
cascading keys (starting with /) will retrieve the same path in all namespaces
.IP "\(bu" 2
/ will retrieve all keys 
.PP
.br
\fIks\fP the (pre-initialized) \fBKeySet\fP returned with all keys found will not be changed on error or if no update is required 
.RE
.PP
\fBSee also:\fP
.RS 4
\fBksLookup()\fP, \fBksLookupByName()\fP for powerful lookups after the \fBKeySet\fP was retrieved 
.PP
\fBkdbOpen()\fP which needs to be called before 
.PP
\fBkdbSet()\fP to save the configuration afterwards and \fBkdbClose()\fP to finish affairs with the \fBKey\fP database\&. 
.RE
.PP
\fBReturn values:\fP
.RS 4
\fI1\fP if the keys were retrieved successfully 
.br
\fI0\fP if there was no update - no changes are made to the keyset then 
.br
\fI-1\fP on failure - no changes are made to the keyset then
.RE
.PP
\fBParameters:\fP
.RS 4
\fIreturned\fP the keyset where the keys will be in 
.br
\fIparentKey\fP the parentKey of returned
.RE
.PP
\fBReturn values:\fP
.RS 4
\fI0\fP if no key was updated 
.br
\fI1\fP if user or system keys were updated 
.br
\fI2\fP if user and system keys were updated
.RE
.PP
\fBExceptions:\fP
.RS 4
\fIKDBException\fP if there were problems with the database 
.RE
.PP

.SS "void kdb::KDB::open (\fBKey\fP & errorKey)\fC [inline]\fP"

.PP
Open the database\&. 
.PP
\fBParameters:\fP
.RS 4
\fIerrorKey\fP is useful if you want to get the warnings in the successful case, when no exception is thrown\&.
.RE
.PP
Opens the session with the \fBKey\fP database\&. 
.PP
\fBPrecondition:\fP
.RS 4
errorKey must be a valid key, e\&.g\&. created with \fBkeyNew()\fP
.RE
.PP
The method will bootstrap itself the following way\&. The first step is to open the default backend\&. With it system/elektra/mountpoints will be loaded and all needed libraries and mountpoints will be determined\&. These libraries for backends will be loaded and with it the \fC\fBKDB\fP\fP datastructure will be initialized\&.
.PP
You must always call this method before retrieving or committing any keys to the database\&. In the end of the program, after using the key database, you must not forget to \fBkdbClose()\fP\&.
.PP
The pointer to the \fC\fBKDB\fP\fP structure returned will be initialized like described above, and it must be passed along on any kdb*() method your application calls\&.
.PP
Get a \fC\fBKDB\fP\fP handle for every thread using elektra\&. Don't share the handle across threads, and also not the pointer accessing it:
.PP
.PP
.nf
void thread1()
{
        Key *parent = keyNew("/app/part1", KEY_CASCADING_NAME, KEY_END);
        KDB * h = kdbOpen(parent);
        // fetch keys and work with them
        kdbClose(h, parent);
}
void thread2()
{
        Key *parent = keyNew("/app/part2", KEY_CASCADING_NAME, KEY_END);
        KDB * h = kdbOpen(parent);
        // fetch keys and work with them
        kdbClose(h, parent);
}
.fi
.PP
 You don't need \fBkdbOpen()\fP if you only want to manipulate plain in-memory \fBKey\fP or \fBKeySet\fP objects\&.
.PP
\fBPrecondition:\fP
.RS 4
errorKey must be a valid key, e\&.g\&. created with \fBkeyNew()\fP
.RE
.PP
\fBParameters:\fP
.RS 4
\fIerrorKey\fP the key which holds errors and warnings which were issued 
.RE
.PP
\fBSee also:\fP
.RS 4
\fBkdbGet()\fP, \fBkdbClose()\fP to end all affairs to the \fBKey\fP database\&. 
.RE
.PP
\fBReturn values:\fP
.RS 4
\fIhandle\fP on success 
.br
\fINULL\fP on failure 
.RE
.PP

.SS "int kdb::KDB::set (\fBKeySet\fP & returned, std::string const & keyname)\fC [inline]\fP"

.PP
Set all keys below keyname\&. If the keyname of the parentKey is invalid (e\&.g\&. empty) all keys will be set\&.
.PP
Set keys in an atomic and universal way\&. 
.PP
\fBPrecondition:\fP
.RS 4
\fBkdbGet()\fP must be called before \fBkdbSet()\fP:
.IP "\(bu" 2
initially (after \fBkdbOpen()\fP)
.IP "\(bu" 2
after conflict errors in \fBkdbSet()\fP\&.
.PP
.PP
The \fCreturned\fP \fBKeySet\fP must be a valid \fBKeySet\fP, e\&.g\&. constructed with \fBksNew()\fP\&.
.PP
The \fCparentKey\fP \fBKey\fP must be a valid \fBKey\fP, e\&.g\&. constructed with
.RE
.PP
With \fCparentKey\fP you can give an hint which part of the given keyset is of interest for you\&. Then you promise, you only modified or removed keys below this key\&.
.PP
\fBErrors\fP
.RS 4
If some error occurs, \fBkdbSet()\fP will stop\&. In this situation the \fBKeySet\fP internal cursor will be set on the key that generated the error\&. None of the keys are actually committed in this situation (no configuration file will be modified)\&.
.RE
.PP
In case of errors you should present the error message to the user and let the user decide what to do\&. Possible solutions are:
.IP "\(bu" 2
remove the problematic key and use \fBkdbSet()\fP again (for validation or type errors)
.IP "\(bu" 2
change the value of the problematic key and use \fBkdbSet()\fP again (for validation errors)
.IP "\(bu" 2
do a \fBkdbGet()\fP (for conflicts, i\&.e\&. error 30) and then
.IP "  \(bu" 4
set the same keyset again (in favour of what was set by this user)
.IP "  \(bu" 4
drop the old keyset (in favour of what was set from another application)
.IP "  \(bu" 4
merge the original, your own and the other keyset
.PP

.IP "\(bu" 2
export the configuration into a file (for unresolvable errors)
.IP "\(bu" 2
repeat the same kdbSet might be of limited use if the operator does not explicitly request it, because temporary errors are rare and its unlikely that they fix themselves (e\&.g\&. disc full, permission problems)
.PP
.PP
\fBOptimization\fP
.RS 4
Each key is checked with \fBkeyNeedSync()\fP before being actually committed\&. So only changed keys are updated\&. If no key of a backend needs to be synced any affairs to backends are omitted and 0 is returned\&.
.RE
.PP
.PP
.nf
KeySet *myConfig = ksNew(0, KS_END);
Key *parentKey = keyNew("system/sw/MyApp",KEY_END);
KDB *handle = kdbOpen(parentKey);

kdbGet(handle, myConfig, parentKey); // kdbGet needs to be called first!
KeySet *base = ksDup(myConfig); // save a copy of original keyset

// change the keys within myConfig

KeySet *ours = ksDup(myConfig); // save a copy of our keyset
KeySet *theirs; // needed for 3-way merging
int ret=kdbSet(handle, myConfig, parentKey);
while (ret == -1) // as long as we have an error
{
        // We got an error\&. Warn user\&.
        Key *problemKey = ksCurrent(myConfig);
        // parentKey has the errorInformation
        // problemKey is the faulty key (may be null)
        int userInput = showElektraErrorDialog (parentKey, problemKey);
        switch (userInput)
        {
        case INPUT_USE_OURS:
                kdbGet(handle, myConfig, parentKey); // refresh key database
                ksDel(myConfig);
                myConfig = ours;
                break;
        case INPUT_DO_MERGE:
                theirs = ksDup(ours);
                kdbGet(handle, theirs, parentKey); // refresh key database
                KeySet * res=doElektraMerge(ours, theirs, base);
                ksDel(theirs);
                myConfig = res;
                break;
        case INPUT_USE_THEIRS:
                // should always work, we just write what we got
                // but to be sure always give the user another way
                // to exit the loop
                kdbGet(handle, myConfig, parentKey); // refresh key database
                break;
        // other cases \&.\&.\&.
        }
        ret=kdbSet(handle, myConfig, parentKey);
}

ksDel (ours);
ksDel (base);
ksDel (myConfig); // delete the in-memory configuration

kdbClose(handle, parentKey); // no more affairs with the key database\&.
keyDel(parentKey);
.fi
.PP
 showElektraErrorDialog() and doElektraMerge() need to be implemented by the user of Elektra\&. For doElektraMerge a 3-way merge algorithm exists in libelektra-tools\&.
.PP
\fBParameters:\fP
.RS 4
\fIhandle\fP contains internal information of \fBopened \fP key database 
.br
\fIks\fP a \fBKeySet\fP which should contain changed keys, otherwise nothing is done 
.br
\fIparentKey\fP is used to add warnings and set an error information\&. Additionally, its name is an hint which keys should be committed (it is possible that more are changed)\&.
.IP "\(bu" 2
cascading keys (starting with /) will set the path in all namespaces
.IP "\(bu" 2
/ will commit all keys
.IP "\(bu" 2
meta-names will be rejected (error 104)
.IP "\(bu" 2
empty/invalid (error 105) 
.PP
.RE
.PP
\fBReturn values:\fP
.RS 4
\fI1\fP on success 
.br
\fI0\fP if nothing had to be done, no changes in \fBKDB\fP 
.br
\fI-1\fP on failure, no changes in \fBKDB\fP 
.RE
.PP
\fBSee also:\fP
.RS 4
\fBkeyNeedSync()\fP 
.PP
\fBksCurrent()\fP contains the error \fBKey\fP 
.PP
\fBkdbOpen()\fP and \fBkdbGet()\fP that must be called first 
.PP
\fBkdbClose()\fP that must be called afterwards
.RE
.PP
\fBReturn values:\fP
.RS 4
\fI0\fP if no key was updated 
.br
\fI1\fP if user or system keys were updated 
.br
\fI2\fP if user and system keys were updated
.RE
.PP
\fBParameters:\fP
.RS 4
\fIreturned\fP the keyset where the keys will be in 
.br
\fIkeyname\fP the keyname below the names should be set
.RE
.PP
\fBExceptions:\fP
.RS 4
\fIKDBException\fP if there were problems with the database 
.RE
.PP

.SS "int kdb::KDB::set (\fBKeySet\fP & returned, \fBKey\fP & parentKey)\fC [inline]\fP"

.PP
Set all keys below parentKey\&. If the keyname of the parentKey is invalid (e\&.g\&. empty) all keys will be set\&.
.PP
Set keys in an atomic and universal way\&. 
.PP
\fBPrecondition:\fP
.RS 4
\fBkdbGet()\fP must be called before \fBkdbSet()\fP:
.IP "\(bu" 2
initially (after \fBkdbOpen()\fP)
.IP "\(bu" 2
after conflict errors in \fBkdbSet()\fP\&.
.PP
.PP
The \fCreturned\fP \fBKeySet\fP must be a valid \fBKeySet\fP, e\&.g\&. constructed with \fBksNew()\fP\&.
.PP
The \fCparentKey\fP \fBKey\fP must be a valid \fBKey\fP, e\&.g\&. constructed with
.RE
.PP
With \fCparentKey\fP you can give an hint which part of the given keyset is of interest for you\&. Then you promise, you only modified or removed keys below this key\&.
.PP
\fBErrors\fP
.RS 4
If some error occurs, \fBkdbSet()\fP will stop\&. In this situation the \fBKeySet\fP internal cursor will be set on the key that generated the error\&. None of the keys are actually committed in this situation (no configuration file will be modified)\&.
.RE
.PP
In case of errors you should present the error message to the user and let the user decide what to do\&. Possible solutions are:
.IP "\(bu" 2
remove the problematic key and use \fBkdbSet()\fP again (for validation or type errors)
.IP "\(bu" 2
change the value of the problematic key and use \fBkdbSet()\fP again (for validation errors)
.IP "\(bu" 2
do a \fBkdbGet()\fP (for conflicts, i\&.e\&. error 30) and then
.IP "  \(bu" 4
set the same keyset again (in favour of what was set by this user)
.IP "  \(bu" 4
drop the old keyset (in favour of what was set from another application)
.IP "  \(bu" 4
merge the original, your own and the other keyset
.PP

.IP "\(bu" 2
export the configuration into a file (for unresolvable errors)
.IP "\(bu" 2
repeat the same kdbSet might be of limited use if the operator does not explicitly request it, because temporary errors are rare and its unlikely that they fix themselves (e\&.g\&. disc full, permission problems)
.PP
.PP
\fBOptimization\fP
.RS 4
Each key is checked with \fBkeyNeedSync()\fP before being actually committed\&. So only changed keys are updated\&. If no key of a backend needs to be synced any affairs to backends are omitted and 0 is returned\&.
.RE
.PP
.PP
.nf
KeySet *myConfig = ksNew(0, KS_END);
Key *parentKey = keyNew("system/sw/MyApp",KEY_END);
KDB *handle = kdbOpen(parentKey);

kdbGet(handle, myConfig, parentKey); // kdbGet needs to be called first!
KeySet *base = ksDup(myConfig); // save a copy of original keyset

// change the keys within myConfig

KeySet *ours = ksDup(myConfig); // save a copy of our keyset
KeySet *theirs; // needed for 3-way merging
int ret=kdbSet(handle, myConfig, parentKey);
while (ret == -1) // as long as we have an error
{
        // We got an error\&. Warn user\&.
        Key *problemKey = ksCurrent(myConfig);
        // parentKey has the errorInformation
        // problemKey is the faulty key (may be null)
        int userInput = showElektraErrorDialog (parentKey, problemKey);
        switch (userInput)
        {
        case INPUT_USE_OURS:
                kdbGet(handle, myConfig, parentKey); // refresh key database
                ksDel(myConfig);
                myConfig = ours;
                break;
        case INPUT_DO_MERGE:
                theirs = ksDup(ours);
                kdbGet(handle, theirs, parentKey); // refresh key database
                KeySet * res=doElektraMerge(ours, theirs, base);
                ksDel(theirs);
                myConfig = res;
                break;
        case INPUT_USE_THEIRS:
                // should always work, we just write what we got
                // but to be sure always give the user another way
                // to exit the loop
                kdbGet(handle, myConfig, parentKey); // refresh key database
                break;
        // other cases \&.\&.\&.
        }
        ret=kdbSet(handle, myConfig, parentKey);
}

ksDel (ours);
ksDel (base);
ksDel (myConfig); // delete the in-memory configuration

kdbClose(handle, parentKey); // no more affairs with the key database\&.
keyDel(parentKey);
.fi
.PP
 showElektraErrorDialog() and doElektraMerge() need to be implemented by the user of Elektra\&. For doElektraMerge a 3-way merge algorithm exists in libelektra-tools\&.
.PP
\fBParameters:\fP
.RS 4
\fIhandle\fP contains internal information of \fBopened \fP key database 
.br
\fIks\fP a \fBKeySet\fP which should contain changed keys, otherwise nothing is done 
.br
\fIparentKey\fP is used to add warnings and set an error information\&. Additionally, its name is an hint which keys should be committed (it is possible that more are changed)\&.
.IP "\(bu" 2
cascading keys (starting with /) will set the path in all namespaces
.IP "\(bu" 2
/ will commit all keys
.IP "\(bu" 2
meta-names will be rejected (error 104)
.IP "\(bu" 2
empty/invalid (error 105) 
.PP
.RE
.PP
\fBReturn values:\fP
.RS 4
\fI1\fP on success 
.br
\fI0\fP if nothing had to be done, no changes in \fBKDB\fP 
.br
\fI-1\fP on failure, no changes in \fBKDB\fP 
.RE
.PP
\fBSee also:\fP
.RS 4
\fBkeyNeedSync()\fP 
.PP
\fBksCurrent()\fP contains the error \fBKey\fP 
.PP
\fBkdbOpen()\fP and \fBkdbGet()\fP that must be called first 
.PP
\fBkdbClose()\fP that must be called afterwards
.RE
.PP
\fBReturn values:\fP
.RS 4
\fI0\fP if no key was updated 
.br
\fI1\fP if user or system keys were updated 
.br
\fI2\fP if user and system keys were updated
.RE
.PP
\fBParameters:\fP
.RS 4
\fIreturned\fP the keyset where the keys are passed to the user 
.br
\fIparentKey\fP the parentKey of returned
.RE
.PP
\fBExceptions:\fP
.RS 4
\fIKDBException\fP if there were problems with the database 
.RE
.PP


.SH "Author"
.PP 
Generated automatically by Doxygen for Elektra from the source code\&.