## InfAdoptedSession

InfAdoptedSession — Session handling concurrency control via the adOPTed algorithm.

## Stability Level

Unstable, unless otherwise indicated

## Functions

InfIo * | inf_adopted_session_get_io ()
InfAdoptedAlgorithm * | inf_adopted_session_get_algorithm ()
void | inf_adopted_session_broadcast_request ()
void | inf_adopted_session_undo ()
void | inf_adopted_session_redo ()
gboolean | inf_adopted_session_read_request_info ()
void | inf_adopted_session_write_request_info ()

## Properties

InfAdoptedAlgorithm * | algorithm | Read
InfIo * | io | Read / Write / Construct Only
guint | max-total-log-size | Read / Write / Construct Only

## Signals

gboolean | check-request | Run Last

## Types and Values

enum | InfAdoptedSessionError
struct | InfAdoptedSession
struct | InfAdoptedSessionClass

## Object Hierarchy

        GObject
        ╰── InfSession
            ╰── InfAdoptedSession

## Implemented Interfaces

InfAdoptedSession implements InfCommunicationObject.

## Includes

    #include <libinfinity/adopted/inf-adopted-session.h>

## Description

InfAdoptedSession handles concurrency control with an InfAdoptedAlgorithm on top of a InfSession. It takes care of sending all necessary information to joining users, receives requests from the network (passing them to InfAdoptedAlgorithm) and transfers local requests to the other users. It also makes sure to periodically send the state the local host is in to other uses even if the local users are idle (which is required for others to cleanup their request logs and request caches).

## Functions

### inf_adopted_session_get_io ()

    InfIo *
    inf_adopted_session_get_io (InfAdoptedSession *session);

Returns the InfIo object of `session` .

#### Parameters

session | A InfAdoptedSession. |

#### Returns

A InfIo.

[transfer none]

### inf_adopted_session_get_algorithm ()

    InfAdoptedAlgorithm *
    inf_adopted_session_get_algorithm (InfAdoptedSession *session);

Returns the InfAdoptedAlgorithm object of `session` . Returns `NULL` if `session` has status `INF_SESSION_PRESYNC` or `INF_SESSION_SYNCHRONIZING` because there the algorithm object is not yet created before successful synchronization.

#### Parameters

session | A InfAdoptedSession. |

#### Returns

A InfAdoptedAlgorithm, or `NULL`.

[transfer none]

### inf_adopted_session_broadcast_request ()

    void
    inf_adopted_session_broadcast_request (InfAdoptedSession *session,
                                           InfAdoptedRequest *request);

Sends a request to all subscribed connections. The request should originate from a call to `inf_adopted_algorithm_generate_request()`, with `session` 's InfAdoptedAlgorithm.

#### Parameters

session | A InfAdoptedSession. |
request | A InfAdoptedRequest obtained from `session` 's algorithm. |

### inf_adopted_session_undo ()

    void
    inf_adopted_session_undo (InfAdoptedSession *session,
                              InfAdoptedUser *user,
                              guint n);

This is a shortcut for creating `n` undo requests and broadcasting them. If `n` > 1 then this is also more efficient.

#### Parameters

session | A InfAdoptedSession. |
user | A local InfAdoptedUser. |
n | The number of undo requests to issue. |

### inf_adopted_session_redo ()

    void
    inf_adopted_session_redo (InfAdoptedSession *session,
                              InfAdoptedUser *user,
                              guint n);

This is a shortcut for creating `n` redo requests and broadcasting them. If `n` > 1 then this is also more efficient.

#### Parameters

session | A InfAdoptedSession. |
user | A local InfAdoptedUser. |
n | The number of redo requests to issue. |

### inf_adopted_session_read_request_info ()

    gboolean
    inf_adopted_session_read_request_info (InfAdoptedSession *session,
                                           xmlNodePtr xml,
                                           InfAdoptedStateVector *diff_vec,
                                           InfAdoptedUser **user,
                                           InfAdoptedStateVector **time,
                                           xmlNodePtr *operation,
                                           GError **error);

This function reads common information such as the state vector the request was made and the user that made the request from XML. It is most likely to be used by implementations of the xml_to_request virtual function.

#### Parameters

session | A InfAdoptedSession. |
xml | The XML to read the data from. |
diff_vec | The reference vector of the time vector of the request, or `NULL`. |
user | Location to store the user of the request, or `NULL`. | [out][transfer none][allow-none]
time | Location to store the state the request was made, or `NULL`. | [out][transfer full][allow-none]
operation | Location to store the operation of the request, or `NULL`. | [out][transfer none][allow-none]
error | Location to place an error, if any. |

#### Returns

`TRUE` if the data could be read successfully, `FALSE` if the XML request does not contain valid request data, in which case `error` is set.

### inf_adopted_session_write_request_info ()

    void
    inf_adopted_session_write_request_info
                                   (InfAdoptedSession *session,
                                    InfAdoptedRequest *request,
                                    InfAdoptedStateVector *diff_vec,
                                    xmlNodePtr xml,
                                    xmlNodePtr operation);

This function writes common data from `request` , such as the user that issued the request and the state in which the request was made into `xml` . If `diff_vec` is given, then the state is written as a diff to this vector, see `inf_adopted_state_vector_to_string_diff()`. Deserializing this data again (via `inf_adopted_session_read_request_info()`) requires the same `diff_vec` then.

This function is most likely to be used by implementations of the request_to_xml virtual function.

#### Parameters

session | A InfAdoptedSession. |
diff_vec | A reference state vector, or `NULL`. |
request | The InfAdoptedRequest whose info to write. |
xml | The XML node to write the data into. |
operation | An XML node representing the operation of the request, or `NULL`. |

## Types and Values

### enum InfAdoptedSessionError

Error codes for InfAdoptedSession. These only occur when invalid requests are received from the network.

#### Members

INF_ADOPTED_SESSION_ERROR_NO_SUCH_USER | The "user" field in a request message does not contain a valid user ID. |
INF_ADOPTED_SESSION_ERROR_MISSING_OPERATION | A request message does not contain an operation. |
INF_ADOPTED_SESSION_ERROR_INVALID_REQUEST | A request in a synchronized request log is invalid. Invalid means that it is not the request that was issued after the previous request in the log, or that it is an Undo or Redo request without a request to Undo or Redo, respectively. |
INF_ADOPTED_SESSION_ERROR_MISSING_STATE_VECTOR | A synchronized user does not contain that the state that user currently is in. |
INF_ADOPTED_SESSION_ERROR_FAILED | No further specified error code. |

### struct InfAdoptedSession

    struct InfAdoptedSession;

InfAdoptedSession is an opaque data type. You should only access it via the public API functions.

### struct InfAdoptedSessionClass

    struct InfAdoptedSessionClass {
      InfAdoptedRequest*(*xml_to_request)(InfAdoptedSession* session,
                                          xmlNodePtr xml,
                                          InfAdoptedStateVector* diff_vec,
                                          gboolean for_sync,
                                          GError** error);

      void(*request_to_xml)(InfAdoptedSession* session,
                            xmlNodePtr xml,
                            InfAdoptedRequest* request,
                            InfAdoptedStateVector* diff_vec,
                            gboolean for_sync);

      /* Signals */

      gboolean(*check_request)(InfAdoptedSession* session,
                               InfAdoptedRequest* request,
                               InfAdoptedUser* user);
    };

Virtual functions and default signal handlers for InfAdoptedSession.

#### Members

`xml_to_request` () | Virtual function to deserialize an InfAdoptedRequest from XML. The implementation of this function can use `inf_adopted_session_read_request_info()` to read the common info. |
`request_to_xml` () | Virtual function to serialize an InfAdoptedRequest to XML. This function should add properties and children to the given XML node. At might use `inf_adopted_session_write_request_info()` to write the common info. |
`check_request` () | Default signal handler of the InfAdoptedSession::check-request signal. |

## Property Details

### The `“algorithm”` property

      “algorithm”                InfAdoptedAlgorithm *

The adOPTed algorithm used for translating incoming requests.

Owner: InfAdoptedSession

Flags: Read

### The `“io”` property

      “io”                       InfIo *

The IO object used for timeouts.

Owner: InfAdoptedSession

Flags: Read / Write / Construct Only

### The `“max-total-log-size”` property

      “max-total-log-size”       guint

The maximum number of requests to keep in all user's logs.

Owner: InfAdoptedSession

Flags: Read / Write / Construct Only

Default value: 2048

## Signal Details

### The `“check-request”` signal

    gboolean
    user_function (InfAdoptedSession *session,
                   InfAdoptedRequest *request,
                   InfAdoptedUser    *user,
                   gpointer           user_data)

This signal is emitted whenever the session received a request from a non-local user. It is used to decide whether the request should be processed or not. Note that generally not processing a request results is loss of synchronization, since other hosts might process the request. Only if the same condition can be applied on all sites a request should be rejected. Another possibility is to reject a request at a central host before it gets distributed to all other clients. If there is one signal handler returning `TRUE` the request is rejected, i.e. only if all signal handlers return `FALSE` it is accepted.

#### Parameters

session | The InfAdoptedSession which is about to process a request. |
request | The request to be processed. |
user | The user who issued the request. |
user_data | user data set when the signal handler was connected. |

Flags: Run Last

## See Also

InfSession, InfAdoptedAlgorithm