inf_adopted_algorithm_new ()

InfAdoptedAlgorithm *
inf_adopted_algorithm_new (InfUserTable *user_table,
                           InfBuffer *buffer);

Creates a InfAdoptedAlgorithm.

[constructor]

inf_adopted_algorithm_new_full ()

InfAdoptedAlgorithm *
inf_adopted_algorithm_new_full (InfUserTable *user_table,
                                InfBuffer *buffer,
                                guint max_total_log_size);

Note that it is possible that request logs need to grow a bit larger than max_total_log_size in high-latency situations or when a user does not send status updates frequently. However, when all requests have been processed by all users, the sum of all requests in the logs is guaranteed to be lower or equal to this value.

Set to G_MAXUINT to disable limitation. In theory, this would allow everyone to undo every operation up to the first one ever made. In practise, this issues a huge amount of data that needs to be synchronized on user join and is too expensive to compute anyway.

The default value is 2048.

[constructor]

inf_adopted_algorithm_get_current ()

InfAdoptedStateVector *
inf_adopted_algorithm_get_current (InfAdoptedAlgorithm *algorithm);

Returns the current vector time of algorithm .

inf_adopted_algorithm_get_execute_request ()

InfAdoptedRequest *
inf_adopted_algorithm_get_execute_request
                               (InfAdoptedAlgorithm *algorithm);

Returns whether the algorithm is currently transforming a request to the current state and appling its state to the buffer. If it is the function is returning the request that was received and is currently being executed, other wise the function returns NULL. Note that the request execution is not re-entrant, i.e. two requests cannot be executed concurrently at the same time, or recursively.

inf_adopted_algorithm_generate_request ()

InfAdoptedRequest *
inf_adopted_algorithm_generate_request
                               (InfAdoptedAlgorithm *algorithm,
                                InfAdoptedRequestType type,
                                InfAdoptedUser *user,
                                InfAdoptedOperation *operation);

Creates a new request that can be applied to the current document state. The request is made by the given user. If operation is of type INF_ADOPTED_REQUEST_DO, then operation specifies the operation to be performed. Otherwise, operation must be NULL.

To apply the effect of the request to the document, run inf_adopted_algorithm_execute_request(). Note that even if the effect is already applied to the document, the function must still be called with the apply parameter set to FALSE, so that the algorithm knows that the request has been applied.

inf_adopted_algorithm_translate_request ()

InfAdoptedRequest *
inf_adopted_algorithm_translate_request
                               (InfAdoptedAlgorithm *algorithm,
                                InfAdoptedRequest *request,
                                InfAdoptedStateVector *to);

Translates request so that it can be applied to the document at state to . request will not be modified but a new, translated request is returned instead.

There are several preconditions for this function to be called. to must be a reachable point in the state space. Also, requests can only be translated in forward direction, so request 's vector time must be causally before (see inf_adopted_state_vector_causally_before()) to .

inf_adopted_algorithm_execute_request ()

gboolean
inf_adopted_algorithm_execute_request (InfAdoptedAlgorithm *algorithm,
                                       InfAdoptedRequest *request,
                                       gboolean apply,
                                       GError **error);

This function transforms the given request such that it can be applied to the current document state and then applies it the buffer and adds it to the request log of the algorithm, so that it is used for future transformations of other requests.

If apply is FALSE then the request is not applied to the buffer. In this case, it is assumed that the buffer is already modified, and that the request is made as a result from the buffer modification. This also means that the request must be applicable to the current document state, without requiring transformation.

In addition, the function emits the “begin-execute-request” and “end-execute-request” signals, and makes inf_adopted_algorithm_get_execute_request() return request during that period.

This allows other code to hook in before and after request processing. This does not cause any loss of generality because this function is not re-entrant anyway: it cannot work when used concurrently by multiple threads nor in a recursive manner, because only when one request has been added to the log the next request can be translated, since it might need the previous request for the translation path and it needs to be translated to a state where the effect of the previous request is included so that it can consistently applied to the buffer.

There are also runtime errors that can occur if request execution fails. In this case the function returns FALSE and error is set. Possible reasons for this include request being an INF_ADOPTED_REQUEST_UNDO or INF_ADOPTED_REQUEST_REDO request without there being an operation to undo or redo, or if the translated operation cannot be applied to the buffer. This usually means that the input request was invalid. However, this is not considered a programmer error because typically requests are received from untrusted input sources such as network connections. Note that there cannot be any runtime errors if apply is set to FALSE. In that case it is safe to call the function with NULL error.

inf_adopted_algorithm_cleanup ()

void
inf_adopted_algorithm_cleanup (InfAdoptedAlgorithm *algorithm);

Removes requests in all users request logs which are no longer needed. This includes requests which cannot be undone or redone anymore due to the constraints of the “max-total-log-size” property, and requests that every participant is guaranteed to have processed already.

This function can be called after every executed request to keep memory use to a minimum, or it can be called in regular intervals, or it can also be omitted if the request history should be preserved.

inf_adopted_algorithm_can_undo ()

gboolean
inf_adopted_algorithm_can_undo (InfAdoptedAlgorithm *algorithm,
                                InfAdoptedUser *user);

Returns whether user can issue an undo request in the current state. Note that if user is non-local, then the result of this function does not depend on the current state but on the state that we know user is guaranteed to have reached. This is because user might still issue an Undo request even if the max-total-log-size is already exceeded if user does not know yet that it is exceeded.

inf_adopted_algorithm_can_redo ()

gboolean
inf_adopted_algorithm_can_redo (InfAdoptedAlgorithm *algorithm,
                                InfAdoptedUser *user);

Returns whether user can issue a redo request in the current state. Note that if user is non-local, then the result of this function does not depend on the current state but on the state that we know user is guaranteed to have reached. This is because user might still issue a Redo request even if the max-total-log-size is already exceeded if user does not know yet that it is exceeded.

enum InfAdoptedAlgorithmError

Error codes for InfAdoptedAlgorithm. These can occur when invalid requests are passed to inf_adopted_algorithm_execute_request().

struct InfAdoptedAlgorithm

struct InfAdoptedAlgorithm;

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

struct InfAdoptedAlgorithmClass

struct InfAdoptedAlgorithmClass {
  void(*can_undo_changed)(InfAdoptedAlgorithm* algorithm,
                          InfAdoptedUser* user,
                          gboolean can_undo);

  void(*can_redo_changed)(InfAdoptedAlgorithm* algorithm,
                          InfAdoptedUser* user,
                          gboolean can_redo);

  void(*begin_execute_request)(InfAdoptedAlgorithm* algorithm,
                               InfAdoptedUser* user,
                               InfAdoptedRequest* request);

  void(*end_execute_request)(InfAdoptedAlgorithm* algorithm,
                             InfAdoptedUser* user,
                             InfAdoptedRequest* request,
                             InfAdoptedRequest* translated_request,
                             const GError* error);
};

Signals for the InfAdoptedAlgorithm class.

The “buffer” property

  “buffer”                   InfBuffer *

The buffer to apply operations to.

Owner: InfAdoptedAlgorithm

Flags: Read / Write / Construct Only

The “buffer-modified-state” property

  “buffer-modified-state”    InfAdoptedStateVector *

The state in which the buffer is considered not being modified.

Owner: InfAdoptedAlgorithm

Flags: Read

The “current-state” property

  “current-state”            InfAdoptedStateVector *

The state vector describing the current document state.

Owner: InfAdoptedAlgorithm

Flags: Read

The “max-total-log-size” property

  “max-total-log-size”       guint

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

Owner: InfAdoptedAlgorithm

Flags: Read / Write / Construct Only

Default value: 2048

The “user-table” property

  “user-table”               InfUserTable *

The user table.

Owner: InfAdoptedAlgorithm

Flags: Read / Write / Construct Only

The “begin-execute-request” signal

void
user_function (InfAdoptedAlgorithm *algorithm,
               InfAdoptedUser      *user,
               InfAdoptedRequest   *request,
               gpointer             user_data)

This signal is emitted every time the algorithm executes a request, i.e. transforms it such that it can be applied to the current state, resolves undo/redo operations and applies the resulting operation to the buffer.

Flags: Run Last

The “can-redo-changed” signal

void
user_function (InfAdoptedAlgorithm *algorithm,
               InfAdoptedUser      *user,
               gboolean             can_undo,
               gpointer             user_data)

This signal is emitted every time the can-redo state of a local user in algorithm 's user table changed. The can-redo state defines whether user can generate a redo request (via inf_adopted_algorithm_generate_request()) in the current situation, see also inf_adopted_algorithm_can_redo().

Flags: Run Last

The “can-undo-changed” signal

void
user_function (InfAdoptedAlgorithm *algorithm,
               InfAdoptedUser      *user,
               gboolean             can_undo,
               gpointer             user_data)

This signal is emitted every time the can-undo state of a local user in algorithm 's user table changed. The can-undo state defines whether user can generate an undo request (via inf_adopted_algorithm_generate_request()) in the current situation, see also inf_adopted_algorithm_can_undo().

Flags: Run Last

The “end-execute-request” signal

void
user_function (InfAdoptedAlgorithm *algorithm,
               InfAdoptedUser      *user,
               InfAdoptedRequest   *request,
               InfAdoptedRequest   *translated,
               GError              *error,
               gpointer             user_data)

This signal is emitted after a request has been executed. The request parameter is not necessarily the same as the one in the corresponding emission of “begin-execute-request”, however its effect on the buffer is the same. The difference is that the request in this signal might be reversible while the request in the “begin-execute-request” emission might not be reversible. The algorithm can make some requests reversible during their execution.

The translated request is the result of the transformation, i.e. it is always a INF_ADOPTED_REQUEST_DO type request and its state vector corresponds to the current state. It has already been applied on the buffer by the algorithm. If request is of type INF_ADOPTED_REQUEST_UNDO or INF_ADOPTED_REQUEST_REDO then translated represents the operation that actually was performed on the buffer to undo or redo the effect of a previous request.

It can happen that an error occurs during execution. Usually this is due to invalid input, such as a request that cannot be transformed to the current state, a INF_ADOPTED_REQUEST_UNDO request which has no corresponding INF_ADOPTED_REQUEST_DO or INF_ADOPTED_REQUEST_REDO request, or a request that ends up in an invalid operation (e.g. inserting text behind the end of the document). If such an error occurs then request is the same as the one in the InfAdoptedAlgorithm::begin-execute-request emission, translated may or may not be NULL and error contains information on the error occurred.

Flags: Run Last