Timeouts: libfprint Reference Manual

## Timeouts Timeouts — Timeout handling helpers |

## Functions

void | (*fpi_timeout_fn) ()
fpi_timeout * | fpi_timeout_add ()
void | fpi_timeout_set_name ()
void | fpi_timeout_cancel ()

## Types and Values

typedef | fpi_timeout

## Includes

    #include <fpi-poll.h>

## Description

Helper functions to schedule a function call to be made after a timeout. This is useful to avoid making blocking calls while waiting for hardware to answer for example.

## Functions

### fpi_timeout_fn ()

    void
    (*fpi_timeout_fn) (struct fp_dev *dev,
                       void *data);

The prototype of the callback function for `fpi_timeout_add()`. Note that after the callback is called, the fpi_timeout structure will be freed.

#### Parameters

dev | the struct fp_dev passed to `fpi_timeout_add()` |
data | the data passed to `fpi_timeout_add()` |

### fpi_timeout_add ()

    fpi_timeout *
    fpi_timeout_add (unsigned int msec,
                     fpi_timeout_fn callback,
                     struct fp_dev *dev,
                     void *data);

A timeout is the asynchronous equivalent of sleeping. You create a timeout saying that you'd like to have a function invoked at a certain time in the future.

Note that you should hold onto the return value of this function to cancel it use `fpi_timeout_cancel()`, otherwise the callback could be called while the driver is being torn down.

This function can be considered to never fail.

#### Parameters

msec | the time before calling the function, in milliseconds (1/1000ths of a second) |
callback | function to callback |
dev | a struct fp_dev |
data | data to pass to `callback` , or `NULL` |

#### Returns

an fpi_timeout structure

### fpi_timeout_set_name ()

    void
    fpi_timeout_set_name (fpi_timeout *timeout,
                          const char *name);

Sets a name for a timeout, allowing that name to be printed along with any timeout related debug.

#### Parameters

timeout | a fpi_timeout |
name | the name to give the timeout |

### fpi_timeout_cancel ()

    void
    fpi_timeout_cancel (fpi_timeout *timeout);

Cancels a timeout scheduled with `fpi_timeout_add()`, and frees the `timeout` structure.

#### Parameters

timeout | an fpi_timeout structure |

## Types and Values

### fpi_timeout

    typedef struct fpi_timeout fpi_timeout;

An opaque structure representing a scheduled function call, created with `fpi_timeout_add()`.