Modules | Data Structures | Macros | Typedefs | Functions | Variables
Eina Futures

Methods and structures dealing with Eina_Future. More...

Modules

 Eina Future Callbacks
 Methods and structures dealing with Eina_Future callbacks.
 

Data Structures

struct  _Eina_Future_Race_Result
 The struct that is used to store the race result. More...
 
struct  Eina_Future
 An opaque structure representing a callback to be called when a promise is fulfilled. More...
 
struct  _Eina_Future_Desc
 A struct used to define a callback and data for a future. More...
 

Macros

#define EINA_FUTURE_SENTINEL   ((void *)(unsigned long)-1)
 Used by eina_promise_race_array() and eina_promise_all_array() and friends to flag the end of the array. More...
 
#define eina_promise_race(...)   eina_promise_race_array((Eina_Future *[]){__VA_ARGS__, EINA_FUTURE_SENTINEL})
 A syntactic sugar over eina_promise_race_array(). More...
 
#define eina_future_race(...)   eina_future_race_array((Eina_Future *[]){__VA_ARGS__, EINA_FUTURE_SENTINEL})
 A syntactic sugar over eina_future_race_array(). More...
 
#define eina_future_all(...)   eina_future_all_array((Eina_Future *[]){__VA_ARGS__, EINA_FUTURE_SENTINEL})
 A syntactic sugar over eina_future_all_array(). More...
 
#define eina_promise_all(...)   eina_promise_all_array((Eina_Future *[]){__VA_ARGS__, EINA_FUTURE_SENTINEL})
 A syntactic sugar over eina_promise_all_array(). More...
 
#define eina_future_cb_easy(...)   eina_future_cb_easy_from_desc((Eina_Future_Cb_Easy_Desc){__VA_ARGS__})
 A syntactic sugar over eina_future_cb_easy_from_desc(). More...
 
#define eina_future_chain(_prev, ...)   eina_future_chain_array(_prev, (Eina_Future_Desc[]){__VA_ARGS__, {.cb = NULL, .data = NULL}})
 A syntactic sugar over eina_future_chain_array(). More...
 
#define eina_future_then(_prev, ...)   eina_future_then_from_desc(_prev, (Eina_Future_Desc){__VA_ARGS__})
 A syntactic sugar over eina_future_then_from_desc(). More...
 
#define eina_future_cb_console(...)   eina_future_cb_console_from_desc((Eina_Future_Cb_Console_Desc){__VA_ARGS__})
 A syntactic sugar over eina_future_cb_console_from_desc(). More...
 
#define eina_future_cb_log_dbg(_prefix, _suffix)
 A syntactic sugar over eina_future_cb_log_from_desc(). More...
 
#define eina_future_cb_log_crit(_prefix, _suffix)
 A syntactic sugar over eina_future_cb_log_from_desc(). More...
 
#define eina_future_cb_log_err(_prefix, _suffix)
 A syntactic sugar over eina_future_cb_log_from_desc(). More...
 
#define eina_future_cb_log_info(_prefix, _suffix)
 A syntactic sugar over eina_future_cb_log_from_desc(). More...
 
#define eina_future_cb_log_warn(_prefix, _suffix)
 A syntactic sugar over eina_future_cb_log_from_desc(). More...
 
#define eina_future_then_easy(_prev, ...)   eina_future_then_from_desc(_prev, eina_future_cb_easy(__VA_ARGS__))
 A syntactic sugar over eina_future_then() and eina_future_cb_easy(). More...
 
#define eina_future_chain_easy(_prev, ...)   eina_future_chain_easy_array(_prev, (Eina_Future_Cb_Easy_Desc[]) {__VA_ARGS__, {NULL, NULL, NULL, NULL, NULL}})
 A syntactic sugar over eina_future_chain() and eina_future_cb_easy(). More...
 

Typedefs

typedef struct _Eina_Future_Desc Eina_Future_Desc
 Convenience wrapper over _Eina_Future_Desc. More...
 
typedef struct _Eina_Future_Race_Result Eina_Future_Race_Result
 Convenience wrapper over _Eina_Future_Race_Result. More...
 

Functions

EAPI void eina_future_cancel (Eina_Future *f)
 Cancels a future. More...
 
EAPI void eina_future_desc_flush (Eina_Future_Desc *desc)
 Flushes an Eina_Future_Desc. More...
 
EAPI void eina_future_cb_easy_desc_flush (Eina_Future_Cb_Easy_Desc *desc)
 Flushes an Eina_Future_Cb_Easy_Desc. More...
 
EAPI Eina_Value eina_promise_as_value (Eina_Promise *p)
 Creates a new Eina_Value from a promise. More...
 
EAPI Eina_Value eina_future_as_value (Eina_Future *f)
 Creates an Eina_Value from a future. More...
 
EAPI Eina_Futureeina_future_new (Eina_Promise *p)
 Creates a new future. More...
 
EAPI Eina_Futureeina_future_resolved (Eina_Future_Scheduler *scheduler, Eina_Value value)
 Creates a new future that is already resolved to a value. More...
 
EAPI Eina_Futureeina_future_rejected (Eina_Future_Scheduler *scheduler, Eina_Error err)
 Creates a new future that is already rejected to a specified error. More...
 
EAPI Eina_Futureeina_future_then_from_desc (Eina_Future *prev, const Eina_Future_Desc desc)
 Register an Eina_Future_Desc to be used when the future is resolved/rejected. More...
 
EAPI Eina_Future_Desc eina_future_cb_log_from_desc (const Eina_Future_Cb_Log_Desc desc)
 Creates an Eina_Future_Desc that will log the previous future resolved value. More...
 
EAPI Eina_Futureeina_future_chain_array (Eina_Future *prev, const Eina_Future_Desc descs[])
 Creates a future chain. More...
 
EAPI Eina_Futureeina_future_chain_easy_array (Eina_Future *prev, const Eina_Future_Cb_Easy_Desc descs[])
 Wrapper around eina_future_chain_array() and eina_future_cb_easy_from_desc() More...
 
EAPI Eina_Future_Desc eina_future_cb_console_from_desc (const Eina_Future_Cb_Console_Desc desc)
 Creates an Eina_Future_Desc that will print the previous future's resolved value. More...
 
EAPI Eina_Future_Desc eina_future_cb_ignore_error (Eina_Error err)
 Returns an Eina_Future_Desc that ignores an error. More...
 
EAPI Eina_Future_Desc eina_future_cb_convert_to (const Eina_Value_Type *type)
 Creates an Eina_Future_Desc which will convert the received eina value to a given type. More...
 
EAPI Eina_Future_Desc eina_future_cb_easy_from_desc (const Eina_Future_Cb_Easy_Desc desc)
 Creates an Eina_Future_Desc based on an Eina_Future_Cb_Easy_Desc. More...
 
EAPI Eina_Promiseeina_promise_all_array (Eina_Future *array[])
 Creates an all promise. More...
 
EAPI Eina_Promiseeina_promise_all_iterator (Eina_Iterator *iterator)
 Creates an all promise from an iterator. More...
 
EAPI Eina_Promiseeina_promise_race_array (Eina_Future *array[])
 Creates a race promise. More...
 
static Eina_Futureeina_future_all_array (Eina_Future *array[])
 Creates a future that will be resolved once all futures from array is resolved. More...
 
static Eina_Futureeina_future_all_iterator (Eina_Iterator *iterator)
 Creates a future that will be resolved once all futures from iterator are resolved. More...
 
static Eina_Futureeina_future_race_array (Eina_Future *array[])
 Creates a future that will be resolved once a future array is resolved. More...
 

Variables

EAPI const Eina_Value_Struct_DescEINA_PROMISE_RACE_STRUCT_DESC
 A pointer to the race struct description, which is used by eina_promise_race_array(). More...
 

Detailed Description

Methods and structures dealing with Eina_Future.

Macro Definition Documentation

◆ EINA_FUTURE_SENTINEL

#define EINA_FUTURE_SENTINEL   ((void *)(unsigned long)-1)

Used by eina_promise_race_array() and eina_promise_all_array() and friends to flag the end of the array.

See also
eina_promise_race_array()
eina_promise_all_array()

◆ eina_promise_race

#define eina_promise_race (   ...)    eina_promise_race_array((Eina_Future *[]){__VA_ARGS__, EINA_FUTURE_SENTINEL})

A syntactic sugar over eina_promise_race_array().

Usage:

promise = eina_promise_race(future1, future2, future3, future4);
See also
eina_promise_race_array()

◆ eina_future_race

#define eina_future_race (   ...)    eina_future_race_array((Eina_Future *[]){__VA_ARGS__, EINA_FUTURE_SENTINEL})

A syntactic sugar over eina_future_race_array().

Usage:

future = eina_future_race(future1, future2, future3, future4);
See also
eina_future_race_array()

◆ eina_future_all

#define eina_future_all (   ...)    eina_future_all_array((Eina_Future *[]){__VA_ARGS__, EINA_FUTURE_SENTINEL})

A syntactic sugar over eina_future_all_array().

Usage:

future = eina_future_all(future1, future2, future3, future4);
See also
eina_future_all_array()

◆ eina_promise_all

#define eina_promise_all (   ...)    eina_promise_all_array((Eina_Future *[]){__VA_ARGS__, EINA_FUTURE_SENTINEL})

A syntactic sugar over eina_promise_all_array().

Usage:

promise = eina_promise_all(future1, future2, future3, future4);
See also
eina_promise_all_array()

◆ eina_future_cb_easy

#define eina_future_cb_easy (   ...)    eina_future_cb_easy_from_desc((Eina_Future_Cb_Easy_Desc){__VA_ARGS__})

A syntactic sugar over eina_future_cb_easy_from_desc().

Usage:

future_desc = eina_future_cb_easy(_success_cb, _error_cb, _free_cb, EINA_VALUE_TYPE_INT, my_data);
See also
eina_future_cb_easy_from_desc()

◆ eina_future_chain

#define eina_future_chain (   _prev,
  ... 
)    eina_future_chain_array(_prev, (Eina_Future_Desc[]){__VA_ARGS__, {.cb = NULL, .data = NULL}})

A syntactic sugar over eina_future_chain_array().

Usage:

future = eina_future_chain(future, {.cb = _my_cb, .data = my_data}, {.cb = _my_another_cb, .data = NULL});
See also
eina_future_chain_array()

◆ eina_future_then

#define eina_future_then (   _prev,
  ... 
)    eina_future_then_from_desc(_prev, (Eina_Future_Desc){__VA_ARGS__})

A syntactic sugar over eina_future_then_from_desc().

Usage:

future = eina_future_then(future, _my_cb, my_data);
See also
eina_future_then_from_desc()
eina_future_then_easy()

◆ eina_future_cb_console

#define eina_future_cb_console (   ...)    eina_future_cb_console_from_desc((Eina_Future_Cb_Console_Desc){__VA_ARGS__})

A syntactic sugar over eina_future_cb_console_from_desc().

Usage:

desc = eina_future_cb_console(.prefix = "prefix", .suffix = "suffix");
See also
eina_future_cb_console_from_desc()

◆ eina_future_cb_log_dbg

#define eina_future_cb_log_dbg (   _prefix,
  _suffix 
)
Value:
EAPI Eina_Future_Desc eina_future_cb_log_from_desc(const Eina_Future_Cb_Log_Desc desc)
Creates an Eina_Future_Desc that will log the previous future resolved value.
Definition: eina_promise.c:1545
Debug log level.
Definition: eina_log.h:461
#define EINA_LOG_DOMAIN_DEFAULT
This macro defines the domain to use with the macros EINA_LOG_DOM_DBG(), EINA_LOG_DOM_INFO(),...
Definition: eina_log.h:284
This struct is used by eina_future_cb_log_from_desc() and its contents will be routed to eina_log_pri...
Definition: eina_promise.h:398

A syntactic sugar over eina_future_cb_log_from_desc().

This macro will set the following fields of the Eina_Future_Cb_Log_Desc:

Usage:

desc = eina_future_cb_log_dbg(.prefix = "prefix", .suffix = "suffix");
See also
eina_future_cb_log_from_desc()

◆ eina_future_cb_log_crit

#define eina_future_cb_log_crit (   _prefix,
  _suffix 
)
Value:
EAPI Eina_Future_Desc eina_future_cb_log_from_desc(const Eina_Future_Cb_Log_Desc desc)
Creates an Eina_Future_Desc that will log the previous future resolved value.
Definition: eina_promise.c:1545
Critical log level.
Definition: eina_log.h:457
#define EINA_LOG_DOMAIN_DEFAULT
This macro defines the domain to use with the macros EINA_LOG_DOM_DBG(), EINA_LOG_DOM_INFO(),...
Definition: eina_log.h:284
This struct is used by eina_future_cb_log_from_desc() and its contents will be routed to eina_log_pri...
Definition: eina_promise.h:398

A syntactic sugar over eina_future_cb_log_from_desc().

This macro will set the following fields of the Eina_Future_Cb_Log_Desc:

Usage:

desc = eina_future_cb_log_crit(.prefix = "prefix", .suffix = "suffix");
See also
eina_future_cb_log_from_desc()

◆ eina_future_cb_log_err

#define eina_future_cb_log_err (   _prefix,
  _suffix 
)
Value:
Error log level.
Definition: eina_log.h:458
EAPI Eina_Future_Desc eina_future_cb_log_from_desc(const Eina_Future_Cb_Log_Desc desc)
Creates an Eina_Future_Desc that will log the previous future resolved value.
Definition: eina_promise.c:1545
#define EINA_LOG_DOMAIN_DEFAULT
This macro defines the domain to use with the macros EINA_LOG_DOM_DBG(), EINA_LOG_DOM_INFO(),...
Definition: eina_log.h:284
This struct is used by eina_future_cb_log_from_desc() and its contents will be routed to eina_log_pri...
Definition: eina_promise.h:398

A syntactic sugar over eina_future_cb_log_from_desc().

This macro will set the following fields of the Eina_Future_Cb_Log_Desc:

Usage:

desc = eina_future_cb_log_err(.prefix = "prefix", .suffix = "suffix");
See also
eina_future_cb_log_from_desc()

◆ eina_future_cb_log_info

#define eina_future_cb_log_info (   _prefix,
  _suffix 
)
Value:
EAPI Eina_Future_Desc eina_future_cb_log_from_desc(const Eina_Future_Cb_Log_Desc desc)
Creates an Eina_Future_Desc that will log the previous future resolved value.
Definition: eina_promise.c:1545
#define EINA_LOG_DOMAIN_DEFAULT
This macro defines the domain to use with the macros EINA_LOG_DOM_DBG(), EINA_LOG_DOM_INFO(),...
Definition: eina_log.h:284
This struct is used by eina_future_cb_log_from_desc() and its contents will be routed to eina_log_pri...
Definition: eina_promise.h:398
Information log level.
Definition: eina_log.h:460

A syntactic sugar over eina_future_cb_log_from_desc().

This macro will set the following fields of the Eina_Future_Cb_Log_Desc:

Usage:

desc = eina_future_cb_log_info(.prefix = "prefix", .suffix = "suffix");
See also
eina_future_cb_log_from_desc()

◆ eina_future_cb_log_warn

#define eina_future_cb_log_warn (   _prefix,
  _suffix 
)
Value:
EAPI Eina_Future_Desc eina_future_cb_log_from_desc(const Eina_Future_Cb_Log_Desc desc)
Creates an Eina_Future_Desc that will log the previous future resolved value.
Definition: eina_promise.c:1545
#define EINA_LOG_DOMAIN_DEFAULT
This macro defines the domain to use with the macros EINA_LOG_DOM_DBG(), EINA_LOG_DOM_INFO(),...
Definition: eina_log.h:284
This struct is used by eina_future_cb_log_from_desc() and its contents will be routed to eina_log_pri...
Definition: eina_promise.h:398
Warning log level.
Definition: eina_log.h:459

A syntactic sugar over eina_future_cb_log_from_desc().

This macro will set the following fields of the Eina_Future_Cb_Log_Desc:

Usage:

desc = eina_future_cb_log_warn(.prefix = "prefix", .suffix = "suffix");
Parameters
_prefixPREFIX
_suffixSUFFIX
Returns
SOMETHING
See also
eina_future_cb_log_from_desc()

◆ eina_future_then_easy

#define eina_future_then_easy (   _prev,
  ... 
)    eina_future_then_from_desc(_prev, eina_future_cb_easy(__VA_ARGS__))

A syntactic sugar over eina_future_then() and eina_future_cb_easy().

Usage:

f = eina_future_then_easy(f, .success = _success_cb, .success_type = EINA_VALUE_TYPE_DOUBLE, .data = NULL, );
See also
eina_future_then_from_desc()
eina_future_easy()
eina_future_then()
eina_future_cb_easy_from_desc()

◆ eina_future_chain_easy

#define eina_future_chain_easy (   _prev,
  ... 
)    eina_future_chain_easy_array(_prev, (Eina_Future_Cb_Easy_Desc[]) {__VA_ARGS__, {NULL, NULL, NULL, NULL, NULL}})

A syntactic sugar over eina_future_chain() and eina_future_cb_easy().

Usage:

f = eina_future_chain_easy(f, {.success = _success_cb, .success_type = EINA_VALUE_TYPE_DOUBLE, .data = NULL},
{ .success = _success2_cb }, {.error = error_cb});
See also
eina_future_chain_array()
eina_future_easy()
eina_future_chain_easy_array()
eina_future_cb_easy_from_desc()

Typedef Documentation

◆ Eina_Future_Desc

Convenience wrapper over _Eina_Future_Desc.

◆ Eina_Future_Race_Result

Convenience wrapper over _Eina_Future_Race_Result.

Function Documentation

◆ eina_future_cancel()

EAPI void eina_future_cancel ( Eina_Future f)

Cancels a future.

This function will cancel the whole future chain immediately (it will not be schedule to the next mainloop pass) and it will also cancel the promise linked against it. The Eina_Future_Cb will be called with an Eina_Value typed as EINA_VALUE_TYPE_ERROR, with its value set to ECANCELED

Parameters
[in,out]fThe future to cancel.

◆ eina_future_desc_flush()

EAPI void eina_future_desc_flush ( Eina_Future_Desc desc)

Flushes an Eina_Future_Desc.

This function is mainly used by bindings to flush an Eina_Future_Desc. It will call the Eina_Future_Cb with ENOMEM and zero the desc contents.

Parameters
[in,out]descThe Eina_Future_Desc to flush, if NULL this is a noop.

◆ eina_future_cb_easy_desc_flush()

EAPI void eina_future_cb_easy_desc_flush ( Eina_Future_Cb_Easy_Desc desc)

Flushes an Eina_Future_Cb_Easy_Desc.

This function is mainly used by bindings to flush an Eina_Future_Cb_Easy_Desc. It will call the Eina_Future_Error_Cb with ENOMEM, the Eina_Future_Free_Cb and zero the desc contents.

Parameters
[in,out]descThe Eina_Future_Cb_Easy_Desc to flush, if NULL this is a noop.

References _Eina_Future_Cb_Easy_Desc::data, eina_value_flush(), _Eina_Future_Cb_Easy_Desc::error, and _Eina_Future_Cb_Easy_Desc::free.

◆ eina_promise_as_value()

EAPI Eina_Value eina_promise_as_value ( Eina_Promise p)

Creates a new Eina_Value from a promise.

This function creates a new Eina_Value that will store an Eina_Promise in it. This function is useful for dealing with promises inside an Eina_Future_Cb. By returning a promise inside the Eina_Value the whole chain will wait until the promise is resolved in order to continue its execution. Example:

static Eina_Value
_file_data_ready(const *data EINA_UNUSED, const Eina_Value v, const Eina_Future *dead EINA_UNUSED)
{
const char *file_data;
// It was not possible to fetch the file size.
if (v.type == EINA_VALUE_TYPE_ERROR)
{
eina_value_get(&v, &err);
fprintf(stderr, "Could not get the file data. Reason: %s\n", eina_error_msg_get(err));
return v;
}
else if (v.type != EINA_VALUE_TYPE_STRING)
{
fprintf(stderr, "Expecting type '%s' - received '%s'\n", EINA_VALUE_TYPE_STRING->name, v.type->name);
return v;
}
eina_value_get(&v, &file_data);
// count_words will count the words in the background and resolve the promise once it is over...
p = count_words(file_data);
}
static Eina_Value
_word_count_ready(const *data EINA_UNUSED, const Eina_Value v, const Eina_Future *dead EINA_UNUSED)
{
// The _word_count_ready will only be called once count_words() resolves/rejects the promise returned by _file_data_ready()
int count;
if (v.type == EINA_VALUE_TYPE_ERROR)
{
eina_value_get(&v, &err);
fprintf(stderr, "Could not count the file words. Reason: %s\n", eina_error_msg_get(err));
return v;
}
else if (v.type != EINA_VALUE_TYPE_INT)
{
fprintf(stderr, "Expecting type '%s' - received '%s'\n", EINA_VALUE_TYPE_INT->name, v.type->name);
return v;
}
eina_value_get(&v, &count);
printf("File word count %d\n", count);
return v;
}
void
file_operation(void)
{
Eina_Future *f = get_file_data("/MyFile.txt");
eina_future_chain(f, {.cb = _file_data_ready, .data = NULL},
{.cb = _word_count_ready, .data = NULL});
}
Parameters
[in,out]pThe promise object to wrap in a value.
Returns
An Eina_Value. On error the value's type will be NULL.
Note
If an error happens the promise will be CANCELED.
See also
eina_future_as_value()
eina_promise_reject()
eina_promise_resolve()

References DBG, EINA_SAFETY_ON_FALSE_GOTO, EINA_VALUE_EMPTY, eina_value_flush(), eina_value_pset(), eina_value_setup(), and EINA_VALUE_TYPE_PROMISE.

Referenced by eina_future_as_value().

◆ eina_future_as_value()

EAPI Eina_Value eina_future_as_value ( Eina_Future f)

Creates an Eina_Value from a future.

This function is used for the same purposes as eina_promise_as_value(), but receives an Eina_Future instead.

Parameters
[in,out]fA future to create a Eina_Value from.
Returns
An Eina_Value. On error the value's type will be NULL.
Note
If an error happens the future f will be CANCELED
See also
eina_promise_as_value()

References DBG, eina_future_then, eina_promise_as_value(), eina_promise_new(), EINA_SAFETY_ON_NULL_GOTO, EINA_VALUE_EMPTY, EINA_VALUE_TYPE_PROMISE, and ERR.

◆ eina_future_new()

EAPI Eina_Future* eina_future_new ( Eina_Promise p)

Creates a new future.

This function creates a new future and can be used to report that an operation has succeeded or failed using eina_promise_resolve() or eina_promise_reject().

Futures can also be canceled using eina_future_cancel(), which will cause the whole chain to be canceled alongside with any pending promise.

Note
A promise can only have one future attached to it, calling eina_future_new() on the same promise twice will result in an error (NULL is returned) and the future attached to the promise will be canceled!
Parameters
[in,out]pA promise used to attach a future. May not be NULL.
Returns
The future or NULL on error.
Note
If an error happens this function will CANCEL the promise.
See also
eina_promise_new()
eina_promise_reject()
eina_promise_resolve()
eina_future_cancel()

References _Eina_Future_Desc::cb, and EINA_SAFETY_ON_TRUE_GOTO.

Referenced by eina_future_all_array(), eina_future_all_iterator(), eina_future_race_array(), eina_future_rejected(), and eina_future_resolved().

◆ eina_future_resolved()

EAPI Eina_Future* eina_future_resolved ( Eina_Future_Scheduler scheduler,
Eina_Value  value 
)

Creates a new future that is already resolved to a value.

This function creates a new future with an already known value, that will be resolved and dispatched by the given scheduler as usual.

This is a helper that behaves the same as eina_promise_new() followed by eina_future_new() and then eina_promise_resolve().

Futures can also be canceled using eina_future_cancel(), which will cause the whole chain to be canceled alongside with any pending promise.

Parameters
[in,out]schedulerThe scheduler to use.
[in]valueThe value to be delivered. Note that the value contents must survive this function scope, that is, do not use stack allocated blobs, arrays, structures or types that keep references to memory you give. Values will be automatically cleaned up using eina_value_flush() once they are unused (no more future or futures returned a new value).
Returns
The future or NULL on error.
See also
eina_promise_new()
eina_future_new()
eina_promise_reject()
eina_promise_resolve()
eina_future_cancel()

References eina_future_new(), eina_promise_new(), eina_promise_resolve(), EINA_SAFETY_ON_NULL_GOTO, and eina_value_flush().

◆ eina_future_rejected()

EAPI Eina_Future* eina_future_rejected ( Eina_Future_Scheduler scheduler,
Eina_Error  err 
)

Creates a new future that is already rejected to a specified error.

This function creates a new future with an already known error, that will be resolved and dispatched by the given scheduler as usual.

This is a helper that behaves the same as eina_promise_new() followed by eina_future_new() and then eina_promise_reject().

Futures can also be canceled using eina_future_cancel(), which will cause the whole chain to be canceled alongside with any pending promise.

Parameters
[in,out]schedulerThe scheduler to use.
[in]errAn Eina_Error value
Returns
The future or NULL on error.
See also
eina_promise_new()
eina_future_new()
eina_promise_reject()
eina_promise_resolve()
eina_future_cancel()

References eina_future_new(), eina_promise_new(), eina_promise_reject(), and EINA_SAFETY_ON_NULL_GOTO.

◆ eina_future_then_from_desc()

EAPI Eina_Future* eina_future_then_from_desc ( Eina_Future prev,
const Eina_Future_Desc  desc 
)

Register an Eina_Future_Desc to be used when the future is resolved/rejected.

With this function a callback and data is attached to the future and then once it's resolved or rejected the callback will be informed.

If during the future creation an error happens this function will return NULL, and the Eina_Future_Desc::cb will be called reporting an error (EINVAL or ENOMEM), so the user has a chance to free Eina_Future_Desc::data.

In case a future in the chain is canceled, the whole chain will be canceled immediately and the error ECANCELED will be reported.

Here's a simple usage of this function.

static Eina_Value
_file_ready(const *data, const Eina_Value v, const Eina_Future *dead EINA_UNUSED)
{
Ctx *ctx = data;
// It was not possible to fetch the file size.
if (v.type == EINA_VALUE_TYPE_ERROR)
{
eina_value_get(&v, &err);
fprintf(stderr, "Could not read the file size. Reason: %s\n", eina_error_msg_get(err));
return v;
}
else if (v.type != EINA_VALUE_TYPE_INT)
{
fprintf(stderr, "Expecting type '%s' - received '%s'\n", EINA_VALUE_TYPE_INT->name, v.type->name);
return v;
}
eina_value_get(&v, &ctx->size);
printf("File size is %d bytes\n", ctx->size);
return v;
}
void
file_operation(void)
{
Eina_Future *f = get_file_size_async("/MyFile.txt");
eina_future_then_from_desc(f, (const Eina_Future_Desc){.cb = _size_ready, .data = NULL});
// There's a helper macro called eina_future_then() which simplifies the usage.
// The code below has the same effect.
// eina_future_then(f, _size_ready, NULL);
}

Although the code presented at _size_ready() is very simple, most of it is just used to check the Eina_Value type. In order to avoid this type of code the function eina_future_cb_easy_from_desc() was created. Please, check its documentation for more information.

This function can also be used to create a future chain, making it possible to execute the future result in a cascade order. When using a future chain the Eina_Value returned by a Eina_Future_Desc::cb will be delivered to the next Eina_Future_Desc::cb in the chain.

Here's an example:

static Eina_Value
_future_cb1(const *data EINA_UNUSED, const Eina_Value v)
{
Eina_Value new_v;
int i;
// There's no need to check the Eina_Value type since we're using eina_future_cb_easy()
eina_value_get(&v, &i);
printf("File size as int: %d\n", i);
// Convert the file size to string
eina_value_convert(&v, &new_v);
return new_v;
}
static Eina_Value
_future_cb2(const *data EINA_UNUSED, const Eina_Value v)
{
Eina_Value new_v;
const char *file_size_str;
// There's no need to check the Eina_Value type since we're using eina_future_cb_easy()
eina_value_get(&v, &file_size_str);
printf("File size as string: %s\n", file_size_str);
eina_value_convert(&v, &new_v);
return new_v;
}
static Eina_Value
_future_cb3(const *data EINA_UNUSED, const Eina_Value v)
{
double d;
// There's no need to check the Eina_Value type since we're using eina_future_cb_easy()
eina_value_get(&v, &d);
printf("File size as double: %g\n", d);
return v;
}
static Eina_Value
_future_err(void *data EINA_UNUSED, Eina_Error err)
{
// This function is called if future result type does not match or another error occurred
Eina_Value new_v;
eina_value_set(&new_v, err);
fprintf(stderr, "Error during future process. Reason: %s\n", eina_error_msg_get(err));
// Pass the error to the next future in the chain..
return new_v;
}
void chain(void)
{
Eina_Future *f = get_file_size_async("/MyFile.txt");
f = eina_future_then_easy(f, .success = _future_cb1, .success_type = EINA_VALUE_TYPE_INT);
// _future_cb2 will be executed after _future_cb1()
f = eina_future_then_easy(f, .success = _future_cb2, .success_type = EINA_VALUE_TYPE_STRING);
// _future_cb3 will be executed after _future_cb2()
f = eina_future_then_easy(f, .success = _future_cb3, .success_type = EINA_VALUE_TYPE_DOUBLE);
// If an error happens _future_err will be called
eina_future_then_easy(f, .error = _future_err);
}

Although it's possible to create a future chain using eina_future_then() and eina_future_then_from_desc() there's a function that makes this task much easier, please check eina_future_chain_array() for more information.

Note
This example does manual conversion and print, however Eina offers eina_future_cb_convert_to() and eina_future_cb_console_from_desc() to make those common case easier.
Parameters
[in,out]prevA future to link against
[in]descA description struct containing the callback and data.
Returns
A new future or NULL on error.
Note
If an error happens the whole future chain will CANCELED and desc.cb will be called in order to free desc.data.
See also
eina_future_new()
eina_future_then()
Eina_Future_Desc
eina_future_chain_array()
eina_future_chain()
eina_future_cb_console_from_desc()
eina_future_cb_easy_from_desc()
eina_future_cb_easy()
eina_future_cb_convert_to()
eina_future_cancel()
eina_future_then_easy()
eina_future_cb_log_from_desc()

References EINA_SAFETY_ON_TRUE_GOTO.

◆ eina_future_cb_log_from_desc()

EAPI Eina_Future_Desc eina_future_cb_log_from_desc ( const Eina_Future_Cb_Log_Desc  desc)

Creates an Eina_Future_Desc that will log the previous future resolved value.

This function can be used to quickly log the value that an Eina_Future_Desc::cb is returning. The returned value will be passed to the next future in the chain without modifications.

There are some helper macros like eina_future_cb_log_dbg() which will automatically fill the following fields:

Parameters
[in]descThe description data to be used.
Returns
An Eina_Future_Desc
See also
Eina_Future_Cb_Log_Desc
eina_future_then()
eina_future_chain()
eina_future_cb_log_dbg()
eina_future_cb_log_crit()
eina_future_cb_log_err()
eina_future_cb_log_info()
eina_future_cb_log_warn()
eina_future_cb_console_from_desc()

References _Eina_Future_Cb_Log_Desc::domain, EINA_SAFETY_ON_NULL_GOTO, _Eina_Future_Cb_Log_Desc::file, _Eina_Future_Cb_Log_Desc::func, _Eina_Future_Cb_Log_Desc::level, _Eina_Future_Cb_Log_Desc::line, _Eina_Future_Cb_Log_Desc::prefix, and _Eina_Future_Cb_Log_Desc::suffix.

◆ eina_future_chain_array()

EAPI Eina_Future* eina_future_chain_array ( Eina_Future prev,
const Eina_Future_Desc  descs[] 
)

Creates a future chain.

This behaves exactly like eina_future_then_from_desc(), but makes it easier to create future chains.

If during the future chain creation an error happens this function will return NULL, and the Eina_Future_Desc::cb from the descs array will be called reporting an error (EINVAL or ENOMEM), so the user has a chance to free Eina_Future_Desc::data.

Just like eina_future_then_from_desc(), the value returned by a Eina_Future_Desc::cb callback will be delivered to the next Eina_Future_Desc::cb in the chain.

In case a future in the chain is canceled, the whole chain will be canceled immediately and the error ECANCELED will be reported.

Here's an example:

// callbacks code....
Eina_Future* chain(void)
{
Eina_Future *f = get_file_size_async("/MyFile.txt");
return eina_future_chain(f, eina_future_cb_easy(_future_cb1, _future_err, NULL, EINA_VALUE_TYPE_INT, NULL),
eina_future_cb_easy(_future_cb2, _future_err, NULL, EINA_VALUE_TYPE_STRING, NULL),
eina_future_cb_easy(_future_cb3, _future_err, NULL, EINA_VALUE_TYPE_DOUBLE, NULL),
{.cb = _future_cb4, .data = NULL });
}
Parameters
[in,out]prevThe previous future
[in]descsAn array of descriptions. The last element of the array must have the Eina_Future_Desc::cb set to NULL
Returns
A future or NULL on error.
Note
If an error happens the whole future chain will CANCELED and desc.cb will be called in order to free desc.data.
See also
eina_future_new()
eina_future_then()
Eina_Future_Desc
eina_future_chain()
eina_future_cb_ignore_error()
eina_future_cb_console_from_desc()
eina_future_cb_log_from_desc()
eina_future_cb_easy_from_desc()
eina_future_cb_easy()
eina_future_then_from_desc()
eina_future_then_easy()
eina_future_cb_convert_to()

References _Eina_Future_Desc::cb, EINA_SAFETY_ON_NULL_GOTO, and EINA_SAFETY_ON_TRUE_GOTO.

◆ eina_future_chain_easy_array()

EAPI Eina_Future* eina_future_chain_easy_array ( Eina_Future prev,
const Eina_Future_Cb_Easy_Desc  descs[] 
)

Wrapper around eina_future_chain_array() and eina_future_cb_easy_from_desc()

This functions makes it easier to use eina_future_chain_array() with eina_future_cb_easy_from_desc(), check the macro eina_future_chain_easy() for a syntax sugar.

Parameters
[in,out]prevThe previous future
[in]descsAn array of descriptions. The last element of the array must have the Eina_Future_Desc::cb set to NULL
Returns
A future or NULL on error.
Note
If an error happens the whole future chain will CANCELED and desc.cb will be called in order to free desc.data.
See also
eina_future_chain_easy()
eina_future_chain()
eina_future_cb_easy()
eina_future_chain_array()
eina_future_cb_easy_from_desc()

References eina_future_cb_easy_from_desc(), EINA_SAFETY_ON_NULL_GOTO, EINA_SAFETY_ON_TRUE_GOTO, eina_value_flush(), _Eina_Future_Cb_Easy_Desc::error, _Eina_Future_Cb_Easy_Desc::free, _Eina_Future_Cb_Easy_Desc::success, and _Eina_Future_Cb_Easy_Desc::success_type.

◆ eina_future_cb_console_from_desc()

EAPI Eina_Future_Desc eina_future_cb_console_from_desc ( const Eina_Future_Cb_Console_Desc  desc)

Creates an Eina_Future_Desc that will print the previous future's resolved value.

This function can be used to quickly inspect the value that an Eina_Future_Desc::cb is returning. The returned value will be passed to the next future in the chain without modifications.

There's also a helper macro called eina_future_cb_console() which makes this function easier to use.

Example:

eina_future_chain(a_future, {.cb = cb1, .data = NULL},
//Inspect the cb1 value and pass to cb2 without modifications
eina_future_cb_console("cb1 value:"),
{.cb = cb2, .data = NULL},
//Inspect the cb2 value
eina_future_cb_console("cb2 value:", " cb2 value suffix\n"))
Parameters
[in]descDescription object with contextual information.
Returns
An Eina_Future_Desc

The description object, desc, can (optionally) include a prefix, suffix, filename and function name. If these are NULL, empty strings ("") are used instead. If desc->suffix is provided, the '\n' should be provided to ensure the printed string ends with a line feed.

See also
eina_future_then()
Eina_Future_Desc
eina_future_chain()
eina_future_cb_easy_from_desc()
eina_future_cb_easy()
eina_future_then_from_desc()
eina_future_then_easy()
eina_future_cb_console()
eina_future_cb_ignore_error()
eina_future_cb_log_from_desc()

References _Eina_Future_Desc::cb, _Eina_Future_Desc::data, EINA_SAFETY_ON_NULL_GOTO, _Eina_Future_Cb_Console_Desc::prefix, and _Eina_Future_Cb_Console_Desc::suffix.

◆ eina_future_cb_ignore_error()

EAPI Eina_Future_Desc eina_future_cb_ignore_error ( Eina_Error  err)

Returns an Eina_Future_Desc that ignores an error.

This function may be used if one wants to ignore an error. If the specified error happens an EINA_VALUE_EMPTY will be delivered to the next future in the chain.

Parameters
[in]errThe error to be ignored.
Returns
A future descriptor to be used with eina_future_then() or eina_future_chain()

◆ eina_future_cb_convert_to()

EAPI Eina_Future_Desc eina_future_cb_convert_to ( const Eina_Value_Type type)

Creates an Eina_Future_Desc which will convert the received eina value to a given type.

Parameters
[in]typeThe Eina_Value_Type to convert to.
Returns
An Eina_Future_Desc
See also
eina_future_then()
Eina_Future_Desc
eina_future_chain()
eina_future_cb_easy_from_desc()
eina_future_cb_easy()
eina_future_then_from_desc()
eina_future_then_easy()

References _Eina_Future_Desc::cb.

◆ eina_future_cb_easy_from_desc()

EAPI Eina_Future_Desc eina_future_cb_easy_from_desc ( const Eina_Future_Cb_Easy_Desc  desc)

Creates an Eina_Future_Desc based on an Eina_Future_Cb_Easy_Desc.

This function aims to be used in conjunction with eina_future_chain(), eina_future_then_from_desc() and friends and its main objective is to simplify error handling and Eina_Value type checks. It uses three callbacks to inform the user about the future's result and life cycle. They are:

  • Eina_Future_Cb_Easy_Desc::free: Called after the future was freed and any resources allocated must be freed at this point. This callback is always called.

Check the example below for a sample usage:

static Eina_Value
_file_size_ok(void *data, Eina_Value v)
{
Ctx *ctx = data;
// Since an Eina_Future_Cb_Easy_Desc::success_type was provided, there's no need to check the value type
int s;
eina_value_get(&v, &s);
printf("File size is %d bytes\n", s);
ctx->file_size = s;
return v;
}
static Eina_Value
_file_size_err(void *data, Eina_Error err)
{
fprintf(stderr, "Could not read the file size. Reason: %s\n", eina_error_msg_get(err));
// Stop propagating the error.
}
static void
_future_freed(void *data, const Eina_Future dead)
{
Ctx *ctx = data;
printf("Future %p deleted\n", dead);
ctx->file_size_handler_cb(ctx->file_size);
free(ctx);
}
void do_work(File_Size_Handler_Cb cb)
{
Ctx *ctx = malloc(sizeof(Ctx));
ctx->f = get_file_size("/tmp/todo.txt");
ctx->file_size = -1;
ctx->file_size_handler_cb = cb;
eina_future_then_easy(f, _file_size_ok, _file_size_err, _future_freed, EINA_VALUE_TYPE_INT, ctx);
}
Parameters
[in]descThe easy callback's description.
Returns
An Eina_Future_Desc
See also
eina_future_chain()
eina_future_then()
eina_future_cb_easy()

References EINA_SAFETY_ON_NULL_GOTO.

Referenced by eina_future_chain_easy_array().

◆ eina_promise_all_array()

EAPI Eina_Promise* eina_promise_all_array ( Eina_Future array[])

Creates an all promise.

Creates a promise that is resolved once all the futures from the array are resolved. The promise is resolved with an Eina_Value type array which contains EINA_VALUE_TYPE_VALUE elements. The result array is ordered according to the array argument. Example:

static const char *
_get_operation_name_by_index(int idx)
{
switch (idx)
{
case 0: return "Get file data";
case 1: return "Get file size";
default: return "sum";
}
}
static Eina_Value
_all_cb(const void *data EINA_UNUSED, const Eina_Value array, const Eina_Future *dead EINA_UNUSED)
{
unsigned int i, len;
{
eina_value_get(&array, &err);
fprintf(stderr, "Could not complete all operations. Reason: %s\n", eina_error_msg_get(err));
return array;
}
len = eina_value_array_count(&array);
for (i = 0; i < len; i++)
{
eina_value_array_get(&array, i, &v);
if (v.type == EINA_VALUE_TYPE_ERROR)
{
eina_value_get(&v, &err);
fprintf(stderr, "Could not complete operation '%s'. Reason: %s\n", _get_operation_name_by_index(i), eina_error_msg_get(err));
continue;
}
if (!i)
{
const char *msg;
if (v.type != EINA_VALUE_TYPE_STRING)
{
fprintf(stderr, "Operation %s expects '%s' - received '%s'\n", _get_operation_name_by_index(i), EINA_VALUE_TYPE_STRING->name, v.type->name);
continue;
}
eina_value_get(&v, &msg);
printf("File content:%s\n", msg);
}
else if (i == 1)
{
int i;
if (v.type != EINA_VALUE_TYPE_INT)
{
fprintf(stderr, "Operation %s expects '%s' - received '%s'\n", _get_operation_name_by_index(i), EINA_VALUE_TYPE_INT->name, v.type->name);
continue;
}
eina_value_get(&v, &i);
printf("File size: %d\n", i);
}
else
{
double p;
if (v.type != EINA_VALUE_TYPE_DOUBLE)
{
fprintf(stderr, "Operation %s expects '%s' - received '%s'\n", _get_operation_name_by_index(i), EINA_VALUE_TYPE_DOUBLE->name, v.type->name);
continue;
}
eina_value_get(&v, &p);
printf("50 places of PI: %f\n", p);
}
}
return array;
}
void func(void)
{
Eina_Future *f1, *f2, *f3, f_all;
f1 = read_file("/tmp/todo.txt");
f2 = get_file_size("/tmp/file.txt");
// calculates 50 places of PI
f3 = calc_pi(50);
f_all = eina_future_all(f1, f2, f3);
eina_future_then(f_all, _all_cb, NULL);
}
Parameters
[in,out]arrayAn array of futures, terminated with EINA_FUTURE_SENTINEL.
Returns
A promise or NULL on error.
Note
On error all the futures will be CANCELED.
See also
eina_future_all_array()

References eina_mempool_free(), EINA_SAFETY_ON_FALSE_GOTO, EINA_SAFETY_ON_NULL_GOTO, EINA_SAFETY_ON_NULL_RETURN_VAL, eina_value_array_append(), eina_value_array_setup(), eina_value_flush(), eina_value_setup(), EINA_VALUE_TYPE_INT, and EINA_VALUE_TYPE_VALUE.

Referenced by eina_future_all_array().

◆ eina_promise_all_iterator()

EAPI Eina_Promise* eina_promise_all_iterator ( Eina_Iterator iterator)

Creates an all promise from an iterator.

Creates a promise that is resolved once all the futures from the iterator are resolved. The promise is resolved with an Eina_Value type array which contains EINA_VALUE_TYPE_VALUE elements. The result array is ordered according to the iterator order.

Parameters
[in]iteratorAn iterator of futures. Will be destroyed after the call.
Returns
A promise or NULL on error.
Note
On error all the futures will be CANCELED.
See also
eina_future_all_iterator()

References eina_future_then, EINA_ITERATOR_FOREACH, eina_iterator_free(), eina_iterator_next(), eina_mempool_free(), eina_promise_new(), EINA_SAFETY_ON_FALSE_GOTO, EINA_SAFETY_ON_NULL_GOTO, EINA_SAFETY_ON_NULL_RETURN_VAL, eina_value_array_append(), eina_value_array_setup(), eina_value_flush(), eina_value_setup(), EINA_VALUE_TYPE_INT, and EINA_VALUE_TYPE_VALUE.

Referenced by eina_future_all_iterator().

◆ eina_promise_race_array()

EAPI Eina_Promise* eina_promise_race_array ( Eina_Future array[])

Creates a race promise.

Creates a promise that resolves when a future from the array is completed. The remaining futures will be canceled with the error code ECANCELED

The resulting value is an EINA_VALUE_TYPE_STRUCT with two fields:

  • A field named value containing an Eina_Value with the result itself.
  • A field named index containing the index of the completed function relative to the array.

Example:

static const char *
_get_operation_name_by_index(int idx)
{
switch (idx)
{
case 0: return "Get file data";
case 1: return "Get file size";
default: return "sum";
}
}
static Eina_Value
_race_cb(const void *data EINA_UNUSED, const Eina_Value v)
{
unsigned int i;
Eina_Value result;
// No need to check for the 'v' type. eina_future_cb_easy() did that for us.
// However we should check if the struct has the correct description
st = eina_value_memory_get(&v);
{
fprintf(stderr, "Eina_Value is not a race struct\n");
return v;
}
eina_value_struct_get(&v, "index", &i);
// Get the operation result
eina_value_struct_get(&v, "value", &result);
if (!i)
{
const char *msg;
fprintf(stderr, "Operation %s expects '%s' - received '%s'\n", _get_operation_name_by_index(i), EINA_VALUE_TYPE_STRING->name, result.type->name);
else
{
eina_value_get(&result, &msg);
printf("File content:%s\n", msg);
}
}
else if (i == 1)
{
int i;
if (result.type != EINA_VALUE_TYPE_INT)
fprintf(stderr, "Operation %s expects '%s' - received '%s'\n", _get_operation_name_by_index(i), EINA_VALUE_TYPE_INT->name, v.type->name);
else
{
eina_value_get(&result, &i);
printf("File size: %d\n", i);
}
}
else
{
double p;
fprintf(stderr, "Operation %s expects '%s' - received '%s'\n", _get_operation_name_by_index(i), EINA_VALUE_TYPE_DOUBLE->name, result.type->name);
else
{
eina_value_get(&result, &p);
printf("50 places of PI: %f\n", p);
}
}
eina_value_flush(&result);
return v;
}
static Eina_Value
_race_err(void *data, Eina_Error err)
{
fprintf(stderr, "Could not complete the race future. Reason: %s\n", eina_error_msg_get(err));
}
void func(void)
{
static const *Eina_Future[] = {NULL, NULL, NULL, NULL};
Eina_List *l = NULL;
futures[0] = read_file("/tmp/todo.txt");
futures[1] = get_file_size("/tmp/file.txt");
// calculates 50 places of PI
futures[2] = calc_pi(50);
f_race = eina_future_race_array(futures);
eina_future_then_easy(f_race, _race_cb, _race_err, NULL, EINA_VALUE_TYPE_STRUCT, NULL);
}
Parameters
[in,out]arrayAn array of futures, terminated by EINA_FUTURE_SENTINEL.
Returns
A promise or NULL on error.
Note
On error all the futures will be CANCELED.
See also
eina_future_race_array()
_Eina_Future_Race_Result

References EINA_SAFETY_ON_FALSE_GOTO, EINA_SAFETY_ON_NULL_GOTO, and EINA_SAFETY_ON_NULL_RETURN_VAL.

Referenced by eina_future_race_array().

◆ eina_future_all_array()

static Eina_Future* eina_future_all_array ( Eina_Future array[])
inlinestatic

Creates a future that will be resolved once all futures from array is resolved.

This is a helper over eina_promise_all_array()

Parameters
[in,out]arrayA future array, must be terminated with EINA_FUTURE_SENTINEL.
Returns
A future.
See also
eina_promise_all_array()
EINA_FUTURE_SENTINEL

References eina_future_new(), and eina_promise_all_array().

◆ eina_future_all_iterator()

static Eina_Future* eina_future_all_iterator ( Eina_Iterator iterator)
inlinestatic

Creates a future that will be resolved once all futures from iterator are resolved.

This is a helper over eina_promise_all_iterator()

Parameters
[in]iteratorAn iterator containing futures. Will be destroyed on exit of the function.
Returns
A future.
See also
eina_promise_all_iterator()

References eina_future_new(), and eina_promise_all_iterator().

◆ eina_future_race_array()

static Eina_Future* eina_future_race_array ( Eina_Future array[])
inlinestatic

Creates a future that will be resolved once a future array is resolved.

This is a helper over eina_promise_race_array()

Parameters
[in,out]arrayA future array, must be terminated with EINA_FUTURE_SENTINEL
Returns
A future.
See also
eina_promise_race_array()
EINA_FUTURE_SENTINEL

References eina_future_new(), and eina_promise_race_array().

Variable Documentation

◆ EINA_PROMISE_RACE_STRUCT_DESC

const Eina_Value_Struct_Desc * EINA_PROMISE_RACE_STRUCT_DESC

A pointer to the race struct description, which is used by eina_promise_race_array().

This struct contains two members:

See also
eina_promise_race_array()
_Eina_Future_Race_Result