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qbarray.h(3) libqb qbarray.h(3)

NAME

qbarray.h - This is a dynamic array (it can grow, but without moving memory).

SYNOPSIS

#include <stdint.h>
#include <unistd.h>
#include <qb/qbdefs.h>

Macros


#define QB_ARRAY_MAX_INDEX_BITS 16
#define QB_ARRAY_MAX_ELEMENTS (1 << QB_ARRAY_MAX_INDEX_BITS)

Typedefs


typedef struct qb_array qb_array_t
This is an opaque data type representing an instance of an array. typedef void(* qb_array_new_bin_cb_fn) (qb_array_t *a, uint32_t bin)

Functions


qb_array_t * qb_array_create (size_t max_elements, size_t element_size)
Create an array with fixed sized elements. qb_array_t * qb_array_create_2 (size_t max_elements, size_t element_size, size_t autogrow_elements)
Create an array with fixed sized elements. int32_t qb_array_index (qb_array_t *a, int32_t idx, void **element_out)
Get an element at a particular index. int32_t qb_array_grow (qb_array_t *a, size_t max_elements)
Grow the array. size_t qb_array_num_bins_get (qb_array_t *a)
Get the number of bins used by the array. size_t qb_array_elems_per_bin_get (qb_array_t *a)
Get the number of elements per bin. int32_t qb_array_new_bin_cb_set (qb_array_t *a, qb_array_new_bin_cb_fn fn)
Get a callback when a new bin is allocated. void qb_array_free (qb_array_t *a)
Free all the memory used by the array.

Detailed Description

This is a dynamic array (it can grow, but without moving memory). 

arr = qb_array_create_2(64, sizeof(struct my_struct), 256);
...
res = qb_array_index(arr, idx, (void**)&my_ptr);
if (res < 0) {
     return res;
}
// use my_ptr, now even if there is a grow, this pointer will be valid.

Currently, this dynamic array abstract data type can accommodate only 2^QB_ARRAY_MAX_INDEX_BITS elements, and with standard zero-based indexing, this gives a valid index range [0, QB_ARRAY_MAX_ELEMENTS), where the notation denotes the beginning of the interval is included and the end is excluded. In other words, client space shall avoid a pitfall of relying solely on the type of max_elements parameter to qb_array_create and/or of idx parameter to qb_array_index (these types conflict, anyway).

Macro Definition Documentation

#define QB_ARRAY_MAX_ELEMENTS (1 << QB_ARRAY_MAX_INDEX_BITS)

#define QB_ARRAY_MAX_INDEX_BITS 16

Typedef Documentation

typedef void(* qb_array_new_bin_cb_fn) (qb_array_t *a, uint32_t bin)

typedef struct qb_array qb_array_t

This is an opaque data type representing an instance of an array.

Function Documentation

qb_array_t* qb_array_create (size_t max_elements, size_t element_size)

Create an array with fixed sized elements.

Parameters:

max_elements initial max elements
element_size size of each element

Returns:

array instance

qb_array_t* qb_array_create_2 (size_t max_elements, size_t element_size, size_t autogrow_elements)

Create an array with fixed sized elements.

Parameters:

max_elements initial max elements
element_size size of each element
autogrow_elements the number of elements to grow automatically by.

Returns:

array instance

size_t qb_array_elems_per_bin_get (qb_array_t * a)

Get the number of elements per bin.

void qb_array_free (qb_array_t * a)

Free all the memory used by the array.

Parameters:

a array instance

int32_t qb_array_grow (qb_array_t * a, size_t max_elements)

Grow the array.

Parameters:

a array instance
max_elements the new maximum size of the array

Returns:

(0 == success, else -errno)

int32_t qb_array_index (qb_array_t * a, int32_t idx, void ** element_out)

Get an element at a particular index.

Parameters:

a array instance
idx the index, valid in [0, QB_ARRAY_MAX_ELEMENTS) range
element_out the pointer to the element data

Returns:

(0 == success, else -errno)

int32_t qb_array_new_bin_cb_set (qb_array_t * a, qb_array_new_bin_cb_fn fn)

Get a callback when a new bin is allocated.

size_t qb_array_num_bins_get (qb_array_t * a)

Get the number of bins used by the array.

Author

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Fri Apr 26 2019 Version 1.0.5