NAME
vrb_init - initialize a virtual ring buffer
LIBRARY
-lvrb
SYNOPSIS
#include <vrb.h>
vrb_p vrb_init(vrb_p vrb, size_t size, const char *name);
DESCRIPTION
vrb_init Initialize a static or pre-allocated virtual ring buffer
structure.
A virtual ring buffer is a character FIFO queue with the special
property that any sequence of characters in the buffer may be accessed
as a single contiguous block of memory, eliminating the need to split
any sequence to handle a buffer wraparound.
ARGUMENTS
vrb_p vrb
specifies the virtual ring buffer structure to be initialized. The
caller must release buffer resources via vrb_uninit(3) when this
virtual ring buffer is no longer needed. If NULL is given, a new
virtual ring buffer structure is allocated and the caller must release
buffer resources via vrb_destroy(3) when an allocated virtual ring
buffer is no longer needed.
size_t size
specifies the requested minimum buffer size to be allocated. The given
value will be rounded up to the nearest or equal whole multiple of the
system page size. The virtual ring buffer is implemented by mapping
two adjacent blocks of memory to the same memory object. Thus, twice
as much virtual address space will be used and the specified size must
be less than half of the available virtual address space for this
process.
const char *name
specifies an optional temporary name pattern or an actual name of a
file to be used as backing store via mmap(2) in a mounted filesystem in
which the process has write permission. If the name string ends in
"XXXXXX" then mkstemp(3) will be used to make the file unique.
Otherwise it will be used as is. If the named file already exists or
otherwise cannot be opened for write, an error will occur. If NULL is
given, swap space will be used as backing store via shmat(2).
RETURN VALUE
vrb_p
On success, a handle (pointer) to the newly created virtual ring buffer
is returned. On error, NULL is returned.
ERRORS
If an error is returned, then errno will have one of the following
values:
EINVAL A buffer size was requested which is too large for address space
allocation arithmetic.
ENOMEM Out of memory allocating the virtual ring buffer structure.
- An errno value set by a failing system call.
SEE ALSO
vrb(3), vrb_capacity(3), vrb_data_len(3), vrb_data_ptr(3),
vrb_destroy(3), vrb_get(3), vrb_get_min(3), vrb_give(3),
vrb_init_opt(3), vrb_is_empty(3), vrb_is_full(3), vrb_is_not_empty(3),
vrb_is_not_full(3), vrb_move(3), vrb_new(3), vrb_new_opt(3),
vrb_put(3), vrb_put_all(3), vrb_read(3), vrb_read_min(3),
vrb_resize(3), vrb_space_len(3), vrb_space_ptr(3), vrb_take(3),
vrb_uninit(3), vrb_write(3), vrb_write_min(3)