AICommon::IDGenerator< N > Class Template Reference

Class used to generate unique numbers. More...

#include <IDGenerator.h>

Public Member Functions
	IDGenerator (unsigned offset=0)
int	get ()
bool	put (int id)
void	clear ()

Private Attributes
const unsigned	mOffset
unsigned	mLfsr
std::mutex	mLock
std::bitset< mSize >	mUsed

Static Private Attributes
static const unsigned	mSize = (1u << N)
static const unsigned	mPolynomial

Detailed Description

template<std::size_t N>
class AICommon::IDGenerator< N >

Class used to generate unique numbers.

Why? there a few places in the code were we create some resource and then return a unique 'id' for it, this is typically done for resources created over dbus.

This class is guaranteed to return unique id numbers in a non-linear sequence.

The N template parameters refers to the number of bits in the generator range. Avoid large values for N, as for each entry we allocate a bit to tell if it's in use or not, in addition in the worst case we have to iterate through all 2^N possible values to find a free one.

The api has a get() and a put() operation, obviously get() returns a new id and put() releases the id back to the pool. The id's returned are not sequential, instead they are created using a pseudo random repeating sequence (fibonacci LFSR).

When the pool is exhausted get() will return -1.

Member Data Documentation

mPolynomial

template<std::size_t N>

const unsigned AICommon::IDGenerator< N >::mPolynomial

staticprivate

Initial value:

= (N == 4)  ? 0x9     :
                                        (N == 5)  ? 0x1B    :
                                        (N == 6)  ? 0x36    :
                                        (N == 7)  ? 0x5F    :
                                        (N == 8)  ? 0xE1    :
                                        (N == 9)  ? 0x1B0   :
                                        (N == 10) ? 0x3A6   :
                                        (N == 11) ? 0x574   :
                                        (N == 12) ? 0xC48   :
                                        (N == 13) ? 0x11D4  :
                                        (N == 14) ? 0x214E  :
                                        (N == 15) ? 0x41A6  :
                                        (N == 16) ? 0x84BE  :
                                        (N == 17) ? 0x1022E :
                                        (N == 18) ? 0x20196 :
                                        (N == 19) ? 0x4032F :
                                        (N == 20) ? 0x80534 : 0

---

The documentation for this class was generated from the following file:

• AppInfrastructure/Common/include/IDGenerator.h