removed invalid nullptr checks.
New allocation doesn't gurantee that returns nullptr when it's failed.
It's useless on the modern compliers and our policy respects it.
if many canvas instances own private memory pool,
the memory usage can be increased linearly.
To prevent memory usage, flush out memory pool from the clear()
if the canvas uses private memory pool.
We have encountered that multi-threading usage that user creates,
multiple canvases owned by multiple user threads.
Current sw_engine memory pool has been considered only for multi-threads,
spawned by tvg task scheduler.
In this case it's safe but when user threads introduced, it can occur race-condition.
Thus, Here is a renewal policy that non-threading tvg(initialized threads with zero),
takes care of multiple user threads bu changing its policy,
each of canvases should have individual memory pool to guarantee mutual-exclusion.
@API additions
enum MempoolPolicy
{
Default = 0, ///< Default behavior that ThorVG is designed to.
Shareable, ///< Memory Pool is shared among the SwCanvases.
Individual ///< Allocate designated memory pool that is only used by current instance.
};
Result SwCanvas::mempool(MempoolPolicy policy) noexcept;
All in all, if user calls multiple threads, set memory pool policy to Individual.
