On 2/20/23 17:09, Frederick Virchanza Gotham via Std-Proposals wrote:
> On Mon, Feb 20, 2023 at 7:51 PM Julien Villemure-Fréchette via
> Std-Proposals <std-proposals_at_[hidden]> wrote:
>>
>> global operator new and delete can be replaced by a non inline, non static global operator new with equivalent signature
>
>
> I wrote a program one time and I wanted it to be lightning fast, and
> so I overloaded 'new' so that it allocated massive chunks at a time,
> and 'delete' didn't do anything. I of course was wasting memory but it
> was fine as I had enough RAM. Here's what I did:

So yeah Frederick, if you don't mind I'll use your code and add
garbage-collector-style deallocations, make it thread-local, allocation
rate-based and type-based as a new project in my own Github with can
simply link to under Linux and LGPL it:
https://github.com/philippeb8

> #include <cstddef> // size_t
> #include <cstdlib> // malloc
> #include <new> // required otherwise we get a compiler error
> for the 'noexcept'
>
> using std::size_t;
>
> size_t g_total_allocation = 0u;
>
> inline void *Implementation_Global_New(size_t size) noexcept
> {
> size += 8u - (size % 8u);
>
> static size_t constexpr bytes_at_a_time = 10485760u; /* We
> allocate 10 megabytes at a time */
>
> if ( size > bytes_at_a_time ) return nullptr;
>
> static void *p = nullptr;
>
> static size_t bytes_allocated_so_far = 0u;
>
> for (; /* ever */ ;)
> {
> if ( nullptr == p )
> {
> p = std::malloc(bytes_at_a_time);
>
> if ( nullptr == p ) return nullptr;
>
> g_total_allocation += bytes_at_a_time;
> }
>
> if ( (bytes_allocated_so_far + size) > bytes_at_a_time )
> {
> p = nullptr;
>
> bytes_allocated_so_far = 0u;
> }
> else
> {
> break;
> }
> }
>
> void *const retval = static_cast<char*>(p) + bytes_allocated_so_far;
>
> bytes_allocated_so_far += size;
>
> return retval;
> }
>
> void *operator new (size_t const size) noexcept { return
> Implementation_Global_New(size); }
> void *operator new[](size_t const size) noexcept { return
> Implementation_Global_New(size); }
> void operator delete (void *const p) noexcept { /* Do Nothing */ }
> void operator delete[](void *const p) noexcept { /* Do Nothing */ }

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