Function pgrx_pg_sys::GetMemoryChunkContext

pub unsafe fn GetMemoryChunkContext(pointer: *mut c_void) -> MemoryContext

Given a currently-allocated chunk of Postgres allocated memory, determine the context it belongs to.

All chunks allocated by any memory context manager are required to be preceded by the corresponding MemoryContext stored, without padding, in the preceding sizeof(void*) bytes. A currently-allocated chunk must contain a backpointer to its owning context. The backpointer is used by pfree() and repalloc() to find the context to call.

Safety

The specified pointer must be one allocated by Postgres (via [palloc] and friends).

Panics

This function will panic if pointer is null, if it’s not properly aligned, or if the memory it points to doesn’t have a prefix that looks like a memory context pointer