gnzlbg/slice_deque

Wasm support? (Compilation fails on wasm)

Boscop opened this issue · 2 comments

I'd really like to use SliceDeque on wasm instead of VecDeque because it has a better API and supports splice. But it fails to build:

error[E0425]: cannot find function `allocation_granularity` in this scope
 --> C:\Users\me\.cargo\registry\src\github.com-1ecc6299db9ec823\slice-deque-0.3.0\src\mirrored\buffer.rs:7:14
  |
7 |     let ag = allocation_granularity();
  |              ^^^^^^^^^^^^^^^^^^^^^^ not found in this scope
error[E0425]: cannot find function `allocation_granularity` in this scope
   --> C:\Users\me\.cargo\registry\src\github.com-1ecc6299db9ec823\slice-deque-0.3.0\src\mirrored\buffer.rs:112:15
    |
112 |             * allocation_granularity();
    |               ^^^^^^^^^^^^^^^^^^^^^^ not found in this scope
error[E0425]: cannot find function `allocation_granularity` in this scope
   --> C:\Users\me\.cargo\registry\src\github.com-1ecc6299db9ec823\slice-deque-0.3.0\src\mirrored\buffer.rs:135:41
    |
135 |         assert!(mem::align_of::<T>() <= allocation_granularity());
    |                                         ^^^^^^^^^^^^^^^^^^^^^^ not found in this scope

error[E0425]: cannot find function `allocation_granularity` in this scope
   --> C:\Users\me\.cargo\registry\src\github.com-1ecc6299db9ec823\slice-deque-0.3.0\src\mirrored\buffer.rs:148:36
    |
148 |         debug_assert!(alloc_size % allocation_granularity() == 0);
    |                                    ^^^^^^^^^^^^^^^^^^^^^^ not found in this scope
error[E0425]: cannot find function `allocate_mirrored` in this scope
   --> C:\Users\me\.cargo\registry\src\github.com-1ecc6299db9ec823\slice-deque-0.3.0\src\mirrored\buffer.rs:151:19
    |
151 |         let ptr = allocate_mirrored(alloc_size)?;
    |                   ^^^^^^^^^^^^^^^^^ not found in this scope
error[E0425]: cannot find function `deallocate_mirrored` in this scope
   --> C:\Users\me\.cargo\registry\src\github.com-1ecc6299db9ec823\slice-deque-0.3.0\src\mirrored\buffer.rs:172:18
    |
172 |         unsafe { deallocate_mirrored(first_half_ptr, buffer_size_in_bytes) };
    |                  ^^^^^^^^^^^^^^^^^^^ not found in this scope
error: aborting due to 6 previous errors

After a brief look, It appears the issue here is that wasm doesn't have a function for 'mirroring' a region of memory. The allocate_mirrored function makes two allocations contiguously and maps them to the same logical file so that writes to one are reflected in reads to the other using mmap.

It seems wasm doesn't have this yet because it doesn't have a notion of memory mapped files?

I ran into the same problem building for wasm. Is there any solution yet?