github.com/tetratelabs/wazero@v1.7.1/experimental/memory.go (about)

     1  package experimental
     2  
     3  import (
     4  	"context"
     5  
     6  	"github.com/tetratelabs/wazero/internal/expctxkeys"
     7  )
     8  
     9  // MemoryAllocator is a memory allocation hook,
    10  // invoked to create a LinearMemory.
    11  type MemoryAllocator interface {
    12  	// Allocate should create a new LinearMemory with the given specification:
    13  	// cap is the suggested initial capacity for the backing []byte,
    14  	// and max the maximum length that will ever be requested.
    15  	//
    16  	// Notes:
    17  	//   - To back a shared memory, the address of the backing []byte cannot
    18  	//     change. This is checked at runtime. Implementations should document
    19  	//     if the returned LinearMemory meets this requirement.
    20  	Allocate(cap, max uint64) LinearMemory
    21  }
    22  
    23  // MemoryAllocatorFunc is a convenience for defining inlining a MemoryAllocator.
    24  type MemoryAllocatorFunc func(cap, max uint64) LinearMemory
    25  
    26  // Allocate implements MemoryAllocator.Allocate.
    27  func (f MemoryAllocatorFunc) Allocate(cap, max uint64) LinearMemory {
    28  	return f(cap, max)
    29  }
    30  
    31  // LinearMemory is an expandable []byte that backs a Wasm linear memory.
    32  type LinearMemory interface {
    33  	// Reallocates the linear memory to size bytes in length.
    34  	//
    35  	// Notes:
    36  	//   - To back a shared memory, Reallocate can't change the address of the
    37  	//     backing []byte (only its length/capacity may change).
    38  	Reallocate(size uint64) []byte
    39  	// Free the backing memory buffer.
    40  	Free()
    41  }
    42  
    43  // WithMemoryAllocator registers the given MemoryAllocator into the given
    44  // context.Context.
    45  func WithMemoryAllocator(ctx context.Context, allocator MemoryAllocator) context.Context {
    46  	if allocator != nil {
    47  		return context.WithValue(ctx, expctxkeys.MemoryAllocatorKey{}, allocator)
    48  	}
    49  	return ctx
    50  }