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package experimental
import (
"context"
"github.com/tetratelabs/wazero/internal/expctxkeys"
)
// MemoryAllocator is a memory allocation hook,
// invoked to create a LinearMemory.
type MemoryAllocator interface {
// Allocate should create a new LinearMemory with the given specification:
// cap is the suggested initial capacity for the backing []byte,
// and max the maximum length that will ever be requested.
//
// Notes:
// - To back a shared memory, the address of the backing []byte cannot
// change. This is checked at runtime. Implementations should document
// if the returned LinearMemory meets this requirement.
Allocate(cap, max uint64) LinearMemory
}
// MemoryAllocatorFunc is a convenience for defining inlining a MemoryAllocator.
type MemoryAllocatorFunc func(cap, max uint64) LinearMemory
// Allocate implements MemoryAllocator.Allocate.
func (f MemoryAllocatorFunc) Allocate(cap, max uint64) LinearMemory {
return f(cap, max)
}
// LinearMemory is an expandable []byte that backs a Wasm linear memory.
type LinearMemory interface {
// Reallocates the linear memory to size bytes in length.
//
// Notes:
// - To back a shared memory, Reallocate can't change the address of the
// backing []byte (only its length/capacity may change).
Reallocate(size uint64) []byte
// Free the backing memory buffer.
Free()
}
// WithMemoryAllocator registers the given MemoryAllocator into the given
// context.Context.
func WithMemoryAllocator(ctx context.Context, allocator MemoryAllocator) context.Context {
if allocator != nil {
return context.WithValue(ctx, expctxkeys.MemoryAllocatorKey{}, allocator)
}
return ctx
}
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