首页 > 解决方案 > 当在 C 中管理(取消)分配时,Haskell 运行时中的垃圾收集器问题

问题描述

我想使用 Haskell 的 FFI 功能在 C 和 Haskell 之间共享数据(在最简单的情况下是整数数组)。C端创建数据(相应地分配内存),但在释放之前从不修改它,所以我认为以下方法是“安全的”:

然而,使用这种方法会导致相当不确定的崩溃。小例子往往会起作用,但是“一旦 GC 启动”,我开始在GHC 的“疏散”部分中的这一行或这一行中遇到分段错误到“barf”的各种错误。

我在这里做错了什么?做这样的事情的“正确方法”是什么?

一个例子

我有一个带有以下声明的 C 标头:

typedef struct CVector {
    const int32_t *pointer;
    size_t length;
} Vector;

void create_c_vector(struct CVector *vector);
void free_buffer(void *buff);

Haskell 代码是使用c2hs从以下.chs文件生成的:

import Foreign.C.Types
import Foreign.Concurrent
import Foreign.Marshal.Alloc
import Foreign.Ptr
import Foreign.Storable

import qualified Data.Vector.Storable as V

#include <cvector.h>


data ForeignVector = ForeignVector
  { pointerFV  :: Ptr CInt
  , lengthFV   :: CULong
  }

instance Storable ForeignVector where
  sizeOf _ = {#sizeof CVector #}
  alignment _ = {#alignof CVector #}
  peek p =
    ForeignVector
      <$> {#get CVector->pointer #} p
      <*> {#get CVector->length #} p
  poke p (ForeignVector vecP l) =
    do {#set CVector.pointer #} p (castPtr vecP)
       {#set CVector.length #} p l

peekUnit :: Storable a => Ptr () -> IO a
peekUnit = peek . castPtr

{#fun create_c_vector as ^ { alloca- `ForeignVector' peekUnit*} -> `()' #}
{#fun free_buffer as ^ { `Ptr ()' } -> `()' #}

fromForeign :: ForeignVector -> IO (V.Vector CInt)
fromForeign (ForeignVector p l) =
  V.unsafeFromForeignPtr0
    <$> newForeignPtr p (freeBuffer . castPtr $ p)
    <*> pure (fromIntegral l)

createVector :: IO (V.Vector CInt)
createVector = fromForeign =<< createCVector

internal error: evacuate: strange closure type 177在对createVector.

PS:这就是为什么我想使用Foreign.Concurrent.newForeignPtr 而不是更“标准”的 原因Foreign.ForeignPtr.newForeignPtr:在我期待的一些更复杂的情况下,在释放指针的同时还应该清理其他可能依赖于从 Haskell 传递的参数的东西。因此,我想要一个“具有多个参数的终结器”并将部分应用程序作为实际的终结器传递。这意味着我不能使用指向 C 函数的指针作为终结器。虽然我读过可以FinalizerPtr使用“包装”机制从 Haskell 函数中为终结器制作所需的内容,但根据文档,以这种方式获得的函数指针需要显式释放,freeHaskellFunPtr我不想做簿记为了那个原因。

PPS:这是一个带有上述示例完整源代码的 base64 编码的 tarball(包括重现上述错误的可执行文件的代码):
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标签: haskellgarbage-collectionffi

解决方案



推荐阅读