通过线程之间的环形（循环）缓冲区发送消息（在 C 中）

Question

我需要使用 WinAPI 和 Ring Buffer 将消息从主线程发送到我创建的线程。

我为我的环形缓冲区定义了结构并编写了函数。环形缓冲区 - 它包含头、尾、大小和指向具有数据长度和数据本身的结构描述符的指针。由于我需要向 CreateThread 函数发送 2 个参数，因此我创建了第三个结构 ThreadParams 以保留 2 个参数。

我想让这个结构保持现在的样子，不可更改。

typedef struct _Descriptor
{
    uint32_t dataLen;
    void * data;
} Descriptor;

typedef struct _ringBuffer
{
    Descriptor *bufferData;
    int head;
    int tail;
    int size;
} ringBuffer;

typedef struct _ThreadParams
{
    void * ptr1;
    void * ptr2;
} ThreadParams;

这里有我对Ring Buffer函数的实现：

void bufferFree(ringBuffer *buffer)
{
    free(buffer->bufferData);
}

void ringInitialization(ringBuffer *buffer, int size)
{
    buffer->size = size;
    buffer->head = 0;
    buffer->tail = 0;
    buffer->bufferData = (Descriptor*)malloc(sizeof(Descriptor) * size);
}

int pushBack(ringBuffer *buffer, void * data) // fill buffer
{
    buffer->bufferData[buffer->tail++] = *(Descriptor*)data;
    if (buffer->tail == buffer->size)
    {
        buffer->tail = 0;
    }
    return 0;
}

int popFront(ringBuffer *buffer)
{
    if (buffer->head != buffer->tail)
    {
        buffer->head++;
        if (buffer->head == buffer->size)
        {
            buffer->head = 0;
        }
    }
    return 0;
}

我的主要任务：我检查过我可以发送几个字节（内存在线程之间共享），现在我需要通过 Ring Buffer 发送一个大消息（> BUFF_SIZE）我正在尝试在 while() 循环中做。这里的问题是：我应该怎么做？我的东西不起作用，因为我在 printf() 函数中捕获了一个异常（内存访问冲突）。

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <windows.h>
#include <strsafe.h>
#include <stdint.h>

#define RING_SIZE 256
#define BUFFER_SIZE 1024

DWORD WINAPI HandleSendThread(LPVOID params);

uint8_t * getPointer(uint8_t *buffer, uint32_t index)
{
    uint8_t * ptr = ((uint8_t*)buffer) + index * BUFFER_SIZE;
    return ptr;
}

int main(int argc, char * argv[])      
{
    //Descriptor * ringData = (Descriptor *)malloc(sizeof(Descriptor) * RING_SIZE);

    ringBuffer ring;
    ringInitialization(&ring, RING_SIZE);
    void * packetBuffer = malloc(BUFFER_SIZE * RING_SIZE);
    uint8_t * currentBuffer = getPointer(packetBuffer, 0);
    uint8_t * str = "Mr. and Mrs. Dursley, of number four, Privet Drive, were proud to say that they were perfectly normal, thank you very much. They were the last people you'd expect to be involved in anything strange or mysterious, because they just didn't hold with such nonsense. Mr.Dursley was the director of a firm called Grunnings, which made drills.He was a big, beefy man with hardly any neck, although he did have a very large mustache.Mrs.Dursley was thin and blonde and had nearly twice the usual amount of neck, which came in very useful as she spent so much of her time craning over garden fences, spying on the neighbors.The Dursleys had a small son called Dudley and in their opinion there was no finer boy anywhere.";

    strcpy(currentBuffer, str);
    ring.bufferData[0].data = currentBuffer;
    ring.bufferData[0].dataLen = strlen(str);

    int currentSize = 0;
    int ringSize = RING_SIZE;
    while(ring.bufferData[0].data != '[=12=]')
    {
        for (int i = currentSize; i < ringSize; i + RING_SIZE)
        {
            pushBack(&ring, currentBuffer); 
            printf("h = %s, tail = %s, dataBuffer = %s\n", (char*)ring.head, (char*)ring.tail, (char*)ring.bufferData[i].data);
        }
        currentSize = ringSize;
        ringSize = 2 * ringSize;
        popFront(&ring);
    }

    ThreadParams params = { &ring, packetBuffer };
    HANDLE MessageThread = 0;
    MessageThread = CreateThread(NULL, 0, HandleSendThread, &params, 0, NULL);
    if (MessageThread == NULL)
    {
        ExitProcess(MessageThread);
    }

    WaitForSingleObject(MessageThread, INFINITE);
    CloseHandle(MessageThread);
    system("pause");
    return 0;
}

还有我的 CreateThread 函数：

DWORD WINAPI HandleSendThread(LPVOID params)
{
    ringBuffer * ring = ((ThreadParams*)params)->ptr1;
    void * buffer = ((ThreadParams*)params)->ptr2;
    //ring->bufferData[0].dataLen = sizeof(buffer) + sizeof(ring->bufferData[0])*1024;

    printf("Shared memory check: ringBuffer data = \"%s\", \nlength = %d\n", (char*)ring->bufferData[0].data, ring->bufferData[0].dataLen);
    return 0;
}

Answer 1

您最直接的问题是 pushBack() 中的代码与您的主函数中的代码之间的不一致，它期望 data 指向 Descriptor一个指向字符串的指针。

如果您已正确声明 pushBack()，即

void pushBack(ringBuffer *buffer, Descriptor * data)
{
    buffer->bufferData[buffer->tail++] = *data;
    if (buffer->tail == buffer->size)
    {
        buffer->tail = 0;
    }
}

然后编译器就可以警告您存在差异。

你这里也有一个无限循环：

for (int i = currentSize; i < ringSize; i + RING_SIZE)

你的意思可能是

for (int i = currentSize; i < ringSize; i += RING_SIZE)

...虽然在我看来它仍然不会做任何明智的事情。我也不明白外循环的目的，它比较一个指针和一个字符。

Answer 2

找到解决方案

int main(int argc, char * argv[])
{
    ringBuffer ring;
    ringInitialization(&ring, RING_SIZE);
    void * packetBuffer = malloc(BUFFER_SIZE * RING_SIZE);
    Descriptor temp = { 0 };
    uint8_t * currentBuffer = getPointer(packetBuffer, 0);
    uint8_t * str = "Mr. and Mrs. Dursley, of number four, Privet Drive, were proud to say that they were perfectly normal, thank you very much. They were the last people you'd expect to be involved in anything strange or mysterious, because they just didn't hold with such nonsense. Mr.Dursley was the director of a firm called Grunnings, which made drills.He was a big, beefy man with hardly any neck, although he did have a very large mustache.Mrs.Dursley was thin and blonde and had nearly twice the usual amount of neck, which came in very useful as she spent so much of her time craning over garden fences, spying on the neighbors.The Dursleys had a small son called Dudley and in their opinion there was no finer boy anywhere.";

    strcpy(currentBuffer, str);
    temp.dataLen = strlen(str);
    temp.data = currentBuffer;

    pushBack(&ring, &temp);
    ThreadParams params = { &ring, packetBuffer };
    HANDLE MessageThread = 0;
    MessageThread = CreateThread(NULL, 0, HandleSendThread, &params, 0, NULL);
    if (MessageThread == NULL)
    {
        ExitProcess(MessageThread);
    }
    WaitForSingleObject(MessageThread, INFINITE);
    CloseHandle(MessageThread);
    system("pause");
    return 0;
}

DWORD WINAPI HandleSendThread(LPVOID params)
{
    ringBuffer * ring = ((ThreadParams*)params)->ptr1;
    void * buffer = ((ThreadParams*)params)->ptr2;
    Descriptor * temp = &ring->bufferData[ring->head];

    for (int i = 0; i < temp->dataLen; i++)
    {
        printf("%c", ((char*)temp->data)[i]);
    }
    printf("\n");
    return 0;
}

通过线程之间的环形（循环）缓冲区发送消息（在 C 中）

Send message through Ring (Circular) Buffer between Threads (in C)

c

windows

winapi

circular-buffer