I/O Thread

I/O thread is another kind of thread pool. But this component is mainly used for GUI applications. Usually, GUI applications will have one user thread and one I/O thread, so that when I/O is processed, it will not prevent to respond to user operations (such as click).

This module is not supported in the MSVC.

Header file

#include "mln_iothread.h"

Module

iothread

Functions/Macros

mln_iothread_init

int mln_iothread_init(mln_iothread_t *t, mln_u32_t nthread, mln_iothread_entry_t entry, void *args, mln_iothread_msg_process_t handler);

typedef void *(*mln_iothread_entry_t)(void *); //I/O thread entry function
typedef void (*mln_iothread_msg_process_t)(mln_iothread_t *t, mln_iothread_ep_type_t from, mln_iothread_msg_t *msg);//message handler

Description: Initialize t according to attr.

• nthread Total number of I/O threads.
• entry I/O thread entry function.
• args I/O thread entry parameters.
• handler message handler.

Return value: return 0 on success, otherwise return -1

mln_iothread_destroy

void mln_iothread_destroy(mln_iothread_t *t);

Description: Destroy an iothread instance.

Return value: none

mln_iothread_send

extern int mln_iothread_send(mln_iothread_t *t, mln_u32_t type, void *data, mln_iothread_ep_type_t to, int feedback);

typedef enum {
    io_thread,
    user_thread
} mln_iothread_ep_type_t;

Description: Send a message with message type type and message data data to the destination to, and determine whether to block waiting for feedback according to feedback.

Return value:

• 0 - on success
• -1 - on failure
• 1 - send buffer full

mln_iothread_recv

int mln_iothread_recv(mln_iothread_t *t, mln_iothread_ep_type_t from);

Description: Receive a message from the side of from. After receiving, the message processing function set during initialization will be called to process the message.

Return value: The number of received messages.

mln_iothread_sockfd_get

 mln_iothread_iofd_get(p)

Description: According to the value of t, get the communication socket of the I/O thread or user thread from the mln_iothread_t structure pointed to by p . Usually to add it to an event.

Return value: socket descriptor

Note: The socket is only used to notify the other thread(s) that the thread(s) at the other end has a message sent. User can use epoll, kqueue, select and other event mechanisms to monitor.

mln_iothread_msg_hold

mln_iothread_msg_hold(m)

Description: Hold message m. Which means this message won't be freed if the message handler returned. This macro only work on feedback message.

Return value: None

mln_iothread_msg_release

mln_iothread_msg_release(m)

Description: Release message m. This macro only work on feedback message.

Return value: None

mln_iothread_msg_type

mln_iothread_msg_type(m)

Description: Get message type.

Return value: unsigned int type

mln_iothread_msg_data

mln_iothread_msg_data(m)

Description: Get user data from message m.

Return value: user data pointer

Example

#include "mln_iothread.h"
#include <string.h>
#include <stdio.h>
#include <errno.h>

static void msg_handler(mln_iothread_t *t, mln_iothread_ep_type_t from, mln_iothread_msg_t *msg)
{
    mln_u32_t type = mln_iothread_msg_type(msg);
    printf("msg type: %u\n", type);
}

static void *entry(void *args)
{
    int n;
    mln_iothread_t *t = (mln_iothread_t *)args;
    while (1) {
        n = mln_iothread_recv(t, user_thread);
        printf("recv %d message(s)\n", n);
    }

    return NULL;
}

int main(void)
{
    int i, rc;
    mln_iothread_t t;

    if (mln_iothread_init(&t, 1, (mln_iothread_entry_t)entry, &t, (mln_iothread_msg_process_t)msg_handler) < 0) {
        fprintf(stderr, "iothread init failed\n");
        return -1;
    }
    for (i = 0; i < 1000000; ++i) {
        if ((rc = mln_iothread_send(&t, i, NULL, io_thread, 1)) < 0) {
            fprintf(stderr, "send failed\n");
            return -1;
        } else if (rc > 0)
            continue;
    }
    sleep(1);
    mln_iothread_destroy(&t);
    sleep(3);
    printf("DONE\n");

    return 0;
}