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向 Node.js 的底层再走一步

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关于 Node.js 的异步编程之前已经稍微了解过了，再来继续深入研究一下用来支持它异步能力的底层事件库 —— Libuv。

这个标志还是很霸气的，也象征了这个库简单粗暴又高效的特点。

先扔两段代码：

单线程异步：

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/* ***********************************************
MYID	: Chen Fan
LANG	: G++
PROG	: libuv thread test
************************************************ */

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>

#include "uv.h"

using namespace std;

uv_loop_t *loop;
uv_async_t async[5];
int wait[5] = {0, 1, 1, 2, 2};

void update_wait(int index)
{
    wait[index]--;
    if (wait[index] == 0)
        uv_async_send(&async[index]);
}

void f0(uv_async_t *handle)
{
    uv_thread_t id = uv_thread_self();
    cout << "f0 run in " << id << endl;
    update_wait(1);
    uv_close((uv_handle_t*)&async[0], NULL);
}

void f1(uv_async_t *handle)
{
    uv_thread_t id = uv_thread_self();
    cout << "f1 run in " << id << endl;
    update_wait(2);
    update_wait(3);
    update_wait(4);
    uv_close((uv_handle_t*)&async[1], NULL);
}

void f2(uv_async_t *handle)
{
    uv_thread_t id = uv_thread_self();
    cout << "f2 run in " << id << endl;
    update_wait(3);
    uv_close((uv_handle_t*)&async[2], NULL);
}

void f3(uv_async_t *handle)
{
    uv_thread_t id = uv_thread_self();
    cout << "f3 run in " << id << endl;
    update_wait(4);
    uv_close((uv_handle_t*)&async[3], NULL);
}

void f4(uv_async_t *handle)
{
    uv_thread_t id = uv_thread_self();
    cout << "f4 run in " << id << endl;
    uv_close((uv_handle_t*)&async[4], NULL);
}

int main()
{
    cout << "Test Start" << endl;

    uv_thread_t id = uv_thread_self();
    cout << "Thread " << id << endl;

    loop = uv_default_loop();
    uv_async_init(loop, &async[0], f0);
    uv_async_init(loop, &async[1], f1);
    uv_async_init(loop, &async[2], f2);
    uv_async_init(loop, &async[3], f3);
    uv_async_init(loop, &async[4], f4);

    uv_async_send(&async[0]);

    uv_run(loop, UV_RUN_DEFAULT);

    cout << "Loop End" << endl;

    return 0;
}

多线程（queue_work 自带线程池）异步：

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/* ***********************************************
MYID	: Chen Fan
LANG	: G++
PROG	: libuv thread test
************************************************ */

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>

#include "uv.h"

using namespace std;

uv_loop_t *loop;
uv_async_t async[5];
int wait[5] = {0, 1, 1, 2, 2};

void update_wait(int index)
{
    wait[index]--;
    if (wait[index] == 0)
        uv_async_send(&async[index]);
}

void f0(uv_work_t *req)
{
    uv_thread_t id = uv_thread_self();
    cout << "f0 run in " << id << endl;
    update_wait(1);
    uv_close((uv_handle_t*)&async[0], NULL);
}

void f1(uv_work_t *req)
{
    uv_thread_t id = uv_thread_self();
    cout << "f1 run in " << id << endl;
    update_wait(2);
    update_wait(3);
    update_wait(4);
    uv_close((uv_handle_t*)&async[1], NULL);
}

void f2(uv_work_t *req)
{
    uv_thread_t id = uv_thread_self();
    cout << "f2 run in " << id << endl;
    update_wait(3);
    uv_close((uv_handle_t*)&async[2], NULL);
}

void f3(uv_work_t *req)
{
    uv_thread_t id = uv_thread_self();
    cout << "f3 run in " << id << endl;
    update_wait(4);
    uv_close((uv_handle_t*)&async[3], NULL);
}

void f4(uv_work_t *req)
{
    uv_thread_t id = uv_thread_self();
    cout << "f4 run in " << id << endl;
    uv_close((uv_handle_t*)&async[4], NULL);
}

void after(uv_work_t *req, int status) {

}

void new_run(uv_async_t *handle)
{
    cout << "New Run" << endl;
    uv_work_t *req = new uv_work_t();
    uv_queue_work(loop, req, (uv_work_cb)(uv_work_cb*)handle->data, after);
}

int main()
{
    cout << "Test Start" << endl;

    uv_thread_t id = uv_thread_self();
    cout << "Thread " << id << endl;

    loop = uv_default_loop();

    async[0].data = (void*)&f0;
    async[1].data = (void*)&f1;
    async[2].data = (void*)&f2;
    async[3].data = (void*)&f3;
    async[4].data = (void*)&f4;

    uv_async_init(loop, &async[0], new_run);
    uv_async_init(loop, &async[1], new_run);
    uv_async_init(loop, &async[2], new_run);
    uv_async_init(loop, &async[3], new_run);
    uv_async_init(loop, &async[4], new_run);

    uv_async_send(&async[0]);

    uv_run(loop, UV_RUN_DEFAULT);

    cout << "Loop End" << endl;

    int aaaaaa;
    cin >> aaaaaa;

    return 0;
}

To be continued …

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