code_scanner/common/event_monitor.h

#pragma once

// event monitor
//
// created on 2022-11-29
//

#include "referer.h"
#include <thread>
#include <memory>

typedef std::shared_ptr<std::thread>    THREAD_PTR;

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// event definition ...
enum scanner_event
{
    SCANNER_EVENT_NONE = 0,

    // 1 - IPC
    SCANNER_EVENT_IPC_DATA_RECEIVED = 1,
    SCANNER_EVENT_IPC_DATA_SENT,

    // 2 - image-collector
    SCANNER_EVENT_COLLECTOR_WORKING = 100,		// on_event(, nullptr, 0), the first message after start success

    // normal image, double feeding image, jammed image, stapled imge, size-check error image ...
    SCANNER_EVENT_COLLECTOR_IMG_BEGIN,			// on_event(, LPPACKIMAGE/*data_size can be ZERO*/, (bool)local_display/*show mesaage to local-liquid-crystal screen*/), start a new image data transferring
    SCANNER_EVENT_COLLECOTR_GET_BUF,            // on_event(, LPREQBUF, len)
    SCANNER_EVENT_COLLECTOR_IMG_DATA,			// on_event(, (uint8_t*)data, bytes of data), image data transfer
    SCANNER_EVENT_COLLECTOR_IMG_END,			// on_event(, LPPACKIMAGE, sizeof(PACKIMAGE)), an image data has been transmitted

    SCANNER_EVENT_COLLECTOR_PAPER_ON,			// on_event(, (bool*)paper_on, (bool)local_display)
    SCANNER_EVENT_COLLECTOR_COVER_OPENNED,		// on_event(, (bool*)openned, (bool)local_display)
    SCANNER_EVENT_COLLECTOR_SLEEPPING,			// on_event(, (bool*)sleepping, (bool)local_display)
    SCANNER_EVENT_COLLECTOR_ERROR,				// on_event(, (char*)err-msg, (bool)local_display), used when unknown fatal error occurs! 

    SCANNER_EVENT_COLLECTOR_STOPPED,			// on_event(, (char*)err-msg, (size_t)err-code), the last message after start success

    // 3 - image-process
    SCANNER_EVENT_IMAGE_PROC_FINAL_BUF = 200,   // on_event(, (void**)buf, (size_t)len), get buffer for store the final image
    SCANNER_EVENT_IMAGE_PROC_OK,
    SCANNER_EVENT_IMAGE_PROC_ERR,

    // 4 - resource
    SCANNER_EVENT_RESOURCE_LOW_MEM = 300,
    SCANNER_EVENT_RESOURCE_LOW_DISK,
    SCANNER_EVENT_RESOURCE_HIGH_CPU,
};

typedef struct _req_buf
{
    size_t  len;
    uint8_t* buf;
}REQBUF, *LPREQBUF;

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// object event_handler
//
// derived from 'event_handler' if your class will handle some events of drived by events
//
class event_handler : public refer
{
protected:
    event_handler();
    virtual ~event_handler();

public:
    virtual int32_t on_event(int32_t ev, void* data, size_t data_len) = 0;
    virtual int32_t get_fd(void) = 0;

    enum
    {
        EVENT_READ = 0,
        EVENT_WRITE,
    };
};

class parent_holder : public refer
{
protected:
    parent_holder();
    virtual ~parent_holder();

public:
    virtual int32_t stop(void) = 0; // stop work and release parent ptr
};

// event_monitor to manage an event-driven model, this will trigger EVENT_READ/EVENT_WRITE events to 'handler'
//
class event_monitor : public refer
{
protected:
    std::string desc_;

protected:
    event_monitor(const char* desc);
    virtual ~event_monitor();

public:
    virtual int32_t start(int32_t threads = 1) = 0;
    virtual int32_t stop(void) = 0;

    virtual int32_t add_fd(event_handler* handler) = 0;
    virtual int32_t remove_fd(event_handler* handler) = 0;

    enum
    {
        EV_TYPE_POLL = 1,
        EV_TYPE_EPOLL,
    };
    static event_monitor* create(const char* desc, int32_t type = EV_TYPE_EPOLL);
};