mariadb-columnstore-engine/src/ReadTask.cpp

#include "ReadTask.h"
#include "messageFormat.h"
#include "IOCoordinator.h"
#include <errno.h>

using namespace std;

extern storagemanager::IOCoordinator *ioc;

namespace storagemanager
{

ReadTask::ReadTask(int sock, uint len) : PosixTask(sock, len)
{
}

ReadTask::~ReadTask()
{
}

#define check_error(msg) \
    if (!success) \
    { \
        handleError(msg, errno); \
        return; \
    }

void ReadTask::run()
{
    uint8_t buf[1024] = {0};

    // get the parameters
    if (getLength() > 1023) {
        handleError("ReadTask read", EFAULT);
        return;
    }
    
    bool success;
    success = read(buf, getLength());
    check_error("ReadTask read cmd");
    cmd_overlay *cmd = (cmd_overlay *) buf;
    
    // read from IOC, write to the socket
    vector<uint8_t> outbuf;
    outbuf.resize(cmd->count + SM_HEADER_LEN);
    uint32_t *outbuf32 = (uint32_t *) &outbuf[0];
    outbuf32[0] = SM_MSG_START;
    outbuf32[1] = cmd->count;
    
    // todo: do the reading and writing in chunks
    // todo: need to make this use O_DIRECT
    ioc->willRead(cmd->filename, cmd->offset, cmd->count);
    int count = 0, err;
    while (count < cmd->count)
    {
        err = ioc->read(cmd->filename, &outbuf[SM_HEADER_LEN + count], cmd->offset + count, cmd->count - count);
        if (err <= 0) {
            if (count > 0)
                outbuf32[1] = count;
            else {
                int l_errno = errno;
                outbuf.resize(16);
                outbuf32[1] = 8;
                outbuf32[2] = err;
                outbuf32[3] = l_errno;
            }
            break;
        }
        count += err;
    }
    
    write(outbuf);
}



}