异步输出如何保证输出日志的完整？

[Zeedff]

例如我将日志存储在一个10K环形缓冲区内，每次取5K的数据输出，但是会出现数据截取5K数据最后一条Log不完整改怎么解决？

void elog_async_restore_data(size_t size){
	uint32_t recoveryCount = 0;
    recoveryCount = last_read_index;
    recoveryCount =  (recoveryCount < size) ? recoveryCount : size;
    read_index += (last_read_index - recoveryCount);
    while(read_index >= ELOG_ASYNC_OUTPUT_BUF_SIZE)
    {
        read_index -= ELOG_ASYNC_OUTPUT_BUF_SIZE;
    }

	last_read_index = 0;
}
size_t elog_async_get_logchunk(char *log, size_t size) {
    size_t used = 0;
    /* lock output */
    elog_output_lock();
    used = elog_async_get_buf_used();
    /* no log */
    if (!used || !size || last_read_index) {
        size = 0;
        goto __exit;
    }
	/* less log */
	if (used < size) {
        size = 0;
        buf_is_empty = true;
    }
	else
	{
		memcpy(log,log_buf + read_index,size);
		read_index = (read_index + size) > OUTPUT_BUF_SIZE ?  OUTPUT_BUF_SIZE : read_index + size;	
	}
	last_read_index = size;
    buf_is_full = false;
__exit:
    /* lock output */
    elog_output_unlock();
    return size;
}

size_t When_Close_get_logchunk(char *log, size_t size) {
    size_t used = 0;
    size_t bytes_to_copy = 0;

    used = elog_async_get_buf_used();


    if (!used) {
        return 0;
    }

    bytes_to_copy = (used < size) ? used : size;

    if (read_index + bytes_to_copy <= OUTPUT_BUF_SIZE) 
	{
        memcpy(log, log_buf + read_index, bytes_to_copy);
    } 
	else 
	{

        size_t first_part_size = OUTPUT_BUF_SIZE - read_index;
        memcpy(log, log_buf + read_index, OUTPUT_BUF_SIZE - read_index);
        memcpy(log + first_part_size, log_buf, bytes_to_copy - first_part_size);
    }

    read_index += bytes_to_copy;

    if (read_index >= OUTPUT_BUF_SIZE) {
        read_index -= OUTPUT_BUF_SIZE;
    }

    last_read_index = read_index;

    if (used == bytes_to_copy) {
        buf_is_empty = true;
    }
    return bytes_to_copy;
}

switch (msg.instruction)
{
		case 1: //Open
		{
			get_log_size = elog_async_get_logchunk(log_Writebuf,LOG_CHUNK_SIZE);
			if(get_log_size>=LOG_CHUNK_SIZE)
			{
//						uint16_t strLen = strlen(log_Writebuf);
//						if(strLen > LOG_CHUNK_SIZE) strLen = LOG_CHUNK_SIZE;
				Log_Write(FileName, log_Writebuf, LOG_CHUNK_SIZE,NULL);
				elog_async_restore_data(LOG_CHUNK_SIZE);
				memset(log_Writebuf,0,LOG_CHUNK_SIZE);
				get_log_size = 0;							
			}
			break;
		}
		case 0: //Close
		{
			get_log_size = When_Close_get_logchunk(log_Writebuf_WhenClose, ELOG_LINE_BUF_SIZE);
			uint16_t strLen = strlen(log_Writebuf);
			if (strLen > LOG_CHUNK_SIZE) strLen = LOG_CHUNK_SIZE;
			//
			Log_Write(FileName, log_Writebuf_WhenClose, strLen,1);

			elog_async_restore_data(LOG_CHUNK_SIZE);
			memset(log_Writebuf, 0, sizeof(log_Writebuf));				
			Send_Control(2,NULL);		//4:
			break;
		}
	}
}

[ancientwaiting]

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