关于easyflash和easylog开启ELOG_BUF_OUTPUT_ENABLE和ELOG_FLASH_USING_BUF_MODE

发布于 2024-11-15 09:08:45 浏览：23 订阅该版

[tocm]

elog_buf.c：

```c
void elog_buf_output(const char *log, size_t size) {
    size_t write_size = 0, write_index = 0;

if (!is_enabled) {
        elog_port_output(log, size);
        return;
    }

while (true) {
        if (buf_write_size + size > ELOG_BUF_OUTPUT_BUF_SIZE) {
            write_size = ELOG_BUF_OUTPUT_BUF_SIZE - buf_write_size;
            memcpy(log_buf + buf_write_size, log + write_index, write_size);
            write_index += write_size;
            size -= write_size;
            /* output log */
            elog_port_output(log_buf, ELOG_BUF_OUTPUT_BUF_SIZE);
            /* reset write index */
            buf_write_size = 0;
        } else {
            memcpy(log_buf + buf_write_size, log + write_index, size);
            buf_write_size += size;
            break;
        }
    }
}
```

elog_flash.c

```c
/**
 * Write log to flash. The flash write use buffer mode.
 *
 * @param log log
 * @param size log size
 */
void elog_flash_write(const char *log, size_t size) {
...
...
    while (true) {
        if (cur_buf_size + size > ELOG_FLASH_BUF_SIZE) {
            write_size = ELOG_FLASH_BUF_SIZE - cur_buf_size;
            elog_memcpy(log_buf + cur_buf_size, log + write_index, write_size);
            write_index += write_size;
            size -= write_size;
            cur_buf_size += write_size;
            /* unlock flash log buffer */
            log_buf_unlock();
            /* write all buffered log to flash, cur_buf_size will reset */
            elog_flash_flush();
            /* lock flash log buffer */
            log_buf_lock();
        } else {
            elog_memcpy(log_buf + cur_buf_size, log + write_index, size);
            cur_buf_size += size;
            break;
        }
    }
...
...
}
```

## 疑问：
这里当缓存的buffer满之后去打印或者存储的处理，是不是会存在最后一条日志缺失的问题？
elog_buf.c:
```c
write_size = ELOG_BUF_OUTPUT_BUF_SIZE - buf_write_size;
```

elog_flash.c
```c
write_size = ELOG_FLASH_BUF_SIZE - cur_buf_size;
```
最后一条日志的write_size理论上永远比实际的size小，存在`size -= write_size`的字节被丢弃的问题。