private boolean waitForPermit(String permitName, int permitLen) {
        boolean suc = false;
        while (!suc) {
            suc = MemoryManager.getInstance().tryAcquire(permitName, permitLen);
            if (!suc) {
                MemoryManager.getInstance().printDetail(permitName, "source");
                if (!isRunnable()) {
                    return false;
                }
                AgentUtils.silenceSleepInMs(WAIT_TIMEOUT_MS);
            }
        }
        return true;
    }
After preparation work, we started to truly read data from the data source

@return source data list
inlong-agent/agent-plugins/src/main/java/org/apache/inlong/agent/plugin/sources/file/AbstractSource.java