XX-net/XX-Net · warning

SendBuffer put 0

Error message

SendBuffer put 0

What it means

SendBuffer.put() was called with an empty bytes object. It refuses to add zero-length data (returns False) because an empty buffer block would corrupt the send-stream accounting.

Source

Thrown at code/default/x_tunnel/local/base_container.py:230

        self.mutex = threading.Lock()
        self.max_payload = max_payload
        self.reset()

    def reset(self):
        xlog.debug("SendBuffer reset")
        self.pool_size = 0
        self.last_put_time = time.time()
        with self.mutex:
            self.head_sn = 1
            self.tail_sn = 1
            self.block_list = {}
            self.last_block = WriteBuffer()

    def put(self, data):
        dlen = len(data)
        # xlog.debug("SendBuffer len:%d", dlen)
        if dlen == 0:
            xlog.warn("SendBuffer put 0")
            return False

        # xlog.debug("SendBuffer put len:%d", len(data))
        self.last_put_time = time.time()
        with self.mutex:
            self.pool_size += dlen
            self.last_block.append(data)

            if len(self.last_block) > self.max_payload:
                self.block_list[self.head_sn] = self.last_block
                self.last_block = WriteBuffer()
                self.head_sn += 1
        return True

    def get(self):
        with self.mutex:
            if self.tail_sn < self.head_sn:
                data = self.block_list[self.tail_sn]

View on GitHub (pinned to cfa5bc17b6)

Solutions

  1. Find the caller passing empty data and skip sending when the read/payload is empty
  2. Guard upstream: if not data: return before calling put
  3. Add an assert/log at the caller to identify which path produces empty buffers
  4. Treat empty payload as EOF signal if that is the semantic

Example fix

# before
buf.put(data)
# after
if data:
    buf.put(data)
Defensive patterns

Strategy: validation

Validate before calling

if not data: return False  # before calling put

Type guard

def has_payload(d): return len(d) > 0

Prevention

When it happens

Trigger: Caller passes b'' to SendBuffer.put, typically when an upstream read returned 0 bytes but was still forwarded, or a caller didn't check for empty payloads.

Common situations: EOF handling that forwards the empty read result; encoder returning empty output for empty input; edge-case in chunked assembly producing empty frames.

Related errors

AI-assisted analysis of XX-net/XX-Net@cfa5bc17b6 (2026-08-27). Data as JSON: /api/errors/cb068f27f3f18216. Report an issue: GitHub.