11.2 Reading and parsing a frame

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struct rsi_request {
    uint64_t    request_id;   /* echo this in the response */
    uint64_t    txn_id;       /* transaction id (0 outside a transaction) */
    const void *payload;      /* borrowed; valid until the frame is reused */
    uint32_t    payload_len;
    uint16_t    op_code;      /* RSI_LOOKUP, RSI_SET_VALUE, … — dispatch on this */
};

ssize_t rsi_read_request(int fd, void *buf, size_t cap);
int     rsi_parse_request(const void *frame, size_t len, struct rsi_request *out);
  • rsi_read_request reads one framed request from the source fd into buf — a thin read(2) wrapper that blocks until a request is queued, then returns the frame length (pass it to rsi_parse_request). It returns 0 at EOF (the source is closing — leave the loop) or -1 with errno, notably EMSGSIZE if cap is smaller than the pending frame (size buf generously, or grow and retry).
  • rsi_parse_request splits a frame into its header and payload view, filling out with the request_id (which you must echo in the response), the txn_id (0 when the request is not inside a transaction), the op_code to dispatch on, and a borrowed payload pointer. Returns 0, or -1 with errno (EINVAL on NULL args, EBADMSG on a malformed frame).

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