74 lines
1.9 KiB
Markdown
74 lines
1.9 KiB
Markdown
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QUIC Statistics Manager
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=======================
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The statistics manager keeps track of RTT statistics for use by the QUIC
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implementation.
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It provides the following interface:
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Instantiation
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-------------
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The QUIC statistics manager is instantiated as follows:
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```c
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typedef struct ossl_statm_st {
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...
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} OSSL_STATM;
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int ossl_statm_init(OSSL_STATM *statm);
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void ossl_statm_destroy(OSSL_STATM *statm);
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```
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The structure is defined in headers, so it may be initialised without needing
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its own memory allocation. However, other code should not examine the fields of
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`OSSL_STATM` directly.
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Get RTT Info
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------------
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The current RTT info is retrieved using the function `ossl_statm_get_rtt_info`,
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which fills an `OSSL_RTT_INFO` structure:
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```c
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typedef struct ossl_rtt_info_st {
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/* As defined in RFC 9002. */
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OSSL_TIME smoothed_rtt, latest_rtt, rtt_variance, min_rtt,
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max_ack_delay;
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} OSSL_RTT_INFO;
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void ossl_statm_get_rtt_info(OSSL_STATM *statm, OSSL_RTT_INFO *rtt_info);
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```
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Update RTT
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----------
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New RTT samples are provided using the `ossl_statm_update_rtt` function:
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- `ack_delay`. This is the ACK Delay value; see RFC 9000.
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- `override_latest_rtt` provides a new latest RTT sample. If it is
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`OSSL_TIME_ZERO`, the existing Latest RTT value is used when updating the
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RTT.
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The maximum ACK delay configured using `ossl_statm_set_max_ack_delay` is not
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enforced automatically on the `ack_delay` argument as the circumstances where
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this should be enforced are context sensitive. It is the caller's responsibility
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to retrieve the value and enforce the maximum ACK delay if appropriate.
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```c
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void ossl_statm_update_rtt(OSSL_STATM *statm,
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OSSL_TIME ack_delay,
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OSSL_TIME override_latest_rtt);
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```
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Set Max. Ack Delay
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------------------
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Sets the maximum ACK delay field reported by `OSSL_RTT_INFO`.
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```c
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void ossl_statm_set_max_ack_delay(OSSL_STATM *statm, OSSL_TIME max_ack_delay);
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```
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