ServerRateLimiter Class Reference

Tracks per-server backoff state triggered by HTTP 429 responses. More...

#include <server_rate_limiter.h>

Public Member Functions
bool	isRateLimited (const QString &host, const QDateTime &now) const
	Checks whether a host is currently in backoff.
int	rounds (const QString &host) const
QDateTime	deadline (const QString &host) const
QDateTime	earliestDeadline (const QDateTime &now) const
QDateTime	on429 (const QString &host, const QDateTime &now, qint64 retryAfterMs=0)
	Registers a 429 response for the given host.
void	onSuccess (const QString &host)
	Clears all penalty state for a host after a successful request.
void	clearExpired (const QDateTime &now)
	Removes expired backoffs, refreshing the round budget of hosts that have been idle past the reset grace period.

Static Public Attributes
static constexpr int	MAX_RETRIES = 5
	Max 429 rounds per host before the budget is exhausted.
static constexpr int	MIN_429_BACKOFF_MS = 30000
	Minimum wait after a 429 (scryfall documented cool-down).
static constexpr int	MAX_BACKOFF_MS = 60000
	Cap for a single backoff period.
static constexpr int	EXHAUSTED_BACKOFF_MS = 60000
	Cool-down once the retry budget is exhausted.
static constexpr qint64	RESET_GRACE_MS = 300000
	Idle time after which the retry budget refreshes.

Private Attributes
QMap< QString, QDateTime >	backoffUntil
	When each host may be contacted again.
QMap< QString, int >	retryRounds
	Consecutive 429 rounds per host.
QMap< QString, QDateTime >	last429
	When each host was last rate limited.

Detailed Description

Tracks per-server backoff state triggered by HTTP 429 responses.

Keeps a monotonic backoff deadline per host and a retry-round budget that escalates once per backoff window (a burst of concurrent 429s counts as a single round). The budget is refreshed after a long period without 429s so a server is not permanently blacklisted after a past overload.

Member Function Documentation

clearExpired()

void ServerRateLimiter::clearExpired

(

const QDateTime &

now

)

Removes expired backoffs, refreshing the round budget of hosts that have been idle past the reset grace period.

Parameters

now	The current time

deadline()

QDateTime ServerRateLimiter::deadline ( const QString & host ) const

nodiscard

Returns

The current backoff deadline for the host, or an invalid QDateTime.

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earliestDeadline()

QDateTime ServerRateLimiter::earliestDeadline ( const QDateTime & now ) const

nodiscard

Returns

The earliest active backoff deadline across all hosts, or an invalid QDateTime.

isRateLimited()

bool ServerRateLimiter::isRateLimited ( const QString & host, const QDateTime & now ) const

nodiscard

Checks whether a host is currently in backoff.

Parameters

host	The host to check
now	The current time

Returns

True if requests to the host should be paused

on429()

QDateTime ServerRateLimiter::on429	(	const QString &	host,
		const QDateTime &	now,
		qint64	retryAfterMs = 0 )

Registers a 429 response for the given host.

Parameters

host	The host that returned 429
now	The time the response was received
retryAfterMs	A Retry-After hint in milliseconds, or 0 if absent

Returns

The new backoff deadline for the host

The round counter only escalates once the previous backoff window has fully passed, so concurrent 429s from a burst do not consume the whole budget. The deadline is extended monotonically and never shortened.

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onSuccess()

void ServerRateLimiter::onSuccess

(

const QString &

host

)

Clears all penalty state for a host after a successful request.

rounds()

int ServerRateLimiter::rounds ( const QString & host ) const

nodiscard

Returns

The number of consecutive 429 rounds recorded for the host.

Member Data Documentation

backoffUntil

QMap<QString, QDateTime> ServerRateLimiter::backoffUntil

private

When each host may be contacted again.

EXHAUSTED_BACKOFF_MS

int ServerRateLimiter::EXHAUSTED_BACKOFF_MS = 60000

staticconstexpr

Cool-down once the retry budget is exhausted.

last429

QMap<QString, QDateTime> ServerRateLimiter::last429

private

When each host was last rate limited.

MAX_BACKOFF_MS

int ServerRateLimiter::MAX_BACKOFF_MS = 60000

staticconstexpr

Cap for a single backoff period.

MAX_RETRIES

int ServerRateLimiter::MAX_RETRIES = 5

staticconstexpr

Max 429 rounds per host before the budget is exhausted.

MIN_429_BACKOFF_MS

int ServerRateLimiter::MIN_429_BACKOFF_MS = 30000

staticconstexpr

Minimum wait after a 429 (scryfall documented cool-down).

RESET_GRACE_MS

qint64 ServerRateLimiter::RESET_GRACE_MS = 300000

staticconstexpr

Idle time after which the retry budget refreshes.

retryRounds

QMap<QString, int> ServerRateLimiter::retryRounds

private

Consecutive 429 rounds per host.

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The documentation for this class was generated from the following files:

• libcockatrice_utility/libcockatrice/utility/server_rate_limiter.h
• libcockatrice_utility/libcockatrice/utility/server_rate_limiter.cpp