Method consume

rate_limiter/src/lib.rs:378–425

Attempts to consume tokens and returns whether that is possible. If rate limiting is disabled on provided `token_type`, this function will always succeed.

(&self, tokens: u64, token_type: TokenType)

    ///
    /// If rate limiting is disabled on provided `token_type`, this function will always succeed.
    pub fn consume(&self, tokens: u64, token_type: TokenType) -> bool {
        // If the timer is active, we can't consume tokens from any bucket and the function fails.
        if self.is_blocked() {
            return false;
        }
        let mut guard = self.inner.lock().unwrap();
        // Identify the required token bucket.
        let token_bucket = match token_type {
            TokenType::Bytes => guard.bandwidth.as_mut(),
            TokenType::Ops => guard.ops.as_mut(),
        };
        // Try to consume from the token bucket.
        if let Some(bucket) = token_bucket {
            let refill_time = bucket.refill_time_ms();
            match bucket.reduce(tokens) {
                // When we report budget is over, there will be no further calls here,
                // register a timer to replenish the bucket and resume processing;
                // make sure there is only one running timer for this limiter.
                BucketReduction::Failure => {
                    if !self.is_blocked() {
                        guard.activate_timer(TIMER_REFILL_DUR, &self.timer_active);
                    }
                    false
                }
                // The operation succeeded and further calls can be made.
                BucketReduction::Success => true,
                // The operation succeeded as the tokens have been consumed
                // but the timer still needs to be armed.
                BucketReduction::OverConsumption(ratio) => {
                    // The operation "borrowed" a number of tokens `ratio` times
                    // greater than the size of the bucket, and since it takes
                    // `refill_time` milliseconds to fill an empty bucket, in
                    // order to enforce the bandwidth limit we need to prevent
                    // further calls to the rate limiter for
                    // `ratio * refill_time` milliseconds.
                    guard.activate_timer(
                        Duration::from_millis((ratio * refill_time as f64) as u64),
                        &self.timer_active,
                    );
                    true
                }
            }
        } else {
            // If bucket is not present rate limiting is disabled on token type,
            // consume() will always succeed.
            true
        }
    }

    /// Adds tokens of `token_type` to their respective bucket.
    ///