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797bc316bf
On any `Curl_rlimit_start()` the rate limit needs to reset its values before calculating the effective step duration and adjust the tokens/burst per step. Add two fields to the struct to remember the original values. Closes #21086
109 lines
4.7 KiB
C
109 lines
4.7 KiB
C
#ifndef HEADER_CURL_RLIMIT_H
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#define HEADER_CURL_RLIMIT_H
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/***************************************************************************
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* _ _ ____ _
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* Project ___| | | | _ \| |
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* / __| | | | |_) | |
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* | (__| |_| | _ <| |___
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* \___|\___/|_| \_\_____|
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*
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* Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
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*
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* This software is licensed as described in the file COPYING, which
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* you should have received as part of this distribution. The terms
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* are also available at https://curl.se/docs/copyright.html.
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*
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* You may opt to use, copy, modify, merge, publish, distribute and/or sell
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* copies of the Software, and permit persons to whom the Software is
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* furnished to do so, under the terms of the COPYING file.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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* SPDX-License-Identifier: curl
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*
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***************************************************************************/
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#include "curlx/timeval.h"
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struct Curl_easy;
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/* This is a rate limiter that provides "tokens" to be consumed
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* per second. In the literature, this is referred to as a
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* "token bucket" (https://en.wikipedia.org/wiki/Token_bucket).
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* Example:
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* A rate limit of 1 megabyte per second.
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* - initially 1 million tokens are available.
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* - these are drained in the first second.
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* - checking available tokens before the 2nd second will return 0.
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* - at/after the 2nd second, 1 million tokens are available again.
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* - nothing happens for a second, the 1 million tokens would grow
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* to 2 million, however the burst limit caps those at 1.5 million.
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* Thus:
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* - setting "burst" to CURL_OFF_T_MAX would average tokens over the
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* complete lifetime. E.g. for a download, at the *end* of it, the
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* average rate from start to finish would be the rate limit.
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* - setting "burst" to the same value as "rate" would make a
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* download always try to stay *at/below* the rate and slow times will
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* not generate extra tokens.
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*
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* A rate limit can be blocked, causing the available tokens to become
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* always 0 until unblocked. After unblocking, the rate limiting starts
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* again with no history of the past.
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*
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* Finally, a rate limiter with rate 0 will always have CURL_OFF_T_MAX
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* tokens available, unless blocked.
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*/
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struct Curl_rlimit {
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int64_t rate_per_sec; /* rate tokens generated per second */
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int64_t burst_per_sec; /* burst rate of tokens per second */
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int64_t rate_per_step; /* rate tokens generated per step us */
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int64_t burst_per_step; /* burst rate of tokens per step us */
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timediff_t step_us; /* microseconds between token increases */
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int64_t tokens; /* tokens available in the next second */
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timediff_t spare_us; /* microseconds unaffecting tokens */
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struct curltime ts; /* time of the last update */
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BIT(blocked); /* blocking sets available tokens to 0 */
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};
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void Curl_rlimit_init(struct Curl_rlimit *r,
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int64_t rate_per_sec,
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int64_t burst_per_sec,
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const struct curltime *pts);
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/* Start ratelimiting with the given timestamp. Resets available tokens.
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* `total_tokens` is either -1 or the number of total tokens expected
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* to be consumed. */
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void Curl_rlimit_start(struct Curl_rlimit *r, const struct curltime *pts,
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int64_t total_tokens);
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/* How many milliseconds to wait until token are available again. */
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timediff_t Curl_rlimit_wait_ms(struct Curl_rlimit *r,
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const struct curltime *pts);
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/* When the rate limit will update its tokens again */
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timediff_t Curl_rlimit_next_step_ms(struct Curl_rlimit *r,
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const struct curltime *pts);
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/* Return if rate limiting of tokens is active */
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bool Curl_rlimit_active(struct Curl_rlimit *r);
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bool Curl_rlimit_is_blocked(struct Curl_rlimit *r);
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int64_t Curl_rlimit_per_step(struct Curl_rlimit *r);
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/* Return how many tokens are available to spend, may be negative */
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int64_t Curl_rlimit_avail(struct Curl_rlimit *r,
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const struct curltime *pts);
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/* Drain tokens from the ratelimit, give an estimate of how many tokens
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* remain to be drained in the future (-1 for unknown). */
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void Curl_rlimit_drain(struct Curl_rlimit *r,
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size_t tokens,
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const struct curltime *pts);
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/* Block/unblock ratelimiting. A blocked ratelimit has 0 tokens available. */
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void Curl_rlimit_block(struct Curl_rlimit *r,
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bool activate,
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const struct curltime *pts);
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#endif /* HEADER_CURL_RLIMIT_H */
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