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78 lines
1.8 KiB
C++
78 lines
1.8 KiB
C++
/*
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Copyright (C) 2016 Draios inc.
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This file is part of falco.
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falco is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License version 2 as
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published by the Free Software Foundation.
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falco is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with falco. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include <cstdint>
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// A simple token bucket that accumulates tokens at a fixed rate and allows
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// for limited bursting in the form of "banked" tokens.
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class token_bucket
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{
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public:
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token_bucket();
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virtual ~token_bucket();
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//
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// Initialize the token bucket and start accumulating tokens
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//
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void init(double rate, double max_tokens, uint64_t now = 0);
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//
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// Try to claim tokens tokens from the token bucket, using a
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// timestamp of now. Returns true if the tokens could be
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// claimed. Also updates internal metrics.
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//
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bool claim(double tokens, uint64_t now);
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// Simpler version of claim that claims a single token and
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// uses the current time for now
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bool claim();
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// Return the current number of tokens available
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double get_tokens();
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// Return the last time someone tried to claim a token.
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uint64_t get_last_seen();
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private:
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//
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// The number of tokens generated per second.
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//
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double m_rate;
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//
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// The maximum number of tokens that can be banked for future
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// claim()s.
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//
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double m_max_tokens;
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//
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// The current number of tokens
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//
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double m_tokens;
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//
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// The last time claim() was called (or the object was created).
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// Nanoseconds since the epoch.
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//
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uint64_t m_last_seen;
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};
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