├── .gitignore ├── .travis.yml ├── LICENSE ├── README.markdown ├── pom.xml └── src ├── main └── java │ └── org │ └── isomorphism │ └── util │ ├── FixedIntervalRefillStrategy.java │ ├── TokenBucket.java │ ├── TokenBucketImpl.java │ └── TokenBuckets.java └── test └── java └── org └── isomorphism └── util ├── FixedIntervalRefillStrategyTest.java ├── TokenBucketBuilderTest.java └── TokenBucketImplTest.java /.gitignore: -------------------------------------------------------------------------------- 1 | # IntelliJ Files 2 | .idea/ 3 | *.ipr 4 | *.iws 5 | *.iml 6 | 7 | # Eclipse Files 8 | .classpath 9 | .project 10 | 11 | # Build outputs 12 | target/ 13 | reports/ 14 | -------------------------------------------------------------------------------- /.travis.yml: -------------------------------------------------------------------------------- 1 | language: java 2 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | 2 | Apache License 3 | Version 2.0, January 2004 4 | http://www.apache.org/licenses/ 5 | 6 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 7 | 8 | 1. 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We also recommend that a 186 | file or class name and description of purpose be included on the 187 | same "printed page" as the copyright notice for easier 188 | identification within third-party archives. 189 | 190 | Copyright [yyyy] [name of copyright owner] 191 | 192 | Licensed under the Apache License, Version 2.0 (the "License"); 193 | you may not use this file except in compliance with the License. 194 | You may obtain a copy of the License at 195 | 196 | http://www.apache.org/licenses/LICENSE-2.0 197 | 198 | Unless required by applicable law or agreed to in writing, software 199 | distributed under the License is distributed on an "AS IS" BASIS, 200 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 201 | See the License for the specific language governing permissions and 202 | limitations under the License. 203 | -------------------------------------------------------------------------------- /README.markdown: -------------------------------------------------------------------------------- 1 | Introduction 2 | ------------ 3 | This library provides an implementation of a token bucket algorithm which is useful for providing rate limited access 4 | to a portion of code. The implementation provided is that of a "leaky bucket" in the sense that the bucket has a finite 5 | capacity and any added tokens that would exceed this capacity will "overflow" out of the bucket and be lost forever. 6 | 7 | In this implementation the rules for refilling the bucket are encapsulated in a provided RefillStrategy instance. Prior 8 | to attempting to consume any tokens the refill strategy will be consulted to see how many tokens should be added to the 9 | bucket 10 | 11 | We use [Travis CI](http://about.travis-ci.org) for build verification. [![Build Status](https://secure.travis-ci.org/bbeck/token-bucket.png?branch=master)](http://travis-ci.org/bbeck/token-bucket) 12 | 13 | See also: 14 | 15 | * [Wikipedia - Token Bucket](http://en.wikipedia.org/wiki/Token_bucket) 16 | * [Wikipedia - Leaky Bucket](http://en.wikipedia.org/wiki/Leaky_bucket) 17 | 18 | Usage 19 | ----- 20 | Using a token bucket is incredibly easy and is best illustrated by an example. Suppose you have a piece of code that 21 | polls a website and you would only like to be able to access the site once per second: 22 | 23 | ```java 24 | // Create a token bucket with a capacity of 1 token that refills at a fixed interval of 1 token/sec. 25 | TokenBucket bucket = TokenBuckets.builder() 26 | .withCapacity(1) 27 | .withFixedIntervalRefillStrategy(1, 1, TimeUnit.SECONDS) 28 | .build(); 29 | 30 | // ... 31 | 32 | while (true) { 33 | // Consume a token from the token bucket. If a token is not available this method will block until 34 | // the refill strategy adds one to the bucket. 35 | bucket.consume(1); 36 | 37 | poll(); 38 | } 39 | ``` 40 | 41 | As another example suppose you wanted to rate limit the size response of a server to the client to 20 kb/sec but want to 42 | allow for a periodic burst rate of 40 kb/sec: 43 | 44 | ```java 45 | // Create a token bucket with a capacity of 40 kb tokens that refills at a fixed interval of 20 kb tokens per second 46 | TokenBucket bucket = TokenBuckets.builder() 47 | .withCapacity(40960) 48 | .withFixedIntervalRefillStrategy(20480, 1, TimeUnit.SECONDS) 49 | .build(); 50 | 51 | // ... 52 | 53 | while (true) { 54 | String response = prepareResponse(); 55 | 56 | // Consume tokens from the bucket commensurate with the size of the response 57 | bucket.consume(response.length()); 58 | 59 | send(response); 60 | } 61 | ``` 62 | 63 | Maven Setup 64 | ----------- 65 | The token bucket library is distributed through maven central. Just include it as a dependency in your ```pom.xml```. 66 | 67 | ```xml 68 | 69 | org.isomorphism 70 | token-bucket 71 | 1.6 72 | 73 | ``` 74 | 75 | License 76 | ------- 77 | Copyright 2012-2015 Brandon Beck 78 | Licensed under the Apache Software License, Version 2.0: . 79 | -------------------------------------------------------------------------------- /pom.xml: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4.0.0 4 | 5 | org.isomorphism 6 | token-bucket 7 | 1.8-SNAPSHOT 8 | jar 9 | 10 | 11 | org.sonatype.oss 12 | oss-parent 13 | 9 14 | 15 | 16 | token-bucket 17 | Token bucket algorithm for rate-limiting 18 | http://github.com/bbeck/token-bucket 19 | 20 | 21 | The Apache Software License, Version 2.0 22 | http://www.apache.org/licenses/LICENSE-2.0 23 | repo 24 | 25 | 26 | 27 | 28 | UTF-8 29 | UTF-8 30 | 31 | 32 | 33 | http://github.com/bbeck/token-bucket 34 | scm:git:git@github.com:bbeck/token-bucket.git 35 | scm:git:git@github.com:bbeck/token-bucket.git 36 | HEAD 37 | 38 | 39 | 40 | 41 | 42 | 43 | org.apache.maven.plugins 44 | maven-release-plugin 45 | 2.5.1 46 | 47 | v@{project.version} 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | bbeck 56 | Brandon Beck 57 | http://github.com/bbeck 58 | 59 | 60 | 61 | 62 | 63 | com.google.guava 64 | guava 65 | 18.0 66 | 67 | 68 | 69 | junit 70 | junit 71 | 4.12 72 | test 73 | 74 | 75 | 76 | org.mockito 77 | mockito-core 78 | 1.10.19 79 | test 80 | 81 | 82 | 83 | -------------------------------------------------------------------------------- /src/main/java/org/isomorphism/util/FixedIntervalRefillStrategy.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2012-2014 Brandon Beck 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package org.isomorphism.util; 17 | 18 | import com.google.common.base.Ticker; 19 | 20 | import java.util.concurrent.TimeUnit; 21 | 22 | /** 23 | * A token bucket refill strategy that will provide N tokens for a token bucket to consume every T units of time. 24 | * The tokens are refilled in bursts rather than at a fixed rate. This refill strategy will never allow more than 25 | * N tokens to be consumed during a window of time T. 26 | */ 27 | public class FixedIntervalRefillStrategy implements TokenBucketImpl.RefillStrategy 28 | { 29 | private final Ticker ticker; 30 | private final long numTokensPerPeriod; 31 | private final long periodDurationInNanos; 32 | private long lastRefillTime; 33 | private long nextRefillTime; 34 | 35 | /** 36 | * Create a FixedIntervalRefillStrategy. 37 | * 38 | * @param ticker A ticker to use to measure time. 39 | * @param numTokensPerPeriod The number of tokens to add to the bucket every period. 40 | * @param period How often to refill the bucket. 41 | * @param unit Unit for period. 42 | */ 43 | public FixedIntervalRefillStrategy(Ticker ticker, long numTokensPerPeriod, long period, TimeUnit unit) 44 | { 45 | this.ticker = ticker; 46 | this.numTokensPerPeriod = numTokensPerPeriod; 47 | this.periodDurationInNanos = unit.toNanos(period); 48 | this.lastRefillTime = -periodDurationInNanos; 49 | this.nextRefillTime = -periodDurationInNanos; 50 | } 51 | 52 | @Override 53 | public synchronized long refill() 54 | { 55 | long now = ticker.read(); 56 | if (now < nextRefillTime) { 57 | return 0; 58 | } 59 | 60 | // We now know that we need to refill the bucket with some tokens, the question is how many. We need to count how 61 | // many periods worth of tokens we've missed. 62 | long numPeriods = Math.max(0, (now - lastRefillTime) / periodDurationInNanos); 63 | 64 | // Move the last refill time forward by this many periods. 65 | lastRefillTime += numPeriods * periodDurationInNanos; 66 | 67 | // ...and we'll refill again one period after the last time we refilled. 68 | nextRefillTime = lastRefillTime + periodDurationInNanos; 69 | 70 | return numPeriods * numTokensPerPeriod; 71 | } 72 | 73 | @Override 74 | public long getDurationUntilNextRefill(TimeUnit unit) 75 | { 76 | long now = ticker.read(); 77 | return unit.convert(Math.max(0, nextRefillTime - now), TimeUnit.NANOSECONDS); 78 | } 79 | } 80 | 81 | -------------------------------------------------------------------------------- /src/main/java/org/isomorphism/util/TokenBucket.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2012-2014 Brandon Beck 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package org.isomorphism.util; 17 | 18 | import java.util.concurrent.TimeUnit; 19 | 20 | /** 21 | * A token bucket is used for rate limiting access to a portion of code. 22 | * 23 | * @see Token Bucket on Wikipedia 24 | * @see Leaky Bucket on Wikipedia 25 | */ 26 | public interface TokenBucket 27 | { 28 | /** 29 | * Returns the capacity of this token bucket. This is the maximum number of tokens that the bucket can hold at 30 | * any one time. 31 | * 32 | * @return The capacity of the bucket. 33 | */ 34 | long getCapacity(); 35 | 36 | /** 37 | * Returns the current number of tokens in the bucket. If the bucket is empty then this method will return 0. 38 | * 39 | * @return The current number of tokens in the bucket. 40 | */ 41 | long getNumTokens(); 42 | 43 | /** 44 | * Returns the amount of time in the specified time unit until the next group of tokens can be added to the token 45 | * bucket. 46 | * 47 | * @see org.isomorphism.util.TokenBucket.RefillStrategy#getDurationUntilNextRefill(java.util.concurrent.TimeUnit) 48 | * @param unit The time unit to express the return value in. 49 | * @return The amount of time until the next group of tokens can be added to the token bucket. 50 | */ 51 | long getDurationUntilNextRefill(TimeUnit unit) throws UnsupportedOperationException; 52 | 53 | /** 54 | * Attempt to consume a single token from the bucket. If it was consumed then {@code true} is returned, otherwise 55 | * {@code false} is returned. 56 | * 57 | * @return {@code true} if a token was consumed, {@code false} otherwise. 58 | */ 59 | boolean tryConsume(); 60 | 61 | /** 62 | * Attempt to consume a specified number of tokens from the bucket. If the tokens were consumed then {@code true} 63 | * is returned, otherwise {@code false} is returned. 64 | * 65 | * @param numTokens The number of tokens to consume from the bucket, must be a positive number. 66 | * @return {@code true} if the tokens were consumed, {@code false} otherwise. 67 | */ 68 | boolean tryConsume(long numTokens); 69 | 70 | /** 71 | * Consume a single token from the bucket. If no token is currently available then this method will block until a 72 | * token becomes available. 73 | */ 74 | void consume(); 75 | 76 | /** 77 | * Consumes multiple tokens from the bucket. If enough tokens are not currently available then this method will block 78 | * until 79 | * 80 | * @param numTokens The number of tokens to consume from teh bucket, must be a positive number. 81 | */ 82 | void consume(long numTokens); 83 | 84 | /** 85 | * Refills the bucket with the specified number of tokens. If the bucket is currently full or near capacity then 86 | * fewer than {@code numTokens} may be added. 87 | * 88 | * @param numTokens The number of tokens to add to the bucket. 89 | */ 90 | void refill(long numTokens); 91 | 92 | /** Encapsulation of a refilling strategy for a token bucket. */ 93 | static interface RefillStrategy 94 | { 95 | /** 96 | * Returns the number of tokens to add to the token bucket. 97 | * 98 | * @return The number of tokens to add to the token bucket. 99 | */ 100 | long refill(); 101 | 102 | /** 103 | * Returns the amount of time in the specified time unit until the next group of tokens can be added to the token 104 | * bucket. Please note, depending on the {@code SleepStrategy} used by the token bucket, tokens may not actually 105 | * be added until much after the returned duration. If for some reason the implementation of 106 | * {@code RefillStrategy} doesn't support knowing when the next batch of tokens will be added, then an 107 | * {@code UnsupportedOperationException} may be thrown. Lastly, if the duration until the next time tokens will 108 | * be added to the token bucket is less than a single unit of the passed in time unit then this method will 109 | * return 0. 110 | * 111 | * @param unit The time unit to express the return value in. 112 | * @return The amount of time until the next group of tokens can be added to the token bucket. 113 | */ 114 | long getDurationUntilNextRefill(TimeUnit unit) throws UnsupportedOperationException; 115 | } 116 | 117 | /** Encapsulation of a strategy for relinquishing control of the CPU. */ 118 | static interface SleepStrategy 119 | { 120 | /** 121 | * Sleep for a short period of time to allow other threads and system processes to execute. 122 | */ 123 | void sleep(); 124 | } 125 | } 126 | -------------------------------------------------------------------------------- /src/main/java/org/isomorphism/util/TokenBucketImpl.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2012-2014 Brandon Beck 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package org.isomorphism.util; 17 | 18 | import java.util.concurrent.TimeUnit; 19 | 20 | import static com.google.common.base.Preconditions.checkArgument; 21 | import static com.google.common.base.Preconditions.checkNotNull; 22 | 23 | /** 24 | * A token bucket implementation that is of a leaky bucket in the sense that it has a finite capacity and any added 25 | * tokens that would exceed this capacity will "overflow" out of the bucket and are lost forever. 26 | *

27 | * In this implementation the rules for refilling the bucket are encapsulated in a provided {@code RefillStrategy} 28 | * instance. Prior to attempting to consume any tokens the refill strategy will be consulted to see how many tokens 29 | * should be added to the bucket. 30 | *

31 | * In addition in this implementation the method of yielding CPU control is encapsulated in the provided 32 | * {@code SleepStrategy} instance. For high performance applications where tokens are being refilled incredibly quickly 33 | * and an accurate bucket implementation is required, it may be useful to never yield control of the CPU and to instead 34 | * busy wait. This strategy allows the caller to make this decision for themselves instead of the library forcing a 35 | * decision. 36 | */ 37 | class TokenBucketImpl implements TokenBucket 38 | { 39 | private final long capacity; 40 | private final RefillStrategy refillStrategy; 41 | private final SleepStrategy sleepStrategy; 42 | private long size; 43 | 44 | TokenBucketImpl(long capacity, long initialTokens, RefillStrategy refillStrategy, SleepStrategy sleepStrategy) 45 | { 46 | checkArgument(capacity > 0); 47 | checkArgument(initialTokens <= capacity); 48 | 49 | this.capacity = capacity; 50 | this.refillStrategy = checkNotNull(refillStrategy); 51 | this.sleepStrategy = checkNotNull(sleepStrategy); 52 | this.size = initialTokens; 53 | } 54 | 55 | /** 56 | * Returns the capacity of this token bucket. This is the maximum number of tokens that the bucket can hold at 57 | * any one time. 58 | * 59 | * @return The capacity of the bucket. 60 | */ 61 | @Override 62 | public long getCapacity() 63 | { 64 | return capacity; 65 | } 66 | 67 | /** 68 | * Returns the current number of tokens in the bucket. If the bucket is empty then this method will return 0. 69 | * 70 | * @return The current number of tokens in the bucket. 71 | */ 72 | @Override 73 | public synchronized long getNumTokens() 74 | { 75 | // Give the refill strategy a chance to add tokens if it needs to so that we have an accurate 76 | // count. 77 | refill(refillStrategy.refill()); 78 | 79 | return size; 80 | } 81 | 82 | /** 83 | * Returns the amount of time in the specified time unit until the next group of tokens can be added to the token 84 | * bucket. 85 | * 86 | * @see org.isomorphism.util.TokenBucket.RefillStrategy#getDurationUntilNextRefill(java.util.concurrent.TimeUnit) 87 | * @param unit The time unit to express the return value in. 88 | * @return The amount of time until the next group of tokens can be added to the token bucket. 89 | */ 90 | @Override 91 | public long getDurationUntilNextRefill(TimeUnit unit) throws UnsupportedOperationException 92 | { 93 | return refillStrategy.getDurationUntilNextRefill(unit); 94 | } 95 | 96 | /** 97 | * Attempt to consume a single token from the bucket. If it was consumed then {@code true} is returned, otherwise 98 | * {@code false} is returned. 99 | * 100 | * @return {@code true} if a token was consumed, {@code false} otherwise. 101 | */ 102 | public boolean tryConsume() 103 | { 104 | return tryConsume(1); 105 | } 106 | 107 | /** 108 | * Attempt to consume a specified number of tokens from the bucket. If the tokens were consumed then {@code true} 109 | * is returned, otherwise {@code false} is returned. 110 | * 111 | * @param numTokens The number of tokens to consume from the bucket, must be a positive number. 112 | * @return {@code true} if the tokens were consumed, {@code false} otherwise. 113 | */ 114 | public synchronized boolean tryConsume(long numTokens) 115 | { 116 | checkArgument(numTokens > 0, "Number of tokens to consume must be positive"); 117 | checkArgument(numTokens <= capacity, "Number of tokens to consume must be less than the capacity of the bucket."); 118 | 119 | refill(refillStrategy.refill()); 120 | 121 | // Now try to consume some tokens 122 | if (numTokens <= size) { 123 | size -= numTokens; 124 | return true; 125 | } 126 | 127 | return false; 128 | } 129 | 130 | /** 131 | * Consume a single token from the bucket. If no token is currently available then this method will block until a 132 | * token becomes available. 133 | */ 134 | public void consume() 135 | { 136 | consume(1); 137 | } 138 | 139 | /** 140 | * Consumes multiple tokens from the bucket. If enough tokens are not currently available then this method will block 141 | * until 142 | * 143 | * @param numTokens The number of tokens to consume from teh bucket, must be a positive number. 144 | */ 145 | public void consume(long numTokens) 146 | { 147 | while (true) { 148 | if (tryConsume(numTokens)) { 149 | break; 150 | } 151 | 152 | sleepStrategy.sleep(); 153 | } 154 | } 155 | 156 | /** 157 | * Refills the bucket with the specified number of tokens. If the bucket is currently full or near capacity then 158 | * fewer than {@code numTokens} may be added. 159 | * 160 | * @param numTokens The number of tokens to add to the bucket. 161 | */ 162 | public synchronized void refill(long numTokens) 163 | { 164 | long newTokens = Math.min(capacity, Math.max(0, numTokens)); 165 | size = Math.max(0, Math.min(size + newTokens, capacity)); 166 | } 167 | } 168 | -------------------------------------------------------------------------------- /src/main/java/org/isomorphism/util/TokenBuckets.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2012-2014 Brandon Beck 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package org.isomorphism.util; 17 | 18 | import com.google.common.base.Ticker; 19 | import com.google.common.util.concurrent.Uninterruptibles; 20 | 21 | import java.util.concurrent.TimeUnit; 22 | 23 | import static com.google.common.base.Preconditions.checkArgument; 24 | import static com.google.common.base.Preconditions.checkNotNull; 25 | 26 | /** Static utility methods pertaining to creating {@link TokenBucketImpl} instances. */ 27 | public final class TokenBuckets 28 | { 29 | private TokenBuckets() {} 30 | 31 | /** Create a new builder for token buckets. */ 32 | public static Builder builder() 33 | { 34 | return new Builder(); 35 | } 36 | 37 | public static class Builder 38 | { 39 | private Long capacity = null; 40 | private long initialTokens = 0; 41 | private TokenBucketImpl.RefillStrategy refillStrategy = null; 42 | private TokenBucketImpl.SleepStrategy sleepStrategy = YIELDING_SLEEP_STRATEGY; 43 | private final Ticker ticker = Ticker.systemTicker(); 44 | 45 | /** Specify the overall capacity of the token bucket. */ 46 | public Builder withCapacity(long numTokens) 47 | { 48 | checkArgument(numTokens > 0, "Must specify a positive number of tokens"); 49 | capacity = numTokens; 50 | return this; 51 | } 52 | 53 | /** Initialize the token bucket with a specific number of tokens. */ 54 | public Builder withInitialTokens(long numTokens) 55 | { 56 | checkArgument(numTokens > 0, "Must specify a positive number of tokens"); 57 | initialTokens = numTokens; 58 | return this; 59 | } 60 | 61 | /** Refill tokens at a fixed interval. */ 62 | public Builder withFixedIntervalRefillStrategy(long refillTokens, long period, TimeUnit unit) 63 | { 64 | return withRefillStrategy(new FixedIntervalRefillStrategy(ticker, refillTokens, period, unit)); 65 | } 66 | 67 | /** Use a user defined refill strategy. */ 68 | public Builder withRefillStrategy(TokenBucket.RefillStrategy refillStrategy) 69 | { 70 | this.refillStrategy = checkNotNull(refillStrategy); 71 | return this; 72 | } 73 | 74 | /** Use a sleep strategy that will always attempt to yield the CPU to other processes. */ 75 | public Builder withYieldingSleepStrategy() 76 | { 77 | return withSleepStrategy(YIELDING_SLEEP_STRATEGY); 78 | } 79 | 80 | /** 81 | * Use a sleep strategy that will not yield the CPU to other processes. It will busy wait until more tokens become 82 | * available. 83 | */ 84 | public Builder withBusyWaitSleepStrategy() 85 | { 86 | return withSleepStrategy(BUSY_WAIT_SLEEP_STRATEGY); 87 | } 88 | 89 | /** Use a user defined sleep strategy. */ 90 | public Builder withSleepStrategy(TokenBucket.SleepStrategy sleepStrategy) 91 | { 92 | this.sleepStrategy = checkNotNull(sleepStrategy); 93 | return this; 94 | } 95 | 96 | /** Build the token bucket. */ 97 | public TokenBucket build() 98 | { 99 | checkNotNull(capacity, "Must specify a capacity"); 100 | checkNotNull(refillStrategy, "Must specify a refill strategy"); 101 | 102 | return new TokenBucketImpl(capacity, initialTokens, refillStrategy, sleepStrategy); 103 | } 104 | } 105 | 106 | private static final TokenBucketImpl.SleepStrategy YIELDING_SLEEP_STRATEGY = new TokenBucketImpl.SleepStrategy() 107 | { 108 | @Override 109 | public void sleep() 110 | { 111 | // Sleep for the smallest unit of time possible just to relinquish control 112 | // and to allow other threads to run. 113 | Uninterruptibles.sleepUninterruptibly(1, TimeUnit.NANOSECONDS); 114 | } 115 | }; 116 | 117 | private static final TokenBucketImpl.SleepStrategy BUSY_WAIT_SLEEP_STRATEGY = new TokenBucketImpl.SleepStrategy() 118 | { 119 | @Override 120 | public void sleep() 121 | { 122 | // Do nothing, don't sleep. 123 | } 124 | }; 125 | } 126 | -------------------------------------------------------------------------------- /src/test/java/org/isomorphism/util/FixedIntervalRefillStrategyTest.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2012-2014 Brandon Beck 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package org.isomorphism.util; 17 | 18 | import com.google.common.base.Ticker; 19 | import org.junit.Test; 20 | 21 | import java.util.concurrent.TimeUnit; 22 | 23 | import static org.junit.Assert.assertEquals; 24 | 25 | public class FixedIntervalRefillStrategyTest 26 | { 27 | private static final long N = 5; // 5 tokens 28 | private static final long P = 10; // every 10 29 | private static final TimeUnit U = TimeUnit.SECONDS; // seconds 30 | 31 | private final MockTicker ticker = new MockTicker(); 32 | private final FixedIntervalRefillStrategy strategy = new FixedIntervalRefillStrategy(ticker, N, P, U); 33 | 34 | @Test 35 | public void testFirstRefill() 36 | { 37 | assertEquals(N, strategy.refill()); 38 | } 39 | 40 | @Test 41 | public void testNoRefillUntilPeriodUp() 42 | { 43 | strategy.refill(); 44 | 45 | // Another refill shouldn't come for P time units. 46 | for (int i = 0; i < P - 1; i++) { 47 | ticker.advance(1, U); 48 | assertEquals(0, strategy.refill()); 49 | } 50 | } 51 | 52 | @Test 53 | public void testRefillEveryPeriod() 54 | { 55 | strategy.refill(); 56 | 57 | ticker.advance(P, U); 58 | assertEquals(N, strategy.refill()); 59 | 60 | ticker.advance(P, U); 61 | assertEquals(N, strategy.refill()); 62 | 63 | ticker.advance(P, U); 64 | assertEquals(N, strategy.refill()); 65 | } 66 | 67 | @Test 68 | public void testRefillEveryOtherPeriod() 69 | { 70 | strategy.refill(); 71 | 72 | // Move time forward two periods, since we're skipping a period next time we should add double the tokens. 73 | ticker.advance(2 * P, U); 74 | assertEquals(2 * N, strategy.refill()); 75 | 76 | ticker.advance(2 * P, U); 77 | assertEquals(2 * N, strategy.refill()); 78 | } 79 | 80 | @Test 81 | public void testRefillOnNonEvenPeriods() 82 | { 83 | // The strategy is configured to refill tokens every P time units. So we should only get refills at 0, P, 2P, 3P, 84 | // etc. Any other time should return 0 tokens. 85 | 86 | // t = 0 87 | assertEquals(N, strategy.refill()); 88 | 89 | // t = P+1 90 | ticker.advance(P + 1, U); 91 | assertEquals(N, strategy.refill()); 92 | 93 | // t = 2P+1 94 | ticker.advance(P, U); 95 | assertEquals(N, strategy.refill()); 96 | 97 | // t = 3P 98 | ticker.advance(P - 1, U); 99 | assertEquals(N, strategy.refill()); 100 | 101 | // t = 4P-1 102 | ticker.advance(P - 1, U); 103 | assertEquals(0, strategy.refill()); 104 | 105 | // t = 4P 106 | ticker.advance(1, U); 107 | assertEquals(N, strategy.refill()); 108 | } 109 | 110 | @Test 111 | public void testDurationUntilFirstRefill() 112 | { 113 | // A refill has never happened, so one is supposed to happen immediately. 114 | assertEquals(0, strategy.getDurationUntilNextRefill(TimeUnit.SECONDS)); 115 | } 116 | 117 | @Test 118 | public void testDurationAfterFirstRefill() 119 | { 120 | strategy.refill(); 121 | 122 | for (int i = 0; i < P - 1; i++) { 123 | assertEquals(P - i, strategy.getDurationUntilNextRefill(TimeUnit.SECONDS)); 124 | ticker.advance(1, U); 125 | } 126 | } 127 | 128 | @Test 129 | public void testDurationAtSecondRefillTime() 130 | { 131 | strategy.refill(); 132 | ticker.advance(P, U); 133 | 134 | assertEquals(0, strategy.getDurationUntilNextRefill(TimeUnit.SECONDS)); 135 | } 136 | 137 | @Test 138 | public void testDurationInProperUnits() 139 | { 140 | strategy.refill(); 141 | 142 | assertEquals(10000, strategy.getDurationUntilNextRefill(TimeUnit.MILLISECONDS)); 143 | } 144 | 145 | private static final class MockTicker extends Ticker 146 | { 147 | private long now = 0; 148 | 149 | @Override 150 | public long read() 151 | { 152 | return now; 153 | } 154 | 155 | public void advance(long delta, TimeUnit unit) 156 | { 157 | now += unit.toNanos(delta); 158 | } 159 | } 160 | } 161 | -------------------------------------------------------------------------------- /src/test/java/org/isomorphism/util/TokenBucketBuilderTest.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2012-2014 Brandon Beck 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package org.isomorphism.util; 17 | 18 | import org.junit.Test; 19 | 20 | public class TokenBucketBuilderTest 21 | { 22 | private final TokenBuckets.Builder builder = TokenBuckets.builder(); 23 | 24 | @Test(expected = IllegalArgumentException.class) 25 | public void testNegativeCapacity() { 26 | builder.withCapacity(-1); 27 | } 28 | 29 | @Test(expected = IllegalArgumentException.class) 30 | public void testZeroCapacity() { 31 | builder.withCapacity(0); 32 | } 33 | 34 | @Test(expected = IllegalArgumentException.class) 35 | public void testNegativeInitialTokens() { 36 | builder.withInitialTokens(-1); 37 | } 38 | } 39 | -------------------------------------------------------------------------------- /src/test/java/org/isomorphism/util/TokenBucketImplTest.java: -------------------------------------------------------------------------------- 1 | /* 2 | * Copyright 2012-2014 Brandon Beck 3 | * 4 | * Licensed under the Apache License, Version 2.0 (the "License"); 5 | * you may not use this file except in compliance with the License. 6 | * You may obtain a copy of the License at 7 | * 8 | * http://www.apache.org/licenses/LICENSE-2.0 9 | * 10 | * Unless required by applicable law or agreed to in writing, software 11 | * distributed under the License is distributed on an "AS IS" BASIS, 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | * See the License for the specific language governing permissions and 14 | * limitations under the License. 15 | */ 16 | package org.isomorphism.util; 17 | 18 | import org.junit.Test; 19 | 20 | import java.util.concurrent.TimeUnit; 21 | 22 | import static org.junit.Assert.assertEquals; 23 | import static org.junit.Assert.assertFalse; 24 | import static org.junit.Assert.assertTrue; 25 | import static org.mockito.Mockito.mock; 26 | 27 | public class TokenBucketImplTest 28 | { 29 | private static final long CAPACITY = 10; 30 | 31 | private final MockRefillStrategy refillStrategy = new MockRefillStrategy(); 32 | private final TokenBucket.SleepStrategy sleepStrategy = mock(TokenBucket.SleepStrategy.class); 33 | private final TokenBucketImpl bucket = new TokenBucketImpl(CAPACITY, 0, refillStrategy, sleepStrategy); 34 | 35 | @Test(expected = IllegalArgumentException.class) 36 | public void testNegativeCapacity() 37 | { 38 | new TokenBucketImpl(-1, 0, refillStrategy, sleepStrategy); 39 | } 40 | 41 | @Test(expected = IllegalArgumentException.class) 42 | public void testZeroCapacity() 43 | { 44 | new TokenBucketImpl(0, 0, refillStrategy, sleepStrategy); 45 | } 46 | 47 | @Test(expected = IllegalArgumentException.class) 48 | public void testMoreInitialTokensThanCapacity() 49 | { 50 | new TokenBucketImpl(1, 2, refillStrategy, sleepStrategy); 51 | } 52 | 53 | @Test 54 | public void testGetCapacity() 55 | { 56 | assertEquals(CAPACITY, bucket.getCapacity()); 57 | } 58 | 59 | @Test 60 | public void testEmptyBucketHasZeroTokens() 61 | { 62 | assertEquals(0, bucket.getNumTokens()); 63 | } 64 | 65 | @Test 66 | public void testBucketWithInitialTokens() 67 | { 68 | TokenBucketImpl bucket = new TokenBucketImpl(CAPACITY, CAPACITY, refillStrategy, sleepStrategy); 69 | assertEquals(CAPACITY, bucket.getNumTokens()); 70 | } 71 | 72 | @Test 73 | public void testAddingTokenIncreasesNumTokens() 74 | { 75 | refillStrategy.addToken(); 76 | assertEquals(1, bucket.getNumTokens()); 77 | } 78 | 79 | @Test 80 | public void testAddingMultipleTokensIncreasesNumTokens() 81 | { 82 | refillStrategy.addTokens(2); 83 | assertEquals(2, bucket.getNumTokens()); 84 | } 85 | 86 | @Test 87 | public void testAtCapacityNumTokens() 88 | { 89 | refillStrategy.addTokens(CAPACITY); 90 | assertEquals(CAPACITY, bucket.getNumTokens()); 91 | } 92 | 93 | @Test 94 | public void testOverCapacityNumTokens() 95 | { 96 | refillStrategy.addTokens(CAPACITY + 1); 97 | assertEquals(CAPACITY, bucket.getNumTokens()); 98 | } 99 | 100 | @Test 101 | public void testConsumingTokenDecreasesNumTokens() 102 | { 103 | refillStrategy.addTokens(1); 104 | bucket.consume(); 105 | assertEquals(0, bucket.getNumTokens()); 106 | } 107 | 108 | @Test 109 | public void testConsumingMultipleTokensDecreasesNumTokens() 110 | { 111 | refillStrategy.addTokens(CAPACITY); 112 | bucket.consume(2); 113 | assertEquals(CAPACITY - 2, bucket.getNumTokens()); 114 | } 115 | 116 | @Test 117 | public void testEmptyNumTokens() 118 | { 119 | refillStrategy.addTokens(CAPACITY); 120 | bucket.consume(CAPACITY); 121 | assertEquals(0, bucket.getNumTokens()); 122 | } 123 | 124 | @Test 125 | public void testFailedConsumeKeepsNumTokens() 126 | { 127 | refillStrategy.addTokens(1); 128 | bucket.tryConsume(2); 129 | assertEquals(1, bucket.getNumTokens()); 130 | } 131 | 132 | @Test(expected = IllegalArgumentException.class) 133 | public void testTryConsumeZeroTokens() 134 | { 135 | bucket.tryConsume(0); 136 | } 137 | 138 | @Test(expected = IllegalArgumentException.class) 139 | public void testTryConsumeNegativeTokens() 140 | { 141 | bucket.tryConsume(-1); 142 | } 143 | 144 | @Test(expected = IllegalArgumentException.class) 145 | public void testTryConsumeMoreThanCapacityTokens() 146 | { 147 | bucket.tryConsume(100); 148 | } 149 | 150 | @Test 151 | public void testTryConsumeOnEmptyBucket() 152 | { 153 | assertFalse(bucket.tryConsume()); 154 | } 155 | 156 | @Test 157 | public void testTryConsumeOneToken() 158 | { 159 | refillStrategy.addToken(); 160 | assertTrue(bucket.tryConsume()); 161 | } 162 | 163 | @Test 164 | public void testTryConsumeMoreTokensThanAreAvailable() 165 | { 166 | refillStrategy.addToken(); 167 | assertFalse(bucket.tryConsume(2)); 168 | } 169 | 170 | @Test 171 | public void testTryManuallyRefillOneToken() 172 | { 173 | bucket.refill(1); 174 | assertTrue(bucket.tryConsume()); 175 | } 176 | 177 | @Test 178 | public void testTryManuallyRefillCapacityTokens() 179 | { 180 | bucket.refill(CAPACITY); 181 | assertTrue(bucket.tryConsume(CAPACITY)); 182 | assertFalse(bucket.tryConsume(1)); 183 | } 184 | 185 | @Test 186 | public void testTryManuallyRefillMoreThanCapacityTokens() 187 | { 188 | bucket.refill(CAPACITY + 1); 189 | assertTrue(bucket.tryConsume(CAPACITY)); 190 | assertFalse(bucket.tryConsume(1)); 191 | } 192 | 193 | @Test 194 | public void testTryManualRefillAndStrategyRefill() { 195 | bucket.refill(CAPACITY); 196 | refillStrategy.addTokens(CAPACITY); 197 | assertTrue(bucket.tryConsume(CAPACITY)); 198 | assertFalse(bucket.tryConsume(1)); 199 | } 200 | 201 | @Test 202 | public void testTryRefillMoreThanCapacityTokens() 203 | { 204 | refillStrategy.addTokens(CAPACITY + 1); 205 | assertTrue(bucket.tryConsume(CAPACITY)); 206 | assertFalse(bucket.tryConsume(1)); 207 | } 208 | 209 | @Test 210 | public void testTryRefillWithTooManyTokens() 211 | { 212 | refillStrategy.addTokens(CAPACITY); 213 | assertTrue(bucket.tryConsume()); 214 | 215 | refillStrategy.addTokens(Long.MAX_VALUE); 216 | assertTrue(bucket.tryConsume(CAPACITY)); 217 | assertFalse(bucket.tryConsume(1)); 218 | } 219 | 220 | private static final class MockRefillStrategy implements TokenBucketImpl.RefillStrategy 221 | { 222 | private long numTokensToAdd = 0; 223 | 224 | public long refill() 225 | { 226 | long numTokens = numTokensToAdd; 227 | numTokensToAdd = 0; 228 | return numTokens; 229 | } 230 | 231 | @Override 232 | public long getDurationUntilNextRefill(TimeUnit unit) throws UnsupportedOperationException 233 | { 234 | throw new UnsupportedOperationException(); 235 | } 236 | 237 | public void addToken() 238 | { 239 | numTokensToAdd++; 240 | } 241 | 242 | public void addTokens(long numTokens) 243 | { 244 | numTokensToAdd += numTokens; 245 | } 246 | } 247 | } 248 | --------------------------------------------------------------------------------