Java tutorial
/* * Copyright 2011-2019 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * https://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.springframework.data.redis.support.atomic; import java.io.Serializable; import java.util.Date; import java.util.concurrent.TimeUnit; import java.util.function.IntBinaryOperator; import java.util.function.IntUnaryOperator; import org.springframework.dao.DataRetrievalFailureException; import org.springframework.data.redis.connection.DataType; import org.springframework.data.redis.connection.RedisConnectionFactory; import org.springframework.data.redis.core.BoundKeyOperations; import org.springframework.data.redis.core.RedisOperations; import org.springframework.data.redis.core.RedisTemplate; import org.springframework.data.redis.core.ValueOperations; import org.springframework.data.redis.serializer.GenericToStringSerializer; import org.springframework.data.redis.serializer.RedisSerializer; import org.springframework.lang.Nullable; import org.springframework.util.Assert; /** * Atomic integer backed by Redis. Uses Redis atomic increment/decrement and watch/multi/exec operations for CAS * operations. * * @author Costin Leau * @author Thomas Darimont * @author Christoph Strobl * @author Mark Paluch * @author Graham MacMaster * @author Ning Wei * @see java.util.concurrent.atomic.AtomicInteger */ public class RedisAtomicInteger extends Number implements Serializable, BoundKeyOperations<String> { private static final long serialVersionUID = 1L; private volatile String key; private final ValueOperations<String, Integer> operations; private final RedisOperations<String, Integer> generalOps; /** * Constructs a new {@link RedisAtomicInteger} instance. Uses the value existing in Redis or 0 if none is found. * * @param redisCounter Redis key of this counter. * @param factory connection factory. */ public RedisAtomicInteger(String redisCounter, RedisConnectionFactory factory) { this(redisCounter, factory, null); } /** * Constructs a new {@link RedisAtomicInteger} instance. * * @param redisCounter Redis key of this counter. * @param factory connection factory. * @param initialValue initial value to set if the Redis key is absent. */ public RedisAtomicInteger(String redisCounter, RedisConnectionFactory factory, int initialValue) { this(redisCounter, factory, Integer.valueOf(initialValue)); } /** * Constructs a new {@link RedisAtomicInteger} instance. Uses the value existing in Redis or 0 if none is found. * * @param redisCounter Redis key of this counter. * @param template the template. * @see #RedisAtomicInteger(String, RedisConnectionFactory, int) */ public RedisAtomicInteger(String redisCounter, RedisOperations<String, Integer> template) { this(redisCounter, template, null); } /** * Constructs a new {@link RedisAtomicInteger} instance. Note: You need to configure the given {@code template} with * appropriate {@link RedisSerializer} for the key and value. As an alternative one could use the * {@link #RedisAtomicInteger(String, RedisConnectionFactory, Integer)} constructor which uses appropriate default * serializers. * * @param redisCounter Redis key of this counter. * @param template the template. * @param initialValue initial value to set if the Redis key is absent. */ public RedisAtomicInteger(String redisCounter, RedisOperations<String, Integer> template, int initialValue) { this(redisCounter, template, Integer.valueOf(initialValue)); } private RedisAtomicInteger(String redisCounter, RedisConnectionFactory factory, @Nullable Integer initialValue) { RedisTemplate<String, Integer> redisTemplate = new RedisTemplate<>(); redisTemplate.setKeySerializer(RedisSerializer.string()); redisTemplate.setValueSerializer(new GenericToStringSerializer<>(Integer.class)); redisTemplate.setExposeConnection(true); redisTemplate.setConnectionFactory(factory); redisTemplate.afterPropertiesSet(); this.key = redisCounter; this.generalOps = redisTemplate; this.operations = generalOps.opsForValue(); if (initialValue == null) { initializeIfAbsent(); } else { set(initialValue); } } private RedisAtomicInteger(String redisCounter, RedisOperations<String, Integer> template, @Nullable Integer initialValue) { Assert.hasText(redisCounter, "a valid counter name is required"); Assert.notNull(template, "a valid template is required"); Assert.notNull(template.getKeySerializer(), "a valid key serializer in template is required"); Assert.notNull(template.getValueSerializer(), "a valid value serializer in template is required"); this.key = redisCounter; this.generalOps = template; this.operations = generalOps.opsForValue(); if (initialValue == null) { initializeIfAbsent(); } else { set(initialValue); } } private void initializeIfAbsent() { operations.setIfAbsent(key, 0); } /** * Get the current value. * * @return the current value. */ public int get() { Integer value = operations.get(key); if (value != null) { return value; } throw new DataRetrievalFailureException(String.format("The key '%s' seems to no longer exist.", key)); } /** * Set to the given value. * * @param newValue the new value. */ public void set(int newValue) { operations.set(key, newValue); } /** * Set to the given value and return the old value. * * @param newValue the new value. * @return the previous value. */ public int getAndSet(int newValue) { Integer value = operations.getAndSet(key, newValue); return value != null ? value : 0; } /** * Atomically set the value to the given updated value if the current value {@code ==} the expected value. * * @param expect the expected value. * @param update the new value. * @return {@literal true} if successful. {@literal false} indicates that the actual value was not equal to the * expected value. */ public boolean compareAndSet(int expect, int update) { return generalOps.execute(new CompareAndSet<>(this::get, this::set, key, expect, update)); } /** * Atomically increment by one the current value. * * @return the previous value. */ public int getAndIncrement() { return incrementAndGet() - 1; } /** * Atomically decrement by one the current value. * * @return the previous value. */ public int getAndDecrement() { return decrementAndGet() + 1; } /** * Atomically add the given value to current value. * * @param delta the value to add. * @return the previous value. */ public int getAndAdd(int delta) { return addAndGet(delta) - delta; } /** * Atomically update the current value using the given {@link IntUnaryOperator update function}. * * @param updateFunction the function which calculates the value to set. Should be a pure function (no side effects), * because it will be applied several times if update attempts fail due to concurrent calls. Must not be * {@literal null}. * @return the previous value. * @since 2.2 */ public int getAndUpdate(IntUnaryOperator updateFunction) { Assert.notNull(updateFunction, "Update function must not be null!"); int previousValue, newValue; do { previousValue = get(); newValue = updateFunction.applyAsInt(previousValue); } while (!compareAndSet(previousValue, newValue)); return previousValue; } /** * Atomically update the current value using the given {@link IntBinaryOperator accumulator function}. The new value * is calculated by applying the accumulator function to the current value and the given {@code updateValue}. * * @param updateValue the value which will be passed into the accumulator function. * @param accumulatorFunction the function which calculates the value to set. Should be a pure function (no side * effects), because it will be applied several times if update attempts fail due to concurrent calls. Must * not be {@literal null}. * @return the previous value. * @since 2.2 */ public int getAndAccumulate(int updateValue, IntBinaryOperator accumulatorFunction) { Assert.notNull(accumulatorFunction, "Accumulator function must not be null!"); int previousValue, newValue; do { previousValue = get(); newValue = accumulatorFunction.applyAsInt(previousValue, updateValue); } while (!compareAndSet(previousValue, newValue)); return previousValue; } /** * Atomically increment by one the current value. * * @return the updated value. */ public int incrementAndGet() { return operations.increment(key).intValue(); } /** * Atomically decrement by one the current value. * * @return the updated value. */ public int decrementAndGet() { return operations.decrement(key).intValue(); } /** * Atomically add the given value to current value. * * @param delta the value to add. * @return the updated value. */ public int addAndGet(int delta) { return operations.increment(key, delta).intValue(); } /** * Atomically update the current value using the given {@link IntUnaryOperator update function}. * * @param updateFunction the function which calculates the value to set. Should be a pure function (no side effects), * because it will be applied several times if update attempts fail due to concurrent calls. Must not be * {@literal null}. * @return the updated value. * @since 2.2 */ public int updateAndGet(IntUnaryOperator updateFunction) { Assert.notNull(updateFunction, "Update function must not be null!"); int previousValue, newValue; do { previousValue = get(); newValue = updateFunction.applyAsInt(previousValue); } while (!compareAndSet(previousValue, newValue)); return newValue; } /** * Atomically update the current value using the given {@link IntBinaryOperator accumulator function}. The new value * is calculated by applying the accumulator function to the current value and the given {@code updateValue}. * * @param updateValue the value which will be passed into the accumulator function. * @param accumulatorFunction the function which calculates the value to set. Should be a pure function (no side * effects), because it will be applied several times if update attempts fail due to concurrent calls. Must * not be {@literal null}. * @return the updated value. * @since 2.2 */ public int accumulateAndGet(int updateValue, IntBinaryOperator accumulatorFunction) { Assert.notNull(accumulatorFunction, "Accumulator function must not be null!"); int previousValue, newValue; do { previousValue = get(); newValue = accumulatorFunction.applyAsInt(previousValue, updateValue); } while (!compareAndSet(previousValue, newValue)); return newValue; } /** * @return the String representation of the current value. */ @Override public String toString() { return Integer.toString(get()); } /* * (non-Javadoc) * @see org.springframework.data.redis.core.BoundKeyOperations#getKey() */ @Override public String getKey() { return key; } /* * (non-Javadoc) * @see org.springframework.data.redis.core.BoundKeyOperations#getType() */ @Override public DataType getType() { return DataType.STRING; } /* * (non-Javadoc) * @see org.springframework.data.redis.core.BoundKeyOperations#getExpire() */ @Override public Long getExpire() { return generalOps.getExpire(key); } /* * (non-Javadoc) * @see org.springframework.data.redis.core.BoundKeyOperations#expire(long, java.util.concurrent.TimeUnit) */ @Override public Boolean expire(long timeout, TimeUnit unit) { return generalOps.expire(key, timeout, unit); } /* * (non-Javadoc) * @see org.springframework.data.redis.core.BoundKeyOperations#expireAt(java.util.Date) */ @Override public Boolean expireAt(Date date) { return generalOps.expireAt(key, date); } /* * (non-Javadoc) * @see org.springframework.data.redis.core.BoundKeyOperations#persist() */ @Override public Boolean persist() { return generalOps.persist(key); } /* * (non-Javadoc) * @see org.springframework.data.redis.core.BoundKeyOperations#rename(java.lang.Object) */ @Override public void rename(String newKey) { generalOps.rename(key, newKey); key = newKey; } /* * (non-Javadoc) * @see java.lang.Number#intValue() */ @Override public int intValue() { return get(); } /* * (non-Javadoc) * @see java.lang.Number#longValue() */ @Override public long longValue() { return get(); } /* * (non-Javadoc) * @see java.lang.Number#floatValue() */ @Override public float floatValue() { return get(); } /* * (non-Javadoc) * @see java.lang.Number#doubleValue() */ @Override public double doubleValue() { return get(); } }