[inmemory] Initial contribution (openhab#15063)

This is the initial contribution of a new volatile persistence service. It does store values in memory only and can especially be used for forecasts or other data where volatile storage is sufficient.

Signed-off-by: Jan N. Klug <[email protected]>
Signed-off-by: Matt Myers <[email protected]>

bom/openhab-addons/pom.xml

@@ -1961,6 +1961,11 @@
       <artifactId>org.openhab.persistence.influxdb</artifactId>
       <version>${project.version}</version>
     </dependency>
+    <dependency>
+      <groupId>org.openhab.addons.bundles</groupId>
+      <artifactId>org.openhab.persistence.inmemory</artifactId>
+      <version>${project.version}</version>
+    </dependency>
     <dependency>
       <groupId>org.openhab.addons.bundles</groupId>
       <artifactId>org.openhab.persistence.jdbc</artifactId>

bundles/org.openhab.persistence.inmemory/NOTICE

@@ -0,0 +1,13 @@
+This content is produced and maintained by the openHAB project.
+
+* Project home: https://www.openhab.org
+
+== Declared Project Licenses
+
+This program and the accompanying materials are made available under the terms
+of the Eclipse Public License 2.0 which is available at
+https://www.eclipse.org/legal/epl-2.0/.
+
+== Source Code
+
+https://github.com/openhab/openhab-addons

bundles/org.openhab.persistence.inmemory/README.md

@@ -0,0 +1,14 @@
+# InMemory Persistence
+
+The InMemory persistence service provides a volatile storage, i.e. it is cleared on shutdown.
+Because of that the `restoreOnStartup` strategy is not supported for this service.
+
+The main use-case is to store data that is needed during runtime, e.g. temporary storage of forecast data that is retrieved from a binding.
+
+Since all data is stored in memory only, there is no default strategy for this service.
+Unlike other persistence services, you MUST add a configuration, otherwise no data will be persisted.
+To avoid excessive memory usage, it is recommended to persist only a limited number of items and use a strategy that stores only data that is actually needed.
+
+The service has a global configuration option `maxEntries` to limit the number of datapoints per item, the default value is `512`.
+When the number of datapoints is reached and a new value is persisted, the oldest (by timestamp) value will be removed.
+A `maxEntries` value of `0` disables automatic purging.

bundles/org.openhab.persistence.inmemory/pom.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+
+  <modelVersion>4.0.0</modelVersion>
+
+  <parent>
+    <groupId>org.openhab.addons.bundles</groupId>
+    <artifactId>org.openhab.addons.reactor.bundles</artifactId>
+    <version>4.0.0-SNAPSHOT</version>
+  </parent>
+
+  <artifactId>org.openhab.persistence.inmemory</artifactId>
+
+  <name>openHAB Add-ons :: Bundles :: Persistence Service :: InMemory</name>
+
+</project>

bundles/org.openhab.persistence.inmemory/src/main/feature/feature.xml

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<features name="org.openhab.persistence.inmemory-${project.version}" xmlns="http://karaf.apache.org/xmlns/features/v1.4.0">
+	<repository>mvn:org.openhab.core.features.karaf/org.openhab.core.features.karaf.openhab-core/${ohc.version}/xml/features</repository>
+
+	<feature name="openhab-persistence-inmemory" description="InMemory Persistence" version="${project.version}">
+		<feature>openhab-runtime-base</feature>
+		<bundle start-level="80">mvn:org.openhab.addons.bundles/org.openhab.persistence.inmemory/${project.version}</bundle>
+	</feature>
+
+</features>

bundles/org.openhab.persistence.inmemory/src/main/java/org/openhab/persistence/inmemory/internal/InMemoryPersistenceService.java

@@ -0,0 +1,311 @@
+/**
+ * Copyright (c) 2010-2023 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.persistence.inmemory.internal;
+
+import java.time.Instant;
+import java.time.ZonedDateTime;
+import java.util.Comparator;
+import java.util.Date;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+import java.util.TreeSet;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.stream.Collectors;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.core.config.core.ConfigParser;
+import org.openhab.core.config.core.ConfigurableService;
+import org.openhab.core.items.Item;
+import org.openhab.core.persistence.FilterCriteria;
+import org.openhab.core.persistence.HistoricItem;
+import org.openhab.core.persistence.ModifiablePersistenceService;
+import org.openhab.core.persistence.PersistenceItemInfo;
+import org.openhab.core.persistence.PersistenceService;
+import org.openhab.core.persistence.strategy.PersistenceStrategy;
+import org.openhab.core.types.State;
+import org.openhab.core.types.UnDefType;
+import org.osgi.framework.Constants;
+import org.osgi.service.component.annotations.Activate;
+import org.osgi.service.component.annotations.Component;
+import org.osgi.service.component.annotations.Deactivate;
+import org.osgi.service.component.annotations.Modified;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * This is the implementation of the volatile {@link PersistenceService}.
+ *
+ * @author Jan N. Klug - Initial contribution
+ */
+@NonNullByDefault
+@Component(service = { PersistenceService.class,
+        ModifiablePersistenceService.class }, configurationPid = "org.openhab.inmemory", //
+        property = Constants.SERVICE_PID + "=org.openhab.inmemory")
+@ConfigurableService(category = "persistence", label = "InMemory Persistence Service", description_uri = InMemoryPersistenceService.CONFIG_URI)
+public class InMemoryPersistenceService implements ModifiablePersistenceService {
+
+    private static final String SERVICE_ID = "inmemory";
+    private static final String SERVICE_LABEL = "In Memory";
+
+    protected static final String CONFIG_URI = "persistence:inmemory";
+    private final String MAX_ENTRIES_CONFIG = "maxEntries";
+    private final long MAX_ENTRIES_DEFAULT = 512;
+
+    private final Logger logger = LoggerFactory.getLogger(InMemoryPersistenceService.class);
+
+    private final Map<String, PersistItem> persistMap = new ConcurrentHashMap<>();
+    private long maxEntries = MAX_ENTRIES_DEFAULT;
+
+    @Activate
+    public void activate(Map<String, Object> config) {
+        modified(config);
+        logger.debug("InMemory persistence service is now activated.");
+    }
+
+    @Modified
+    public void modified(Map<String, Object> config) {
+        maxEntries = ConfigParser.valueAsOrElse(config.get(MAX_ENTRIES_CONFIG), Long.class, MAX_ENTRIES_DEFAULT);
+
+        persistMap.values().forEach(persistItem -> {
+            Lock lock = persistItem.lock();
+            lock.lock();
+            try {
+                while (persistItem.database().size() > maxEntries) {
+                    persistItem.database().pollFirst();
+                }
+            } finally {
+                lock.unlock();
+            }
+        });
+    }
+
+    @Deactivate
+    public void deactivate() {
+        logger.debug("InMemory persistence service deactivated.");
+    }
+
+    @Override
+    public String getId() {
+        return SERVICE_ID;
+    }
+
+    @Override
+    public String getLabel(@Nullable Locale locale) {
+        return SERVICE_LABEL;
+    }
+
+    @Override
+    public Set<PersistenceItemInfo> getItemInfo() {
+        return persistMap.entrySet().stream().map(this::toItemInfo).collect(Collectors.toSet());
+    }
+
+    @Override
+    public void store(Item item) {
+        internalStore(item.getName(), ZonedDateTime.now(), item.getState());
+    }
+
+    @Override
+    public void store(Item item, @Nullable String alias) {
+        String finalName = Objects.requireNonNullElse(alias, item.getName());
+        internalStore(finalName, ZonedDateTime.now(), item.getState());
+    }
+
+    @Override
+    public void store(Item item, ZonedDateTime date, State state) {
+        internalStore(item.getName(), date, state);
+    }
+
+    @Override
+    public boolean remove(FilterCriteria filter) throws IllegalArgumentException {
+        String itemName = filter.getItemName();
+        if (itemName == null) {
+            return false;
+        }
+
+        PersistItem persistItem = persistMap.get(itemName);
+        if (persistItem == null) {
+            return false;
+        }
+
+        Lock lock = persistItem.lock();
+        lock.lock();
+        try {
+            List<PersistEntry> toRemove = persistItem.database().stream().filter(e -> applies(e, filter)).toList();
+            toRemove.forEach(persistItem.database()::remove);
+        } finally {
+            lock.unlock();
+        }
+        return true;
+    }
+
+    @Override
+    public Iterable<HistoricItem> query(FilterCriteria filter) {
+        String itemName = filter.getItemName();
+        if (itemName == null) {
+            return List.of();
+        }
+
+        PersistItem persistItem = persistMap.get(itemName);
+        if (persistItem == null) {
+            return List.of();
+        }
+
+        Lock lock = persistItem.lock();
+        lock.lock();
+        try {
+            return persistItem.database().stream().filter(e -> applies(e, filter)).map(e -> toHistoricItem(itemName, e))
+                    .toList();
+        } finally {
+            lock.unlock();
+        }
+    }
+
+    @Override
+    public List<PersistenceStrategy> getDefaultStrategies() {
+        // persist nothing by default
+        return List.of();
+    }
+
+    private PersistenceItemInfo toItemInfo(Map.Entry<String, PersistItem> itemEntry) {
+        Lock lock = itemEntry.getValue().lock();
+        lock.lock();
+        try {
+            String name = itemEntry.getKey();
+            Integer count = itemEntry.getValue().database().size();
+            Instant earliest = itemEntry.getValue().database().first().timestamp().toInstant();
+            Instant latest = itemEntry.getValue().database.last().timestamp.toInstant();
+            return new PersistenceItemInfo() {
+
+                @Override
+                public String getName() {
+                    return name;
+                }
+
+                @Override
+                public @Nullable Integer getCount() {
+                    return count;
+                }
+
+                @Override
+                public @Nullable Date getEarliest() {
+                    return Date.from(earliest);
+                }
+
+                @Override
+                public @Nullable Date getLatest() {
+                    return Date.from(latest);
+                }
+            };
+        } finally {
+            lock.unlock();
+        }
+    }
+
+    private HistoricItem toHistoricItem(String itemName, PersistEntry entry) {
+        return new HistoricItem() {
+            @Override
+            public ZonedDateTime getTimestamp() {
+                return entry.timestamp();
+            }
+
+            @Override
+            public State getState() {
+                return entry.state();
+            }
+
+            @Override
+            public String getName() {
+                return itemName;
+            }
+        };
+    }
+
+    private void internalStore(String itemName, ZonedDateTime timestamp, State state) {
+        if (state instanceof UnDefType) {
+            return;
+        }
+
+        PersistItem persistItem = Objects.requireNonNull(persistMap.computeIfAbsent(itemName,
+                k -> new PersistItem(new TreeSet<>(Comparator.comparing(PersistEntry::timestamp)),
+                        new ReentrantLock())));
+
+        Lock lock = persistItem.lock();
+        lock.lock();
+        try {
+            persistItem.database().add(new PersistEntry(timestamp, state));
+
+            while (persistItem.database.size() > maxEntries) {
+                persistItem.database().pollFirst();
+            }
+        } finally {
+            lock.unlock();
+        }
+    }
+
+    @SuppressWarnings({ "rawType", "unchecked" })
+    private boolean applies(PersistEntry entry, FilterCriteria filter) {
+        ZonedDateTime beginDate = filter.getBeginDate();
+        if (beginDate != null && entry.timestamp().isBefore(beginDate)) {
+            return false;
+        }
+        ZonedDateTime endDate = filter.getEndDate();
+        if (endDate != null && entry.timestamp().isAfter(endDate)) {
+            return false;
+        }
+
+        State refState = filter.getState();
+        FilterCriteria.Operator operator = filter.getOperator();
+        if (refState == null) {
+            // no state filter
+            return true;
+        }
+
+        if (operator == FilterCriteria.Operator.EQ) {
+            return entry.state().equals(refState);
+        }
+
+        if (operator == FilterCriteria.Operator.NEQ) {
+            return !entry.state().equals(refState);
+        }
+
+        if (entry.state() instanceof Comparable comparableState && entry.state.getClass().equals(refState.getClass())) {
+            if (operator == FilterCriteria.Operator.GT) {
+                return comparableState.compareTo(refState) > 0;
+            }
+            if (operator == FilterCriteria.Operator.GTE) {
+                return comparableState.compareTo(refState) >= 0;
+            }
+            if (operator == FilterCriteria.Operator.LT) {
+                return comparableState.compareTo(refState) < 0;
+            }
+            if (operator == FilterCriteria.Operator.LTE) {
+                return comparableState.compareTo(refState) <= 0;
+            }
+        } else {
+            logger.warn("Using operator {} but state {} is not comparable!", operator, refState);
+        }
+        return true;
+    }
+
+    private record PersistEntry(ZonedDateTime timestamp, State state) {
+    };
+
+    private record PersistItem(TreeSet<PersistEntry> database, Lock lock) {
+    };
+}