Refactor L2 cache tenant awareness - add TenantAwareCache

The design change is to use TenantAwareCache to deal with wrap/unwrap of tenant aware keys, removing any tenant awareness from the underlying cache implementations (DefaultServerCache, redis, hazelcast etc).

ebean-api/src/main/java/io/ebean/cache/ServerCache.java

@@ -104,4 +104,11 @@ public interface ServerCache {
   default void visit(MetricVisitor visitor) {
     // do nothing by default
   }
+
+  /**
+   * Unwrap the underlying ServerCache.
+   */
+  default <T> T unwrap(Class<T> cls) {
+    return (T) this;
+  }
 }

ebean-api/src/main/java/io/ebean/cache/ServerCacheConfig.java

@@ -13,6 +13,7 @@ public class ServerCacheConfig {
   private final ServerCacheOptions cacheOptions;
   private final CurrentTenantProvider tenantProvider;
   private final QueryCacheEntryValidate queryCacheEntryValidate;
+  private final TenantAwareKey tenantAwareKey;
 
   public ServerCacheConfig(ServerCacheType type, String cacheKey, String shortName, ServerCacheOptions cacheOptions, CurrentTenantProvider tenantProvider, QueryCacheEntryValidate queryCacheEntryValidate) {
     this.type = type;
@@ -21,6 +22,14 @@ public class ServerCacheConfig {
     this.cacheOptions = cacheOptions;
     this.tenantProvider = tenantProvider;
     this.queryCacheEntryValidate = queryCacheEntryValidate;
+    this.tenantAwareKey = (tenantProvider == null) ? null : new TenantAwareKey(tenantProvider);
+  }
+
+  /**
+   * Return the ServerCache taking into account if multi-tenant is used.
+   */
+  public ServerCache tenantAware(ServerCache cache) {
+    return tenantAwareKey == null ? cache : new TenantAwareCache(cache, tenantAwareKey);
   }
 
   /**

ebean-api/src/main/java/io/ebean/cache/TenantAwareCache.java

@@ -0,0 +1,104 @@
+package io.ebean.cache;
+
+import io.ebean.meta.MetricVisitor;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+/**
+ * A ServerCache proxy that is tenant aware.
+ */
+public final class TenantAwareCache implements ServerCache {
+
+  private final ServerCache delegate;
+  private final TenantAwareKey tenantAwareKey;
+
+  /**
+   * Create given the TenantAwareKey and delegate cache to proxy to.
+   *
+   * @param delegate       The cache to proxy to
+   * @param tenantAwareKey Provides tenant aware keys to use in the cache
+   */
+  public TenantAwareCache(ServerCache delegate, TenantAwareKey tenantAwareKey) {
+    this.delegate = delegate;
+    this.tenantAwareKey = tenantAwareKey;
+  }
+
+  /**
+   * Return the underlying ServerCache that is being delegated to.
+   */
+  @Override
+  public <T> T unwrap(Class<T> cls) {
+    return (T)delegate;
+  }
+
+  @Override
+  public void visit(MetricVisitor visitor) {
+    delegate.visit(visitor);
+  }
+
+  private Object key(Object key) {
+    return tenantAwareKey.key(key);
+  }
+
+  @Override
+  public Object get(Object id) {
+    return delegate.get(key(id));
+  }
+
+  @Override
+  public void put(Object id, Object value) {
+    delegate.put(key(id), value);
+  }
+
+  @Override
+  public void remove(Object id) {
+    delegate.remove(key(id));
+  }
+
+  @Override
+  public void clear() {
+    delegate.clear();
+  }
+
+  @Override
+  public int size() {
+    return delegate.size();
+  }
+
+  @Override
+  public int getHitRatio() {
+    return delegate.getHitRatio();
+  }
+
+  @Override
+  public ServerCacheStatistics getStatistics(boolean reset) {
+    return delegate.getStatistics(reset);
+  }
+
+  @Override
+  public Map<Object, Object> getAll(Set<Object> keys) {
+    Map<Object, Object> keyMapping = new HashMap<>(keys.size());
+    keys.forEach(k -> keyMapping.put(key(k), k));
+    Map<Object, Object> tmp = delegate.getAll(keyMapping.keySet());
+    Map<Object, Object> ret = new HashMap<>(keys.size());
+    // unwrap tenant info here
+    tmp.forEach((k,v)-> ret.put(((TenantAwareKey.CacheKey) k).key, v));
+    return ret;
+  }
+
+  @Override
+  public void putAll(Map<Object, Object> keyValues) {
+    Map<Object, Object> tmp = new HashMap<>();
+    keyValues.forEach((k, v) -> tmp.put(key(k), v));
+    delegate.putAll(tmp);
+  }
+
+  @Override
+  public void removeAll(Set<Object> keys) {
+    delegate.removeAll(keys.stream().map(this::key).collect(Collectors.toSet()));
+  }
+
+}