Cache SqlEngine

cloudata-structured/src/main/java/com/cloudata/structured/sql/SqlEngineFactory.java

@@ -1,26 +1,64 @@
 package com.cloudata.structured.sql;
 
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 
+import javax.annotation.Nonnull;
+import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 import javax.inject.Singleton;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import com.cloudata.structured.StructuredStateMachine;
 import com.cloudata.structured.StructuredStore;
+import com.google.common.base.Throwables;
+import com.google.common.cache.CacheBuilder;
+import com.google.common.cache.CacheLoader;
+import com.google.common.cache.LoadingCache;
 
 @Singleton
 public class SqlEngineFactory {
+    private static final Logger log = LoggerFactory.getLogger(SqlEngineFactory.class);
 
     @Inject
     StructuredStateMachine stateMachine;
 
     final ExecutorService executor = Executors.newCachedThreadPool();
 
-    public SqlEngine get(long storeId) {
-        StructuredStore structuredStore = stateMachine.getStructuredStore(storeId);
+    final LoadingCache<Long, SqlEngine> sqlEngineCache;
 
-        return new SqlEngine(structuredStore, executor);
+    public SqlEngineFactory() {
+        SqlEngineLoader loader = new SqlEngineLoader();
+        this.sqlEngineCache = CacheBuilder.newBuilder().recordStats().build(loader);
     }
 
+    public SqlEngine get(long storeId) {
+        try {
+            return sqlEngineCache.get(storeId);
+        } catch (ExecutionException e) {
+            throw Throwables.propagate(e);
+        }
+    }
+
+    @Immutable
+    final class SqlEngineLoader extends CacheLoader<Long, SqlEngine> {
+
+        @Override
+        public SqlEngine load(@Nonnull Long id) throws Exception {
+            checkNotNull(id);
+            try {
+                StructuredStore structuredStore = stateMachine.getStructuredStore(id);
+
+                return new SqlEngine(structuredStore, executor);
+            } catch (Exception e) {
+                log.warn("Error building SqlEngine", e);
+                throw e;
+            }
+        }
+    }
 }