1 files changed, 187 insertions, 0 deletions
diff --git a/upstream/odl-aaa-moon/aaa/aaa-h2-store/src/main/java/org/opendaylight/aaa/h2/persistence/AbstractStore.java b/upstream/odl-aaa-moon/aaa/aaa-h2-store/src/main/java/org/opendaylight/aaa/h2/persistence/AbstractStore.java
new file mode 100644
index 00000000..ba00eb84
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+++ b/upstream/odl-aaa-moon/aaa/aaa-h2-store/src/main/java/org/opendaylight/aaa/h2/persistence/AbstractStore.java
@@ -0,0 +1,187 @@
+/*
+ * Copyright © 2016 Red Hat, Inc. and others.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.opendaylight.aaa.h2.persistence;
+
+import java.sql.Connection;
+import java.sql.DatabaseMetaData;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Base class for H2 stores.
+ */
+abstract class AbstractStore<T> {
+    /**
+     * Logger.
+     */
+    private static final Logger LOG = LoggerFactory.getLogger(AbstractStore.class);
+
+    /**
+     * The name of the table used to represent this store.
+     */
+    private final String tableName;
+
+    /**
+     * Database connection, only used for tests.
+     */
+    Connection dbConnection = null;
+
+    /**
+     * Table types we're interested in (when checking tables' existence).
+     */
+    public static final String[] TABLE_TYPES = new String[] { "TABLE" };
+
+    /**
+     * Creates an instance.
+     *
+     * @param tableName The name of the table being managed.
+     */
+    protected AbstractStore(String tableName) {
+        this.tableName = tableName;
+    }
+
+    /**
+     * Returns a database connection. It is the caller's responsibility to close it. If the managed table does not
+     * exist, it will be created (using {@link #getTableCreationStatement()}).
+     *
+     * @return A database connection.
+     *
+     * @throws StoreException if an error occurs.
+     */
+    protected Connection dbConnect() throws StoreException {
+        Connection conn = H2Store.getConnection(dbConnection);
+        try {
+            // Ensure table check/creation is atomic
+            synchronized (this) {
+                DatabaseMetaData dbm = conn.getMetaData();
+                try (ResultSet rs = dbm.getTables(null, null, tableName, TABLE_TYPES)) {
+                    if (rs.next()) {
+                        LOG.debug("Table {} already exists", tableName);
+                    } else {
+                        LOG.info("Table {} does not exist, creating it", tableName);
+                        try (Statement stmt = conn.createStatement()) {
+                            stmt.executeUpdate(getTableCreationStatement());
+                        }
+                    }
+                }
+            }
+        } catch (SQLException e) {
+            LOG.error("Error connecting to the H2 database", e);
+            throw new StoreException("Cannot connect to database server", e);
+        }
+        return conn;
+    }
+
+    /**
+     * Empties the store.
+     *
+     * @throws StoreException if a connection error occurs.
+     */
+    protected void dbClean() throws StoreException {
+        try (Connection c = dbConnect()) {
+            // The table name can't be a parameter in a prepared statement
+            String sql = "DELETE FROM " + tableName;
+            c.createStatement().execute(sql);
+        } catch (SQLException e) {
+            LOG.error("Error clearing table {}", tableName, e);
+            throw new StoreException("Error clearing table " + tableName, e);
+        }
+    }
+
+    /**
+     * Returns the SQL code required to create the managed table.
+     *
+     * @return The SQL table creation statement.
+     */
+    protected abstract String getTableCreationStatement();
+
+    /**
+     * Lists all the stored items.
+     *
+     * @return The stored item.
+     *
+     * @throws StoreException if an error occurs.
+     */
+    protected List<T> listAll() throws StoreException {
+        List<T> result = new ArrayList<>();
+        String query = "SELECT * FROM " + tableName;
+        try (Connection conn = dbConnect();
+             Statement stmt = conn.createStatement();
+             ResultSet rs = stmt.executeQuery(query)) {
+            while (rs.next()) {
+                result.add(fromResultSet(rs));
+            }
+        } catch (SQLException e) {
+            LOG.error("Error listing all items from {}", tableName, e);
+            throw new StoreException(e);
+        }
+        return result;
+    }
+
+    /**
+     * Lists the stored items returned by the given statement.
+     *
+     * @param ps The statement (which must be ready for execution). It is the caller's reponsibility to close this.
+     *
+     * @return The stored items.
+     *
+     * @throws StoreException if an error occurs.
+     */
+    protected List<T> listFromStatement(PreparedStatement ps) throws StoreException {
+        List<T> result = new ArrayList<>();
+        try (ResultSet rs = ps.executeQuery()) {
+            while (rs.next()) {
+                result.add(fromResultSet(rs));
+            }
+        } catch (SQLException e) {
+            LOG.error("Error listing matching items from {}", tableName, e);
+            throw new StoreException(e);
+        }
+        return result;
+    }
+
+    /**
+     * Extracts the first item returned by the given statement, if any.
+     *
+     * @param ps The statement (which must be ready for execution). It is the caller's reponsibility to close this.
+     *
+     * @return The first item, or {@code null} if none.
+     *
+     * @throws StoreException if an error occurs.
+     */
+    protected T firstFromStatement(PreparedStatement ps) throws StoreException {
+        try (ResultSet rs = ps.executeQuery()) {
+            if (rs.next()) {
+                return fromResultSet(rs);
+            } else {
+                return null;
+            }
+        } catch (SQLException e) {
+            LOG.error("Error listing first matching item from {}", tableName, e);
+            throw new StoreException(e);
+        }
+    }
+
+    /**
+     * Converts a single row in a result set to an instance of the managed type.
+     *
+     * @param rs The result set (which is ready for extraction; {@link ResultSet#next()} must <b>not</b> be called).
+     *
+     * @return The corresponding instance.
+     *
+     * @throws SQLException if an error occurs.
+     */
+    protected abstract T fromResultSet(ResultSet rs) throws SQLException;
+}