Merge pull request #1160 from katzyn/ResultTempTable

Close lost instances of ResultTempTable on garbage collection

h2/src/main/org/h2/result/ResultTempTable.java

@@ -5,6 +5,7 @@
  */
 package org.h2.result;
 
+import java.lang.ref.Reference;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.BitSet;
@@ -21,6 +22,7 @@ import org.h2.schema.Schema;
 import org.h2.table.Column;
 import org.h2.table.IndexColumn;
 import org.h2.table.Table;
+import org.h2.util.TempFileDeleter;
 import org.h2.value.Value;
 import org.h2.value.ValueNull;
 
@@ -29,6 +31,53 @@ import org.h2.value.ValueNull;
  */
 public class ResultTempTable implements ResultExternal {
 
+    private static final class CloseImpl implements AutoCloseable {
+        private final Session session;
+        private final Table table;
+        Index index;
+
+        CloseImpl(Session session, Table table) {
+            this.session = session;
+            this.table = table;
+        }
+
+        @Override
+        public void close() throws Exception {
+            Database database = session.getDatabase();
+            // Need to lock because not all of the code-paths
+            // that reach here have already taken this lock,
+            // notably via the close() paths.
+            synchronized (session) {
+                synchronized (database) {
+                    table.truncate(session);
+                }
+            }
+            // This session may not lock the sys table (except if it already has
+            // locked it) because it must be committed immediately, otherwise
+            // other threads can not access the sys table. If the table is not
+            // removed now, it will be when the database is opened the next
+            // time. (the table is truncated, so this is just one record)
+            if (!database.isSysTableLocked()) {
+                Session sysSession = database.getSystemSession();
+                table.removeChildrenAndResources(sysSession);
+                if (index != null) {
+                    // need to explicitly do this,
+                    // as it's not registered in the system session
+                    session.removeLocalTempTableIndex(index);
+                }
+                // the transaction must be committed immediately
+                // TODO this synchronization cascade is very ugly
+                synchronized (session) {
+                    synchronized (sysSession) {
+                        synchronized (database) {
+                            sysSession.commit(false);
+                        }
+                    }
+                }
+            }
+        }
+    }
+
     private static final String COLUMN_NAME = "DATA";
     private final boolean distinct;
     private final SortOrder sort;
@@ -42,7 +91,21 @@ public class ResultTempTable implements ResultExternal {
     private final ResultTempTable parent;
     private boolean closed;
     private int childCount;
-    private final boolean containsLob;
+
+    /**
+     * Temporary file deleter.
+     */
+    private final TempFileDeleter tempFileDeleter;
+
+    /**
+     * Closeable to close the storage.
+     */
+    private final CloseImpl closeable;
+
+    /**
+     * Reference to the record in the temporary file deleter.
+     */
+    private final Reference<?> fileRef;
 
     ResultTempTable(Session session, Expression[] expressions, boolean distinct, SortOrder sort) {
         this.session = session;
@@ -51,17 +114,15 @@ public class ResultTempTable implements ResultExternal {
         this.columnCount = expressions.length;
         Schema schema = session.getDatabase().getSchema(Constants.SCHEMA_MAIN);
         CreateTableData data = new CreateTableData();
-        boolean b = false;
+        boolean containsLob = false;
         for (int i = 0; i < expressions.length; i++) {
             int type = expressions[i].getType();
-            Column col = new Column(COLUMN_NAME + i,
-                    type);
+            Column col = new Column(COLUMN_NAME + i, type);
             if (type == Value.CLOB || type == Value.BLOB) {
-                b = true;
+                containsLob = true;
             }
             data.columns.add(col);
         }
-        containsLob = b;
         data.id = session.getDatabase().allocateObjectId();
         data.tableName = "TEMP_RESULT_SET_" + data.id;
         data.temporary = true;
@@ -70,10 +131,26 @@ public class ResultTempTable implements ResultExternal {
         data.create = true;
         data.session = session;
         table = schema.createTable(data);
+        parent = null;
+        if (containsLob) {
+            // contains BLOB or CLOB: cannot truncate on close,
+            // otherwise the BLOB and CLOB entries are removed
+            tempFileDeleter = null;
+            closeable = null;
+            fileRef = null;
+        } else {
+            tempFileDeleter = session.getDatabase().getTempFileDeleter();
+            closeable = new CloseImpl(session, table);
+            fileRef = tempFileDeleter.addFile(closeable, this);
+        }
+        /*
+         * If ORDER BY or DISTINCT is specified create the index immediately. If
+         * they are not specified index still may be created later if required
+         * for IN (SELECT ...) etc.
+         */
         if (sort != null || distinct) {
             getIndex();
         }
-        parent = null;
     }
 
     private ResultTempTable(ResultTempTable parent) {
@@ -84,8 +161,9 @@ public class ResultTempTable implements ResultExternal {
         this.table = parent.table;
         this.rowCount = parent.rowCount;
         this.sort = parent.sort;
-        this.containsLob = parent.containsLob;
-        reset();
+        this.tempFileDeleter = null;
+        this.closeable = null;
+        this.fileRef = null;
     }
 
     private Index getIndex() {
@@ -129,12 +207,14 @@ public class ResultTempTable implements ResultExternal {
                 indexCols[i] = createIndexColumn(i);
             }
         }
-        String indexName = table.getSchema().getUniqueIndexName(session,
-                table, Constants.PREFIX_INDEX);
+        String indexName = table.getSchema().getUniqueIndexName(session, table, Constants.PREFIX_INDEX);
         int indexId = session.getDatabase().allocateObjectId();
         IndexType indexType = IndexType.createNonUnique(true);
-        return index = table.addIndex(session, indexName, indexId, indexCols,
-                indexType, true, null);
+        index = table.addIndex(session, indexName, indexId, indexCols, indexType, true, null);
+        if (closeable != null) {
+            closeable.index = index;
+        }
+        return index;
     }
 
     private IndexColumn createIndexColumn(int index) {
@@ -203,7 +283,7 @@ public class ResultTempTable implements ResultExternal {
 
     private synchronized void closeChild() {
         if (--childCount == 0 && closed) {
-            dropTable();
+            delete();
         }
     }
 
@@ -217,55 +297,14 @@ public class ResultTempTable implements ResultExternal {
             parent.closeChild();
         } else {
             if (childCount == 0) {
-                dropTable();
+                delete();
             }
         }
     }
 
-    private void dropTable() {
-        if (table == null) {
-            return;
-        }
-        if (containsLob) {
-            // contains BLOB or CLOB: can not truncate now,
-            // otherwise the BLOB and CLOB entries are removed
-            return;
-        }
-        try {
-            Database database = session.getDatabase();
-            // Need to lock because not all of the code-paths
-            // that reach here have already taken this lock,
-            // notably via the close() paths.
-            synchronized (session) {
-                synchronized (database) {
-                    table.truncate(session);
-                }
-            }
-            // This session may not lock the sys table (except if it already has
-            // locked it) because it must be committed immediately, otherwise
-            // other threads can not access the sys table. If the table is not
-            // removed now, it will be when the database is opened the next
-            // time. (the table is truncated, so this is just one record)
-            if (!database.isSysTableLocked()) {
-                Session sysSession = database.getSystemSession();
-                table.removeChildrenAndResources(sysSession);
-                if (index != null) {
-                    // need to explicitly do this,
-                    // as it's not registered in the system session
-                    session.removeLocalTempTableIndex(index);
-                }
-                // the transaction must be committed immediately
-                // TODO this synchronization cascade is very ugly
-                synchronized (session) {
-                    synchronized (sysSession) {
-                        synchronized (database) {
-                            sysSession.commit(false);
-                        }
-                    }
-                }
-            }
-        } finally {
-            table = null;
+    private void delete() {
+        if (tempFileDeleter != null) {
+            tempFileDeleter.deleteFile(fileRef, closeable);
         }
     }
 
@@ -329,4 +368,3 @@ public class ResultTempTable implements ResultExternal {
     }
 
 }
-