Added delete flag to Dbi.drop which will enable deleteing a database. (#67)

weidaru · bp-alex · commit 388e15a6fec7 · 2017-08-24T14:25:23.000+10:00
diff --git a/src/main/java/org/lmdbjava/Dbi.java b/src/main/java/org/lmdbjava/Dbi.java
@@ -62,6 +62,8 @@ public final class Dbi<T> {
   private final BufferProxy<T> proxy;
   private final Pointer ptr;
 
+  private boolean isClean;
+
   Dbi(final Env<T> env, final Txn<T> txn, final byte[] name,
       final Comparator<T> comparator, final DbiFlags... flags) {
     this.env = env;
@@ -101,11 +103,19 @@ public final class Dbi<T> {
    * state accordingly.
    */
   public void close() {
+    clean();
+    LIB.mdb_dbi_close(env.pointer(), ptr);
+  }
+
+  private void clean() {
+    if (isClean) {
+      return;
+    }
+    isClean = true;
     if (compKeyA != null) {
       proxy.deallocate(compKeyA);
       proxy.deallocate(compKeyB);
     }
-    LIB.mdb_dbi_close(env.pointer(), ptr);
   }
 
   /**
@@ -186,12 +196,28 @@ public boolean delete(final Txn<T> txn, final T key, final T val) {
    * @param txn transaction handle (not null; not committed; must be R-W)
    */
   public void drop(final Txn<T> txn) {
+    drop(txn, false);
+  }
+
+  /**
+   * Drops the database. If delete is set to true, the database will be deleted
+   * and handle will be closed. See {@link #close()} for implication of handle close.
+   * Otherwise, only the data in this database will be dropped.
+   *
+   * @param txn transaction handle (not null; not committed; must be R-W)
+   * @param delete whether database should be deleted.
+   */
+  public void drop(final Txn<T> txn, final boolean delete) {
     if (SHOULD_CHECK) {
       requireNonNull(txn);
       txn.checkReady();
       txn.checkWritesAllowed();
     }
-    checkRc(LIB.mdb_drop(txn.pointer(), ptr, 0));
+    if (delete) {
+      clean();
+    }
+    final int del = delete ? 1 : 0;
+    checkRc(LIB.mdb_drop(txn.pointer(), ptr, del));
   }
 
   /**
diff --git a/src/test/java/org/lmdbjava/DbiTest.java b/src/test/java/org/lmdbjava/DbiTest.java
@@ -29,6 +29,7 @@
 import static java.nio.ByteBuffer.allocateDirect;
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static java.util.Collections.nCopies;
+
 import java.util.Comparator;
 import java.util.List;
 import java.util.Random;
@@ -145,6 +146,38 @@ public void drop() {
     }
   }
 
+  @Test
+  public void dropAndDelete() {
+    final Dbi<ByteBuffer> db = env.openDbi(DB_1, MDB_CREATE);
+    final Dbi<ByteBuffer> nameDb = env.openDbi((byte[]) null);
+    final byte[] dbNameBytes = DB_1.getBytes(UTF_8);
+    final ByteBuffer dbNameBuffer = allocateDirect(dbNameBytes.length);
+    dbNameBuffer.put(dbNameBytes).flip();
+
+    try (Txn<ByteBuffer> txn = env.txnWrite()) {
+      assertThat(nameDb.get(txn, dbNameBuffer), not(nullValue()));
+      db.drop(txn, true);
+      assertThat(nameDb.get(txn, dbNameBuffer), is(nullValue()));
+      txn.commit();
+    }
+  }
+
+  @Test
+  public void dropAndDeleteAnonymousDb() {
+    env.openDbi(DB_1, MDB_CREATE);
+    final Dbi<ByteBuffer> nameDb = env.openDbi((byte[]) null);
+    final byte[] dbNameBytes = DB_1.getBytes(UTF_8);
+    final ByteBuffer dbNameBuffer = allocateDirect(dbNameBytes.length);
+    dbNameBuffer.put(dbNameBytes).flip();
+
+    try (Txn<ByteBuffer> txn = env.txnWrite()) {
+      assertThat(nameDb.get(txn, dbNameBuffer), not(nullValue()));
+      nameDb.drop(txn, true);
+      assertThat(nameDb.get(txn, dbNameBuffer), is(nullValue()));
+      txn.commit();
+    }
+  }
+
   @Test
   public void getName() {
     final Dbi<ByteBuffer> db = env.openDbi(DB_1, MDB_CREATE);
