lmdbjava · bp-alex · Dec 16, 2018 · Dec 11, 2018 · Dec 11, 2018 · Dec 11, 2018
diff --git a/src/main/java/org/lmdbjava/Env.java b/src/main/java/org/lmdbjava/Env.java
@@ -383,6 +383,15 @@ Pointer pointer() {
    return ptr;
  }

+  /**
+   * Set the size of the data memory map.
+   *
+   * @param mapSize the new size, in bytes
+   */
+  public void setMapSize(final long mapSize) {
+    checkRc(LIB.mdb_env_set_mapsize(ptr, mapSize));
+  }
+
  /**
   * Object has already been closed and the operation is therefore prohibited.
   */

diff --git a/src/test/java/org/lmdbjava/EnvTest.java b/src/test/java/org/lmdbjava/EnvTest.java
@@ -250,6 +250,54 @@ public void mapFull() throws IOException {
    }
  }

+  @Test
+  public void setMapSize() throws IOException {
+    final File path = tmp.newFolder();
+    final byte[] k = new byte[500];
+    final ByteBuffer key = allocateDirect(500);
+    final ByteBuffer val = allocateDirect(1_024);
+    final Random rnd = new Random();
+    try (Env<ByteBuffer> env = create().setMapSize(50_000)
+            .setMaxDbs(1).open(path)) {
+      final Dbi<ByteBuffer> db = env.openDbi(DB_1, MDB_CREATE);
+
+      db.put(bb(1), bb(42));
+      boolean mapFullExThrown = false;
+      try {
+        for (int i = 0; i < 30; i++) {
+          rnd.nextBytes(k);
+          key.clear();
+          key.put(k).flip();
+          val.clear();
+          db.put(key, val);
+        }
+      } catch (final MapFullException mfE) {
+        mapFullExThrown = true;
+      }
+      assertThat(mapFullExThrown, is(true));
+
+      env.setMapSize(500_000);
+
+      try (Txn<ByteBuffer> roTxn = env.txnRead()) {
+        assertThat(db.get(roTxn, bb(1)), is(bb(42)));
+      }
+
+      mapFullExThrown = false;
+      try {
+        for (int i = 0; i < 30; i++) {
+          rnd.nextBytes(k);
+          key.clear();
+          key.put(k).flip();
+          val.clear();
+          db.put(key, val);
+        }
+      } catch (final MapFullException mfE) {
+        mapFullExThrown = true;
+      }
+      assertThat(mapFullExThrown, is(false));
+    }
+  }
+
  @Test
  public void readOnlySupported() throws IOException {
    final File path = tmp.newFolder();