Add Meta.error

bp-alex · bp-alex · commit 231c25fa29ef · 2016-06-09T15:00:54.000+10:00
diff --git a/src/main/java/org/lmdbjava/Library.java b/src/main/java/org/lmdbjava/Library.java
@@ -85,6 +85,11 @@ public MDB_envinfo(jnr.ffi.Runtime runtime) {
 
   public interface Lmdb {
 
+    /**
+     * Return the error description for this result code.
+     */
+    String mdb_strerror(int rc);
+    
     Pointer mdb_version(IntByReference major, IntByReference minor, IntByReference patch);
 
     /**
diff --git a/src/main/java/org/lmdbjava/Meta.java b/src/main/java/org/lmdbjava/Meta.java
@@ -23,6 +23,22 @@
  */
 public final class Meta {
 
+  /**
+   * Fetches the LMDB error code description.
+   * <p>
+   * End users should not need this method, as LmdbJava converts all LMDB
+   * exceptions into a typed Java exception that incorporates the error code.
+   * However it is provided here for verification and troubleshooting (eg if the
+   * user wishes to see the original LMDB description of the error code, or
+   * there is a newer library version etc).
+   *
+   * @param err the error code returned from LMDB
+   * @return the description
+   */
+  public static String error(final int err) {
+    return lib.mdb_strerror(err);
+  }
+
   /**
    * Obtains the LMDB C library version information.
    *
diff --git a/src/test/java/org/lmdbjava/MetaTest.java b/src/test/java/org/lmdbjava/MetaTest.java
@@ -5,7 +5,9 @@
 import static org.hamcrest.CoreMatchers.nullValue;
 import static org.hamcrest.MatcherAssert.assertThat;
 import org.junit.Test;
+import static org.lmdbjava.LmdbNativeException.PageCorruptedException.MDB_CORRUPTED;
 import org.lmdbjava.Meta.Version;
+import static org.lmdbjava.Meta.error;
 import static org.lmdbjava.TestUtils.invokePrivateConstructor;
 
 public class MetaTest {
@@ -15,11 +17,18 @@ public void coverPrivateConstructors() throws Exception {
     invokePrivateConstructor(Meta.class);
   }
 
+  @Test
+  public void errCode() {
+    assertThat(error(MDB_CORRUPTED), is(
+               "MDB_CORRUPTED: Located page was wrong type"));
+  }
+
   @Test
   public void version() throws Exception {
     final Version v = Meta.version();
     assertThat(v, not(nullValue()));
     assertThat(v.major, is(0));
     assertThat(v.minor, is(9));
   }
+
 }
