Merge pull request #397 from fyrz/RocksJava-GetIntProperty

[RocksJava] GetIntProperty in RocksDB

java/org/rocksdb/RocksDB.java

@@ -1032,6 +1032,62 @@ public class RocksDB extends RocksObject {
     return getProperty0(nativeHandle_, property, property.length());
   }
 
+  /**
+   * <p> Similar to GetProperty(), but only works for a subset of properties whose
+   * return value is a numerical value. Return the value as long.</p>
+   *
+   * <p><strong>Note</strong>: As the returned property is of type
+   * {@code uint64_t} on C++ side the returning value can be negative
+   * because Java supports in Java 7 only signed long values.</p>
+   *
+   * <p><strong>Java 7</strong>: To mitigate the problem of the non
+   * existent unsigned long tpye, values should be encapsulated using
+   * {@link java.math.BigInteger} to reflect the correct value. The correct
+   * behavior is guaranteed if {@code 2^64} is added to negative values.</p>
+   *
+   * <p><strong>Java 8</strong>: In Java 8 the value should be treated as
+   * unsigned long using provided methods of type {@link Long}.</p>
+   *
+   * @param property to be fetched.
+   *
+   * @return numerical property value.
+   *
+   * @throws RocksDBException if an error happens in the underlying native code.
+   */
+  public long getLongProperty(String property) throws RocksDBException {
+    return getLongProperty(nativeHandle_, property, property.length());
+  }
+
+  /**
+   * <p> Similar to GetProperty(), but only works for a subset of properties whose
+   * return value is a numerical value. Return the value as long.</p>
+   *
+   * <p><strong>Note</strong>: As the returned property is of type
+   * {@code uint64_t} on C++ side the returning value can be negative
+   * because Java supports in Java 7 only signed long values.</p>
+   *
+   * <p><strong>Java 7</strong>: To mitigate the problem of the non
+   * existent unsigned long tpye, values should be encapsulated using
+   * {@link java.math.BigInteger} to reflect the correct value. The correct
+   * behavior is guaranteed if {@code 2^64} is added to negative values.</p>
+   *
+   * <p><strong>Java 8</strong>: In Java 8 the value should be treated as
+   * unsigned long using provided methods of type {@link Long}.</p>
+   *
+   * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
+   *     instance
+   * @param property to be fetched.
+   *
+   * @return numerical property value
+   *
+   * @throws RocksDBException if an error happens in the underlying native code.
+   */
+  public long getLongProperty(ColumnFamilyHandle columnFamilyHandle, String property)
+      throws RocksDBException {
+    return getLongProperty(nativeHandle_, columnFamilyHandle.nativeHandle_, property,
+        property.length());
+  }
+
   /**
    * Return a heap-allocated iterator over the contents of the database.
    * The result of newIterator() is initially invalid (caller must
@@ -1297,6 +1353,10 @@ public class RocksDB extends RocksObject {
       String property, int propertyLength) throws RocksDBException;
   protected native String getProperty0(long nativeHandle, long cfHandle,
       String property, int propertyLength) throws RocksDBException;
+  protected native long getLongProperty(long nativeHandle,
+      String property, int propertyLength) throws RocksDBException;
+  protected native long getLongProperty(long nativeHandle, long cfHandle,
+      String property, int propertyLength) throws RocksDBException;
   protected native long iterator0(long handle);
   protected native long iterator0(long handle, long cfHandle);
   protected native long[] iterators(long handle,

java/org/rocksdb/test/ColumnFamilyTest.java

@@ -351,7 +351,6 @@ public class ColumnFamilyTest {
     }
   }
 
-
   @Test
   public void properties() throws RocksDBException {
     RocksDB db = null;
@@ -371,6 +370,8 @@ public class ColumnFamilyTest {
           cfNames, columnFamilyHandleList);
       assertThat(db.getProperty("rocksdb.estimate-num-keys")).
           isNotNull();
+      assertThat(db.getLongProperty(columnFamilyHandleList.get(0),
+          "rocksdb.estimate-num-keys")).isGreaterThanOrEqualTo(0);
       assertThat(db.getProperty("rocksdb.stats")).isNotNull();
       assertThat(db.getProperty(columnFamilyHandleList.get(0),
           "rocksdb.sstables")).isNotNull();

java/org/rocksdb/test/RocksDBTest.java

@@ -279,4 +279,37 @@ public class RocksDBTest {
       }
     }
   }
+
+  @Test
+  public void getIntProperty() throws RocksDBException {
+    RocksDB db = null;
+    Options options = null;
+    WriteOptions wOpt = null;
+    try {
+      options = new Options();
+      wOpt = new WriteOptions();
+      // Setup options
+      options.setCreateIfMissing(true);
+      options.setMaxWriteBufferNumber(10);
+      options.setMinWriteBufferNumberToMerge(10);
+      wOpt.setDisableWAL(true);
+      db = RocksDB.open(options, dbFolder.getRoot().getAbsolutePath());
+      db.put(wOpt, "key1".getBytes(), "value1".getBytes());
+      db.put(wOpt, "key2".getBytes(), "value2".getBytes());
+      db.put(wOpt, "key3".getBytes(), "value3".getBytes());
+      db.put(wOpt, "key4".getBytes(), "value4".getBytes());
+      assertThat(db.getLongProperty("rocksdb.num-entries-active-mem-table")).isGreaterThan(0);
+      assertThat(db.getLongProperty("rocksdb.cur-size-active-mem-table")).isGreaterThan(0);
+    } finally {
+      if (db != null) {
+        db.close();
+      }
+      if (options != null) {
+        options.dispose();
+      }
+      if (wOpt != null) {
+        wOpt.dispose();
+      }
+    }
+  }
 }

java/rocksjni/rocksjni.cc

@@ -1289,6 +1289,53 @@ jstring Java_org_rocksdb_RocksDB_getProperty0__JJLjava_lang_String_2I(
   return env->NewStringUTF(property_value.data());
 }
 
+/*
+ * Class:     org_rocksdb_RocksDB
+ * Method:    getLongProperty
+ * Signature: (JLjava/lang/String;I)L;
+ */
+jlong Java_org_rocksdb_RocksDB_getLongProperty__JLjava_lang_String_2I(
+    JNIEnv* env, jobject jdb, jlong db_handle, jstring jproperty,
+    jint jproperty_len) {
+  auto db = reinterpret_cast<rocksdb::DB*>(db_handle);
+
+  const char* property = env->GetStringUTFChars(jproperty, 0);
+  rocksdb::Slice property_slice(property, jproperty_len);
+
+  uint64_t property_value = 0;
+  bool retCode = db->GetIntProperty(property_slice, &property_value);
+  env->ReleaseStringUTFChars(jproperty, property);
+
+  if (!retCode) {
+    rocksdb::RocksDBExceptionJni::ThrowNew(env, rocksdb::Status::NotFound());
+  }
+  return property_value;
+}
+
+/*
+ * Class:     org_rocksdb_RocksDB
+ * Method:    getLongProperty
+ * Signature: (JJLjava/lang/String;I)L;
+ */
+jlong Java_org_rocksdb_RocksDB_getLongProperty__JJLjava_lang_String_2I(
+    JNIEnv* env, jobject jdb, jlong db_handle, jlong jcf_handle,
+    jstring jproperty, jint jproperty_len) {
+  auto db = reinterpret_cast<rocksdb::DB*>(db_handle);
+  auto cf_handle = reinterpret_cast<rocksdb::ColumnFamilyHandle*>(jcf_handle);
+
+  const char* property = env->GetStringUTFChars(jproperty, 0);
+  rocksdb::Slice property_slice(property, jproperty_len);
+
+  uint64_t property_value;
+  bool retCode = db->GetIntProperty(cf_handle, property_slice, &property_value);
+  env->ReleaseStringUTFChars(jproperty, property);
+
+  if (!retCode) {
+    rocksdb::RocksDBExceptionJni::ThrowNew(env, rocksdb::Status::NotFound());
+  }
+  return property_value;
+}
+
 //////////////////////////////////////////////////////////////////////////////
 // rocksdb::DB::Flush
 
@@ -1332,4 +1379,3 @@ void Java_org_rocksdb_RocksDB_flush__JJJ(
   auto cf_handle = reinterpret_cast<rocksdb::ColumnFamilyHandle*>(jcf_handle);
   rocksdb_flush_helper(env, db, *flush_options, cf_handle);
 }
-