Add support for PauseBackgroundWork and ContinueBackgroundWork to the Java API (#1087)

Closes https://github.com/facebook/rocksdb/issues/1071

java/rocksjni/rocksjni.cc

@@ -1484,6 +1484,42 @@ void Java_org_rocksdb_RocksDB_compactRange__J_3BI_3BIZIIJ(
       jend, jend_len, jreduce_level, jtarget_level, jtarget_path_id);
 }
 
+//////////////////////////////////////////////////////////////////////////////
+// rocksdb::DB::PauseBackgroundWork
+
+/*
+ * Class:     org_rocksdb_RocksDB
+ * Method:    pauseBackgroundWork
+ * Signature: (J)V
+ */
+void Java_org_rocksdb_RocksDB_pauseBackgroundWork(
+    JNIEnv* env, jobject jobj, jlong jdb_handle) {
+  auto* db = reinterpret_cast<rocksdb::DB*>(jdb_handle);
+  auto s = db->PauseBackgroundWork();
+  if (s.ok()) {
+    return;
+  }
+  rocksdb::RocksDBExceptionJni::ThrowNew(env, s);
+}
+
+//////////////////////////////////////////////////////////////////////////////
+// rocksdb::DB::ContinueBackgroundWork
+
+/*
+ * Class:     org_rocksdb_RocksDB
+ * Method:    continueBackgroundWork
+ * Signature: (J)V
+ */
+void Java_org_rocksdb_RocksDB_continueBackgroundWork(
+    JNIEnv* env, jobject jobj, jlong jdb_handle) {
+  auto* db = reinterpret_cast<rocksdb::DB*>(jdb_handle);
+  auto s = db->ContinueBackgroundWork();
+  if (s.ok()) {
+    return;
+  }
+  rocksdb::RocksDBExceptionJni::ThrowNew(env, s);
+}
+
 //////////////////////////////////////////////////////////////////////////////
 // rocksdb::DB::GetLatestSequenceNumber
 

java/src/main/java/org/rocksdb/RocksDB.java

@@ -1631,6 +1631,23 @@ public class RocksDB extends RocksObject {
         columnFamilyHandle.nativeHandle_);
   }
 
+  /**
+   * This function will wait until all currently running background processes
+   * finish. After it returns, no background process will be run until
+   * {@link #continueBackgroundWork()} is called
+   */
+  public void pauseBackgroundWork() throws RocksDBException {
+    pauseBackgroundWork(nativeHandle_);
+  }
+
+  /**
+   * Resumes backround work which was suspended by
+   * previously calling {@link #pauseBackgroundWork()}
+   */
+  public void continueBackgroundWork() throws RocksDBException {
+    continueBackgroundWork(nativeHandle_);
+  }
+
   /**
    * <p>The sequence number of the most recent transaction.</p>
    *
@@ -1876,6 +1893,8 @@ public class RocksDB extends RocksObject {
   private native void compactRange(long handle, byte[] begin, int beginLen,
       byte[] end, int endLen, boolean reduce_level, int target_level,
       int target_path_id, long cfHandle) throws RocksDBException;
+  private native void pauseBackgroundWork(long handle) throws RocksDBException;
+  private native void continueBackgroundWork(long handle) throws RocksDBException;
   private native long getLatestSequenceNumber(long handle);
   private native void disableFileDeletions(long handle) throws RocksDBException;
   private native void enableFileDeletions(long handle,

java/src/test/java/org/rocksdb/RocksDBTest.java

@@ -637,6 +637,19 @@ public class RocksDBTest {
     }
   }
 
+  @Test
+  public void pauseContinueBackgroundWork() throws RocksDBException {
+    try (final Options options = new Options().setCreateIfMissing(true);
+         final RocksDB db = RocksDB.open(options,
+             dbFolder.getRoot().getAbsolutePath())
+    ) {
+      db.pauseBackgroundWork();
+      db.continueBackgroundWork();
+      db.pauseBackgroundWork();
+      db.continueBackgroundWork();
+    }
+  }
+
   @Test
   public void enableDisableFileDeletions() throws RocksDBException {
     try (final Options options = new Options().setCreateIfMissing(true);