Github user VladRodionov commented on a diff in the pull request:
https://github.com/apache/incubator-ratis/pull/4#discussion_r212154050
--- Diff:
ratis-logservice/src/main/java/org/apache/ratis/logservice/api/LogStream.java
---
@@ -0,0 +1,109 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.ratis.logservice.api;
+
+import java.util.concurrent.CompletableFuture;
+
+/**
+ * A distributed log with "infinite" length that supports reads and writes.
+ */
+public interface LogStream {
+
+ /**
+ * Returns the unique name to identify this log.
+ */
+ LogName getName();
+
+ /**
+ * Returns the size of this LogStream in bytes.
+ */
+ long getSizeInBytes();
+
+ /**
+ * Returns the number of records in this LogStream.
+ */
+ long getSizeInRecords();
+
+ /**
+ * Creates a reader to read this LogStream asynchronously.
+ *
+ * @return An asynchronous reader
+ */
+ AsyncLogReader createAsyncReader();
+
+ /**
+ * Creates a writer to write to this LogStream asynchronously.
+ *
+ * @return An asynchronous writer
+ */
+ AsyncLogWriter createAsyncWriter();
+
+ /**
+ * Creates a reader to read this LogStream synchronously.
+ *
+ * @return A synchronous reader
+ */
+ LogReader createReader();
+
+ /**
+ * Creates a write to write to this LogStream synchronously.
+ *
+ * @return A synchronous writer
+ */
+ LogWriter createWriter();
+
+ /**
+ * Removes the elements in this LogStream prior to the given recordId.
+ *
+ * @param recordId A non-negative recordId for this LogStream
+ */
+ CompletableFuture<Void> truncateBefore(long recordId);
+
+ /**
+ * Returns the recordId which is the start of the LogStream. When there
are records which were truncated
+ * from the LogStream, this will return a value larger than {@code 0}.
+ */
+ CompletableFuture<Long> getFirstRecordId();
+
--- End diff --
Do we really need this? What is the use case?
---
