Github user joshelser commented on a diff in the pull request:
https://github.com/apache/incubator-ratis/pull/4#discussion_r214166342
--- Diff:
ratis-logservice/src/main/java/org/apache/ratis/logservice/api/LogReader.java
---
@@ -0,0 +1,53 @@
+/**
+ * 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.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.List;
+
+/**
+ * Synchronous client interface to read from a LogStream.
+ */
+public interface LogReader extends AutoCloseable {
+
+ /**
+ * Seeks to the position before the record at the provided {@code
offset} in the LogStream.
+ *
+ * @param offset A non-negative, offset in the LogStream
+ * @return A future for when the operation is completed.
+ */
+ void seek(long recordId) throws IOException;
--- End diff --
Ratis has a directory in which is stores many LogSegments. Each of these
are ordered with an Index, per the Raft protocol. Ratis can find the LogSegment
containing the record at an Index using binary search and then does a linear
search over that LogSegment to find the specific ID. I think that's sufficient
for what we need in a first-pass.
I don't think we need to support a "recordId" that is different than the
Raft Index. Just trying to give it a better name.
---
