[GitHub] jvrao commented on a change in pull request #1317: BP-14 Force Ledger Bookie side implementation

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jvrao commented on a change in pull request #1317: BP-14 Force Ledger Bookie side implementation
URL: https://github.com/apache/bookkeeper/pull/1317#discussion_r183226381
 
 

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 File path: bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/LastAddForcedCursor.java
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 @@ -0,0 +1,145 @@
+/**
+ *
+ * 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.bookkeeper.bookie;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+import com.google.common.annotations.VisibleForTesting;
+import java.util.SortedMap;
+import java.util.TreeMap;
+import org.apache.bookkeeper.client.api.WriteAdvHandle;
+import org.apache.bookkeeper.proto.BookieProtocol;
+
+/**
+ * Handle the LastAddForced entryId. As entries do not arrive to the Journal in a known order we have to handle
+ * increments of this pointer. This is how it works: we keep a value for the current {@link #lastAddForced} entryId and
+ * a list of continuous ranges of ids which are known to have been persisted but are 'after' {@link #lastAddForced}.
+ * <p>
+ * Examples:
+ * <ul>
+ * <li>0, 1, 2, 3 we have maxAddForced = 3 (all entries from 0 to 3 are stored)</li>
+ * <li>0, 1, 3, 5 we have maxAddForced = 1 (all entries from 0 to 1 are stored, 2 and 4 are not stored)</li>
+ * <li>1, 2, 3 we have maxAddForced = -1 (not available, as 0 is missing, so there is an gap)</li>
 
 Review comment:
   There can never be contiguous entries in the bookie perspective if Ensemble Size > WQ

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