Bug 2787: Batch AppendEntries to speed up follower sync

[controller.git] / opendaylight / md-sal / sal-akka-raft / src / main / java / org / opendaylight / controller / cluster / raft / ReplicatedLog.java

diff --git a/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/ReplicatedLog.java b/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/ReplicatedLog.java
index 0ad1df3c33bb6433e5ddf0afca46f5f4920d2882..9e99be118451523153871652b964d7824931c1ad 100644 (file)
--- a/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/ReplicatedLog.java
+++ b/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/ReplicatedLog.java
@@ -10,67 +10,61 @@ package org.opendaylight.controller.cluster.raft;
 
 import akka.japi.Procedure;
 import java.util.List;
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
 
 /**
  * Represents the ReplicatedLog that needs to be kept in sync by the RaftActor
  */
 public interface ReplicatedLog {
+    long NO_MAX_SIZE = -1;
+
     /**
-     * Get a replicated log entry at the specified index
+     * Return the replicated log entry at the specified index.
      *
      * @param index the index of the log entry
-     * @return the ReplicatedLogEntry at index. null if index less than 0 or
+     * @return the ReplicatedLogEntry if found, otherwise null if the adjusted index less than 0 or
      * greater than the size of the in-memory journal.
      */
-    ReplicatedLogEntry get(long index);
-
+    @Nullable ReplicatedLogEntry get(long index);
 
     /**
-     * Get the last replicated log entry
-     *
-     * @return
+     * Return the last replicated log entry in the log or null of not found.
      */
-    ReplicatedLogEntry last();
+    @Nullable ReplicatedLogEntry last();
 
     /**
-     *
-     * @return
+     * Return the index of the last entry in the log or -1 if the log is empty.
      */
     long lastIndex();
 
     /**
-     *
-     * @return
+     * Return the term of the last entry in the log or -1 if the log is empty.
      */
     long lastTerm();
 
     /**
-     * To be called when we need to remove entries from the in-memory log.
-     * This method will remove all entries >= index. This method should be used
-     * during recovery to appropriately trim the log based on persisted
-     * information
+     * Removes entries from the in-memory log starting at the given index.
      *
-     * @param index the index of the log entry
-     * @return the adjusted index of the first log entry removed or -1 if log entry not found.
+     * @param index the index of the first log entry to remove
+     * @return the adjusted index of the first log entry removed or -1 if the log entry is not found.
      */
     long removeFrom(long index);
 
-
     /**
-     * To be called when we need to remove entries from the in-memory log and we
-     * need that information persisted to disk. This method will remove all
-     * entries >= index.
+     * Removes entries from the in-memory log a nd the persisted log starting at the given index.
      * <p>
      * The persisted information would then be used during recovery to properly
      * reconstruct the state of the in-memory replicated log
      *
-     * @param index the index of the log entry
+     * @param the index of the first log entry to remove
      */
     void removeFromAndPersist(long index);
 
     /**
-     * Append an entry to the log
-     * @param replicatedLogEntry
+     * Appends an entry to the log.
+     *
+     * @param replicatedLogEntry the entry to append
      */
     void append(ReplicatedLogEntry replicatedLogEntry);
 
@@ -82,24 +76,32 @@ public interface ReplicatedLog {
     void increaseJournalLogCapacity(int amount);
 
     /**
+     * Appends an entry to the in-memory log and persists it as well.
      *
-     * @param replicatedLogEntry
+     * @param replicatedLogEntry the entry to append
      */
     void appendAndPersist(final ReplicatedLogEntry replicatedLogEntry);
 
     void appendAndPersist(ReplicatedLogEntry replicatedLogEntry, Procedure<ReplicatedLogEntry> callback);
 
     /**
+     * Returns a list of log entries starting from the given index to the end of the log.
      *
-     * @param index the index of the log entry
+     * @param index the index of the first log entry to get.
+     * @return the List of entries
      */
-    List<ReplicatedLogEntry> getFrom(long index);
+    @Nonnull List<ReplicatedLogEntry> getFrom(long index);
 
     /**
+     * Returns a list of log entries starting from the given index up to the given maximum of entries or
+     * the given maximum accumulated size, whichever comes first.
      *
-     * @param index the index of the log entry
+     * @param index the index of the first log entry to get
+     * @param maxEntries the maximum number of entries to get
+     * @param maxDataSize the maximum accumulated size of the log entries to get
+     * @return the List of entries meeting the criteria.
      */
-    List<ReplicatedLogEntry> getFrom(long index, int max);
+    @Nonnull List<ReplicatedLogEntry> getFrom(long index, int maxEntries, long maxDataSize);
 
     /**
      *