2 * Copyright (c) 2014 Cisco Systems, Inc. and others. All rights reserved.
4 * This program and the accompanying materials are made available under the
5 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
6 * and is available at http://www.eclipse.org/legal/epl-v10.html
9 package org.opendaylight.controller.cluster.raft;
11 import akka.japi.Procedure;
12 import java.util.List;
13 import javax.annotation.Nonnull;
14 import javax.annotation.Nullable;
17 * Represents the ReplicatedLog that needs to be kept in sync by the RaftActor.
19 public interface ReplicatedLog {
20 long NO_MAX_SIZE = -1;
23 * Return the replicated log entry at the specified index.
25 * @param index the index of the log entry
26 * @return the ReplicatedLogEntry if found, otherwise null if the adjusted index less than 0 or
27 * greater than the size of the in-memory journal
30 ReplicatedLogEntry get(long index);
33 * Return the last replicated log entry in the log or null of not found.
35 * @return the last replicated log entry in the log or null of not found.
38 ReplicatedLogEntry last();
41 * Return the index of the last entry in the log or -1 if the log is empty.
43 * @return the index of the last entry in the log or -1 if the log is empty.
48 * Return the term of the last entry in the log or -1 if the log is empty.
50 * @return the term of the last entry in the log or -1 if the log is empty.
55 * Removes entries from the in-memory log starting at the given index.
57 * @param index the index of the first log entry to remove
58 * @return the adjusted index of the first log entry removed or -1 if the log entry is not found.
60 long removeFrom(long index);
63 * Removes entries from the in-memory log and the persisted log starting at the given index.
66 * The persisted information would then be used during recovery to properly
67 * reconstruct the state of the in-memory replicated log
69 * @param index the index of the first log entry to remove
70 * @return true if entries were removed, false otherwise
72 boolean removeFromAndPersist(long index);
75 * Appends an entry to the log.
77 * @param replicatedLogEntry the entry to append
78 * @return true if the entry was successfully appended, false otherwise. An entry can fail to append if
79 * the index is already included in the log.
81 boolean append(ReplicatedLogEntry replicatedLogEntry);
84 * Optimization method to increase the capacity of the journal log prior to appending entries.
86 * @param amount the amount to increase by
88 void increaseJournalLogCapacity(int amount);
91 * Appends an entry to the in-memory log and persists it as well.
93 * @param replicatedLogEntry the entry to append
94 * @param callback the Procedure to be notified when persistence is complete (optional).
95 * @param doAsync if true, the persistent actor can receive subsequent messages to process in between the persist
96 * call and the execution of the associated callback. If false, subsequent messages are stashed and get
97 * delivered after persistence is complete and the associated callback is executed.
98 * @return true if the entry was successfully appended, false otherwise.
100 boolean appendAndPersist(@Nonnull ReplicatedLogEntry replicatedLogEntry,
101 @Nullable Procedure<ReplicatedLogEntry> callback, boolean doAsync);
104 * Returns a list of log entries starting from the given index to the end of the log.
106 * @param index the index of the first log entry to get.
107 * @return the List of entries
109 @Nonnull List<ReplicatedLogEntry> getFrom(long index);
112 * Returns a list of log entries starting from the given index up to the given maximum of entries or
113 * the given maximum accumulated size, whichever comes first.
115 * @param index the index of the first log entry to get
116 * @param maxEntries the maximum number of entries to get
117 * @param maxDataSize the maximum accumulated size of the log entries to get
118 * @return the List of entries meeting the criteria.
120 @Nonnull List<ReplicatedLogEntry> getFrom(long index, int maxEntries, long maxDataSize);
123 * Returns the number of entries in the journal.
125 * @return the number of entries
130 * Checks if the entry at the specified index is present or not.
132 * @param index the index of the log entry
133 * @return true if the entry is present in the in-memory journal
135 boolean isPresent(long index);
138 * Checks if the entry is present in a snapshot.
140 * @param index the index of the log entry
141 * @return true if the entry is in the snapshot. false if the entry is not in the snapshot even if the entry may
142 * be present in the replicated log
144 boolean isInSnapshot(long index);
147 * Returns the index of the snapshot.
149 * @return the index from which the snapshot was created. -1 otherwise.
151 long getSnapshotIndex();
154 * Returns the term of the snapshot.
156 * @return the term of the index from which the snapshot was created. -1 otherwise
158 long getSnapshotTerm();
161 * Sets the snapshot index in the replicated log.
163 * @param snapshotIndex the index to set
165 void setSnapshotIndex(long snapshotIndex);
168 * Sets snapshot term.
170 * @param snapshotTerm the term to set
172 void setSnapshotTerm(long snapshotTerm);
175 * Clears the journal entries with startIndex (inclusive) and endIndex (exclusive).
177 * @param startIndex the start index (inclusive)
178 * @param endIndex the end index (exclusive)
180 void clear(int startIndex, int endIndex);
183 * Handles all the bookkeeping in order to perform a rollback in the event of SaveSnapshotFailure.
185 * @param snapshotCapturedIndex the new snapshot index
186 * @param snapshotCapturedTerm the new snapshot term
188 void snapshotPreCommit(long snapshotCapturedIndex, long snapshotCapturedTerm);
191 * Sets the Replicated log to state after snapshot success.
193 void snapshotCommit();
196 * Restores the replicated log to a state in the event of a save snapshot failure.
198 void snapshotRollback();
201 * Returns the size of the data in the log (in bytes).
203 * @return the size of the data in the log (in bytes)
208 * Determines if a snapshot needs to be captured based on the count/memory consumed and initiates the capture.
210 * @param replicatedLogEntry the last log entry.
212 void captureSnapshotIfReady(ReplicatedLogEntry replicatedLogEntry);
215 * Determines if a snapshot should be captured based on the count/memory consumed.
217 * @param logIndex the log index to use to determine if the log count has exceeded the threshold
218 * @return true if a snapshot should be captured, false otherwise
220 boolean shouldCaptureSnapshot(long logIndex);