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. In either case the
98 * callback is guaranteed to execute in the context of the actor associated with this log.
99 * @return true if the entry was successfully appended, false otherwise.
101 boolean appendAndPersist(@Nonnull ReplicatedLogEntry replicatedLogEntry,
102 @Nullable Procedure<ReplicatedLogEntry> callback, boolean doAsync);
105 * Returns a list of log entries starting from the given index to the end of the log.
107 * @param index the index of the first log entry to get.
108 * @return the List of entries
110 @Nonnull List<ReplicatedLogEntry> getFrom(long index);
113 * Returns a list of log entries starting from the given index up to the given maximum of entries or
114 * the given maximum accumulated size, whichever comes first.
116 * @param index the index of the first log entry to get
117 * @param maxEntries the maximum number of entries to get
118 * @param maxDataSize the maximum accumulated size of the log entries to get
119 * @return the List of entries meeting the criteria.
121 @Nonnull List<ReplicatedLogEntry> getFrom(long index, int maxEntries, long maxDataSize);
124 * Returns the number of entries in the journal.
126 * @return the number of entries
131 * Checks if the entry at the specified index is present or not.
133 * @param index the index of the log entry
134 * @return true if the entry is present in the in-memory journal
136 boolean isPresent(long index);
139 * Checks if the entry is present in a snapshot.
141 * @param index the index of the log entry
142 * @return true if the entry is in the snapshot. false if the entry is not in the snapshot even if the entry may
143 * be present in the replicated log
145 boolean isInSnapshot(long index);
148 * Returns the index of the snapshot.
150 * @return the index from which the snapshot was created. -1 otherwise.
152 long getSnapshotIndex();
155 * Returns the term of the snapshot.
157 * @return the term of the index from which the snapshot was created. -1 otherwise
159 long getSnapshotTerm();
162 * Sets the snapshot index in the replicated log.
164 * @param snapshotIndex the index to set
166 void setSnapshotIndex(long snapshotIndex);
169 * Sets snapshot term.
171 * @param snapshotTerm the term to set
173 void setSnapshotTerm(long snapshotTerm);
176 * Clears the journal entries with startIndex (inclusive) and endIndex (exclusive).
178 * @param startIndex the start index (inclusive)
179 * @param endIndex the end index (exclusive)
181 void clear(int startIndex, int endIndex);
184 * Handles all the bookkeeping in order to perform a rollback in the event of SaveSnapshotFailure.
186 * @param snapshotCapturedIndex the new snapshot index
187 * @param snapshotCapturedTerm the new snapshot term
189 void snapshotPreCommit(long snapshotCapturedIndex, long snapshotCapturedTerm);
192 * Sets the Replicated log to state after snapshot success.
194 void snapshotCommit();
197 * Restores the replicated log to a state in the event of a save snapshot failure.
199 void snapshotRollback();
202 * Returns the size of the data in the log (in bytes).
204 * @return the size of the data in the log (in bytes)
209 * Determines if a snapshot needs to be captured based on the count/memory consumed and initiates the capture.
211 * @param replicatedLogEntry the last log entry.
213 void captureSnapshotIfReady(ReplicatedLogEntry replicatedLogEntry);
216 * Determines if a snapshot should be captured based on the count/memory consumed.
218 * @param logIndex the log index to use to determine if the log count has exceeded the threshold
219 * @return true if a snapshot should be captured, false otherwise
221 boolean shouldCaptureSnapshot(long logIndex);