szetszwo commented on code in PR #1332:
URL: https://github.com/apache/ratis/pull/1332#discussion_r2666027906
##########
ratis-docs/src/site/markdown/configurations.md:
##########
@@ -209,6 +209,14 @@ if it fails to receive any RPC responses from this peer
within this specified ti
| **Type** | double, ranging from (0.0,1.0) |
| **Default** | 0.9 |
+--------------------------------------------------------------------------------
+
+| **Property** | `raft.server.read-index.use.applied-index.enabled`
|
+|:----------------|:--------------------------------------------------------------------------|
+| **Description** | whether leader return applied index instead of commit
index for ReadIndex |
Review Comment:
Let's don't mention `ReadIndex` since it is a kind of implementation
details. I suggest updating it to
- `whether to enable applied index instead of using commit index for
linearizable read`
##########
ratis-server-api/src/main/java/org/apache/ratis/server/RaftServerConfigKeys.java:
##########
@@ -265,6 +265,17 @@ static void setWriteIndexCacheExpiryTime(RaftProperties
properties, TimeDuration
setTimeDuration(properties::setTimeDuration,
WRITE_INDEX_CACHE_EXPIRY_TIME_KEY, expiryTime);
}
}
+
+ interface ReadIndex {
+ String PREFIX = Read.PREFIX + ".read-index";
+
+ String READ_INDEX_USE_APPLIED_INDEX_ENABLED_KEY = PREFIX +
".use.applied-index.enabled";
Review Comment:
- Let's remove "`use`", i.e. `raft.server.read-index.applied-index.enabled`.
- The field names must be the same as the String value. Otherwise, the
TestConfUtils will fail as shown in the CI.
- ~It needs a setter method.~
```java
interface ReadIndex {
String PREFIX = Read.PREFIX + ".read-index";
String APPLIED_INDEX_ENABLED_KEY = PREFIX + ".applied-index.enabled";
boolean APPLIED_INDEX_ENABLED_DEFAULT = false;
static boolean appliedIndexEnabled(RaftProperties properties) {
return getBoolean(properties::getBoolean, APPLIED_INDEX_ENABLED_KEY,
APPLIED_INDEX_ENABLED_DEFAULT, getDefaultLog());
}
static void setAppliedIndexEnabled(RaftProperties properties, boolean
enabled) {
setBoolean(properties::setBoolean, APPLIED_INDEX_ENABLED_KEY,
enabled);
}
}
```
##########
ratis-server/src/main/java/org/apache/ratis/server/impl/LeaderStateImpl.java:
##########
@@ -389,6 +390,8 @@ boolean isApplied() {
} else {
this.followerMaxGapThreshold = (long) (followerGapRatioMax *
maxPendingRequests);
}
+ this.readIndexUseAppliedIndexEnabled = RaftServerConfigKeys.Read.ReadIndex
Review Comment:
Similarly, remove `use`.
##########
ratis-server/src/main/java/org/apache/ratis/server/impl/LeaderStateImpl.java:
##########
@@ -1134,21 +1137,23 @@ public boolean checkLeadership() {
/**
* Obtain the current readIndex for read only requests. See Raft paper
section 6.4.
* 1. Leader makes sure at least one log from current term is committed.
- * 2. Leader record last committed index as readIndex.
+ * 2. Leader record last committed index or applied index (depending on
configuration) as readIndex.
* 3. Leader broadcast heartbeats to followers and waits for
acknowledgements.
* 4. If majority respond success, returns readIndex.
* @return current readIndex.
*/
CompletableFuture<Long> getReadIndex(Long readAfterWriteConsistentIndex) {
- final long commitIndex = server.getRaftLog().getLastCommittedIndex();
+ final long lastAppliedOrCommitIndex = readIndexUseAppliedIndexEnabled ?
Review Comment:
Let's just call it `index` instead of `lastAppliedOrCommitIndex`.
##########
ratis-docs/src/site/markdown/configurations.md:
##########
@@ -218,6 +218,13 @@ if it fails to receive any RPC responses from this peer
within this specified ti
| **Type** | TimeDuration
|
| **Default** | 60s
|
+### Read Index - Configurations related to ReadIndex used in linearizable read
+
+| **Property** | `raft.server.read.read-index.use.applied-index.enabled`
|
+|:----------------|:--------------------------------------------------------------------------|
+| **Description** | whether leader return applied index instead of commit
index for ReadIndex |
Review Comment:
Suggestion: "whether applied index (instead of commit index) is used for
ReadIndex"
##########
ratis-docs/src/site/markdown/configurations.md:
##########
@@ -209,6 +209,14 @@ if it fails to receive any RPC responses from this peer
within this specified ti
| **Type** | double, ranging from (0.0,1.0) |
| **Default** | 0.9 |
+--------------------------------------------------------------------------------
+
+| **Property** | `raft.server.read-index.use.applied-index.enabled`
|
+|:----------------|:--------------------------------------------------------------------------|
+| **Description** | whether leader return applied index instead of commit
index for ReadIndex |
Review Comment:
Let's don't mention `ReadIndex` since it is a kind of implementation
details. I suggest updating it to
- `whether to enable applied index instead of using commit index for
linearizable read`
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