SzyWilliam commented on code in PR #700:
URL: https://github.com/apache/ratis/pull/700#discussion_r939540111
##########
ratis-server-api/src/main/java/org/apache/ratis/server/RaftServerConfigKeys.java:
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@@ -157,6 +157,42 @@ static void setClientSize(RaftProperties properties, int
port) {
}
}
+ interface Read {
+ String PREFIX = RaftServerConfigKeys.PREFIX
+ + "." + JavaUtils.getClassSimpleName(Read.class).toLowerCase();
+
+ String TIMEOUT_KEY = PREFIX + ".timeout";
+ TimeDuration TIMEOUT_DEFAULT = TimeDuration.valueOf(10, TimeUnit.SECONDS);
+ static TimeDuration timeout(RaftProperties properties) {
+ return
getTimeDuration(properties.getTimeDuration(TIMEOUT_DEFAULT.getUnit()),
+ TIMEOUT_KEY, TIMEOUT_DEFAULT, getDefaultLog(), requirePositive());
+ }
+ static void setTimeout(RaftProperties properties, TimeDuration
readOnlyTimeout) {
+ setTimeDuration(properties::setTimeDuration, TIMEOUT_KEY,
readOnlyTimeout);
+ }
+
+ enum ReadOption {
+ /** Directly query the statemachine. Efficient but may undermine
linearizability */
+ DEFAULT,
+ /** Use ReadIndex (see Raft section 6.4), strictly linearizable */
+ SAFE;
+ // TODO LEADER_LEASE
Review Comment:
LEADER_LEASE obtains ReadIndex in a different way (using lease), which may
undermine linearizability under unbounded CPU clock drift but is about 15%
faster than LINEARIZABLE. So we use either LINEARIZABLE or LEADER_LEASE to
handle read-only requests.
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