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https://issues.apache.org/jira/browse/CASSANDRA-19426?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Ling Mao updated CASSANDRA-19426:
---------------------------------
Description:
_*issue-1:*_
if liveEndpoints.size()=unreachableEndpoints.size()=0; probability will be
{_}Infinity{_}.
randDbl <= probability will always be true, then sendGossip
_*issue-2:*_
comparing two double is safe by using < or >. However missing accuracy will
happen if we compare the equlity of two double by intuition(=). For example:
{code:java}
double probability = 0.1;
double randDbl = 0.10000000000000001; // Slightly greater than probability
if (randDbl <= probability)
{
System.out.println("randDbl <= probability(always here)");
}
else
{
System.out.println("randDbl > probability");
}
{code}
A good example from: _*Gossiper#maybeGossipToUnreachableMember*_
{code:java}
if (randDbl < prob)
{
sendGossip(message, Sets.filter(unreachableEndpoints.keySet(),
ep ->
!isDeadState(getEndpointStateMap().get(ep))));
}{code}
was:I'll write a PR tonight
> Fix Double Type issues in the Gossiper#maybeGossipToCMS
> -------------------------------------------------------
>
> Key: CASSANDRA-19426
> URL: https://issues.apache.org/jira/browse/CASSANDRA-19426
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Ling Mao
> Assignee: Ling Mao
> Priority: Low
>
> _*issue-1:*_
> if liveEndpoints.size()=unreachableEndpoints.size()=0; probability will be
> {_}Infinity{_}.
> randDbl <= probability will always be true, then sendGossip
> _*issue-2:*_
> comparing two double is safe by using < or >. However missing accuracy will
> happen if we compare the equlity of two double by intuition(=). For example:
>
> {code:java}
> double probability = 0.1;
> double randDbl = 0.10000000000000001; // Slightly greater than probability
> if (randDbl <= probability)
> {
> System.out.println("randDbl <= probability(always here)");
> }
> else
> {
> System.out.println("randDbl > probability");
> }
> {code}
>
> A good example from: _*Gossiper#maybeGossipToUnreachableMember*_
> {code:java}
> if (randDbl < prob)
> {
> sendGossip(message, Sets.filter(unreachableEndpoints.keySet(),
> ep ->
> !isDeadState(getEndpointStateMap().get(ep))));
> }{code}
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