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TeamCollection: All machine teams are correct size 

We only create correct size machine teams.
When configuration (e.g., team size) is changed,
the DDTeamCollection will be destroyed and rebuilt
so that the invariant will not be violated.

Based on the invariant, we can count the number of
machine teams more quickly.

Signed-off-by: Meng Xu <meng_xu@apple.com>
This commit is contained in:
Meng Xu 2018-12-05 15:09:35 -08:00
parent 57eab1f283
commit c5047bc8c3
1 changed files with 5 additions and 14 deletions
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19
fdbserver/DataDistribution.actor.cpp
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@ -1348,7 +1348,11 @@ struct DDTeamCollection : ReferenceCounted<DDTeamCollection> {
// Skip unhealthy machines
if (!isMachineHealthy(machine.second)) continue;
int teamCount = countCorrectSizedMachineTeam(machine.second, configuration.storageTeamSize);
// Invariant: We only create correct size machine teams.
// When configuration (e.g., team size) is changed, the DDTeamCollection will be destroyed and rebuilt
// so that the invariant will not be violated.
int teamCount = machine.second->machineTeams.size();
if (teamCount < minTeamCount) {
leastUsedMachines.clear();
minTeamCount = teamCount;
@ -1576,19 +1580,6 @@ struct DDTeamCollection : ReferenceCounted<DDTeamCollection> {
return true;
}
// A machine may have some invalid machine teams, which will eventually be removed
// We should only count valid machine teams for the machine so that the machine can be chosen into a new team
// expectedSize is the expected team size
// Return the number of machine teams that match the correct team size
int countCorrectSizedMachineTeam(Reference<TCMachineInfo>& machine, const int expectedSize) {
int count = 0;
for (auto& machineTeam : machine->machineTeams) {
if (machineTeam->size() == expectedSize) ++count;
}
ASSERT(count == machine->machineTeams.size()); //TODO: If this assert is never triggered, we can remove this function.
return count;
}
// Create server teams based on machine teams
// Before the number of machine teams reaches the threshold, build a machine team for each server team
// When it reaches the threshold, first try to build a server team with existing machine teams; if failed,