8000 Bug fix/agency restart after compaction and holes in log by kvahed · Pull Request #3413 · arangodb/arangodb · GitHub
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Bug fix/agency restart after compaction and holes in log #3413

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Merged
merged 8 commits into from
Oct 13, 2017
Merged

Bug fix/agency restart after compaction and holes in log #3413

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57a8d38
Agent restarting from persistence after compaction kept sending 0-100…
kvahed Oct 13, 2017
e251d66
State fixes holes in RAFT index range
kvahed Oct 13, 2017
4d43a87
Agent restarting from persistence after compaction kept sending 0-100…
kvahed Oct 13, 2017
a45f7b1
removed the bogus code from sendAppendEntries
kvahed Oct 13, 2017
449d115
Avoid application of entries older than compaction index _cur and gua…
kvahed Oct 13, 2017
0d70579
both locks need be acquired for setting _confirmed to _commitIndex
kvahed Oct 13, 2017
317f83c
lastIndex must be cur
kvahed Oct 13, 2017
52d990b
Fix loadRemaining.
neunhoef Oct 13, 2017
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State fixes holes in RAFT index range
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@kvahed
kvahed committed Oct 13, 2017
commit e251d6687bffddfb22f956a39e4e08937aa56140
19 changes: 19 additions & 0 deletions arangod/Agency/State.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -865,6 +865,7 @@ bool State::loadRemaining() {

TRI_ASSERT(_log.empty()); // was cleared in loadCompacted
std::string clientId;
index_t lastIndex = 0;
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lastIndex should probably be initialized with _cur, which has been set to the index of the latest snapshot in loadCompacted just before loadRemaining was called. I think 0 is wrong if there is a persisted snapshot.

for (auto const& i : VPackArrayIterator(result)) {

buffer_t tmp = std::make_shared<arangodb::velocypack::Buffer<uint8_t>>();
Expand All @@ -876,6 +877,21 @@ bool State::loadRemaining() {
clientId = req.hasKey("clientId") ?
req.get("clientId").copyString() : std::string();

// Dummy fill missing entries (Not good at all.)
index_t index(basics::StringUtils::uint64(
ii.get(StaticStrings::KeyString).copyString()));
term_t term(ii.get("term").getNumber<uint64_t>());
if (lastIndex > 0 && index-lastIndex > 1) {
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This is not very robust. Why lastIndex > 0? How do we know that index >= lastIndex and there is no overflow? If index < lastIndex, we must not append at all. If index == lastIndex, we must append if and only if _log is still empty. If index == lastIndex+1 we must append normally and move lastIndex one up. If index > lastindex+1, then we must insert empty entries until index == lastIndex+1.
Note that in all the formulae I typed here there can never be an overflow.

std::shared_ptr<Buffer<uint8_t>> buf =
std::make_shared<Buffer<uint8_t>>();
VPackSlice value = arangodb::basics::VelocyPackHelper::EmptyObjectValue();
buf->append(value.startAs<char const>(), value.byteSize());
for (index_t i = lastIndex+1; i < index; ++i) {
LOG_TOPIC(WARN, Logger::AGENCY) << "Missing index " << i << " in RAFT log.";
_log.push_back(log_t(i, term, buf, std::string()));
}
}

try {
_log.push_back(
log_t(
Expand All @@ -889,6 +905,9 @@ bool State::loadRemaining() {
" to integer."
<< e.what();
}

lastIndex = index;

}
}
if (_log.empty()) {
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