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Remove "Storages" field from data_distribution_stats 

It seems like a cool idea, but it feels rushed to me. Reverting for now.
This commit is contained in:
Andrew Noyes 2020-06-30 15:22:33 +00:00
parent a55b0771c5
commit e1dfa410c1
6 changed files with 45 additions and 59 deletions
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7
documentation/sphinx/source/developer-guide.rst
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@ -850,15 +850,14 @@ Reads in the metrics module are not transactional and may require rpcs to comple
>>> for k, v in db.get_range_startswith('\xff\xff/metrics/data_distribution_stats/', limit=3):
... print(k, v)
...
('\xff\xff/metrics/data_distribution_stats/', '{"ShardBytes":3828000,"Storages":["697f39751849d70067eabd1b079478a5"]}')
('\xff\xff/metrics/data_distribution_stats/mako00079', '{"ShardBytes":2013000,"Storages":["697f39751849d70067eabd1b079478a5"]}')
('\xff\xff/metrics/data_distribution_stats/mako00126', '{"ShardBytes":3201000,"Storages":["697f39751849d70067eabd1b079478a5"]}')
('\xff\xff/metrics/data_distribution_stats/', '{"ShardBytes":3828000}')
('\xff\xff/metrics/data_distribution_stats/mako00079', '{"ShardBytes":2013000}')
('\xff\xff/metrics/data_distribution_stats/mako00126', '{"ShardBytes":3201000}')
========================= ======== ===============
**Field** **Type** **Description**
------------------------- -------- ---------------
ShardBytes number An estimate of the sum of kv sizes for this shard.
Storages [string] A list of the storage process ids currently responsible for this shard.
========================= ======== ===============
Keys starting with ``\xff\xff/metrics/health/`` represent stats about the health of the cluster, suitable for application-level throttling.

49
fdbclient/NativeAPI.actor.cpp
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@ -502,54 +502,7 @@ void DatabaseContext::registerSpecialKeySpaceModule(SpecialKeySpace::MODULE modu
ACTOR Future<Standalone<RangeResultRef>> getWorkerInterfaces(Reference<ClusterConnectionFile> clusterFile);
ACTOR Future<Optional<Value>> getJSON(Database db);
template <class F>
Future<pair<KeyRange, Reference<LocationInfo>>> getKeyLocation(Database const& cx, Key const& key,
F StorageServerInterface::*member,
TransactionInfo const& info, bool isBackward = false);
class DDStatsRangeImpl : public SpecialKeyRangeAsyncImpl {
public:
explicit DDStatsRangeImpl(KeyRangeRef kr);
Future<Standalone<RangeResultRef>> getRange(ReadYourWritesTransaction* ryw, KeyRangeRef kr) const override;
};
ACTOR Future<Standalone<RangeResultRef>> ddMetricsGetRangeActor(ReadYourWritesTransaction* ryw, KeyRangeRef kr) {
state KeyRangeRef keys = kr.removePrefix(ddStatsRange.begin);
state Standalone<VectorRef<DDMetricsRef>> resultWithoutPrefix =
wait(waitDataDistributionMetricsList(ryw->getDatabase(), keys, CLIENT_KNOBS->STORAGE_METRICS_SHARD_LIMIT));
state Standalone<RangeResultRef> result;
ryw->getDatabase()->invalidateCache(keys);
for (const auto& ddMetricsRef_ : resultWithoutPrefix) {
state DDMetricsRef ddMetricsRef = ddMetricsRef_;
// each begin key is the previous end key, thus we only encode the begin key in the result
state KeyRef beginKey = ddMetricsRef.beginKey.withPrefix(ddStatsRange.begin, result.arena());
state pair<KeyRange, Reference<LocationInfo>> ssi = wait(getKeyLocation(
ryw->getDatabase(), ddMetricsRef.beginKey, &StorageServerInterface::getValue, ryw->getTransactionInfo()));
// Use json string encoded in utf-8 to encode the values, easy for adding more fields in the future
JsonBuilderObject statsObj;
statsObj["ShardBytes"] = ddMetricsRef.shardBytes;
JsonBuilderArray storages;
std::vector<UID> uids;
for (int i = 0; i < ssi.second->size(); ++i) {
uids.push_back(ssi.second->getId(i));
}
std::sort(uids.begin(), uids.end());
for (const auto& uid : uids) {
storages.push_back(uid.toString());
}
statsObj["Storages"] = storages;
std::string statsString = statsObj.getJson();
ValueRef bytes(result.arena(), statsString);
result.push_back(result.arena(), KeyValueRef(beginKey, bytes));
}
return result;
}
DDStatsRangeImpl::DDStatsRangeImpl(KeyRangeRef kr) : SpecialKeyRangeAsyncImpl(kr) {}
Future<Standalone<RangeResultRef>> DDStatsRangeImpl::getRange(ReadYourWritesTransaction* ryw, KeyRangeRef kr) const {
return ddMetricsGetRangeActor(ryw, kr);
}
struct WorkerInterfacesSpecialKeyImpl : SpecialKeyRangeBaseImpl {
Future<Standalone<RangeResultRef>> getRange(ReadYourWritesTransaction* ryw, KeyRangeRef kr) const override {
if (ryw->getDatabase().getPtr() && ryw->getDatabase()->getConnectionFile()) {
@ -1507,7 +1460,7 @@ ACTOR Future< pair<KeyRange,Reference<LocationInfo>> > getKeyLocation_internal(
template <class F>
Future<pair<KeyRange, Reference<LocationInfo>>> getKeyLocation(Database const& cx, Key const& key,
F StorageServerInterface::*member,
TransactionInfo const& info, bool isBackward) {
TransactionInfo const& info, bool isBackward = false) {
auto ssi = cx->getCachedLocation( key, isBackward );
if (!ssi.second) {
return getKeyLocation_internal( cx, key, info, isBackward );

5
fdbclient/Schemas.cpp
View File

@ -856,10 +856,7 @@ const KeyRef JSONSchemas::latencyBandConfigurationSchema = LiteralStringRef(R"co
const KeyRef JSONSchemas::dataDistributionStatsSchema = LiteralStringRef(R"""(
{
"ShardBytes": 1947000,
"Storages": [
"697f39751849d70067eabd1b079478a5"
]
"ShardBytes": 1947000
}
)""");

29
fdbclient/SpecialKeySpace.actor.cpp
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@ -348,3 +348,32 @@ Future<Standalone<RangeResultRef>> ConflictingKeysImpl::getRange(ReadYourWritesT
}
return result;
}
ACTOR Future<Standalone<RangeResultRef>> ddMetricsGetRangeActor(ReadYourWritesTransaction* ryw, KeyRangeRef kr) {
try {
auto keys = kr.removePrefix(ddStatsRange.begin);
Standalone<VectorRef<DDMetricsRef>> resultWithoutPrefix =
wait(waitDataDistributionMetricsList(ryw->getDatabase(), keys, CLIENT_KNOBS->STORAGE_METRICS_SHARD_LIMIT));
Standalone<RangeResultRef> result;
for (const auto& ddMetricsRef : resultWithoutPrefix) {
// each begin key is the previous end key, thus we only encode the begin key in the result
KeyRef beginKey = ddMetricsRef.beginKey.withPrefix(ddStatsRange.begin, result.arena());
// Use json string encoded in utf-8 to encode the values, easy for adding more fields in the future
json_spirit::mObject statsObj;
statsObj["ShardBytes"] = ddMetricsRef.shardBytes;
std::string statsString =
json_spirit::write_string(json_spirit::mValue(statsObj), json_spirit::Output_options::raw_utf8);
ValueRef bytes(result.arena(), statsString);
result.push_back(result.arena(), KeyValueRef(beginKey, bytes));
}
return result;
} catch (Error& e) {
throw;
}
}
DDStatsRangeImpl::DDStatsRangeImpl(KeyRangeRef kr) : SpecialKeyRangeAsyncImpl(kr) {}
Future<Standalone<RangeResultRef>> DDStatsRangeImpl::getRange(ReadYourWritesTransaction* ryw, KeyRangeRef kr) const {
return ddMetricsGetRangeActor(ryw, kr);
}

6
fdbclient/SpecialKeySpace.actor.h
View File

@ -190,5 +190,11 @@ public:
Future<Standalone<RangeResultRef>> getRange(ReadYourWritesTransaction* ryw, KeyRangeRef kr) const override;
};
class DDStatsRangeImpl : public SpecialKeyRangeAsyncImpl {
public:
explicit DDStatsRangeImpl(KeyRangeRef kr);
Future<Standalone<RangeResultRef>> getRange(ReadYourWritesTransaction* ryw, KeyRangeRef kr) const override;
};
#include "flow/unactorcompiler.h"
#endif

8
fdbserver/workloads/DataDistributionMetrics.actor.cpp
View File

@ -157,13 +157,15 @@ struct DataDistributionMetricsWorkload : KVWorkload {
.detail("ErrorStr", errorStr.c_str())
.detail("JSON", json_spirit::write_string(json_spirit::mValue(result[i].value.toString())));
totalBytes += valueObj["ShardBytes"].get_int64();
for (const auto& s : valueObj["Storages"].get_array()) {
UID::fromString(s.get_str()); // Will throw if it's not a valid uid
}
}
self->avgBytes = totalBytes / self->numShards;
// fetch data-distribution stats for a smaller range
ASSERT(result.size());
state int idx = deterministicRandom()->randomInt(0, result.size());
Standalone<RangeResultRef> res = wait(tr->getRange(
KeyRangeRef(result[idx].key, idx + 1 < result.size() ? result[idx + 1].key : ddStatsRange.end), 100));
ASSERT_WE_THINK(res.size() == 1 && res[0] == result[idx]); // It works good now. However, not sure in any
// case of data-distribution, the number changes
} catch (Error& e) {
TraceEvent(SevError, "FailedToRetrieveDDMetrics").detail("Error", e.what());
throw;