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don't let read-only transactions block the WAL collector

This commit is contained in:
jsteemann 2017-02-24 17:03:42 +01:00
parent b02168bdf0
commit a70ddf7116
4 changed files with 24 additions and 8 deletions
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6
CHANGELOG
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@ -1,3 +1,9 @@
devel
-----
* don't let read-only transactions block the WAL collector
v3.2.alpha2 (2017-02-20)
------------------------

12
arangod/MMFiles/MMFilesLogfileManager.cpp
View File

@ -535,7 +535,7 @@ void MMFilesLogfileManager::unprepare() {
}
// registers a transaction
int MMFilesLogfileManager::registerTransaction(TRI_voc_tid_t transactionId) {
int MMFilesLogfileManager::registerTransaction(TRI_voc_tid_t transactionId, bool isReadOnlyTransaction) {
auto lastCollectedId = _lastCollectedId.load();
auto lastSealedId = _lastSealedId.load();
@ -546,6 +546,16 @@ int MMFilesLogfileManager::registerTransaction(TRI_voc_tid_t transactionId) {
TRI_ASSERT(lastCollectedId <= lastSealedId);
if (isReadOnlyTransaction) {
// in case this is a read-only transaction, we are sure that the transaction can
// only see committed data (as itself it will not write anything, and write transactions
// run exclusively). we thus can allow the WAL collector to already seal and collect
// logfiles. the only thing that needs to be ensured for read-only transactions is
// that a logfile does not get thrown away while the read-only transaction is
// ongoing
lastSealedId = 0;
}
try {
auto data = std::make_unique<MMFilesTransactionData>(lastCollectedId, lastSealedId);
TransactionManagerFeature::MANAGER->registerTransaction(transactionId, std::move(data));

8
arangod/MMFiles/MMFilesLogfileManager.h
View File

@ -68,8 +68,8 @@ struct MMFilesTransactionData final : public TransactionData {
MMFilesTransactionData() = delete;
MMFilesTransactionData(MMFilesWalLogfile::IdType lastCollectedId, MMFilesWalLogfile::IdType lastSealedId) :
lastCollectedId(lastCollectedId), lastSealedId(lastSealedId) {}
MMFilesWalLogfile::IdType lastCollectedId;
MMFilesWalLogfile::IdType lastSealedId;
MMFilesWalLogfile::IdType const lastCollectedId;
MMFilesWalLogfile::IdType const lastSealedId;
};
struct MMFilesLogfileManagerState {
@ -218,7 +218,7 @@ class MMFilesLogfileManager final : public application_features::ApplicationFeat
}
// registers a transaction
int registerTransaction(TRI_voc_tid_t);
int registerTransaction(TRI_voc_tid_t id, bool isReadOnlyTransaction);
// return the set of dropped collections
/// this is used during recovery and not used afterwards
@ -459,7 +459,7 @@ class MMFilesLogfileManager final : public application_features::ApplicationFeat
bool _allowOversizeEntries = true;
bool _useMLock = false;
std::string _directory = "";
std::string _directory;
uint32_t _historicLogfiles = 10;
bool _ignoreLogfileErrors = false;
bool _ignoreRecoveryErrors = false;

2
arangod/MMFiles/MMFilesTransactionState.cpp
View File

@ -104,7 +104,7 @@ int MMFilesTransactionState::beginTransaction(transaction::Hints hints, int nest
_id = TRI_NewTickServer();
// register a protector
int res = logfileManager->registerTransaction(_id);
int res = logfileManager->registerTransaction(_id, isReadOnlyTransaction());
if (res != TRI_ERROR_NO_ERROR) {
return res;