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Don't lock the BuildSteps table when inserting

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Instead, optimistically insert a row and retry if there is a conflict.
This commit is contained in:
Eelco Dolstra 2017-12-07 14:41:29 +01:00
parent 2660c3cc54
commit 457483ba0e
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GPG key ID: 8170B4726D7198DE
1 changed files with 10 additions and 8 deletions
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18
src/hydra-queue-runner/hydra-queue-runner.cc
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@ -280,10 +280,6 @@ void State::clearBusy(Connection & conn, time_t stopTime)
unsigned int State::allocBuildStep(pqxx::work & txn, BuildID buildId)
{
/* Acquire an exclusive lock on BuildSteps to ensure that we don't
race with other threads creating a step of the same build. */
txn.exec("lock table BuildSteps in exclusive mode");
auto res = txn.parameterized("select max(stepnr) from BuildSteps where build = $1")(buildId).exec();
return res[0][0].is_null() ? 1 : res[0][0].as<int>() + 1;
}
@ -292,10 +288,11 @@ unsigned int State::allocBuildStep(pqxx::work & txn, BuildID buildId)
unsigned int State::createBuildStep(pqxx::work & txn, time_t startTime, BuildID buildId, Step::ptr step,
const std::string & machine, BuildStatus status, const std::string & errorMsg, BuildID propagatedFrom)
{
restart:
auto stepNr = allocBuildStep(txn, buildId);
txn.parameterized
("insert into BuildSteps (build, stepnr, type, drvPath, busy, startTime, system, status, propagatedFrom, errorMsg, stopTime, machine) values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12)")
auto r = txn.parameterized
("insert into BuildSteps (build, stepnr, type, drvPath, busy, startTime, system, status, propagatedFrom, errorMsg, stopTime, machine) values ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12) on conflict do nothing")
(buildId)
(stepNr)
(0) // == build
@ -309,6 +306,8 @@ unsigned int State::createBuildStep(pqxx::work & txn, time_t startTime, BuildID
(startTime, startTime != 0 && status != bsBusy)
(machine).exec();
if (r.affected_rows() == 0) goto restart;
for (auto & output : step->drv.outputs)
txn.parameterized
("insert into BuildStepOutputs (build, stepnr, name, path) values ($1, $2, $3, $4)")
@ -339,10 +338,11 @@ void State::finishBuildStep(pqxx::work & txn, const RemoteResult & result,
int State::createSubstitutionStep(pqxx::work & txn, time_t startTime, time_t stopTime,
Build::ptr build, const Path & drvPath, const string & outputName, const Path & storePath)
{
restart:
auto stepNr = allocBuildStep(txn, build->id);
txn.parameterized
("insert into BuildSteps (build, stepnr, type, drvPath, busy, status, startTime, stopTime) values ($1, $2, $3, $4, $5, $6, $7, $8)")
auto r = txn.parameterized
("insert into BuildSteps (build, stepnr, type, drvPath, busy, status, startTime, stopTime) values ($1, $2, $3, $4, $5, $6, $7, $8) on conflict do nothing")
(build->id)
(stepNr)
(1) // == substitution
@ -352,6 +352,8 @@ int State::createSubstitutionStep(pqxx::work & txn, time_t startTime, time_t sto
(startTime)
(stopTime).exec();
if (r.affected_rows() == 0) goto restart;
txn.parameterized
("insert into BuildStepOutputs (build, stepnr, name, path) values ($1, $2, $3, $4)")
(build->id)(stepNr)(outputName)(storePath).exec();