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The lock special key has the lock UID as the value

This commit is contained in:
Chaoguang Lin 2021-09-03 12:15:56 -07:00
parent f7002e2a66
commit 2aa0a5cf58
3 changed files with 15 additions and 6 deletions
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2
documentation/sphinx/source/special-keys.rst
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@ -199,7 +199,7 @@ that process, and wait for necessary data to be moved away.
While the key is set, any commit that tries to set a key in the range will fail with the ``special_keys_api_failure`` error.
#. ``\xff\xff/management/data_distribution/<mode|rebalance_ignored>`` Read/write. Changing these two keys will change the two corresponding system keys ``\xff/dataDistributionMode`` and ``\xff\x02/rebalanceDDIgnored``. The value of ``\xff\xff/management/data_distribution/mode`` is a literal text of ``0`` (disable) or ``1`` (enable). Transactions committed with invalid values will throw ``special_keys_api_failure`` . The value of ``\xff\xff/management/data_distribution/rebalance_ignored`` is empty. If present, it means data distribution is disabled for rebalance. Any transaction committed with non-empty value for this key will throw ``special_keys_api_failure``. For more details, see help text of ``fdbcli`` command ``datadistribution``.
#. ``\xff\xff/management/consistency_check_suspended`` Read/write. Set or read this key will set or read the underlying system key ``\xff\x02/ConsistencyCheck/Suspend``. The value of this special key is unused thus if present, will be empty. In particular, if the key exists, then consistency is suspended. For more details, see help text of ``fdbcli`` command ``consistencycheck``.
#. ``\xff\xff/management/db_locked`` Read/write. A single key that can be read and modified. Set the key will lock the database and clear the key will unlock. If the database is already locked, then the commit will fail with the ``special_keys_api_failure`` error. For more details, see help text of ``fdbcli`` command ``lock`` and ``unlock``.
#. ``\xff\xff/management/db_locked`` Read/write. A single key that can be read and modified. Set the key with a 32 bytes hex string UID will lock the database and clear the key will unlock. Read the key will return the UID string as the value. If the database is already locked, then the commit will fail with the ``special_keys_api_failure`` error. For more details, see help text of ``fdbcli`` command ``lock`` and ``unlock``.
#. ``\xff\xff/management/auto_coordinators`` Read-only. A single key, if read, will return a set of processes which is able to satisfy the current redundency level and serve as new coordinators. The return value is formatted as a comma delimited string of network addresses of coordinators, i.e. ``<ip:port>,<ip:port>,...,<ip:port>``.
#. ``\xff\xff/management/excluded_locality/<locality>`` Read/write. Indicates that the cluster should move data away from processes matching ``<locality>``, so that they can be safely removed. See :ref:`removing machines from a cluster <removing-machines-from-a-cluster>` for documentation for the corresponding fdbcli command.
#. ``\xff\xff/management/failed_locality/<locality>`` Read/write. Indicates that the cluster should consider matching processes as permanently failed. This allows the cluster to avoid maintaining extra state and doing extra work in the hope that these processes come back. See :ref:`removing machines from a cluster <removing-machines-from-a-cluster>` for documentation for the corresponding fdbcli command.

16
fdbclient/SpecialKeySpace.actor.cpp
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@ -1290,7 +1290,8 @@ ACTOR Future<RangeResult> getLockedKeyActor(ReadYourWritesTransaction* ryw, KeyR
Optional<Value> val = wait(ryw->getTransaction().get(databaseLockedKey));
RangeResult result;
if (val.present()) {
result.push_back_deep(result.arena(), KeyValueRef(kr.begin, val.get()));
UID uid = UID::fromString(BinaryReader::fromStringRef<UID>(val.get().substr(10), Unversioned()).toString());
result.push_back_deep(result.arena(), KeyValueRef(kr.begin, Value(uid.toString())));
}
return result;
}
@ -1313,11 +1314,10 @@ Future<RangeResult> LockDatabaseImpl::getRange(ReadYourWritesTransaction* ryw, K
}
}
ACTOR Future<Optional<std::string>> lockDatabaseCommitActor(ReadYourWritesTransaction* ryw) {
ACTOR Future<Optional<std::string>> lockDatabaseCommitActor(ReadYourWritesTransaction* ryw, UID uid) {
state Optional<std::string> msg;
ryw->getTransaction().setOption(FDBTransactionOptions::LOCK_AWARE);
Optional<Value> val = wait(ryw->getTransaction().get(databaseLockedKey));
UID uid = deterministicRandom()->randomUniqueID();
if (val.present() && BinaryReader::fromStringRef<UID>(val.get().substr(10), Unversioned()) != uid) {
// check database not locked
@ -1348,7 +1348,15 @@ ACTOR Future<Optional<std::string>> unlockDatabaseCommitActor(ReadYourWritesTran
Future<Optional<std::string>> LockDatabaseImpl::commit(ReadYourWritesTransaction* ryw) {
auto lockId = ryw->getSpecialKeySpaceWriteMap()[SpecialKeySpace::getManagementApiCommandPrefix("lock")].second;
if (lockId.present()) {
return lockDatabaseCommitActor(ryw);
std::string uidStr = lockId.get().toString();
UID uid;
try {
uid = UID::fromString(uidStr);
} catch (Error& e) {
return Optional<std::string>(
ManagementAPIError::toJsonString(false, "lock", "Invalid UID hex string: " + uidStr));
}
return lockDatabaseCommitActor(ryw, uid);
} else {
return unlockDatabaseCommitActor(ryw);
}

3
fdbserver/workloads/SpecialKeySpaceCorrectness.actor.cpp
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@ -809,7 +809,8 @@ struct SpecialKeySpaceCorrectnessWorkload : TestWorkload {
try {
tx->setOption(FDBTransactionOptions::SPECIAL_KEY_SPACE_ENABLE_WRITES);
// lock the database
tx->set(SpecialKeySpace::getManagementApiCommandPrefix("lock"), LiteralStringRef(""));
UID uid = deterministicRandom()->randomUniqueID();
tx->set(SpecialKeySpace::getManagementApiCommandPrefix("lock"), uid.toString());
// commit
wait(tx->commit());
break;