dcapwell commented on code in PR #2144:
URL: https://github.com/apache/cassandra/pull/2144#discussion_r1103076257
##########
src/java/org/apache/cassandra/service/accord/async/AsyncOperation.java:
##########
@@ -123,55 +131,114 @@ protected void setState(State state)
this.state = state;
}
- /**
- * callback for loader and writer
- */
- @Override
- public void accept(Object o, Throwable throwable)
+ private void callback(Object o, Throwable throwable)
{
if (throwable != null)
{
logger.error(String.format("Operation %s failed", this),
throwable);
state = State.FAILED;
- tryFailure(throwable);
+ fail(throwable);
}
else
run();
}
+ private void finish(R result)
+ {
+ Preconditions.checkArgument(state == State.COMPLETING);
+ callback.accept(result, null);
+ state = State.FINISHED;
+ }
+
+ private void fail(Throwable throwable)
+ {
+ Preconditions.checkArgument(state != State.FINISHED && state !=
State.FAILED);
+ callback.accept(null, throwable);
+ state = State.FAILED;
+ }
+
+ private static PreExecuteContext preExecuteContext(PreLoadContext
preLoadContext,
+
AccordStateCache.Instance<TxnId, Command> commandCache,
+
AccordStateCache.Instance<RoutableKey, CommandsForKey> cfkCache)
+ {
+ ImmutableMap<TxnId, Command> ctxCommands =
commandCache.getActive(preLoadContext.txnIds());
+ ImmutableMap<RoutableKey, CommandsForKey> ctxCommandsForKey =
cfkCache.getActive(toRoutableKeys(preLoadContext.keys()));
+ return new PreExecuteContext()
+ {
+ @Override
+ public ImmutableMap<TxnId, Command> commands()
+ {
+ return ctxCommands;
+ }
+
+ @Override
+ public ImmutableMap<RoutableKey, CommandsForKey> commandsForKey()
+ {
+ return ctxCommandsForKey;
+ }
+
+ @Override
+ public Iterable<TxnId> txnIds()
+ {
+ return preLoadContext.txnIds();
+ }
+
+ @Override
+ public Seekables<?, ?> keys()
+ {
+ return preLoadContext.keys();
+ }
+ };
+ }
+
+ private static <K, V extends ImmutableState> void
releaseResources(AccordStateCache.Instance<K, V> cache,
+
java.util.Map<K, ContextValue<V>> values)
+ {
+ values.forEach((key, value) -> {
+ cache.release(key, value.original(), value.current());
+ });
+ }
+
+ private void releaseResources()
+ {
+ releaseResources(commandStore.commandCache(),
postExecuteContext.commands);
+ releaseResources(commandStore.commandsForKeyCache(),
postExecuteContext.commandsForKey);
+ }
+
protected void runInternal()
{
- SafeAccordCommandStore safeStore = commandStore.safeStore(context);
switch (state)
{
case INITIALIZED:
state = State.LOADING;
case LOADING:
- if (!loader.load(context, this))
+ if (!loader.load(this::callback))
Review Comment:
If reading this correctly don't we have the following timing issue?
```
O1: load(tx1)
O2: load(tx1)
O1: load completes
O1: runs
O1: save the mutation of tx1 back
O2: load completes
O2: runs
O2 save the mutation of tx1 back
```
where do we make sure it see's O1's mutation?
Looking at
`org.apache.cassandra.service.accord.AccordStateCache.Instance#release` I see
we try to guard against it with the following line
```
Invariants.checkState(node.value() == original ||
(accessor.isEmpty(node.value()) && original == null));
```
but this check *happens-before* we schedule the write to disk!
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