keith-turner commented on a change in pull request #1276: Refactor how
constraint violations are handled
URL: https://github.com/apache/accumulo/pull/1276#discussion_r306070322
##########
File path:
server/tserver/src/main/java/org/apache/accumulo/tserver/tablet/Tablet.java
##########
@@ -1115,53 +1114,29 @@ private synchronized CommitSession
finishPreparingMutations(long time) {
return commitSession;
}
- public CommitSession prepareMutationsForCommit(TservConstraintEnv cenv,
List<Mutation> mutations)
- throws TConstraintViolationException {
-
- ConstraintChecker cc = constraintChecker.derive();
-
- List<Mutation> violators = null;
- Violations violations = new Violations();
+ public TabletMutationPrepAttempt prepareMutationsForCommit(final
TservConstraintEnv cenv,
+ final List<Mutation> mutations) {
cenv.setExtent(extent);
- for (Mutation mutation : mutations) {
- Violations more = cc.check(cenv, mutation);
- if (more != null) {
- violations.add(more);
- if (violators == null) {
- violators = new ArrayList<>();
- }
- violators.add(mutation);
- }
- }
-
- long time = tabletTime.setUpdateTimes(mutations);
-
- if (!violations.isEmpty()) {
-
- HashSet<Mutation> violatorsSet = new HashSet<>(violators);
- ArrayList<Mutation> nonViolators = new ArrayList<>();
-
- for (Mutation mutation : mutations) {
- if (!violatorsSet.contains(mutation)) {
- nonViolators.add(mutation);
- }
- }
-
- CommitSession commitSession = null;
-
- if (nonViolators.size() > 0) {
- // if everything is a violation, then it is expected that
- // code calling this will not log or commit
- commitSession = finishPreparingMutations(time);
- if (commitSession == null) {
- return null;
- }
+ final ConstraintChecker constraints = constraintChecker.derive();
+ final TabletMutationPrepAttempt attempt = new TabletMutationPrepAttempt();
Review comment:
The existing code attempts to minimize the work done when no mutations
violate a constraint. It would be nice to carry this behavior forward, but I
am not sure of the best way to do this.
Below is one possibility I thought of...
```java
Iterator<Mutation> miter = mutations.iterator(); //TODO reverse iterator
would be more efficient when everything is removed
while(miter.hasNext()) {
Mutation mutation = miter.next();
Violations violations = constraints.check(cenv, mutation);
if(violations != null) {
attempt.addViolator(mutation, violations); // TODO this method could
allocate its internal list of vilolators the first time called
miter.remove(); // TODO is it ok to modify the list passed in??
}
}
// if nothing violates, then the passed in list is not copied or modified...
attempt.setMutations(mutations);
```
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