EdColeman opened a new issue, #2821:
URL: https://github.com/apache/accumulo/issues/2821
**Is your feature request related to a problem? Please describe.**
With recent changes in property handling with version information available
we may be able to improve concurrency handling
This was pulled from comments on #2799 by @keith-turner
**Additional context**
Directly from @keith-turner comment
[Atomic property update...] this code may be able to gracefully handle
multiple clients concurrently modifying props. Not completely sure, but think
something like the following may work.
Create a thrift type to return version+props.
```
class ThriftVersionedProperties {
long version;
Map<String, String> props;
}
```
The following code was written quickly and omits a lot of details, trying to
show how we could pass a version back and forth over thrift and use that
version to detect concurrent changes and retry.
```
public void modifyProperties(String tableName, final
Consumer<Map<String,String>> mapMutator)
throws AccumuloException, AccumuloSecurityException,
IllegalArgumentException,
ConcurrentModificationException {
while(true) {
// make thrift call to get props+version
ThriftVersionedProps tvp = client.getTableProperties(...);
// mutate the properties
mapMutator.accept(tvp.properties);
try {
// pass the modified props+version back to thrift call. The
thrift call will throw a thrift exception if the version has changed since we
read props above.
client.modifyTableProperties(...,tableName, tvp);
// successfully modified props, so break out of the retry loop...
probably a better way to do this than a while(true) loop
break;
} catch (PropertiesVersionChanged pvc) {
log.debug("Properties changed since reading, retrying...");
//TODO maybe sleep using retry object
} catch (TableNotFoundException e) {
throw new AccumuloException(e);
}
}
}
```
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