[CASSANDRA-7290] Compaction strategy is not reloaded when compaction strategy options is updated

• Type: Bug
• Status: Resolved
• Priority: Normal
• Resolution: Fixed
• Fix Version/s: 2.0.9
• Component/s: Local/Compaction
• Severity: Normal
• Assignee: Paulo Motta
• Reporter: Paulo Motta

Authors

Paulo Motta

Reviewers

Marcus Eriksson

• Created: 23/May/14 00:17
• Updated: 16/Apr/19 09:31
• Resolved: 27/May/14 08:31

Description

The AbstractCompactionStrategy constructor receives an options map on its constructor:

    protected AbstractCompactionStrategy(ColumnFamilyStore cfs, Map<String, String> options)
    {
        assert cfs != null;
        this.cfs = cfs;
        this.options = options;
    ...

This map is currently the same reference as CFMetadata.compactionStrategyOptions, so ColumnFamilyStore.reload() does not reload the compaction strategy when a compaction strategy option changes:

    private void maybeReloadCompactionStrategy()
    {
        // Check if there is a need for reloading
        if (metadata.compactionStrategyClass.equals(compactionStrategy.getClass()) 
            && metadata.compactionStrategyOptions.equals(compactionStrategy.options)) //metadata.compactionStrategyOptions == compactionStrategy.options, so compaction is never reloaded
            return;

I spotted this in my test, when I tried changing the value of "unchecked_tombstone_compaction" from false to true and calling ColumnFamilyStore.reload() was not reloading the compaction strategy. I don't know if ColumnFamilyStore.reload() is only called during tests, or also whenever the schema changes.

In order to fix the bug, I made AbstractCompactionStrategy.options an ImmutableMap, so if CFMetadata.compactionStrategyOptions is updated, ColumnFamilyStore.maybeReloadCompactionStrategy will actually reload the compaction strategy:

    protected AbstractCompactionStrategy(ColumnFamilyStore cfs, Map<String, String> options)
    {
        assert cfs != null;
        this.cfs = cfs;
        this.options = ImmutableMap.copyOf(options);
    ...