[HDDS-10528] OM: Concatenated keys are evil

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: OM
• Labels: performance
• Assignee: Unassigned
• Reporter: Duong
• Created: 15/Mar/24 17:57
• Updated: 15/Mar/24 18:34

Description

Ozone Manager uses concatenated keys as table/cache keys. For instance, a key of the key_table is a result of: "/" + volume + "/" + "bucket" + "/" + key.

That unnecessarily creates and throws away multiple significant string objects for every request, e.g volume keys, bucket keys, key keys. (Even volume keys are a concatenation of "/" + volume?).

A simple composite key would eliminate the need for string concatenation, e.g. 

public class KeyTableKey {
    private final String volume;
    private final String bucket;
    private final String key;
    privale final int hashCode;
    public KeyIdentifier(String volume, String bucket, String key) {
      this.volume = volume;
      this.bucket = bucket
      this.key = key;
      this.hashCode = volume.hashcode() * 31 * 31 + bucket.hashCode() * 31 + key.hashCode();
    }
    public boolean equals(Object other) {
      // return true if the components are equals
    }
    public int hashCode() {
       return hashCode;
    }
}

For backward compatibility, we can implement a KeyTableKeyCodec that generates the same binary as the concatenated content.

Sub-Tasks

• Remove volume concatenated key: Open
• Remove bucket concatenated key: Open
• Remove key concatenated key: Open