[CASSANDRA-15410] Avoid over-allocation of bytes for UTF8 string serialization

• Type: Improvement
• Status: Resolved
• Priority: Normal
• Resolution: Fixed
• Fix Version/s: 4.0-alpha3, 4.0
• Component/s: Messaging/Client
• Labels: pull-request-available
• Change Category: Performance
• Complexity: Low Hanging Fruit
• Platform: All

Source Control Link

647bdd6a11970f80666d7f20b53af76fbda4ff14

Test and Documentation Plan

JMH benchmark included

• Assignee: Yifan Cai
• Reporter: Yifan Cai

Authors

Yifan Cai

Reviewers

Aleksey Yeschenko

• Created: 11/Nov/19 23:00
• Updated: 10/Feb/21 21:01
• Resolved: 19/Nov/19 16:10

Description

In the current message encoding implementation, it first calculates the `encodeSize` and allocates the bytebuffer with that size.

However, during encoding, it assumes the worst case of writing UTF8 string to allocate bytes, i.e. assuming each letter takes 3 bytes.

The over-estimation further leads to resizing the underlying array and data copy.

Issue Links

• causes: CASSANDRA-16429 Fix incorrect encoding for strings can be UTF8
• links to: GitHub Pull Request #382