optimize readPacket #1705

methane · 2025-04-23T08:34:21Z

Description

Avoid unnecessary allocation.

Checklist

Code compiles correctly
Created tests which fail without the change (if possible)
All tests passing
Extended the README / documentation, if necessary
Added myself / the copyright holder to the AUTHORS file

Summary by CodeRabbit

New Features
- Added a method to retrieve the current length of the internal buffer.
Refactor
- Simplified the process for reading data from the buffer and compressed streams, removing unnecessary parameters and streamlining the interface.
- Centralized and clarified how data is read with timeout handling, improving code maintainability and consistency for end-users.

coderabbitai · 2025-04-23T08:34:27Z

Walkthrough

This change refactors the buffer and compressed IO reading logic by simplifying method signatures and internal data flow. The buffer type gains a new len() method, and its readNext method is simplified to remove error handling and external reader dependencies. Corresponding updates are made in the compressed IO (compIO) logic, eliminating the need to pass reader functions and streamlining packet reading. The mysqlConn type now encapsulates buffer reading and timeout logic within a new readNext method, further centralizing and simplifying byte reading throughout the codebase.

Changes

File(s)	Change Summary
buffer.go	Added `len()` method to `buffer`. Refactored `readNext` to remove error handling and dependency on `readerFunc`.
compress.go	Updated `compIO.readNext` and `readCompressedPacket` to remove `readerFunc` parameter and streamline internal reads.
packets.go	Added `mysqlConn.readNext` for encapsulated buffer reading with timeout. Updated `readPacket` to use new method.

Sequence Diagram(s)

sequenceDiagram
  participant Client
  participant mysqlConn
  participant buffer

  Client->>mysqlConn: readPacket()
  mysqlConn->>mysqlConn: readNext(n)
  mysqlConn->>buffer: readNext(n)
  buffer-->>mysqlConn: []byte
  mysqlConn-->>Client: packet data

Possibly related PRs

stop double-buffering #1643: Refactored the buffer handling by removing double buffering and reworking the readNext method, which is directly built upon in this PR.

Suggested reviewers

shogo82148

Poem

In the warren of code, the buffers align,
No more error hops, just bytes in a line.
The packets now flow, with nibbles so neat,
Refactored and tidy, a developer's treat.
🐇✨

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📥 Commits

Reviewing files that changed from the base of the PR and between f7d94ec and c630c5e.

📒 Files selected for processing (3)

buffer.go (2 hunks)
compress.go (2 hunks)
packets.go (2 hunks)

⏰ Context from checks skipped due to timeout of 90000ms (20)

GitHub Check: test (windows-latest, 1.24, 8.4)
GitHub Check: test (ubuntu-latest, 1.24, mariadb-10.5)
GitHub Check: test (windows-latest, 1.24, mariadb-10.11)
GitHub Check: test (windows-latest, 1.24, mariadb-11.2)
GitHub Check: test (ubuntu-latest, 1.22, 9.0)
GitHub Check: test (windows-latest, 1.24, mariadb-11.1)
GitHub Check: test (windows-latest, 1.24, mariadb-11.4)
GitHub Check: test (macos-latest, 1.24, mariadb-10.5)
GitHub Check: test (windows-latest, 1.24, 9.0)
GitHub Check: test (windows-latest, 1.24, 8.0)
GitHub Check: test (macos-latest, 1.24, mariadb-10.6)
GitHub Check: test (macos-latest, 1.24, mariadb-11.1)
GitHub Check: test (ubuntu-latest, 1.24, mariadb-10.6)
GitHub Check: test (ubuntu-latest, 1.24, mariadb-10.11)
GitHub Check: test (macos-latest, 1.24, 5.7)
GitHub Check: test (macos-latest, 1.24, mariadb-11.4)
GitHub Check: test (ubuntu-latest, 1.24, mariadb-11.2)
GitHub Check: test (ubuntu-latest, 1.24, 5.7)
GitHub Check: test (ubuntu-latest, 1.24, 8.0)
GitHub Check: test (ubuntu-latest, 1.24, 8.4)

🔇 Additional comments (10)

buffer.go (2)

45-48: Good addition of len() method

This is a helpful accessor that simplifies code readability where buffer length needs to be checked.

94-98: Good simplification of readNext method

The method now has a single responsibility - slicing the buffer. The error handling and buffer filling logic is moved elsewhere, improving separation of concerns. The full slice expression (:need:need) prevents capacity leaks by limiting the capacity to exactly what's needed.

packets.go (4)

28-37: Well-designed readNext method

This new method centralizes the buffer filling and timeout handling logic, which was previously spread across different parts of the code. This encapsulation improves code structure and maintainability.

44-47: Good refactoring of packet reading logic

Using the new readNext variable to hold the appropriate reading function (either mc.readNext or mc.compIO.readNext) simplifies the code flow while maintaining the same functionality for both compressed and uncompressed connections.

51-52: Clean implementation of readNext

The code now uses the function reference approach which simplifies error handling while maintaining the same functionality.

99-100: Consistent use of readNext abstraction

This change maintains consistency with the new pattern established earlier in the function.

compress.go (4)

87-95: Good simplification of compIO.readNext

The method now follows the same pattern as other readNext implementations in the codebase. Removing the readerFunc parameter streamlines the code and makes it more consistent with the rest of the implementation.

97-99: Good refactoring of readCompressedPacket

The method now directly uses mc.readNext, which simplifies the code flow and aligns with the broader refactoring approach. This eliminates unnecessary parameter passing while maintaining the same functionality.

106-107: Minor optimization by removing type conversion

Using the byte directly instead of performing unnecessary type conversion is a small but good optimization.

123-126: Consistent use of mc.readNext

This change maintains consistency with the new pattern established earlier in the function, eliminating unnecessary parameter passing.

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methane · 2025-04-23T08:38:35Z

packets.go

-		data, err := readNext(4, mc.readWithTimeout)
+		data, err := readNext(4)


go compiler allocated mc.readWithTimeout method trampoline object.

methane · 2025-04-23T08:38:42Z

packets.go

@@ -85,7 +96,7 @@ func (mc *mysqlConn) readPacket() ([]byte, error) {
 		}

 		// read packet body [pktLen bytes]
-		data, err = readNext(pktLen, mc.readWithTimeout)
+		data, err = readNext(pktLen)


methane · 2025-04-23T08:39:24Z

packets.go

+// read n bytes from mc.buf
+func (mc *mysqlConn) readNext(n int) ([]byte, error) {
+	if mc.buf.len() < n {
+		err := mc.buf.fill(n, mc.readWithTimeout)


Go compiler inlines mc.buff.fill. It doesn't allocate mc.readWithTimeout.

It may be possible to rewrite in cleaner code. But I minimise changes to backport this PR to 1.9 branch.

coveralls · 2025-04-23T08:41:17Z

coverage: 82.758% (-0.08%) from 82.833%
when pulling c630c5e on methane:opt-read
into f7d94ec on go-sql-driver:master.

optimize readPacket

c630c5e

methane mentioned this pull request Apr 23, 2025

Read optimization #1697

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optimize readPacket #1705

optimize readPacket #1705

methane commented Apr 23, 2025 •

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coveralls commented Apr 23, 2025

		data, err := readNext(4, mc.readWithTimeout)
		data, err := readNext(4)

optimize readPacket #1705

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methane commented Apr 23, 2025 • edited by coderabbitai bot Loading

Description

Checklist

Summary by CodeRabbit

coderabbitai bot commented Apr 23, 2025 • edited Loading

Walkthrough

Changes

Sequence Diagram(s)

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