Concarency atomic

[amirhasanpour]

3.4.3 => Add example for atomic compare and swap (CAS)

3.4.4 => Add example for atomic Pointer

Summary by CodeRabbit

• Documentation
  • Added two subsections to chapter 3.4 covering Compare & Swap (CAS) and atomic pointers.
  • Included runnable examples demonstrating lock-free lifecycle control (start/stop) and thread-safe configuration updates under concurrent read/write.
  • Added Persian explanations clarifying atomic operation concepts and practical usage scenarios.

[coderabbitai]

Walkthrough

Two subsections added to the atomic operations chapter: 3.4.3 introduces CAS-based Server state management with Start/Stop/IsActive examples; 3.4.4 introduces an atomic pointer Config manager with New/Update/Get and a concurrent read/write scenario (includes runnable Go snippets and Persian explanations).

Changes

Cohort / File(s)	Summary
Atomic Operations Documentation content/chapter\ 3/3.4-atomic.md	Added 3.4.3 "Compare & Swap (CAS)" with a Go Server example using atomic.CompareAndSwapInt32 for Start/Stop/IsActive and run loop; added 3.4.4 "atomic Pointer" with a thread-safe AtomicConfigManager using an atomic.Pointer[Config], including New/Update/Get and a concurrent read/write demonstration.

Sequence Diagram(s)

sequenceDiagram
    autonumber
    participant Client
    participant Server
    participant Goroutine as RunLoop
    Note over Server: CAS-based active flag (int32)
    Client->>Server: Start()
    Server->>Server: atomic.CompareAndSwapInt32(0,1)
    alt success
        Server->>RunLoop: spawn run loop
        RunLoop->>RunLoop: do work
    else already active
        Server-->>Client: no-op / already running
    end
    Client->>Server: Stop()
    Server->>Server: atomic.CompareAndSwapInt32(1,0)
    alt success
        Server->>RunLoop: signal stop / exit
    else already stopped
        Server-->>Client: no-op
    end

Loading

sequenceDiagram
    autonumber
    participant Writer
    participant AtomicConfigManager as ACM
    participant Reader
    Note over ACM: atomic.Pointer to Config
    Writer->>ACM: UpdateConfig(newCfg)
    ACM->>ACM: atomic.StorePointer(&ptr, &newCfg)
    alt immediate
        Reader->>ACM: cfg := GetConfig()
        ACM->>Reader: return cfg (lock-free)
    end
    Note right of Reader: multiple readers read concurrently without locks

Loading

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Suggested reviewers

• ja7ad

Poem

🐇 I nibble bytes beneath the moonlit log,

CAS clicks softly, I clear the fog.
Pointers hop, no locks in sight,
Configs update through the night.
A rabbit's cheer for thread-safe code — hooray!

Pre-merge checks and finishing touches

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title Check	✅ Passed	The PR title "Concarency atomic" is related to the changeset and correctly identifies the topic of atomic operations. The PR objectives confirm that the main change is adding examples for atomic operations, specifically comparing-and-swap (CAS) and atomic pointers in sections 3.4.3 and 3.4.4. While the title could be more specific by explicitly mentioning that examples are being added or referencing the section additions, it does refer to a real and central aspect of the change. However, the title contains a spelling error—"Concarency" should be "Concurrency"—which slightly diminishes clarity.
Docstring Coverage	✅ Passed	No functions found in the changes. Docstring coverage check skipped.

✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

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[coderabbitai]

Actionable comments posted: 1

🧹 Nitpick comments (1)

content/chapter 3/3.4-atomic.md (1)

116-272: Fix formatting issues: hard tabs and trailing spaces in code blocks

Static analysis flagged multiple markdown linting issues in the code examples:

• Hard tabs used in code indentation (lines 124–186, 200–270)
• Trailing spaces on lines 156, 169, 237
• Spaces inside emphasis markers on lines 217, 223, 227

If your project enforces markdown style rules, convert hard tabs to spaces and trim trailing whitespace. If these rules are too strict for documentation code blocks, consider updating .markdownlint config to exclude code blocks or accept hard tabs as standard Go formatting.

Apply this diff to clean up formatting issues:

-	fmt.Println("Server starting...")
+    fmt.Println("Server starting...")

(Replace all hard tabs with 4 spaces in both code blocks, and trim trailing spaces on lines 156, 169, 237)

📜 Review details

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Review profile: CHILL

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📥 Commits

Reviewing files that changed from the base of the PR and between 8448c4e and f2f1ef8.

📒 Files selected for processing (1)

• content/chapter 3/3.4-atomic.md (1 hunks)

🧰 Additional context used

🪛 markdownlint-cli2 (0.18.1)

content/chapter 3/3.4-atomic.md

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🔇 Additional comments (2)

content/chapter 3/3.4-atomic.md (2)

135-165: CAS example demonstrates lock-free state management correctly.

The Start/Stop methods properly use atomic.CompareAndSwapInt32 to enforce single-instance semantics, and the run() loop uses atomic.LoadInt32 for safe polling. This is a well-chosen example of CAS for stateful resource lifecycle management.

---

217-229: Atomic pointer example correctly demonstrates lock-free reads with eventual consistency.

The use of atomic.StorePointer and atomic.LoadPointer with unsafe.Pointer ensures readers always observe a complete Config snapshot without locks. This is an effective pattern for read-heavy scenarios with infrequent updates. The type casts to/from unsafe.Pointer are handled safely here.

[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (2)

content/chapter 3/3.4-atomic.md (2)

116-190: Section numbering and CAS pattern logic look good.

The section header is now correctly numbered as 3.4.3 (resolving the prior duplicate issue), and the server example effectively demonstrates atomic.CompareAndSwapInt32 for state transitions and graceful shutdown. The use of LoadInt32 in the run loop and WaitGroup coordination is sound.

Minor: Replace hard tabs with spaces throughout the code blocks (lines 124–186) and remove trailing spaces (lines 156, 169) to align with markdown formatting standards.

---

192-272: Section 3.4.4 numbering and atomic pointer pattern are correct.

The section header is correctly labeled as 3.4.4, and the AtomicConfigManager example effectively demonstrates lock-free reads via unsafe.Pointer with atomic store/load operations. The concurrent reader/writer scenario properly illustrates the read-heavy use case where readers avoid blocking.

Minor: Replace hard tabs with spaces throughout the code blocks (lines 200–270) and remove the trailing space (line 237) to comply with markdown formatting standards.

📜 Review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between f2f1ef8 and c21645b.

📒 Files selected for processing (1)

• content/chapter 3/3.4-atomic.md (1 hunks)

🧰 Additional context used

🪛 markdownlint-cli2 (0.18.1)

content/chapter 3/3.4-atomic.md

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