feat(server) added eviction strategy

[orrk-litt]

Solves #1272
Add EvictionStrategy option, allowing fixed eviction where entries are deleted after TTL passes (even if accessed)

Tests

• Simple unit tests
• Changed manually eviction time from Days to Seconds, tested both strategy with client and requests

Summary by CodeRabbit

• New Features

  • Added CLI flag -es/-eviction-strategy to configure interaction data eviction behavior with two options: "sliding" (default, TTL extends on access) and "fixed" (TTL fixed from write time).

• Tests

  • Added tests validating sliding and fixed eviction strategy behaviors.

[coderabbitai]

Walkthrough

The pull request introduces a configurable eviction strategy feature for the Interactsh server. A new CLI flag -eviction-strategy (with short form -es) allows users to select between "sliding" (TTL reset on access) and "fixed" (TTL from write time) eviction policies. The implementation spans CLI parsing, options propagation, type definitions, and cache behavior changes.

Changes

Cohort / File(s)	Summary
Documentation README.md	Documents new -es / -eviction-strategy CLI flag with sliding/fixed options and default "sliding" value.
CLI Configuration cmd/interactsh-server/main.go	Parses new eviction-strategy flag, maps string values to storage.EvictionStrategy constants, and propagates to storage options. Adds EvictionStrategy field to CLIServerOptions.
Options Structures pkg/options/server_options.go, pkg/storage/option.go	Adds EvictionStrategy string field to CLIServerOptions; introduces EvictionStrategy type with EvictionStrategySliding and EvictionStrategyFixed constants; adds EvictionStrategy field to storage.Options with default "Sliding".
Storage Implementation pkg/storage/storagedb.go	Implements strategy-dependent TTL behavior: EvictionStrategyFixed uses expire-after-write, EvictionStrategySliding uses expire-after-access; replaces unconditional expire-after-access with switch-based selection.
Tests pkg/storage/storagedb_test.go	Adds TestSlidingEvictionStrategy and TestFixedEvictionStrategy to validate TTL behavior differences between strategies.

Sequence Diagram

sequenceDiagram
    participant CLI as CLI Parser
    participant Opts as storage.Options
    participant DB as StorageDB
    participant Cache as TTL Cache

    CLI->>Opts: Set EvictionStrategy (Sliding/Fixed)
    
    rect rgba(200, 220, 255, 0.3)
    Note over DB,Cache: Sliding Strategy (expire-after-access)
    DB->>DB: EvictionStrategy == Sliding?
    DB->>Cache: Configure ExpireAfterAccess
    Cache->>Cache: Extend TTL on access
    end
    
    rect rgba(255, 200, 200, 0.3)
    Note over DB,Cache: Fixed Strategy (expire-after-write)
    DB->>DB: EvictionStrategy == Fixed?
    DB->>Cache: Configure ExpireAfterWrite
    Cache->>Cache: TTL fixed from write time
    end

Loading

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

• Files spread across multiple layers: Configuration, options, storage, and tests require understanding the feature end-to-end.
• Logic change in storagedb.go: The switch-based eviction strategy selection introduces new conditional logic that should be validated for correctness.
• Test coverage: Review test assertions to ensure both strategies are exercised with proper timing and access patterns.
• Potential gaps: Verify that the EvictionStrategy field in CLIServerOptions is properly wired through AsServerOptions if needed.

Poem

🐰 Hop through the caches, old and new,
Fixed paths and sliding views—
Pick your strategy, choose your way,
Eviction happens, come what may! ✨

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 20.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main change: adding an eviction strategy feature to the server. It is concise, specific, and directly reflects the primary functionality being introduced.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

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

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[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (1)

pkg/storage/storagedb_test.go (1)

163-181: LGTM! Fixed eviction test correctly validates TTL independence from access.

The test properly verifies that accessing an entry does NOT extend its TTL in fixed mode, confirming expire-after-write behavior.

Optional: Consider slightly larger timing buffers for test robustness.

The tests use 100ms TTL with 10ms buffers. While this should be sufficient, slightly larger buffers (e.g., 20-50ms) could reduce flakiness on slower CI systems. This is optional and not urgent since the current values are reasonable.

📜 Review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between bcbfdb9 and 2f2071b.

📒 Files selected for processing (6)

• README.md (1 hunks)
• cmd/interactsh-server/main.go (2 hunks)
• pkg/options/server_options.go (1 hunks)
• pkg/storage/option.go (1 hunks)
• pkg/storage/storagedb.go (1 hunks)
• pkg/storage/storagedb_test.go (1 hunks)

🧰 Additional context used

🧬 Code graph analysis (4)

cmd/interactsh-server/main.go (1)

pkg/storage/option.go (4)

• EvictionStrategy (5-5)
• EvictionStrategyFixed (9-9)
• EvictionStrategySliding (8-8)
• DefaultOptions (23-26)

pkg/options/server_options.go (1)

pkg/storage/option.go (1)

• EvictionStrategy (5-5)

pkg/storage/storagedb_test.go (2)

pkg/storage/storagedb.go (1)

• New (35-75)

pkg/storage/option.go (4)

• Options (12-17)
• EvictionStrategy (5-5)
• EvictionStrategySliding (8-8)
• EvictionStrategyFixed (9-9)

pkg/storage/storagedb.go (1)

pkg/storage/option.go (3)

• EvictionStrategy (5-5)
• EvictionStrategyFixed (9-9)
• EvictionStrategySliding (8-8)

🔇 Additional comments (10)

README.md (1)

356-356: LGTM! Clear documentation of the new eviction strategy flag.

The documentation follows the established format and clearly specifies the available options and default value.

pkg/options/server_options.go (1)

23-23: LGTM! Field addition is consistent with the existing pattern.

The EvictionStrategy field captures CLI input and is mapped to storage options in main.go, following the same pattern as the Eviction and NoEviction fields.

pkg/storage/storagedb.go (1)

41-48: LGTM! Eviction strategy implementation is correct.

The switch correctly implements the two eviction strategies:

• Fixed: TTL counted from write time (expire-after-write)
• Sliding: TTL counted from last access (expire-after-access, backward compatible default)

pkg/storage/storagedb_test.go (1)

137-161: LGTM! Sliding eviction test correctly validates TTL extension on access.

The test properly verifies that accessing an entry extends its TTL in sliding mode.

pkg/storage/option.go (3)

5-10: LGTM! Clean enum definition with clear documentation.

The EvictionStrategy type and constants are well-defined with helpful comments explaining the behavior of each strategy.

---

16-16: LGTM! Field addition enables configurable eviction strategy.

---

24-25: LGTM! Default to sliding strategy maintains backward compatibility.

Setting EvictionStrategySliding as the default preserves the original expire-after-access behavior.

cmd/interactsh-server/main.go (3)

51-51: LGTM! Flag definition follows established patterns.

The eviction strategy flag is properly defined with a sensible default value.

---

223-232: LGTM! Robust parsing and validation of eviction strategy.

The implementation correctly:

• Uses case-insensitive matching for user convenience
• Maps string values to typed constants
• Provides clear error messaging for invalid input

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237-237: LGTM! Eviction strategy correctly propagated to storage options.