jaldis-cpp

Didn't spend a penny on EngineerPro's course (again). Worshipped the almighty footgun 🔫 instead.

jaldis is a high-performance, Redis-compatible key-value store reimplemented in modern C++26. It is a spiritual successor to my own original OCaml implementation, designed to explore lower-level performance characteristics and manual memory management strategies that were abstracted away in the functional version.

While the OCaml version focused on expressiveness and type safety, this C++ port leverages Linux-native asynchronous I/O (epoll) and custom memory allocators (std::pmr) to provide predictable latency and reduced runtime overhead.

Benchmarking

Performance benchmarks using redis-benchmark against jaldis server:

Test Configuration

• Hardware: Intel Core i5-1135G7
• OS: Linux 6.18.7-arch1-1
• OCaml: 5.3.0
• Network: localhost
• Test Parameters: 1,000,000 SET/GET operations, 100 concurrent connections

# Standard benchmark
redis-benchmark -h 127.0.0.1 -n 1000000 -c 100 -t set,get --csv

# Pipelined benchmark (16 commands per pipeline)
redis-benchmark -h 127.0.0.1 -n 1000000 -c 100 -t set,get -P 16 --csv

Results (on Release build)

Standard Mode (-P 1)

"test","rps","avg_latency_ms","min_latency_ms","p50_latency_ms","p95_latency_ms","p99_latency_ms","max_latency_ms"
"SET","191570.89","0.265","0.064","0.263","0.303","0.375","1.583"
"GET","188040.62","0.270","0.080","0.271","0.311","0.367","1.343"

Pipelined Mode (-P 16)

"test","rps","avg_latency_ms","min_latency_ms","p50_latency_ms","p95_latency_ms","p99_latency_ms","max_latency_ms"
"SET","2024291.50","0.784","0.024","0.783","0.847","0.911","2.095"
"GET","2096436.12","0.753","0.016","0.751","0.799","1.415","2.367"

Features

Core Architecture

• Language: C++26
• I/O Model: Single-threaded, non-blocking event loop using epoll (Linux only).
• Memory Management: Uses std::pmr::monotonic_buffer_resource for zero-allocation parsing and request handling per client.
• Protocol: Full support for RESP (Redis Serialization Protocol).

For a deep dive into the system design, see ARCHITECTURE.md.

Supported Data Types

• Strings - Basic key-value pairs.
• Lists - Double-ended queues (implemented via std::deque).
• Sets - Unordered collections of unique strings.

Implemented Commands

Basic Operations

• PING - Test connection liveness.
• SET / GET - Store and retrieve string values.
• DEL - Remove keys.
• KEYS - List all keys (supports patterns, currently returns all keys).
• FLUSHDB - Remove all keys from the current database.

List Operations

• LPUSH / RPUSH - Push elements to the head/tail of a list.
• LPOP / RPOP - Pop elements from the head/tail.
• LLEN - Get the length of a list.
• LRANGE - Retrieve a range of elements from a list.

Set Operations

• SADD - Add members to a set.
• SREM - Remove members from a set.
• SCARD - Get the number of members in a set.
• SMEMBERS - Get all members of a set.
• SINTER - Intersect multiple sets.
• SISMEMBER - Check if a value is a member of a set.

Expiration

• EXPIRE - Set a timeout on a key (in seconds).
• TTL - Get the remaining time-to-live for a key.
• Strategy: Hybrid approach using lazy expiration on access and probabilistic active sweeping.

Build Instructions

Prerequisites

• A C++26 compliant compiler (e.g., GCC 14+, Clang 18+).
• CMake 3.25 or newer.
• Linux operating system (required for epoll support).

Building from Source

# Clone the repository
git clone https://github.com/jalsol/jaldis.git
cd jaldis

# Configure the build
cmake -Bbuild -S.
cmake -Bbuild -S. -DCMAKE_BUILD_TYPE=Release # Release build

# Build the project
cmake --build build -j

The build process will automatically fetch dependencies (Catch2 for testing) using CMake's FetchContent.

Usage

Start the server:

./build/jaldis

By default, the server binds to 127.0.0.1 on port 6379. You can connect using any standard Redis client:

redis-cli -p 6379 PING
# PONG

Running Tests

The project includes a comprehensive test suite covering the RESP parser, command logic, and storage engine.

# Run all tests via CTest
cd build
ctest --output-on-failure

# Or run individual test binaries directly
./build/resp_tests     # Protocol parser/serializer tests
./build/storage_tests  # Core storage engine tests
./build/command_tests  # Command logic tests

License

MIT License - see LICENSE file for details.