# Chord: Sync, Manage, and Harmonize Contexts 🎵
Welcome to **Chord** — a flexible and powerful Elixir library designed to simplify context management and delta tracking in your distributed or real-time applications.
## 🎯 Why Chord?
When you need a solution for real-time state synchronization, partial updates, and efficient cleanup, Chord strikes the perfect note! Here’s what makes Chord special:
- **Seamless State Sync**: Keep your clients up-to-date with full context or delta-based updates.
- **Customizable Backend**: Use ETS, Redis, or your own backend implementation.
- **Flexible Delta Formatting**: Define how your updates are structured.
- **Periodic Cleanup**: Automatically clear stale contexts or deltas.
- **Developer-Friendly APIs**: Simple, consistent, and easy-to-use APIs.
- **Context Export and Restore**: Export contexts to or restore them from external providers.
- **Partial Updates**: Apply updates to specific fields within a context.
---
## 🚀 Getting Started
### 1️⃣ Install the Library
Add Chord to your Mix dependencies:
```elixir
def deps do
[
{:chord, "~> 0.1.3"}
]
end
```
Run:
```bash
mix deps.get
```
### 2️⃣ Configure Chord
Add your desired configuration in `config/config.exs`:
```elixir
config :chord,
backend: Chord.Backend.ETS, # Choose your backend (Redis, ETS, etc.)
context_auto_delete: false, # Enable or disable auto-deletion of old contexts
context_ttl: :timer.hours(6), # Time-to-live for contexts
delta_ttl: :timer.hours(24), # Time-to-live for deltas
delta_threshold: 100, # Number of deltas to retain
delta_formatter: Chord.Delta.Formatter.Default, # Format for deltas
time_provider: Chord.Utils.Time, # Time provider for consistent timestamps
export_callback: nil, # Optional: Define a callback for exporting contexts
context_external_provider: nil # Optional: Define a function for fetching external contexts
```
---
## 🎹 How to Use Chord
### Setting a Context
```elixir
{:ok, result} = Chord.set_context("user:123", %{status: "online"})
IO.inspect(result, label: "Context Set")
```
### Updating a Context
```elixir
{:ok, result} = Chord.update_context("user:123", %{status: "away"})
IO.inspect(result, label: "Context Updated")
```
### Synchronizing State
```elixir
case Chord.sync_context("user:123", nil) do
{:full_context, context} -> IO.inspect(context, label: "Full Context")
{:delta, delta} -> IO.inspect(delta, label: "Delta Update")
{:no_change, version} -> IO.puts("No changes for version #{version}")
end
```
### Exporting a Context
```elixir
:ok = Chord.export_context("user:123")
```
### Restoring a Context
```elixir
{:ok, restored_context} = Chord.restore_context("user:123")
IO.inspect(restored_context, label: "Restored Context")
```
### Cleanup Operations
Run periodic cleanup to remove stale data:
```elixir
Chord.cleanup(limit: 50)
```
### Managing the Cleanup Server
Start and manage the Cleanup Server for automated periodic cleanup:
```elixir
{:ok, _pid} = Chord.start_cleanup_server(interval: :timer.minutes(30))
Chord.update_cleanup_interval(:timer.minutes(60))
Chord.update_cleanup_backend_opts(limit: 100)
Chord.stop_cleanup_server()
```
---
## 🛠️ Customization
### Backends
Chord supports multiple backends out-of-the-box:
- **ETS** (In-Memory)
- **Redis** (Distributed)
You can implement your own backend by adhering to the `Chord.Backend.Behaviour`.
### Delta Formatters
Customize how deltas are structured by implementing the `Chord.Delta.Formatter` behaviour.
## ⚡ Features at a Glance
| Feature | Description |
|--------------------------|--------------------------------------------------|
| **Real-Time Sync** | Delta-based and full-context synchronization. |
| **Customizable Backends**| Redis, ETS, or your own custom backend. |
| **Periodic Cleanup** | Automatically remove stale data. |
| **Partial Updates** | Update only specific fields in a context. |
| **Delta Tracking** | Efficiently track and retrieve state changes. |
| **Context Export** | Export context to external storage. |
| **Context Restore** | Restore context from external providers. |
---
## 🕰 Benchmark Results
Chord has been benchmarked using Redis and ETS backends under both stateless and stateful architectures. Below are the results for various scenarios:
### Redis Benchmark Results
#### With Input Data
| Scenario | IPS | Avg. Time | Deviation | Median Time | 99th Percentile |
|------------------------------------------------------|--------|-----------|-----------|-------------|-----------------|
| Stateless - Single Context (50 participants) | 62.79 | 15.93 ms | ±18.03% | 15.88 ms | 22.99 ms |
| Stateful - Single Context (50 participants) | 7.69 | 130.07 ms | ±51.34% | 102.08 ms | 270.40 ms |
| Stateless - Multiple Contexts (100 contexts) | 2.08 | 481.38 ms | ±3.48% | 474.73 ms | 511.20 ms |
| Stateful - Multiple Contexts (100 contexts) | 1.85 | 541.19 ms | ±3.51% | 541.24 ms | 566.32 ms |
**Comparison:**
- Stateless - Single Context: 62.79x faster than Stateful - Multiple Contexts.
### ETS Benchmark Results
#### With Input Data
| Scenario | IPS | Avg. Time | Deviation | Median Time | 99th Percentile |
|------------------------------------------------------|--------|-----------|-----------|-------------|-----------------|
| Stateless - Single Context (50 participants) | 151.19 | 6.61 ms | ±20.47% | 6.46 ms | 14.43 ms |
| Stateful - Single Context (50 participants) | 29.56 | 33.82 ms | ±13.06% | 36.05 ms | 45.56 ms |
| Stateless - Multiple Contexts (100 contexts) | 3.51 | 284.85 ms | ±14.28% | 279.17 ms | 405.34 ms |
| Stateful - Multiple Contexts (100 contexts) | 3.73 | 268.05 ms | ±23.67% | 237.10 ms | 374.59 ms |
**Comparison:**
- Stateless - Single Context: 43.07x faster than Stateful - Multiple Contexts.
### Device Information
| Property | Value |
|----------------------------|--------------------------|
| **Operating System** | macOS |
| **CPU Information** | Apple M4 Pro |
| **Number of Cores** | 12 |
| **Available Memory** | 24 GB |
| **Elixir Version** | 1.17.3 |
| **Erlang Version** | 27.1.2 |
| **JIT Enabled** | True |
**Benchmark Suite Configuration:**
- **Warmup:** 2 seconds
- **Execution Time:** 5 seconds
- **Parallel:** 1
- **Inputs:** Data
---
## 🧰 Contributing
Contributions from the community are welcome to make Chord even better! Whether it's fixing bugs, improving documentation, or adding new features, your help is greatly appreciated.
### How to Contribute
1. Fork the repository.
2. Create a new branch for your changes.
3. Make your changes and test them thoroughly.
4. Submit a pull request with a clear description of your changes.
Feel free to open issues for discussion or if you need help. Together, we can build something amazing!
---
## 🛡️ Testing
Chord comes with a robust suite of tests to ensure reliability. Run tests with:
```bash
mix test
```
---
🎵 *"Let Chord orchestrate your state management with precision and elegance."*
