PR Server (prserv)

A high-performance Package Revision (PR) server for BitBake builds, rewritten in Rust with immediate SQLite persistence for reliability.

Features

• Configurable sync modes - Choose between immediate, periodic, or on-shutdown persistence for optimal performance/safety balance
• Async TCP server - High-performance async networking with tokio
• BitBake compatibility - Drop-in replacement for the Python prserv
• History and no-history modes - Supports both PR increment modes
• Read-only mode - Safe querying without modifications
• Structured logging - Comprehensive logging with tracing
• Type-safe errors - Rust's error handling for reliability

Architecture Improvements

This Rust implementation addresses key issues in the original Python prserv:

1. Configurable persistence: Choose sync mode based on your needs - immediate for safety, periodic for balance, or on-shutdown for speed
2. Better concurrency: Uses SQLite WAL mode for improved concurrent access
3. Memory safety: Rust's ownership system prevents common memory issues
4. Performance: Compiled binary with optimized SQLite operations and buffered writes

Installation

Build from source:

cargo build --release

The binary will be available at target/release/prserv.

Usage

Starting the Server

# Start server with default settings (localhost:8585, prserv.db)
prserv server

# Custom database and port
prserv server --database /path/to/prserv.db --bind 0.0.0.0:9090

# Read-only mode
prserv server --read-only

# No-history mode (no PR decrements)
prserv server --nohist

# Different sync modes
prserv server --sync-mode immediate        # Default: safest, writes immediately
prserv server --sync-mode periodic:30     # Balanced: flush every 30 seconds
prserv server --sync-mode on_shutdown     # Fastest: only sync on shutdown

Client Commands

# Get a PR value (creates if doesn't exist)
prserv client get-pr "1.0" "x86_64" "abc123hash"

# Test if PR exists
prserv client test-pr "1.0" "x86_64" "abc123hash"

# Check if package exists
prserv client test-package "1.0" "x86_64"

# Get maximum PR for package
prserv client max-package-pr "1.0" "x86_64"

# Import a PR value
prserv client import-one "1.0" "x86_64" "abc123hash" 42

# Export data
prserv client export --colinfo

# Check server status
prserv client ping
prserv client is-readonly

Database Schema

The server uses SQLite with the following table structure:

CREATE TABLE PRMAIN_hist (
    version TEXT NOT NULL,
    pkgarch TEXT NOT NULL,
    checksum TEXT NOT NULL,
    value INTEGER NOT NULL,
    PRIMARY KEY (version, pkgarch, checksum)
);

CREATE TABLE PRMAIN_nohist (
    version TEXT NOT NULL,
    pkgarch TEXT NOT NULL,
    checksum TEXT NOT NULL,
    value INTEGER NOT NULL,
    PRIMARY KEY (version, pkgarch, checksum)
);

Configuration

The server supports JSON/YAML configuration files:

# config.yaml
server:
  database: "/var/lib/prserv/prserv.db"
  bind_addr: "0.0.0.0:8585"
  read_only: false
  nohist: false
  sync_mode: immediate  # or periodic: { interval_secs: 30 } or on_shutdown
client:
  server_addr: "localhost:8585"

Protocol

The server implements a JSON-RPC style protocol over TCP:

Request Format

{
    "id": "unique-request-id",
    "method": "get-pr",
    "params": {
        "version": "1.0",
        "pkgarch": "x86_64",
        "checksum": "abc123hash"
    }
}

Response Format

{
    "id": "unique-request-id",
    "result": {"value": 42},
    "error": null
}

Supported Methods

• get-pr: Get/create PR value
• test-pr: Test if PR exists
• test-package: Test if package exists
• max-package-pr: Get maximum PR for package
• import-one: Import PR value
• export: Export PR data
• is-readonly: Check server mode
• ping: Health check

Differences from Python Version

1. Configurable sync modes: Choose between immediate, periodic, or on-shutdown persistence
2. WAL mode: Uses SQLite WAL journaling for better concurrency
3. Buffered writes: Periodic and on-shutdown modes use intelligent write batching
4. Better error handling: Type-safe error propagation
5. Async architecture: Non-blocking I/O for better performance

Sync Mode Details

Immediate Mode (Default)

• Safety: ⭐⭐⭐⭐⭐ Highest - Every write is immediately committed to disk
• Performance: ⭐⭐ Slowest - Each operation waits for disk I/O
• Use case: Production builds where data integrity is critical

Periodic Mode

• Safety: ⭐⭐⭐⭐ High - Writes are flushed every N seconds
• Performance: ⭐⭐⭐⭐ Balanced - Good throughput with regular safety checkpoints
• Use case: Development/CI environments with moderate safety requirements
• Configuration: --sync-mode periodic:30 (flush every 30 seconds)

On-Shutdown Mode

• Safety: ⭐⭐ Lowest - Data only written on graceful shutdown
• Performance: ⭐⭐⭐⭐⭐ Fastest - All writes are buffered in memory
• Use case: Testing or temporary builds where speed matters most
• Risk: Data loss if process crashes or is killed ungracefully

Development

Building

cargo build

Testing

cargo test

Running with logs

RUST_LOG=debug cargo run -- server

Environment Variables

You can configure the server using environment variables:

# Server configuration
export PRSERV_DATABASE="/var/lib/prserv/prserv.db"
export PRSERV_BIND_ADDR="0.0.0.0:8585"
export PRSERV_READ_ONLY="false"
export PRSERV_NOHIST="false"
export PRSERV_SYNC_MODE="periodic:60"  # or "immediate" or "on_shutdown"

# Client configuration
export PRSERV_SERVER_ADDR="localhost:8585"

# Start server with environment config
prserv server

License

Apache-2.0