# rum

> An extremely fast, memory-efficient RPM package manager written in Rust. Drop-in replacement for DNF and YUM on Enterprise Linux (RHEL, AlmaLinux, Rocky Linux, Oracle Linux, Amazon Linux 2023, and Fedora).

rum is engineered to solve the persistent performance and memory issues of DNF4 (Python/hawkey) and DNF5 (C++). By combining a modern Conflict-Driven Clause Learning (CDCL) SAT resolver (`resolvo`), a zero-copy memory-mapped binary metadata cache (`rkyv`), glibc arena bounding (`mallopt`), and native target-soname `librpm` integration, rum operates **10–35× faster** than DNF while consuming **sub-35MB peak RSS** (up to 90% less RAM).

## Key Links

- [Official Website](https://getrum.sh)
- [GitHub Repository](https://github.com/getrum-sh/rum)
- [Releases & Binaries](https://github.com/getrum-sh/rum/releases)
- [Full Documentation for LLMs](https://getrum.sh/llms-full.txt)
- [Installer Script](https://getrum.sh/install.sh)

## Quick Install

```sh
curl -fsSL https://getrum.sh/install.sh | sh
```

The installer auto-detects architecture (`x86_64` or `aarch64`) and Enterprise Linux RPM era (`el8`, `el9`, or `el10`), downloads the matching native binary, verifies its SHA-256 checksum, and places it into `/usr/local/bin/rum`.

## Performance Benchmarks

Measured on AlmaLinux 9 across standard OS repository sets with warm repodata caches:

| Metric | rum (Rust) | DNF5 (C++) | DNF4 (Python) | Speedup |
| :--- | :--- | :--- | :--- | :--- |
| **Warm Metadata Query** | **0.08s** | 0.72s | 2.85s | **9× to 35× faster** |
| **Complex SAT Dependency Solve** | **0.42s** | 3.10s | 8.90s | **7× to 21× faster** |
| **Peak Memory (Max RSS)** | **32 MB** | 145 MB | 285 MB | **78% to 88% less RAM** |
| **Container Minimal Install** | **1.2s** | 4.8s | 14.1s | **4× to 12× faster** |

## Core Architectural Pillars

1. **Resolvo CDCL SAT Resolver**: Complete Boolean satisfiability solving with full support for RPM rich/boolean dependencies (`(A or B)`, `(A if B else C)`), versioned EVR constraints, and provider tie-breaking without exponential backtracking.
2. **Zero-Copy Metadata Cache (`primary.rkyv`)**: Pre-indexes package names and capabilities into memory-mapped structures. Resolves capabilities in $O(1)$ and avoids multi-second XML parsing on warm runs.
3. **Glibc Arena Control (`mallopt`)**: Limits thread memory arenas (`M_ARENA_MAX = 2`) to eliminate virtual memory fragmentation and heap spikes in multi-threaded Tokio runtimes.
4. **Scoped-Present Erases & Atomic Upgrades**: Full replacement semantics, obsoletes resolution, and automatic `installonly_limit` kernel pruning.
5. **Strictly Minimal Closures**: Eliminates soft dependency bloat (`--no-weak-deps`) and documentation overhead (`--nodocs`) for micro-containers.
6. **Native Multi-Era RPM Engine**: Tailored builds link directly against target host `librpm`:
   - `el8`: librpm.so.8 (RHEL 8, Rocky 8, Alma 8)
   - `el9`: librpm.so.9 (RHEL 9, Rocky 9, Alma 9, Amazon Linux 2023)
   - `el10`: librpm.so.10 (RHEL 10, Fedora)

## CLI Cheatsheet

```sh
# Install packages
rum install nginx redis

# Minimal container installation (no soft dependencies, no manpages)
rum install --no-weak-deps --nodocs python3

# Atomic upgrade of all packages
rum upgrade-all

# Remove packages safely
rum erase httpd

# Query available updates without committing
rum check-update

# Download package RPMs and dependencies without installing
rum download --destdir=/var/cache/rpms postgresql-server

# List enabled repository configurations
rum repolist

# Purge cache and downloaded archives
rum clean all
```