facebook/watchman
Watchman
Watchman is a filesystem change monitor and recursive directory watcher that operates as a background service to track file modifications in real time. It functions as an event-driven file trigger and state query engine, allowing users to retrieve directory snapshots and lists of changed files since a previous check.
The project provides tooling for incremental builds by identifying exactly which files have changed to compile only necessary project components. It is designed for large scale directory watching, monitoring massive file trees while executing external commands or scripts automatically when detected changes occur within monitored root folders.
The service covers real-time file monitoring, filesystem state querying, and event-driven task automation. It supports subscribing to notifications for file changes and triggering automated actions based on specific events.
Features
- File System Monitors - Tracks modifications to files and directories in real time to trigger automated actions.
- Filesystem Change Monitors - Provides a background service that tracks filesystem modifications in real time to trigger automated actions.
- Filesystem Snapshots - Creates point-in-time baselines of directory trees to compare against future filesystem changes.
- Filesystem State Querying - Retrieves lists of changed files and current directory snapshots to determine processing needs.
- Incremental State Tracking - Records only the differences between filesystem snapshots to minimize the data transmitted to clients.
- Event-Driven Automation Engines - Executes external commands or scripts automatically based on detected filesystem changes.
- Filesystem State Query Engines - Provides a utility for retrieving lists of changed files and directory snapshots since a previous check.
- Incremental Build Engines - Identifies exactly which files changed to allow for the execution of only necessary build steps.
- Build Triggers - Initiates automated build or restart tasks immediately after source code files are modified.
- Event-Driven Triggers - Functions as a system that executes external commands automatically in response to filesystem events.
- Action Triggers - Executes specific external commands or scripts automatically when filesystem changes are detected.
- Large Scale Directory Watching - Efficiently monitors massive file trees for changes without consuming excessive system memory or CPU.
- Directory Watchers - Monitors large directory trees recursively and provides querying capabilities for the current filesystem state.
- Background Daemons - Operates as a background daemon process that maintains long-lived state and handles multiple client connections.
- Real-time Change Tracking - Tracks changes to files and directories in real time to trigger automated tasks or update states.
- Kernel Event Polling - Listens for filesystem change notifications via OS kernels to avoid expensive manual directory scanning.
- Path-Based Subscriptions - Tracks changes by associating specific directory paths with interested clients and their notification preferences.
- Alert Notification Systems - Allows clients to register for real-time alerts when file changes occur within a monitored root.
- File System Utilities - File watching and change triggering.
- Orchestration And Workflow - Service for watching file changes and triggering actions.
- Mobile Device Management and Utilities - Watches file systems and triggers actions on changes.
- Terminal Utilities - Watches files and triggers actions on changes.
- Version Control Add-ons - Triggers incremental builds when files change.
