Examples¶

Blink includes several examples to help you get started. These examples demonstrate different ways to use Blink in your projects.

Simple Example¶

The simple example demonstrates how to use Blink as a library to watch a directory and print events to the console.

package main

import (
 "fmt"
 "os"
 "os/signal"
 "runtime"
 "syscall"
 "time"

 "github.com/TFMV/blink/pkg/blink"
)

func main() {
 // Set verbose mode to see events in the console
 blink.SetVerbose(true)

 // Directory to watch
 path := "."

 // Configure the number of CPUs to use
 maxProcs := runtime.NumCPU()
 if maxProcs > 4 {
  maxProcs = 4 // Limit to 4 CPUs for this example
 }
 runtime.GOMAXPROCS(maxProcs)

 // Print startup information
 fmt.Printf("Blink Example\n")
 fmt.Printf("------------\n")
 fmt.Printf("Watching directory: %s\n", path)
 fmt.Printf("Using %d CPUs\n", maxProcs)
 fmt.Printf("Press Ctrl+C to stop\n\n")

 // Create a channel to receive OS signals
 sigs := make(chan os.Signal, 1)

 // Register for SIGINT (Ctrl+C) and SIGTERM
 signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)

 // Create a new filesystem watcher
 watcher, err := blink.NewRecursiveWatcher(path)
 if err != nil {
  fmt.Printf("Error creating watcher: %v\n", err)
  os.Exit(1)
 }
 defer watcher.Close()

 // Create a channel to track events
 events := make(chan blink.Event, 100)

 // Start a goroutine to collect events
 go func() {
  for {
   select {
   case ev := <-watcher.Events:
    event := blink.Event(ev)
    events <- event
    fmt.Printf("Event: %s %s\n", event.Op.String(), event.Name)
   case err := <-watcher.Errors:
    fmt.Printf("Error: %v\n", err)
   }
  }
 }()

 fmt.Println("Watching for file changes. Events will be printed below:")
 fmt.Println("------------------------------------------------------")

 // Wait for a signal or for the watcher to exit
 <-sigs

 fmt.Println("\nShutting down...")
}

To run this example:

cd examples/simple
go run main.go

Web Example¶

The web example demonstrates how to use Blink with a web interface to display file changes in real-time.

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Blink File Watcher</title>
    <style>
        body {
            font-family: 'Inter', sans-serif;
            background-color: #f8f9fa;
            margin: 0;
            padding: 0;
            display: flex;
            justify-content: center;
            align-items: center;
            min-height: 100vh;
        }
        .container {
            background-color: #ffffff;
            border-radius: 6px;
            box-shadow: 0 4px 8px rgba(0, 0, 0, 0.05);
            padding: 2rem;
            width: 90%;
            max-width: 700px;
        }
        .page-title {
            font-size: 2.25rem;
            font-weight: 600;
            text-align: center;
            margin-bottom: 1.5rem;
            color: #2e86de;
        }
        .status-indicator {
            text-align: center;
            padding: 0.75rem 1.25rem;
            border-radius: 6px;
            font-weight: 500;
            margin-bottom: 1.5rem;
            transition: background-color 0.3s, color 0.3s;
        }
        .status-connected {
            background-color: #d4edda;
            color: #28a745;
            border: 1px solid #c3e6cb;
        }
        .status-disconnected {
            background-color: #f8d7da;
            color: #dc3545;
            border: 1px solid #f5c6cb;
        }
        .button-group {
            display: flex;
            justify-content: center;
            gap: 1rem;
            margin-bottom: 2rem;
        }
        .btn {
            padding: 0.6rem 1.5rem;
            font-size: 1rem;
            border: none;
            border-radius: 6px;
            cursor: pointer;
            transition: background-color 0.3s ease, transform 0.1s ease;
            font-weight: 500;
            text-transform: uppercase;
            letter-spacing: 0.5px;
            background-color: #2e86de;
            color: white;
        }
        .events-list {
            max-height: 400px;
            overflow-y: auto;
            border: 1px solid #dee2e6;
            border-radius: 6px;
            padding: 1rem;
            background-color: #f8f9fa;
        }
        .event-item {
            background-color: #ffffff;
            border: 1px solid #dee2e6;
            border-radius: 6px;
            padding: 0.75rem;
            margin-bottom: 0.75rem;
            box-shadow: 0 4px 8px rgba(0, 0, 0, 0.05);
        }
    </style>
</head>
<body>
    <div class="container">
        <h1 class="page-title">Blink File Watcher</h1>

        <div id="status" class="status-indicator status-disconnected">Disconnected</div>

        <div class="button-group">
            <button id="connect" class="btn">Connect</button>
            <button id="disconnect" class="btn">Disconnect</button>
            <button id="clear" class="btn">Clear Events</button>
        </div>

        <h2>File Change Events</h2>
        <div id="events" class="events-list"></div>
    </div>

    <script>
        let eventSource = null;
        const eventsContainer = document.getElementById('events');
        const statusElement = document.getElementById('status');
        const connectButton = document.getElementById('connect');
        const disconnectButton = document.getElementById('disconnect');
        const clearButton = document.getElementById('clear');

        // Connect to the event source
        function connect() {
            if (eventSource) {
                disconnect();
            }

            eventSource = new EventSource('http://localhost:12345/events');

            eventSource.onopen = function() {
                statusElement.textContent = 'Connected';
                statusElement.classList.remove('status-disconnected');
                statusElement.classList.add('status-connected');
                console.log('Connected to event source');
            };

            eventSource.onmessage = function(event) {
                console.log('Received event:', event.data);

                const eventElement = document.createElement('div');
                eventElement.className = 'event-item';

                const timeElement = document.createElement('div');
                timeElement.className = 'event-time';
                timeElement.textContent = new Date().toLocaleTimeString();
                eventElement.appendChild(timeElement);

                const pathElement = document.createElement('div');
                pathElement.className = 'event-path';
                pathElement.textContent = event.data;
                eventElement.appendChild(pathElement);

                eventsContainer.appendChild(eventElement);
                eventsContainer.scrollTop = eventsContainer.scrollHeight;
            };

            eventSource.onerror = function() {
                statusElement.textContent = 'Error connecting';
                statusElement.classList.remove('status-connected');
                statusElement.classList.add('status-disconnected');

                console.error('Error connecting to event source');
                disconnect();
            };
        }

        // Disconnect from the event source
        function disconnect() {
            if (eventSource) {
                eventSource.close();
                eventSource = null;
                statusElement.textContent = 'Disconnected';
                statusElement.classList.remove('status-connected');
                statusElement.classList.add('status-disconnected');
                console.log('Disconnected from event source');
            }
        }

        // Clear events
        function clearEvents() {
            eventsContainer.innerHTML = '';
        }

        connectButton.addEventListener('click', connect);
        disconnectButton.addEventListener('click', disconnect);
        clearButton.addEventListener('click', clearEvents);
    </script>
</body>
</html>

To use this example:

Start Blink:

blink

Open the HTML file in a web browser:

cd examples/web
# Open index.html in your browser

Click the "Connect" button to connect to the event stream.
Make some changes to files in the watched directory to see events appear in the web interface.

Custom Examples¶

Watching Multiple Directories¶

package main

import (
    "time"
    "github.com/TFMV/blink/pkg/blink"
)

func main() {
    // Start multiple watchers
    go blink.EventServer(
        "/path/to/dir1",
        "*",
        ":12345",
        "/events/dir1",
        100*time.Millisecond,
    )

    go blink.EventServer(
        "/path/to/dir2",
        "*",
        ":12345",
        "/events/dir2",
        100*time.Millisecond,
    )

    // Wait forever
    select {}
}

Custom Event Handling¶

package main

import (
    "fmt"
    "github.com/TFMV/blink/pkg/blink"
)

func main() {
    // Create a watcher
    watcher, err := blink.NewRecursiveWatcher(".")
    if err != nil {
        panic(err)
    }
    defer watcher.Close()

    // Handle events
    for {
        select {
        case event := <-watcher.Events:
            // Custom event handling
            if event.Op&blink.Write != 0 {
                fmt.Printf("File modified: %s\n", event.Name)
                // Do something with the modified file
            }
        case err := <-watcher.Errors:
            fmt.Printf("Error: %v\n", err)
        }
    }
}