A command-line utility for logging messages, counting log entries, and managing log rotation.

• TCP server with thread-based concurrency
• Continuous logging with timestamps
• Log file rotation
• File locking for concurrent access
• Log entry counting
• Live configuration updates using memory-mapped files

The program provides four commands:

1. run - Start the web server (listens for TCP connections)
2. count - Count the number of log entries
3. rotate - Rotate log files (renames http.log to http.1.log, etc.)
4. update-config - Update server configuration while running

To start the web server:

# Start server on default port (8080) with default threads (4)
cargo run -- run

# Start server on specific port with custom number of threads
cargo run -- run --port 3000 --threads 8

To count log entries:

cargo run -- count

To rotate log files:

cargo run -- rotate

To update server configuration:

# Update verbosity level
cargo run -- update-config --verbosity 2

# Update maximum connections
cargo run -- update-config --max-connections 200

# Update timeout
cargo run -- update-config --timeout 60

The server implements a simple text-based protocol:

1. Connect to the server using netcat:

# On macOS/Linux
nc localhost 8080

# On Windows (if you have netcat installed)
nc.exe localhost 8080

2. Send commands:

• hello server - Server responds with hello client
• Any other command - Server responds with unknown command

Log entries are formatted as:

[YYYY-MM-DD HH:MM:SS] message

The program maintains up to 5 log files:

• http.log (current log)
• http.1.log (most recent rotated log)
• http.2.log
• http.3.log
• http.4.log
• http.5.log (oldest rotated log, will be deleted on rotation)

When rotating logs:

1. http.5.log is deleted (if it exists)
2. Each log file is renamed to the next number (e.g., http.1.log → http.2.log)
3. http.log is renamed to http.1.log

When running the server:

• Creates a fixed-size thread pool at startup
• Each incoming connection is handled by a worker thread from the pool
• Threads share configuration through atomic reference counting
• Default thread pool size is 4, but can be configured at startup

The server uses memory-mapped files to share configuration between threads. Configuration parameters include:

• verbosity: Log verbosity level (0-3)
• max_connections: Maximum number of concurrent connections
• timeout_seconds: Connection timeout in seconds

Configuration changes are detected by worker threads in real-time, and they adjust their behavior accordingly. The configuration is stored in config.dat and is shared between all threads.

• Verbosity: 1
• Maximum Connections: 100
• Timeout: 30 seconds