What are read-write locks and can you show me some code examples?

What are read-write locks and can you show me some code examples?

Read-write locks allow concurrent access for reading and exclusive access for writing. Here's a simple example in Python.

Can you provide a code snippet for a read-write lock in Python?

Sure! Here's a basic implementation using the threading module:

import threading

class ReadWriteLock:
    def __init__(self):
        self.readers = 0
        self.lock = threading.Lock()
        self.write_lock = threading.Lock()

    def acquire_read(self):
        with self.lock:
            self.readers += 1
            if self.readers == 1:
                self.write_lock.acquire()

    def release_read(self):
        with self.lock:
            self.readers -= 1
            if self.readers == 0:
                self.write_lock.release()

    def acquire_write(self):
        self.write_lock.acquire()

    def release_write(self):
        self.write_lock.release()

This allows multiple readers or one writer at a time.

How does this implementation handle multiple threads?

The ReadWriteLock class uses a combination of locks to ensure that multiple threads can read simultaneously, but only one can write at a time. The acquire_read method increments the reader count and only blocks writers when the first reader acquires the lock. Conversely, the acquire_write method ensures exclusive access for writing.