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Implement Condition Variable from Scratch

hard6/10

Implement Reader-Writer Lock from Scratch Write Thread Pool: Fixed-Size Pool of Workers Consuming Task Queue

Language

Compiler

2.0s Limit 256MB

Implementation

Implement condition variable with mutex.

Requirements:

cond_wait(mutex, cond): atomic unlock+sleep
cond_signal(cond): wake one waiter
cond_broadcast(cond): wake all waiters
Use mutex for protection
Handle spurious wakeups
Test with producer-consumer
Test with broadcast

Success Criteria:

Consumer blocks when queue empty
Producer wakes consumer
Broadcast wakes all consumers
No missed signals

Why This Matters

This exact wait/signal pattern is what powers `pthread_cond_wait` in glibc, Java's `Object.wait()/notify()`, and every bounded producer-consumer queue in real message brokers like RabbitMQ's internal worker pools. The 'always recheck in a while loop, never an if' rule you'll apply here guards against spurious wakeups, a documented POSIX behavior that has caused real intermittent bugs in code that assumed a single wakeup always means the condition holds.

Hints

0 / 3 revealed

Validation Suite

main.c

Workspace 1.0