Lock Table

Project Hierarchy

Project Overview

• Your task is to implement a lock table module that manages lock objects of multiple threads.
• The module doesnt need to be compatible with your developing database in this step.
• Instead, the module should be correctly working with the given test code.
• This project is a prerequisite step for the next project, Concurrency Control.
• Design your lock table and describe it on hconnect Wiki

Overall Architecture

(mutex)

Overall Architecture

Lock Table APIs

int init_lock_table(void)

• Initialize any data structures required for implementing lock table, such as hash table, lock table latch, etc.
• If success, return 0. Otherwise, return non-zero value.

lock_t* lock_acquire(int table_id, int64_t key)

• Allocate and append a new lock object to the lock list of the record having the
• If there is a predecessors lock object in the lock list, sleep until the predecessor to release its lock.
• If there is no predecessors lock object, return the address of the new lock object.
• If an error occurs, return NULL.

int lock_release(lock_t* lock_obj)

• Remove the lock_obj from the lock list.
• If there is a successors lock waiting for the thread releasing the lock, wake up the successor.
• If success, return 0. Otherwise, return non-zero value.

Lock Table APIs

Hash Table

elements

Lock List

lock_acquire()

lock_acquire()

lock_release()

Lock Object

• The given test code will
• call init_lock_table() API function,
• create multiple threads each of which
• repeatedly acquire and release multiple record locks by calling lock_acquire(), lock_release().
• The test code will safely schedule the operations avoiding deadlock, so you dont have to deal with the deadlock problem in this project.
• Analyze the test code as much as you want.

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Scan thread

Deadline & Regulations

• Deadline: Nov 15 11:59pm
• Well only score your commit before the deadline, and your submission after the deadline will not be accepted.
• You must follow the given project hierarchy and the path of the

unittest_lock_table executable file, otherwise, you cannot get a score.

Thank you