Fixing a potential segfault in tag transactions (when the lru_cache was full, existing references would get dropped)

pmeunier

Jan 7, 2022, 6:45 PM

F2ZG4ZYOQLGYMBCB2EAZAI7XTYZGJ2ZIJW4IJ6JG6JYGWOVXD3LQC

Dependencies

• [2] AETYXHGO Using an LruCache instead of a HashMap for loaded pages in a tag
• [3] N3X5YP7P Adding tag/txn.rs, now that the parser allows it

Change contents

• edit in libpijul/src/tag/txn.rs at line 3
  [3.98]

  [3.148]
  + use std::collections::HashMap;
• edit in libpijul/src/tag/txn.rs at line 5
  [3.170]→[2.0:60](∅→∅)
  −

  − /// Size of the LRU cache.

  − const CACHE_SIZE: usize = 1024;
• replacement in libpijul/src/tag/txn.rs at line 32
  [3.788]→[2.61:141](∅→∅)
  − loaded: Mutex<lru_cache::LruCache<u64, Box<[u8; crate::tag::BLOCK_SIZE]>>>,
  [3.788]

  [3.856]
  + loaded: Mutex<HashMap<u64, Box<[u8; crate::tag::BLOCK_SIZE]>>>,
• replacement in libpijul/src/tag/txn.rs at line 71
  [2.588]→[2.588:658](∅→∅)
  − loaded: Mutex::new(lru_cache::LruCache::new(CACHE_SIZE)),
  [2.588]

  [3.1879]
  + loaded: Mutex::new(HashMap::new()),
• edit in libpijul/src/tag/txn.rs at line 78
  [3.2028]

  [3.2028]
  + }

  +

  + /// Clear the cache, freeing memory.

  + pub fn clear(&mut self) {

  + // This function is only safe because it takes a mutable

  + // borrow, and all references returned by the methods on

  + // `TagTxn` return immutable borrows of `self`.

  + self.loaded.lock().unwrap().clear()