added is_leaf flag, optimized iterators, inlined functions

[mjao1]

Major changes:

• Added an is_leaf flag, which quickly checks if a node is leaf without calling get_first_child (since most of the runtime is stuck on it).
• Adjusted bit allocations to fit the is_leaf flag without exceeding the limit (CHUNK_BITS: 50 -> 49, SHORT_DELTA: 18 -> 17).
• Optimized pre-order traversal and const_pre_order_interator by replacing calls to get_first_child with checks to is_leaf.
• In methods that add children, set is_leaf to false for the parent node, in delete_leaf, check if the parent node becomes a leaf after deletion and update is_leaf if so, in delete_subtree, use is_leaf in the deletion process.

Minor changes:

• Marked functions as inline to suggest inlining to the compiler.
• Minor changes to relevant methods to maintain is_leaf correctness.

Summary by CodeRabbit

• New Features

  • Introduced a new is_leaf flag in the tree structure to better manage leaf nodes.
  • Added getter and setter methods for the is_leaf attribute.

• Improvements

  • Enhanced traversal methods to accurately handle leaf nodes.
  • Optimized performance with inline functions for various tree operations.

• Bug Fixes

  • Adjusted logic for updating the is_leaf flag when children are added or removed.

[coderabbitai]

Walkthrough

The changes in this pull request focus on the Tree_pointers and tree classes within hhds/tree.hpp. Modifications include the reduction of constants CHUNK_BITS and SHORT_DELTA, the addition of a boolean member variable is_leaf, and the introduction of corresponding getter and setter methods. The logic for managing child pointers is updated to reflect the leaf status of nodes. Additionally, traversal methods are enhanced to utilize the is_leaf flag, and several inline functions are introduced to improve performance.

Changes

File

Change Summary

hhds/tree.hpp

- Reduced CHUNK_BITS from 50 to 49 and SHORT_DELTA from 18 to 17. - Added bool is_leaf variable. - Introduced get_is_leaf() and set_is_leaf(bool leaf) methods. - Updated method signatures to inline for get_parent, is_leaf, get_last_child, get_first_child, is_last_child, is_first_child, get_sibling_next, and get_sibling_prev. - Modified logic for child pointer management to update is_leaf appropriately.

Possibly related PRs

• Change explicit bit fields to a packed 128-bit int for the short pointers (v2) #60: The changes in this PR involve modifications to the Tree_pointers class, specifically the consolidation of short pointers into packed 128-bit integers, which relates to the changes made to the Tree_pointers class in the main PR regarding the management of child pointers and the addition of the num_short_del_occ variable.

🐇 In the trees where the shadows play,
A leaf's true nature finds its way.
With pointers adjusted, paths now clear,
The forest whispers, "Have no fear!"
So hop along, dear friend, with glee,
For every leaf holds a tale, you see! 🌳✨

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[github-actions]

Nice job creating a pull request for the first time for HHDS. Thanks for the help

[coderabbitai]

Actionable comments posted: 0

🧹 Outside diff range and nitpick comments (1)

hhds/tree.hpp (1)

991-991: Address the TODO in get_sibling_prev regarding chunk edge cases

There is a TODO comment indicating that handling cases where previous siblings could be within the same chunk but more than one offset away is not implemented. This scenario can occur if a node is deleted from the middle of a chunk.

Would you like assistance in implementing this functionality? I can help generate a solution or open a GitHub issue to track this task.

📜 Review details

Configuration used: CodeRabbit UI
Review profile: CHILL

📥 Commits

Reviewing files that changed from the base of the PR and between c9cd73f and e13c9ca.

📒 Files selected for processing (1)

• hhds/tree.hpp (29 hunks)

🔇 Additional comments (12)

hhds/tree.hpp (12)

55-56: Constants adjusted appropriately to accommodate is_leaf flag

The adjustments to CHUNK_BITS and SHORT_DELTA maintain the 512-bit total limit for Tree_pointers, ensuring the addition of the is_leaf flag doesn't exceed the intended size.

---

77-79: Addition of is_leaf flag enhances performance

Introducing the is_leaf flag allows for a quick check of leaf nodes without invoking get_first_child(), improving traversal efficiency.

---

Line range hint 115-127: Proper initialization of is_leaf in constructors

Setting is_leaf to true in both the default and parameterized constructors ensures new nodes are correctly identified as leaves until they have children added.

---

145-147: Getter and setter for is_leaf maintain encapsulation

Providing get_is_leaf() and set_is_leaf() methods allows controlled access to the is_leaf flag, adhering to good encapsulation practices.

Also applies to: 162-164

---

169-169: Include is_leaf in equality comparison

Adding is_leaf to the operator== ensures that all aspects of Tree_pointers are considered during comparisons, maintaining object equality integrity.

---

258-260: Correctly update is_leaf flag when adding children

The is_leaf flag is appropriately set to false when a node gains children, ensuring accurate representation of the tree structure.

Also applies to: 275-277, 303-307, 333-335, 1161-1163

---

1249-1252: Set is_leaf to true when a node becomes a leaf after deletion

When a node loses all its children through deletion, the is_leaf flag is correctly updated to reflect its new leaf status.

---

402-402: Include Is Leaf status in debug output

Adding the Is Leaf information in the print_tree() method enhances debugging by providing visibility into the leaf status of nodes.

---

551-553: Optimize traversal methods using is_leaf flag

Updating traversal iterators to utilize the is_leaf flag reduces unnecessary function calls to get_first_child(), improving traversal performance.

Also applies to: 625-630, 696-701, 753-758

---

812-812: Inlined frequently used methods for performance

Marking get_parent() and is_leaf() as inline can help reduce function call overhead, improving execution speed for these commonly used methods.

Also applies to: 827-830

---

1125-1126: Initialize num_short_del_occ to zero in add_root

Setting num_short_del_occ to 0 when adding the root node ensures that the root's occupancy is correctly initialized.

---

750-758: Update const_post_order_iterator to use is_leaf

Modifying the const_post_order_iterator to utilize the is_leaf flag streamlines the post-order traversal, improving efficiency.

Also applies to: 762-770