feat(container/gtree): Add the function of popping left and right nodes of red-black tree

[LanceAdd]

摘要

为 RedBlackKVTree（泛型）和 RedBlackTree（非泛型）新增 PopLeft 和 PopRight 方法，支持原子地弹出最小和最大节点。

动机

现有的 Left/Right 方法只能查看极值节点，删除需要再调用 Remove(node.Key)。这两步之间存在竞争窗口：

// 之前：两步操作，非原子
node := m.Left()
v := m.Remove(node.Key)

// 之后：一步操作，原子
node := m.PopLeft()

该模式与 garray.PopLeft/garray.PopRight 保持一致，使 RedBlackKVTree 可以作为并发安全的优先级队列使用，替代 container/heap 且具有更好的类型安全。

实现

两个方法在内部持有写锁，并直接操作底层数据结构，避免调用公开的 Left/Right（会重复加锁导致死锁）：

func (tree *RedBlackKVTree[K, V]) PopLeft() *RedBlackKVTreeNode[K, V] {
    tree.mu.Lock()
    defer tree.mu.Unlock()
    node := tree.tree.Left()     // gods 库原生 Left，不经过 GoFrame 锁
    if node == nil { return nil }
    tree.doRemove(node.Key)      // 内部无锁方法
    return &RedBlackKVTreeNode[K, V]{...}
}

变更文件

文件	变更内容
container/gtree/gtree_k_v_redblacktree.go	新增泛型版 PopLeft、PopRight
container/gtree/gtree_redblacktree.go	新增非泛型版，委托至泛型实现

示例

m := gtree.NewRedBlackKVTree[int, string](gutil.ComparatorT[int], true)
m.Set(3, "c")
m.Set(1, "a")
m.Set(2, "b")

node := m.PopLeft()  // {1, "a"}, O(log n), 原子操作
node = m.PopLeft()   // {2, "b"}
node = m.PopRight()  // {3, "c"}

[Copilot]

Pull request overview

This PR adds atomic “pop” operations to GoFrame’s red-black tree containers (container/gtree), enabling callers to remove-and-return the current minimum/maximum element in a single concurrency-safe operation (aligning with garray.PopLeft/PopRight usage patterns).

Changes:

• Add PopLeft/PopRight to RedBlackKVTree[K,V], removing and returning min/max nodes under a write lock.
• Add PopLeft/PopRight to non-generic RedBlackTree, delegating to the generic implementation after lazyInit().

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
container/gtree/gtree_k_v_redblacktree.go	Implements PopLeft/PopRight on the generic red-black tree with write locking and internal removal.
container/gtree/gtree_redblacktree.go	Adds non-generic PopLeft/PopRight wrappers delegating to the generic tree after lazy initialization.

Comments suppressed due to low confidence (1)

container/gtree/gtree_k_v_redblacktree.go:548

• PopRight already has the right-most node (including its Value), but calling doRemove(node.Key) does an extra tree.Get before removing. This adds an extra O(log n) lookup on every pop; you can remove the key directly here since the value is already known.

	node := tree.tree.Right()
	if node == nil {
		return nil
	}
	tree.doRemove(node.Key)
	return &RedBlackKVTreeNode[K, V]{
		Key:   node.Key,
		Value: node.Value,
	}

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