GoBeansDB

Why

CArray

type CArray struct {
    Body []byte
    Addr uintptr
    Cap  int
}

A: 这里数据结构是重复的，为什么这么做？

Q: 用C来管理内存，减少 GC 压力

// HStore

type HStore struct {
    buckets   []*Bucket
    gcMgr     *GCMgr
    htree     *HTree
    htreeLock sync.Mutex
}

// HTree
type HTree struct {
    sync.Mutex

    /*
     *            Root of hstore.tree
     *               /  | ... \
     *              /   |      \
     * depth -->  ht1  ht2     htN     # root of bucket trees (also are the leafs of hstore tree)
     *             ^
     *             |
     *            pos
     *
     * #bucket (number of buckets) = 16 ^ bucket_tree.depth
     */

    // depth is level (0-based) of root Node (of this htree) in hstore.tree
    depth int

    // bucketID is position (offset) of this htree in the list of htrees at same level.
    bucketID int

    /* runtime */

    // level[0][0] is root of a htree,
    // levels[i] is a list of nodes at same level `i` of htree,
    // Node stores the summary info of its childs.
    // Height of htree = len(levels)
    levels [][]Node

    // leafs is the place to store key related info (e.g. keyhash, version, vhash etc.)
    leafs []SliceHeader

    // tmp, to avoid alloc
    ni NodeInfo
}

type Node struct {
    // count is the number of keys (with version > 0) under this node.
    count uint32

    // hash is the summary of it's child nodes.
    hash uint16

    // isHashUpdated is true iff the hash value of node is updated.
    isHashUpdated bool
}

type NodeInfo struct {
    node   *Node
    level  int
    offset int
    path   []int
}

NOTE

htree.go::getLeafAndInvalidNodes // 看起来没有返回数据，但是更新了tree 的 ni