kellydunn / go-art Goto Github PK

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an adaptive radix tree implementation in go

License: MIT License

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yriveiro nick-codes fredim repustate telles-simbiose bonedaddy helmutkemper isgasho rosegaller

go-art's Issues

License?

Interesting implementation of an interesting concept, but what is the license? Can I use it?

Trim Size of Node members

anachronistic [3:18 PM] 
@kellydunn looking at `ArtNode` (thinking about allocations, etc.) you can shave 8 bytes off regardless of platform by reordering the struct members

anachronistic [3:19 PM] 
type ArtNode struct {
    keys      []byte
    prefix    []byte
    children  []*ArtNode
    prefixLen int
    size      uint8
    nodeType  uint8
    key       []byte
    keySize   uint64
    value     interface{}
} // 72 on 32-bit, 136 on 64-bit

Coupled with the findings at github.com/tv42/benchmark-ordered-map , this lib could dramatically reduce the number of bytes allocated for searching and inserting.

Acceptance criteria:

Change order of node members for optimum spacing
Re-run benchmarks to ensure space savings
Add some sort of test or benchmarking to ensure optimum size of nodes in future.

Go module support

It would be great if this repo could support go modules (and semantically versioned git tags).
Thanks,
Ben

Add a way to search by prefix

It is often useful to look up the set of nodes with a common prefix.

No method to get key from a node?

This makes e.g. iterating the tree a bit pointless; you can't even round-trip a map[string]string to ART and back (without kludges).

Add tree size function

It would be great to have a tree size function to return the number of nodes in the tree.

Crash after inserting >100 keys

package main

import (
    "encoding/binary"
    "math/rand"

    "github.com/kellydunn/go-art"
)

func main() {
    rand.Seed(42)
    key := make([]byte, 8)
    tree := art.NewArtTree()
    for i := 0; i < 135; i++ {
        binary.BigEndian.PutUint64(key, uint64(rand.Int63()))
        tree.Insert(key, key)
    }
}

$ go run bug.go 
panic: runtime error: index out of range

goroutine 1 [running]:
github.com/kellydunn/go-art.(*ArtTree).insertHelper(0xc20800a1f0, 0xc20803f170, 0xc20805c3b0, 0xc20800aca0, 0x9, 0x10, 0x483380, 0xc20801f5c0, 0x1)
    /home/tv/go/src/github.com/kellydunn/go-art/art_tree.go:115 +0x619
github.com/kellydunn/go-art.(*ArtTree).insertHelper(0xc20800a1f0, 0xc20803e090, 0xc20800a1f0, 0xc20800aca0, 0x9, 0x10, 0x483380, 0xc20801f5c0, 0x0)
    /home/tv/go/src/github.com/kellydunn/go-art/art_tree.go:170 +0xde7
github.com/kellydunn/go-art.(*ArtTree).Insert(0xc20800a1f0, 0xc20800aca0, 0x9, 0x10, 0x483380, 0xc20801f5c0)
    /home/tv/go/src/github.com/kellydunn/go-art/art_tree.go:62 +0xa9
main.main()
    /home/tv/tmp/max.go:16 +0x154

goroutine 2 [runnable]:
runtime.forcegchelper()
    /home/tv/src/go1.4/src/runtime/proc.go:90
runtime.goexit()
    /home/tv/src/go1.4/src/runtime/asm_amd64.s:2232 +0x1

goroutine 3 [runnable]:
runtime.bgsweep()
    /home/tv/src/go1.4/src/runtime/mgc0.go:82
runtime.goexit()
    /home/tv/src/go1.4/src/runtime/asm_amd64.s:2232 +0x1

goroutine 4 [runnable]:
runtime.runfinq()
    /home/tv/src/go1.4/src/runtime/malloc.go:712
runtime.goexit()
    /home/tv/src/go1.4/src/runtime/asm_amd64.s:2232 +0x1
exit status 2

Unicode strings with zero-byte values inside the key cannot be inserted

As discovered by @nick-codes, it looks like inserting a unicode key into a new ArtTree panics with an index out of range error.

Here's some code to reproduce the error:

// Tests a Unicode insertion.
func TestArtTreeInsertWithInternalZeroByte(t *testing.T) {
    tree := NewArtTree()

    // ‘a' followed by unicode accent character.
    accent := []byte{0x61, 0x00, 0x60}
    tree.Insert([]byte("a"), "a")
    tree.Insert(accent, string(accent))

    res := tree.Search(accent)
    if res == nil {
        t.Errorf("Could not find Leaf Node with expected key: '%s'", accent)
    } else {
        if !bytes.Equal(res.([]byte), accent) {
            t.Error("Unexpected search result.")
        }
    }
}

Acceptance critieria:

A user can insert a unicode string with an empty byte value inside of it.

Inserted Key needs to be preserved and accessible by the current Node

As requested by a few users, it seems like it would be pretty useful to access the inserted key of the current node. Currently, this isn't possible because the path compression implementation alters the key so it's null terminated to differentiate between an internal node and a leaf node.

Suggested implementation:

Add another field to each Leaf Node such that it can remember the actual key it was inserted in.
Provide a Getter function that returns the original Key of the current node.

kellydunn / go-art Goto Github PK

go-art's People

Contributors

Stargazers

Watchers

Forkers

go-art's Issues

License?

Trim Size of Node members

Go module support

Add a way to search by prefix

No method to get key from a node?

Add tree size function

Crash after inserting >100 keys

Unicode strings with zero-byte values inside the key cannot be inserted

Inserted Key needs to be preserved and accessible by the current Node

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