roaringbitmap / swiftroaring Goto Github PK

Hello, did you consider adding support for base64 encoding to roaring? I imagine that fastbase64 would do the trick.

This is probably more of a croaring issue that SwiftRoaring but we discussed base64 encoding here.

Hello, I am trying to serialise a bloom filter generated in a roaring bitmap format to a base64 string, so that I can save it in MongoDB. But the function portableSerialize is a bit tricky for me.

I am so far just testing how it works and I generate a random bloom filter values that I later try to convert to buffer -> to data -> to base64:

func generateBloomFilterData(){
    let bitmap = RoaringBitmap()
    for i in 0..<50 { 
        let random = arc4random_uniform(2)
        if random == 0 {
            bitmap.add(UInt32(i))
        } 
    }  
    let count = (Int(bitmap.count) * MemoryLayout<Int8>.size)
    var buffer = [Int8](repeating: 0, count: count)
    _ = bitmap.portableSerialize(buffer: &buffer)
    let uintBuffer = buffer.map { UInt8(bitPattern: $0) }
    let bufferData = Data(uintBuffer)
    let base64String = bufferData()
    print("buffer size: \(buffer.count), \(uintBuffer.count), base64: \(bufferData.base64EncodedString())")
    //-> send base64 string to database
}

This generates an error:

malloc: MallocStackLogging: attempting to release an index out of
bounds

The console shows:

buffer size: 20, 20, base64: OjAAAAEAAAAAABMAEAAAAAMABQA=

Is there a way how to simply generate a base64 string out of the above generated RoaringBitmap() ?

I'm confused by the intended semantics of max. In the following example, we have two sets, one which contains a zero and one which is empty. However max returns 0 in both cases. How can I distinguish these cases? Am I supposed to be checking if the set is empty?

func testFirst() {
    // empty
    let a: RoaringBitmap = []
    print("empty")
    for e in a {
        print(e)
    }
    print("a max", a.max())

    // empty
    print("has 0")
    let b: RoaringBitmap = [0]
    for e in b {
        print(e)
    }

    print("b max", b.max())
}