The Mist
The Mist
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CC#
Created by The Mist on 4/27/2024 in #help
✅ :white_check_mark: Dictionary<int, ...> lookup time seems a bit too slow
I was profiling a program, and I saw this: 
100 % HasObject • 136 ms • 189 217 Calls • Engine.Runtime.Heap.HasObject(Int32)
    ↳ 50.3 % FindEntry • 68 ms • 189 217 calls • System.Collections.Generic.Dictionary`2.FindEntry(TKey)
100 % HasObject • 136 ms • 189 217 Calls • Engine.Runtime.Heap.HasObject(Int32)
    ↳ 50.3 % FindEntry • 68 ms • 189 217 calls • System.Collections.Generic.Dictionary`2.FindEntry(TKey)
Here is the code in question: 
private Dictionary<int, RawObjectType> _objectId_object_map = new Dictionary<int, RawObjectType>();

public bool HasObject(int id)  
{  
    return _objectId_object_map.ContainsKey(id);  
}
private Dictionary<int, RawObjectType> _objectId_object_map = new Dictionary<int, RawObjectType>();

public bool HasObject(int id)  
{  
    return _objectId_object_map.ContainsKey(id);  
}
136ms for 190,000 calls is translates to about 1,400 lookups per millisecond. That seems a little slow to me, is it not? If it is, why could this be? I figured looking up an int in a hashmap should be faster than that.
17 replies
CC#
Created by The Mist on 4/1/2024 in #help
Difference algorithm that Git uses
Hello! Quick rundown: I have a need to detect changes in custom bytecode sequences. Essentially, I need to be able to compare two bytecode files (just consider them string sequences, lines of text even), and find: 1) Unchanged lines. 2) Deleted lines. 3) Inserted lines. 4) Moved lines. Modified lines can be considered deleted and inserted. The key is I NEED to detect moved lines. DiffPlex and Python's difflib both satisfy requirements 1, 2 and 3, but neither of them seems to be able to detect MOVED lines. Git's difference algorithm seems to be able to detect moved lines. I tested it using --color-moved and indeed, it correctly identified the moved bytecode blocks, unlike DiffPlex and difflib that consider it deleted and inserted. I believe Git uses the Myer's diff algorithm? I don't think the Myer's diff algorithm recognizes moved lines though, that must be some extra logic on Git's side of things. I could come up with a custom algorithm for detecting the moved lines, like taking the deleted lines from A and finding matching sequences in B with LCS or something like that, but surely someone has already done this? This doesn't seem like an uncommon problem, so I would be surprised if there isn't an open-source, polished and tested solution already, but I haven't been able to find any. C# is preferable, but it doesn't have to be C#, any language or tool will do. I would even consider parsing Git's diff output if I had no other options and if it was better structured. Any input is appreciated!
10 replies
CC#
Created by The Mist on 10/1/2022 in #help
ReferenceEquals?
Am I missing something obvious? 
ReferenceEquals(text.textInfo.meshInfo[0].mesh, text.mesh) // true
ReferenceEquals(text.textInfo.meshInfo[0].mesh.vertices, text.mesh.vertices) // false
ReferenceEquals(text.textInfo.meshInfo[0].mesh, text.mesh) // true
ReferenceEquals(text.textInfo.meshInfo[0].mesh.vertices, text.mesh.vertices) // false
This is Unity, TMPro. If text.textInfo.meshInfo[0].mesh and text.mesh are pointing to the same instance - how come the vertices property of the same instance doesn't return true?
43 replies