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This repository was archived by the owner on Mar 22, 2023. It is now read-only.
This repository was archived by the owner on Mar 22, 2023. It is now read-only.

operator-- may fail in concurrent radix_tree #1159

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operator-- may fail in concurrent radix_tree#1159
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Type: BugSomething isn't workingradix_treeNeeds to be resolved to productize radix_tree

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@lukaszstolarczuk
lukaszstolarczuk
opened on Jul 15, 2021

operator-- may fail (when MtMode is enabled) in some specific cases, e.g.:

  • try_decrement fails due to concurrent erase (it can be the element pointed to by the iterator)
  • operator-- calls lower_bound which returns end() (the tree is now empty)
  • try_decrement crashes because we decrement beyond begin()

ref. #1156

Activity

  1. lukaszstolarczuk
    added
    Type: BugSomething isn't working
    radix_treeNeeds to be resolved to productize radix_tree
    on Jul 15, 2021

  2. igchor commented on Jul 15, 2021

    @igchor
    igchor
    on Jul 15, 2021
    Contributor

    There are two problems for this version: 6300980

    1. If iterator points to end() and try_decrement fails, we will call key() on nullptr (leaf_ == nullptr for end())
    2. Problem mentioned by lukaszstolarczuk is caused by a lack of special value for begin(). When we use operator++ and encounter end() we know it's time to stop. For operator-- be cannot rely on comparison with begin() since its value can change. We could introduce a special past-begin iterator for this purpose.
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