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  1. Core Server
  2. SERVER-62231

Methods for iterating a DBClientCursor should assert that init() has been called

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Details

    • Improvement
    • Status: Closed
    • Major - P3
    • Resolution: Fixed
    • None
    • 6.1.0-rc0
    • Internal Client
    • Fully Compatible
    • QE 2022-06-27, QE 2022-07-11
    • 64

    Description

      In order to fully initialize a DBClientCursor object, one must first call its constructor and then subsequently call DBClientCursor::init(). If the programmer makes a mistake and fails to call init(), the cursor can silently return no results rather than raising an error. Consider code like this:

      DBClientCursor cursor{...};
      while (cursor->more()) {
          BSONObj obj = cursor->nextSafe();
          // Do something with 'obj'.
      }
      

      This code is incorrect, since it fails to call init(). However, the call to cursor->more() simply returns false rather than throwing or tripping an assertion, so the bug could easily go undetected. We should improve the code to uassert() or possibly invariant() in this scenario.

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              catalin.sumanaru@mongodb.com Catalin Sumanaru
              david.storch@mongodb.com David Storch
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                Created:
                Updated:
                Resolved: