Re: [Boost-users] multi_index: thread safety

Subject: Re: [Boost-users] multi_index: thread safety
From: Joaquin M Lopez Munoz (joaquin_at_[hidden])
Date: 2015-03-08 11:06:57

Matwey V. Kornilov <matwey.kornilov <at> gmail.com> writes:

> 
> Hi,
> 
> I have a multi_index container and would like to make concurrent READs.
> Is it thread-safe? I mean that there could be mutable members inside the
> object, so calling formally const functions leaded to concurrent writes.

Adding to Ernest's answer: if your formally const function changes the
value of some mutable data member, then concurrent access is NOT safe.
For instance:

struct X
{
  int x;
  mutable std::size_t count;

  int get_x()const
  {
    ++count;
    return x;
  }
};

Concurrent execution of X::get_x is not safe. This has nothing to do
with Boost.MultiIndex, by the way; if your problem is different please
answer back.

Joaquín M López Muñoz
Telefónica