0005309: Queue.add is not thread/signal safe

(0006041)
mottl (reporter)
2011-07-06 16:02

Nitpicking here:

q.length <- q.length + 1;

can be replaced by:

q.length <- 1;

in the first branch.

(0006923)
gasche (developer)
2012-02-15 09:07

To sum up yesterday's discussion: the OCaml library is not guaranteed to be signal-safe, or rather, it is voluntarily guaranteed *not* to be signal-safe. Users should acknowledge that using mutable data structures expose them to signal hazards, and stick to immutable data structures or use different, specialized signal-hardened libraries.

That said, this specific patch is relatively harmless -- in particular, it does not impact clarity and readability -- and Fabrice may include it.

As a personal note: we may also write

  begin if q.length = 1 then
    ..
  else
    ..
  end;
  q.length <- q.length + 1

to avoid duplicating the common length-extension logic. Of course, it's only a dispensable detail.

(0006936)
lefessan (developer)
2012-02-18 10:36

Fixed in commit r12163 in SVN trunk.

Issue History
Date Modified	Username	Field	Change
2011-07-06 11:03	lefessan	New Issue
2011-07-06 16:02	mottl	Note Added: 0006041
2012-02-15 09:07	gasche	Note Added: 0006923
2012-02-15 09:07	gasche	Assigned To	=> lefessan
2012-02-15 09:07	gasche	Status	new => assigned
2012-02-18 10:36	lefessan	Note Added: 0006936
2012-02-18 10:36	lefessan	Status	assigned => resolved
2012-02-18 10:36	lefessan	Fixed in Version	=> 3.13.0+dev
2012-02-18 10:36	lefessan	Resolution	open => fixed

Notes
(0006041) mottl (reporter) 2011-07-06 16:02	Nitpicking here: q.length <- q.length + 1; can be replaced by: q.length <- 1; in the first branch.

(0006923) gasche (developer) 2012-02-15 09:07	To sum up yesterday's discussion: the OCaml library is not guaranteed to be signal-safe, or rather, it is voluntarily guaranteed not to be signal-safe. Users should acknowledge that using mutable data structures expose them to signal hazards, and stick to immutable data structures or use different, specialized signal-hardened libraries. That said, this specific patch is relatively harmless -- in particular, it does not impact clarity and readability -- and Fabrice may include it. As a personal note: we may also write begin if q.length = 1 then .. else .. end; q.length <- q.length + 1 to avoid duplicating the common length-extension logic. Of course, it's only a dispensable detail.

(0006936) lefessan (developer) 2012-02-18 10:36	Fixed in commit r12163 in SVN trunk.

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