I need to have a multithreaded (or thread safe) data structure management lib.

Write (exclusive) locking may occur on a part of the structure when modifications are needed. Due to a wide range of subroutines called within exclusive lock operations being recursive, possibly comming round the same parts of the structure, I want to know if calling lock() on the same thing, in one thread, will block or not, or at least if there's some defined behaviour. Neither perlfunc lock or perlthrtut had any information on this.

I suppose the most logical work around will be to maintain a nonshared hash of locked parts.

The scheme is a reference to a semaphore, within the lockable part. Shared locks are granted by locking to the reference, and upping the semaphore by one. The lock is then released, and upon cease of shared use, the semaphore is downed witout locking.

Exclusive locks are granted by locking on the reference, and waiting for the semaphore to hit zero. when the lock on the reference goes out of scope, the exclusive lock is tossed.

-nuffin
zz zZ Z Z #!perl

Edit by tye to fix typo noted in reply

In reply to lock() - dynamic or lexical? by nothingmuch

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