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safely access the trampoline weak map

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* libguile/smob.c (scm_i_smob_apply_trampoline): Protect the trampoline
  weak map with a mutex.
This commit is contained in:
Andy Wingo 2011-05-24 21:09:24 +02:00
parent f2ed447383
commit c0937f0988
1 changed files with 12 additions and 3 deletions
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15
libguile/smob.c
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@ -418,12 +418,16 @@ scm_set_smob_apply (scm_t_bits tc, SCM (*apply) (),
} }
static SCM tramp_weak_map = SCM_BOOL_F; static SCM tramp_weak_map = SCM_BOOL_F;
static scm_i_pthread_mutex_t tramp_lock = SCM_I_PTHREAD_MUTEX_INITIALIZER;
SCM SCM
scm_i_smob_apply_trampoline (SCM smob) scm_i_smob_apply_trampoline (SCM smob)
{ {
/* could use hashq-create-handle!, but i don't know what to do if it returns a SCM tramp;
weak pair */
SCM tramp = scm_hashq_ref (tramp_weak_map, smob, SCM_BOOL_F); scm_i_pthread_mutex_lock (&tramp_lock);
tramp = scm_hashq_ref (tramp_weak_map, smob, SCM_BOOL_F);
scm_i_pthread_mutex_unlock (&tramp_lock);
if (scm_is_true (tramp)) if (scm_is_true (tramp))
return tramp; return tramp;
@ -440,7 +444,12 @@ scm_i_smob_apply_trampoline (SCM smob)
SCM_SIMPLE_VECTOR_SET (objtable, 1, scm_from_locale_symbol (name)); SCM_SIMPLE_VECTOR_SET (objtable, 1, scm_from_locale_symbol (name));
tramp = scm_make_program (SCM_SMOB_DESCRIPTOR (smob).apply_trampoline_objcode, tramp = scm_make_program (SCM_SMOB_DESCRIPTOR (smob).apply_trampoline_objcode,
objtable, SCM_BOOL_F); objtable, SCM_BOOL_F);
/* Race conditions (between the ref and this set!) cannot cause
any harm here. */
scm_i_pthread_mutex_lock (&tramp_lock);
scm_hashq_set_x (tramp_weak_map, smob, tramp); scm_hashq_set_x (tramp_weak_map, smob, tramp);
scm_i_pthread_mutex_unlock (&tramp_lock);
return tramp; return tramp;
} }
} }