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really threadsafe access to symbol table

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* libguile/symbols.c (symbols_lock): Rename from intern_lock.
  (lookup_interned_symbol, lookup_interned_latin1_symbol): Instead of
  faith-based programming, just use the mutex.  Though I haven't seen
  this break, Ken is right!
This commit is contained in:
Andy Wingo 2011-05-23 22:24:27 +02:00
parent 2a3db25e28
commit b34608813d
1 changed files with 7 additions and 12 deletions
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19
libguile/symbols.c
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@ -52,6 +52,7 @@
static SCM symbols;
static scm_i_pthread_mutex_t symbols_lock = SCM_I_PTHREAD_MUTEX_INITIALIZER;
#ifdef GUILE_DEBUG
SCM_DEFINE (scm_sys_symbols, "%symbols", 0, 0, 0,
@ -108,13 +109,11 @@ lookup_interned_symbol (SCM name, unsigned long raw_hash)
data.string = name;
data.string_hash = raw_hash;
/* Strictly speaking, we should take a lock here. But instead we rely
on the fact that if this fails, we do take the lock on the
intern_symbol path; and since nothing deletes from the hash table
except GC, we should be OK. */
scm_i_pthread_mutex_lock (&symbols_lock);
handle = scm_hash_fn_get_handle_by_hash (symbols, raw_hash,
string_lookup_predicate_fn,
&data);
scm_i_pthread_mutex_unlock (&symbols_lock);
if (scm_is_true (handle))
return SCM_CAR (handle);
@ -151,13 +150,11 @@ lookup_interned_latin1_symbol (const char *str, size_t len,
data.len = len;
data.string_hash = raw_hash;
/* Strictly speaking, we should take a lock here. But instead we rely
on the fact that if this fails, we do take the lock on the
intern_symbol path; and since nothing deletes from the hash table
except GC, we should be OK. */
scm_i_pthread_mutex_lock (&symbols_lock);
handle = scm_hash_fn_get_handle_by_hash (symbols, raw_hash,
latin1_lookup_predicate_fn,
&data);
scm_i_pthread_mutex_unlock (&symbols_lock);
if (scm_is_true (handle))
return SCM_CAR (handle);
@ -187,8 +184,6 @@ symbol_lookup_assoc_fn (SCM obj, SCM alist, void *closure)
return SCM_BOOL_F;
}
static scm_i_pthread_mutex_t intern_lock = SCM_I_PTHREAD_MUTEX_INITIALIZER;
/* Intern SYMBOL, an uninterned symbol. Might return a different
symbol, if another one was interned at the same time. */
static SCM
@ -196,12 +191,12 @@ intern_symbol (SCM symbol)
{
SCM handle;
scm_i_pthread_mutex_lock (&intern_lock);
scm_i_pthread_mutex_lock (&symbols_lock);
handle = scm_hash_fn_create_handle_x (symbols, symbol, SCM_UNDEFINED,
symbol_lookup_hash_fn,
symbol_lookup_assoc_fn,
NULL);
scm_i_pthread_mutex_unlock (&intern_lock);
scm_i_pthread_mutex_unlock (&symbols_lock);
return SCM_CAR (handle);
}