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authorMark H Weaver <mhw@netris.org>2013-02-28 17:56:58 -0500
committerMark H Weaver <mhw@netris.org>2013-03-05 16:04:55 -0500
commitf57ea23ac8e1436f37ceeda3ea8625243c20e645 (patch)
tree9770b54992f625abae89964d8b6efea62d09dea6
parent29ace173b170a5d77e6becb30fb1d9f253a373d5 (diff)
downloadguile-f57ea23ac8e1436f37ceeda3ea8625243c20e645.tar.gz
Fix thread-unsafe lazy initializations.
* libguile/debug.c (scm_local_eval): libguile/ports.c (scm_current_warning_port): libguile/strports.c (scm_eval_string_in_module): Perform lazy-initialization while holding a mutex. Use SCM_UNDEFINED as the uninitialized value. Use 'scm_c_*_variable'. * doc/ref/api-modules.texi (Accessing Modules from C): Fix 'my_eval_string' example to be thread-safe.
-rw-r--r--doc/ref/api-modules.texi16
-rw-r--r--libguile/debug.c8
-rw-r--r--libguile/ports.c12
-rw-r--r--libguile/strports.c9
4 files changed, 30 insertions, 15 deletions
diff --git a/doc/ref/api-modules.texi b/doc/ref/api-modules.texi
index b9befc00c..47b81601b 100644
--- a/doc/ref/api-modules.texi
+++ b/doc/ref/api-modules.texi
@@ -945,14 +945,18 @@ the @var{name} is not bound in the module, signals an error. Returns a
variable, always.
@example
-SCM my_eval_string (SCM str)
-@{
- static SCM eval_string_var = SCM_BOOL_F;
+static SCM eval_string_var;
- if (scm_is_false (eval_string_var))
- eval_string_var =
- scm_c_public_lookup ("ice-9 eval-string", "eval-string");
+/* NOTE: It is important that the call to 'my_init'
+ happens-before all calls to 'my_eval_string'. */
+void my_init (void)
+@{
+ eval_string_var = scm_c_public_lookup ("ice-9 eval-string",
+ "eval-string");
+@}
+SCM my_eval_string (SCM str)
+@{
return scm_call_1 (scm_variable_ref (eval_string_var), str);
@}
@end example
diff --git a/libguile/debug.c b/libguile/debug.c
index b1a90d84d..9e6328b3a 100644
--- a/libguile/debug.c
+++ b/libguile/debug.c
@@ -211,10 +211,14 @@ SCM_DEFINE (scm_debug_hang, "debug-hang", 0, 1, 0,
SCM
scm_local_eval (SCM exp, SCM env)
{
- static SCM local_eval_var = SCM_BOOL_F;
+ static SCM local_eval_var = SCM_UNDEFINED;
+ static scm_i_pthread_mutex_t local_eval_var_mutex
+ = SCM_I_PTHREAD_MUTEX_INITIALIZER;
- if (scm_is_false (local_eval_var))
+ scm_i_scm_pthread_mutex_lock (&local_eval_var_mutex);
+ if (SCM_UNBNDP (local_eval_var))
local_eval_var = scm_c_public_variable ("ice-9 local-eval", "local-eval");
+ scm_i_pthread_mutex_unlock (&local_eval_var_mutex);
return scm_call_2 (SCM_VARIABLE_REF (local_eval_var), exp, env);
}
diff --git a/libguile/ports.c b/libguile/ports.c
index 55808e272..8737a7672 100644
--- a/libguile/ports.c
+++ b/libguile/ports.c
@@ -418,10 +418,14 @@ SCM_DEFINE (scm_current_error_port, "current-error-port", 0, 0, 0,
SCM
scm_current_warning_port (void)
{
- static SCM cwp_var = SCM_BOOL_F;
-
- if (scm_is_false (cwp_var))
- cwp_var = scm_c_private_lookup ("guile", "current-warning-port");
+ static SCM cwp_var = SCM_UNDEFINED;
+ static scm_i_pthread_mutex_t cwp_var_mutex
+ = SCM_I_PTHREAD_MUTEX_INITIALIZER;
+
+ scm_i_scm_pthread_mutex_lock (&cwp_var_mutex);
+ if (SCM_UNBNDP (cwp_var))
+ cwp_var = scm_c_private_variable ("guile", "current-warning-port");
+ scm_i_pthread_mutex_unlock (&cwp_var_mutex);
return scm_call_0 (scm_variable_ref (cwp_var));
}
diff --git a/libguile/strports.c b/libguile/strports.c
index 14cc93f81..d1b293c21 100644
--- a/libguile/strports.c
+++ b/libguile/strports.c
@@ -534,13 +534,16 @@ SCM_DEFINE (scm_eval_string_in_module, "eval-string", 1, 1, 0,
"procedure returns.")
#define FUNC_NAME s_scm_eval_string_in_module
{
- static SCM eval_string = SCM_BOOL_F, k_module = SCM_BOOL_F;
+ static SCM eval_string = SCM_UNDEFINED, k_module = SCM_UNDEFINED;
+ static scm_i_pthread_mutex_t init_mutex = SCM_I_PTHREAD_MUTEX_INITIALIZER;
- if (scm_is_false (eval_string))
+ scm_i_scm_pthread_mutex_lock (&init_mutex);
+ if (SCM_UNBNDP (eval_string))
{
- eval_string = scm_c_public_lookup ("ice-9 eval-string", "eval-string");
+ eval_string = scm_c_public_variable ("ice-9 eval-string", "eval-string");
k_module = scm_from_locale_keyword ("module");
}
+ scm_i_pthread_mutex_unlock (&init_mutex);
if (SCM_UNBNDP (module))
module = scm_current_module ();