glib/gio/tests/contexts.c
Ryan Lortie 8c104a01e1 GContextSpecificGroup: fix deadlock
There was a theoretical deadlock between the worker trying to emit a
signal at the same time as we were waiting for it to shutdown the
notification (while holding the lock).

The deadlock was particularly annoying because we didn't really need to
wait for the shutdown and because it wasn't possible to signals to
arrive while waiting for a start.  Attempting to deal with start and
stop in an asymmetric way could have lead to other weird situations,
however.

Drop the lock while waiting for the worker thread to start.  This means
that we face the possibility of multiple waiters on the cond at the same
time, so we need to make more of a state machine.

https://bugzilla.gnome.org/show_bug.cgi?id=742599
2015-03-02 15:10:46 -05:00

428 lines
11 KiB
C

#include "gcontextspecificgroup.c"
#include <gio/gio.h>
#include <stdlib.h>
#include <string.h>
#define N_THREADS 10
static gchar *test_file;
char *test_file_buffer;
gsize test_file_size;
static char async_read_buffer[8192];
static void
read_data (GObject *source, GAsyncResult *result, gpointer loop)
{
GInputStream *in = G_INPUT_STREAM (source);
GError *error = NULL;
gssize nread;
nread = g_input_stream_read_finish (in, result, &error);
g_assert_no_error (error);
g_assert_cmpint (nread, >, 0);
g_assert_cmpint (nread, <=, MIN(sizeof (async_read_buffer), test_file_size));
g_assert (memcmp (async_read_buffer, test_file_buffer, nread) == 0);
g_main_loop_quit (loop);
}
static void
opened_for_read (GObject *source, GAsyncResult *result, gpointer loop)
{
GFile *file = G_FILE (source);
GFileInputStream *in;
GError *error = NULL;
in = g_file_read_finish (file, result, &error);
g_assert_no_error (error);
memset (async_read_buffer, 0, sizeof (async_read_buffer));
g_input_stream_read_async (G_INPUT_STREAM (in),
async_read_buffer, sizeof (async_read_buffer),
G_PRIORITY_DEFAULT, NULL,
read_data, loop);
g_object_unref (in);
}
/* Test 1: Async I/O started in a thread with a thread-default context
* will stick to that thread, and will complete even if the default
* main loop is blocked. (NB: the last part would not be true if we
* were testing GFileMonitor!)
*/
static gboolean idle_start_test1_thread (gpointer loop);
static gpointer test1_thread (gpointer user_data);
static gboolean test1_done;
static GCond test1_cond;
static GMutex test1_mutex;
static void
test_thread_independence (void)
{
GMainLoop *loop;
loop = g_main_loop_new (NULL, FALSE);
g_idle_add (idle_start_test1_thread, loop);
g_main_loop_run (loop);
g_main_loop_unref (loop);
}
static gboolean
idle_start_test1_thread (gpointer loop)
{
gint64 time;
GThread *thread;
gboolean io_completed;
g_mutex_lock (&test1_mutex);
thread = g_thread_new ("test1", test1_thread, NULL);
time = g_get_monotonic_time () + 2 * G_TIME_SPAN_SECOND;
while (!test1_done)
{
io_completed = g_cond_wait_until (&test1_cond, &test1_mutex, time);
g_assert (io_completed);
}
g_thread_join (thread);
g_mutex_unlock (&test1_mutex);
g_main_loop_quit (loop);
return G_SOURCE_REMOVE;
}
static gpointer
test1_thread (gpointer user_data)
{
GMainContext *context;
GMainLoop *loop;
GFile *file;
/* Wait for main thread to be waiting on test1_cond */
g_mutex_lock (&test1_mutex);
context = g_main_context_new ();
g_assert (g_main_context_get_thread_default () == NULL);
g_main_context_push_thread_default (context);
g_assert (g_main_context_get_thread_default () == context);
file = g_file_new_for_path (test_file);
g_assert (g_file_supports_thread_contexts (file));
loop = g_main_loop_new (context, FALSE);
g_file_read_async (file, G_PRIORITY_DEFAULT, NULL,
opened_for_read, loop);
g_object_unref (file);
g_main_loop_run (loop);
g_main_loop_unref (loop);
test1_done = TRUE;
g_cond_signal (&test1_cond);
g_mutex_unlock (&test1_mutex);
g_main_context_pop_thread_default (context);
g_main_context_unref (context);
return NULL;
}
/* Test 2: If we push a thread-default context in the main thread, we
* can run async ops in that context without running the default
* context.
*/
static gboolean test2_fail (gpointer user_data);
static void
test_context_independence (void)
{
GMainContext *context;
GMainLoop *loop;
GFile *file;
guint default_timeout;
GSource *thread_default_timeout;
context = g_main_context_new ();
g_assert (g_main_context_get_thread_default () == NULL);
g_main_context_push_thread_default (context);
g_assert (g_main_context_get_thread_default () == context);
file = g_file_new_for_path (test_file);
g_assert (g_file_supports_thread_contexts (file));
/* Add a timeout to the main loop, to fail immediately if it gets run */
default_timeout = g_timeout_add_full (G_PRIORITY_HIGH, 0,
test2_fail, NULL, NULL);
/* Add a timeout to the alternate loop, to fail if the I/O *doesn't* run */
thread_default_timeout = g_timeout_source_new_seconds (2);
g_source_set_callback (thread_default_timeout, test2_fail, NULL, NULL);
g_source_attach (thread_default_timeout, context);
loop = g_main_loop_new (context, FALSE);
g_file_read_async (file, G_PRIORITY_DEFAULT, NULL,
opened_for_read, loop);
g_object_unref (file);
g_main_loop_run (loop);
g_main_loop_unref (loop);
g_source_remove (default_timeout);
g_source_destroy (thread_default_timeout);
g_source_unref (thread_default_timeout);
g_main_context_pop_thread_default (context);
g_main_context_unref (context);
}
static gboolean
test2_fail (gpointer user_data)
{
g_assert_not_reached ();
return FALSE;
}
typedef struct
{
GObject parent_instance;
GMainContext *context;
} PerThreadThing;
typedef GObjectClass PerThreadThingClass;
static GType per_thread_thing_get_type (void);
G_DEFINE_TYPE (PerThreadThing, per_thread_thing, G_TYPE_OBJECT)
static GContextSpecificGroup group;
static gpointer instances[N_THREADS];
static gint is_running;
static gint current_value;
static gint observed_values[N_THREADS];
static void
start_func (void)
{
g_assert (!is_running);
g_atomic_int_set (&is_running, TRUE);
}
static void
stop_func (void)
{
g_assert (is_running);
g_atomic_int_set (&is_running, FALSE);
}
static void
per_thread_thing_finalize (GObject *object)
{
PerThreadThing *thing = (PerThreadThing *) object;
g_context_specific_group_remove (&group, thing->context, thing, stop_func);
G_OBJECT_CLASS (per_thread_thing_parent_class)->finalize (object);
}
static void
per_thread_thing_init (PerThreadThing *thing)
{
}
static void
per_thread_thing_class_init (PerThreadThingClass *class)
{
class->finalize = per_thread_thing_finalize;
g_signal_new ("changed", per_thread_thing_get_type (), G_SIGNAL_RUN_FIRST, 0,
NULL, NULL, g_cclosure_marshal_VOID__VOID, G_TYPE_NONE, 0);
}
static gpointer
per_thread_thing_get (void)
{
return g_context_specific_group_get (&group, per_thread_thing_get_type (),
G_STRUCT_OFFSET (PerThreadThing, context),
start_func);
}
static gpointer
test_identity_thread (gpointer user_data)
{
guint thread_nr = GPOINTER_TO_UINT (user_data);
GMainContext *my_context;
guint i, j;
my_context = g_main_context_new ();
g_main_context_push_thread_default (my_context);
g_assert (!instances[thread_nr]);
instances[thread_nr] = per_thread_thing_get ();
g_assert (g_atomic_int_get (&is_running));
for (i = 0; i < 100; i++)
{
gpointer instance = per_thread_thing_get ();
for (j = 0; j < N_THREADS; j++)
g_assert ((instance == instances[j]) == (thread_nr == j));
g_assert (g_atomic_int_get (&is_running));
g_thread_yield ();
g_assert (g_atomic_int_get (&is_running));
}
for (i = 0; i < 100; i++)
{
g_object_unref (instances[thread_nr]);
for (j = 0; j < N_THREADS; j++)
g_assert ((instances[thread_nr] == instances[j]) == (thread_nr == j));
g_assert (g_atomic_int_get (&is_running));
g_thread_yield ();
}
/* drop the last ref */
g_object_unref (instances[thread_nr]);
instances[thread_nr] = NULL;
g_main_context_pop_thread_default (my_context);
g_main_context_unref (my_context);
/* at least one thread should see this cleared on exit */
return GUINT_TO_POINTER (!group.requested_state);
}
static void
test_context_specific_identity (void)
{
GThread *threads[N_THREADS];
gboolean exited = FALSE;
guint i;
g_assert (!g_atomic_int_get (&is_running));
for (i = 0; i < N_THREADS; i++)
threads[i] = g_thread_new ("test", test_identity_thread, GUINT_TO_POINTER (i));
for (i = 0; i < N_THREADS; i++)
exited |= GPOINTER_TO_UINT (g_thread_join (threads[i]));
g_assert (exited);
g_assert (!g_atomic_int_get (&is_running));
}
static void
changed_emitted (PerThreadThing *thing,
gpointer user_data)
{
gint *observed_value = user_data;
g_atomic_int_set (observed_value, g_atomic_int_get (&current_value));
}
static gpointer
test_emit_thread (gpointer user_data)
{
gint *observed_value = user_data;
GMainContext *my_context;
gpointer instance;
my_context = g_main_context_new ();
g_main_context_push_thread_default (my_context);
instance = per_thread_thing_get ();
g_assert (g_atomic_int_get (&is_running));
g_signal_connect (instance, "changed", G_CALLBACK (changed_emitted), observed_value);
/* observe after connection */
g_atomic_int_set (observed_value, g_atomic_int_get (&current_value));
while (g_atomic_int_get (&current_value) != -1)
g_main_context_iteration (my_context, TRUE);
g_object_unref (instance);
g_main_context_pop_thread_default (my_context);
g_main_context_unref (my_context);
/* at least one thread should see this cleared on exit */
return GUINT_TO_POINTER (!group.requested_state);
}
static void
test_context_specific_emit (void)
{
GThread *threads[N_THREADS];
gboolean exited = FALSE;
guint i, n;
g_assert (!g_atomic_int_get (&is_running));
for (i = 0; i < N_THREADS; i++)
threads[i] = g_thread_new ("test", test_emit_thread, &observed_values[i]);
/* make changes and ensure that they are observed */
for (n = 0; n < 1000; n++)
{
guint64 expiry;
/* don't burn CPU forever */
expiry = g_get_monotonic_time () + 10 * G_TIME_SPAN_SECOND;
g_atomic_int_set (&current_value, n);
/* wake them to notice */
for (i = 0; i < g_test_rand_int_range (1, 5); i++)
g_context_specific_group_emit (&group, g_signal_lookup ("changed", per_thread_thing_get_type ()));
for (i = 0; i < N_THREADS; i++)
while (g_atomic_int_get (&observed_values[i]) != n)
{
g_thread_yield ();
if (g_get_monotonic_time () > expiry)
g_error ("timed out");
}
}
/* tell them to quit */
g_atomic_int_set (&current_value, -1);
g_context_specific_group_emit (&group, g_signal_lookup ("notify", G_TYPE_OBJECT));
for (i = 0; i < N_THREADS; i++)
exited |= GPOINTER_TO_UINT (g_thread_join (threads[i]));
g_assert (exited);
g_assert (!g_atomic_int_get (&is_running));
}
int
main (int argc, char **argv)
{
GError *error = NULL;
int ret;
g_test_init (&argc, &argv, NULL);
test_file = g_test_build_filename (G_TEST_DIST, "contexts.c", NULL);
g_file_get_contents (test_file, &test_file_buffer,
&test_file_size, &error);
g_assert_no_error (error);
g_test_add_func ("/gio/contexts/thread-independence", test_thread_independence);
g_test_add_func ("/gio/contexts/context-independence", test_context_independence);
g_test_add_func ("/gio/contexts/context-specific/identity", test_context_specific_identity);
g_test_add_func ("/gio/contexts/context-specific/emit", test_context_specific_emit);
ret = g_test_run();
g_free (test_file_buffer);
g_free (test_file);
return ret;
}