Kaydet (Commit) ce284096 authored tarafından Dimitar Toshkov Zhekov's avatar Dimitar Toshkov Zhekov

Handle continuous G_IO_IN-s without any data

Some versions of GLib under Linux continuously generate G_IO_IN-s
without any data to read when using recusrive channel watch sources,
causing 100% CPU load. This patch detects such a situation, and
automatically switches the affected source from channel watch to
50ms timeout.
üst 2386153d
......@@ -98,6 +98,7 @@ static gboolean spawn_parse_argv(const gchar *command_line, gint *argcp, gchar *
#endif
#define G_IO_FAILURE (G_IO_ERR | G_IO_HUP | G_IO_NVAL) /* always used together */
#define MAX_EMPTY_GIO_INS 3
/*
......@@ -842,15 +843,14 @@ typedef struct _SpawnChannelData
GString *buffer; /* NULL if recursive */
GString *line_buffer; /* NULL if char buffered */
gsize max_length;
/* stdout/stderr: fix continuous empty G_IO_IN-s for recursive channels */
guint empty_gio_ins;
} SpawnChannelData;
static void spawn_destroy_cb(gpointer data)
static void spawn_destroy_common(SpawnChannelData *sc)
{
SpawnChannelData *sc = (SpawnChannelData *) data;
g_io_channel_shutdown(sc->channel, FALSE, NULL);
sc->channel = NULL;
if (sc->buffer)
g_string_free(sc->buffer, TRUE);
......@@ -860,6 +860,28 @@ static void spawn_destroy_cb(gpointer data)
}
static void spawn_timeout_destroy_cb(gpointer data)
{
SpawnChannelData *sc = (SpawnChannelData *) data;
spawn_destroy_common(sc);
g_io_channel_unref(sc->channel);
sc->channel = NULL;
}
static void spawn_destroy_cb(gpointer data)
{
SpawnChannelData *sc = (SpawnChannelData *) data;
if (sc->empty_gio_ins < MAX_EMPTY_GIO_INS)
{
spawn_destroy_common(sc);
sc->channel = NULL;
}
}
static gboolean spawn_write_cb(GIOChannel *channel, GIOCondition condition, gpointer data)
{
SpawnChannelData *sc = (SpawnChannelData *) data;
......@@ -871,6 +893,16 @@ static gboolean spawn_write_cb(GIOChannel *channel, GIOCondition condition, gpoi
}
static gboolean spawn_read_cb(GIOChannel *channel, GIOCondition condition, gpointer data);
static gboolean spawn_timeout_read_cb(gpointer data)
{
SpawnChannelData *sc = (SpawnChannelData *) data;
/* The solution for continuous empty G_IO_IN-s is to generate them outselves. :) */
return spawn_read_cb(sc->channel, G_IO_IN, data);
}
static gboolean spawn_read_cb(GIOChannel *channel, GIOCondition condition, gpointer data)
{
SpawnChannelData *sc = (SpawnChannelData *) data;
......@@ -878,6 +910,7 @@ static gboolean spawn_read_cb(GIOChannel *channel, GIOCondition condition, gpoin
GString *buffer = sc->buffer ? sc->buffer : g_string_sized_new(sc->max_length);
GIOCondition input_cond = condition & (G_IO_IN | G_IO_PRI);
GIOCondition failure_cond = condition & G_IO_FAILURE;
GIOStatus status = G_IO_STATUS_NORMAL;
/*
* - Normally, read only once. With IO watches, our data processing must be immediate,
* which may give the child time to emit more data, and a read loop may combine it into
......@@ -888,7 +921,6 @@ static gboolean spawn_read_cb(GIOChannel *channel, GIOCondition condition, gpoin
if (input_cond)
{
gsize chars_read;
GIOStatus status;
if (line_buffer)
{
......@@ -967,6 +999,23 @@ static gboolean spawn_read_cb(GIOChannel *channel, GIOCondition condition, gpoin
sc->cb.read(buffer, input_cond | failure_cond, sc->cb_data);
}
/* Check for continuous activations with G_IO_IN | G_IO_PRI, without any
data to read and without errors. If detected, switch to timeout source. */
else if (sc->empty_gio_ins < MAX_EMPTY_GIO_INS && status == G_IO_STATUS_AGAIN)
{
if (++sc->empty_gio_ins == MAX_EMPTY_GIO_INS)
{
GSource *old_source = g_main_current_source();
GSource *new_source = g_timeout_source_new(50);
g_io_channel_ref(sc->channel);
g_source_set_can_recurse(new_source, g_source_get_can_recurse(old_source));
g_source_set_callback(new_source, spawn_timeout_read_cb, data, spawn_timeout_destroy_cb);
g_source_attach(new_source, g_source_get_context(old_source));
g_source_unref(new_source);
failure_cond |= G_IO_ERR;
}
}
if (buffer != sc->buffer)
g_string_free(buffer, TRUE);
......@@ -1003,7 +1052,7 @@ static void spawn_finalize(SpawnWatcherData *sw)
}
static gboolean spawn_timeout_cb(gpointer data)
static gboolean spawn_timeout_watch_cb(gpointer data)
{
SpawnWatcherData *sw = (SpawnWatcherData *) data;
int i;
......@@ -1031,7 +1080,7 @@ static void spawn_watch_cb(GPid pid, gint status, gpointer data)
{
GSource *source = g_timeout_source_new(50);
g_source_set_callback(source, spawn_timeout_cb, data, NULL);
g_source_set_callback(source, spawn_timeout_watch_cb, data, NULL);
g_source_attach(source, sw->main_context);
g_source_unref(source);
return;
......@@ -1066,6 +1115,9 @@ static void spawn_watch_cb(GPid pid, gint status, gpointer data)
* The default max lengths are 24K for line buffered stdout, 8K for line buffered stderr,
* 4K for unbuffered input under Unix, and 2K for unbuffered input under Windows.
*
* Due to a bug in some glib versions, the sources for recursive stdout/stderr callbacks may
* be converted from child watch to timeout(50ms). No callback changes are required.
*
* @c exit_cb is always invoked last, after all I/O callbacks.
*
* The @a child_pid will be closed automatically, after @a exit_cb is invoked.
......@@ -1171,6 +1223,8 @@ gboolean spawn_with_callbacks(const gchar *working_directory, const gchar *comma
sc->line_buffer = g_string_sized_new(sc->max_length +
DEFAULT_IO_LENGTH);
}
sc->empty_gio_ins = 0;
}
source = g_io_create_watch(sc->channel, condition);
......
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