Rewrite xlsclients to use XCB, avoiding many (many) round trips

This version spends bandwidth to reduce latency; in particular, it
aggressively calls query_tree before the answer to get_property(WM_STATE) is
available.

Even on my local box, this version is 4-10 times faster (30ms typical, vs
200ms typical for Xlib). I get similar results over the local network.

At least one person reports this version takes less than 2 seconds over ssh,
vs over a minute for the Xlib version (~30x faster).

Reviewed-by: Jamey Sharp <jamey@minilop.net>

2 files changed, 430 insertions, 100 deletions

diff --git a/configure.ac b/configure.ac
index 1af6ba2..f665380 100644
--- a/configure.ac
+++ b/configure.ac
@@ -36,10 +36,14 @@ AM_CONFIG_HEADER(config.h)
 AC_PROG_CC
 AC_PROG_INSTALL
 
+# Check for functional strnlen
+AC_USE_SYSTEM_EXTENSIONS
+AC_FUNC_STRNLEN
+
 XORG_DEFAULT_OPTIONS
 
 # Checks for pkg-config packages
-PKG_CHECK_MODULES(XLSCLIENTS, x11 xmuu)
+PKG_CHECK_MODULES(XLSCLIENTS, xcb xcb-atom)
 AC_SUBST(XLSCLIENTS_CFLAGS)
 AC_SUBST(XLSCLIENTS_LIBS)
 
diff --git a/xlsclients.c b/xlsclients.c
index 0b6fc15..049bc4c 100644
--- a/xlsclients.c
+++ b/xlsclients.c
@@ -1,8 +1,6 @@
 /*
- * $Xorg: xlsclients.c,v 1.4 2001/02/09 02:05:54 xorgcvs Exp $
- *
- * 
 Copyright 1989, 1998  The Open Group
+Copyright 2009  Open Text Corporation
 
 Permission to use, copy, modify, distribute, and sell this software and its
 documentation for any purpose is hereby granted without fee, provided that
@@ -25,26 +23,36 @@ used in advertising or otherwise to promote the sale, use or other dealings
 in this Software without prior written authorization from The Open Group.
  * *
  * Author:  Jim Fulton, MIT X Consortium
+ * Author:  Peter Harris, Open Text Corporation
  */
-/* $XFree86: xc/programs/xlsclients/xlsclients.c,v 1.5 2001/04/01 14:00:23 tsi Exp $ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <ctype.h>
-#include <X11/Xos.h>
-#include <X11/Xlib.h>
-#include <X11/Xatom.h>
-#include <X11/Xutil.h>
-#include <X11/Xmu/WinUtil.h>
+#include <xcb/xcb.h>
+#include <xcb/xproto.h>
+#include <xcb/xcb_atom.h>
 
 static char *ProgramName;
 
-static void lookat ( Display *dpy, Window root, Bool verbose, int maxcmdlen );
-static void print_client_properties ( Display *dpy, Window w, 
-				      Bool verbose, int maxcmdlen );
-static void print_text_field ( Display *dpy, char *s, XTextProperty *tp );
-static int print_quoted_word ( char *s, int maxlen );
-static void unknown ( Display *dpy, Atom actual_type, int actual_format );
+static xcb_atom_t WM_STATE;
+
+static void lookat (xcb_connection_t *dpy, xcb_window_t root, int verbose, int maxcmdlen);
+static void print_client_properties (xcb_connection_t *dpy, xcb_window_t w,
+				     int verbose, int maxcmdlen );
+static void print_text_field (xcb_connection_t *dpy, char *s, xcb_get_property_reply_t *tp );
+static int print_quoted_word (char *s, int maxlen);
+static void unknown (xcb_connection_t *dpy, xcb_atom_t actual_type, int actual_format );
+
+/* For convenience: */
+typedef int Bool;
+#define False (0)
+#define True (!False)
 
 static void 
 usage(void)
@@ -54,6 +62,73 @@ usage(void)
     exit (1);
 }
 
+typedef void (*queue_func)(void *closure);
+typedef struct queue_blob {
+    queue_func func;
+    void *closure;
+    struct queue_blob *next;
+} queue_blob;
+
+static queue_blob *head = NULL;
+static queue_blob **tail = &head;
+
+static void enqueue(queue_func func, void *closure)
+{
+    queue_blob *blob = malloc(sizeof(*blob));
+    if (!blob)
+	return; /* TODO: print OOM error */
+
+    blob->func = func;
+    blob->closure = closure;
+    blob->next = NULL;
+    *tail = blob;
+    tail = &blob->next;
+}
+
+static void run_queue(void)
+{
+    while (head) {
+	queue_blob *blob = head;
+	blob->func(blob->closure);
+	head = blob->next;
+	free(blob);
+    }
+    tail = &head;
+}
+
+typedef struct {
+    xcb_connection_t *c;
+    xcb_intern_atom_cookie_t cookie;
+    xcb_atom_t *atom;
+} atom_state;
+
+static void atom_done(void *closure)
+{
+    xcb_intern_atom_reply_t *reply;
+    atom_state *as = closure;
+
+    reply = xcb_intern_atom_reply(as->c, as->cookie, NULL);
+    if (!reply)
+	goto done; /* TODO: print Error message */
+
+    *(as->atom) = reply->atom;
+    free(reply);
+
+done:
+    free(as);
+}
+
+static void init_atoms(xcb_connection_t *c)
+{
+    atom_state *as;
+
+    as = malloc(sizeof(*as));
+    as->c = c;
+    as->atom = &WM_STATE;
+    as->cookie = xcb_intern_atom(c, 0, strlen("WM_STATE"), "WM_STATE");
+    enqueue(atom_done, as);
+}
+
 int
 main(int argc, char *argv[])
 {
@@ -61,7 +136,9 @@ main(int argc, char *argv[])
     char *displayname = NULL;
     Bool all_screens = False;
     Bool verbose = False;
-    Display *dpy;
+    xcb_connection_t *dpy;
+    const xcb_setup_t *setup;
+    int screen_number = 0;
     int maxcmdlen = 10000;
 
     ProgramName = argv[0];
@@ -100,146 +177,391 @@ main(int argc, char *argv[])
 	}
     }
 
-    dpy = XOpenDisplay (displayname);
+    dpy = xcb_connect(displayname, &screen_number);
     if (!dpy) {
+	char *name = displayname;
+	if (!name)
+	    name = getenv("DISPLAY");
+	if (!name)
+	    name = "";
 	fprintf (stderr, "%s:  unable to open display \"%s\"\r\n",
-		 ProgramName, XDisplayName (displayname));
+		 ProgramName, name);
 	exit (1);
     }
 
+    init_atoms(dpy);
+
+    setup = xcb_get_setup(dpy);
     if (all_screens) {
-	for (i = 0; i < ScreenCount(dpy); i++) {
-	    lookat (dpy, RootWindow(dpy,i), verbose, maxcmdlen);
-	}
+	xcb_screen_iterator_t screen;
+
+	screen = xcb_setup_roots_iterator(setup);
+	do {
+	    lookat(dpy, screen.data->root, verbose, maxcmdlen);
+	    xcb_screen_next(&screen);
+	} while (screen.rem);
     } else {
-	lookat (dpy, DefaultRootWindow(dpy), verbose, maxcmdlen);
+	xcb_screen_iterator_t screen;
+
+	screen = xcb_setup_roots_iterator(setup);
+	for (i = 0; i < screen_number; i++)
+	    xcb_screen_next(&screen);
+
+	lookat (dpy, screen.data->root, verbose, maxcmdlen);
     }
 
-    XCloseDisplay (dpy);
+    run_queue();
+
+    xcb_disconnect(dpy);
     exit (0);
 }
 
+typedef struct {
+    xcb_connection_t *c;
+    xcb_get_property_cookie_t *prop_cookie;
+    xcb_query_tree_cookie_t *tree_cookie;
+    xcb_window_t *win;
+    xcb_window_t orig_win;
+    int list_length;
+    int verbose;
+    int maxcmdlen;
+} child_wm_state;
+
+static void child_info(void *closure)
+{
+    child_wm_state *cs = closure;
+    xcb_window_t orig = cs->orig_win;
+    xcb_connection_t *c = cs->c;
+    int verbose = cs->verbose;
+    int maxcmdlen = cs->maxcmdlen;
+    int i, j;
+
+    int child_count, num_rep;
+    xcb_query_tree_reply_t **reply;
+
+    for (i = 0; i < cs->list_length; i++) {
+	xcb_get_property_reply_t *reply;
+	reply = xcb_get_property_reply(c, cs->prop_cookie[i], NULL);
+	if (reply) {
+	    if (reply->type) {
+		/* Show information for this window */
+		print_client_properties(c, cs->win[i], cs->verbose, cs->maxcmdlen);
+
+		free(reply);
+
+		/* drain stale replies */
+		for (j = i+1; j < cs->list_length; j++) {
+		    reply = xcb_get_property_reply(c, cs->prop_cookie[j], NULL);
+		    if (reply)
+			free(reply);
+		}
+		for (j = 0; j < cs->list_length; j++) {
+		    xcb_query_tree_reply_t *rep;
+		    rep = xcb_query_tree_reply(c, cs->tree_cookie[j], NULL);
+		    if (rep)
+			free(rep);
+		}
+		goto done;
+	    }
+	    free(reply);
+	}
+    }
+
+    /* WM_STATE not found. Recurse into children: */
+    num_rep = 0;
+    reply = malloc(sizeof(*reply) * cs->list_length);
+    if (!reply)
+	goto done; /* TODO: print OOM message, drain reply queue */
+
+    for (i = 0; i < cs->list_length; i++) {
+	reply[num_rep] = xcb_query_tree_reply(c, cs->tree_cookie[i], NULL);
+	if (reply[num_rep])
+	    num_rep++;
+    }
+
+    child_count = 0;
+    for (i = 0; i < num_rep; i++)
+	child_count += reply[i]->children_len;
+
+    if (!child_count) {
+	/* No children have CS_STATE; try the parent window */
+	print_client_properties(c, cs->orig_win, cs->verbose, cs->maxcmdlen);
+	goto reply_done;
+    }
+
+    cs = malloc(sizeof(*cs) + child_count * (sizeof(*cs->prop_cookie) + sizeof(*cs->tree_cookie) + sizeof(*cs->win)));
+    if (!cs)
+	goto reply_done; /* TODO: print OOM message */
+
+    cs->c = c;
+    cs->verbose = verbose;
+    cs->maxcmdlen = maxcmdlen;
+    cs->orig_win = orig;
+    cs->prop_cookie = (void *)&cs[1];
+    cs->tree_cookie = (void *)&cs->prop_cookie[child_count];
+    cs->win = (void *)&cs->tree_cookie[child_count];
+    cs->list_length = child_count;
+
+    child_count = 0;
+    for (i = 0; i < num_rep; i++) {
+	xcb_window_t *child = xcb_query_tree_children(reply[i]);
+	for (j = 0; j < reply[i]->children_len; j++) {
+	    cs->win[child_count] = child[j];
+	    cs->prop_cookie[child_count] = xcb_get_property(c, 0, child[j],
+			    WM_STATE, XCB_GET_PROPERTY_TYPE_ANY,
+			    0, 0);
+	    /* Just in case the property isn't there, get the tree too */
+	    cs->tree_cookie[child_count++] = xcb_query_tree(c, child[j]);
+	}
+    }
+
+    enqueue(child_info, cs);
+
+reply_done:
+    for (i = 0; i < num_rep; i++)
+	free(reply[i]);
+    free(reply);
+
+done:
+    free(closure);
+}
+
+typedef struct {
+    xcb_connection_t *c;
+    xcb_query_tree_cookie_t cookie;
+    int verbose;
+    int maxcmdlen;
+} root_list_state;
+
+static void root_list(void *closure)
+{
+    int i;
+    xcb_window_t *child;
+    xcb_query_tree_reply_t *reply;
+    root_list_state *rl = closure;
+
+    reply = xcb_query_tree_reply(rl->c, rl->cookie, NULL);
+    if (!reply)
+	goto done;
+
+    child = xcb_query_tree_children(reply);
+    for (i = 0; i < reply->children_len; i++) {
+	/* Get information about each child */
+	child_wm_state *cs = malloc(sizeof(*cs) + sizeof(*cs->prop_cookie) + sizeof(*cs->tree_cookie) + sizeof(*cs->win));
+	if (!cs)
+	    goto done; /* TODO: print OOM message */
+	cs->c = rl->c;
+	cs->verbose = rl->verbose;
+	cs->maxcmdlen = rl->maxcmdlen;
+	cs->prop_cookie = (void *)&cs[1];
+	cs->tree_cookie = (void *)&cs->prop_cookie[1];
+	cs->win = (void *)&cs->tree_cookie[1];
+
+	cs->orig_win = child[i];
+	cs->win[0] = child[i];
+
+	cs->prop_cookie[0] = xcb_get_property(rl->c, 0, child[i],
+			WM_STATE, XCB_GET_PROPERTY_TYPE_ANY,
+			0, 0);
+	/* Just in case the property isn't there, get the tree too */
+	cs->tree_cookie[0] = xcb_query_tree(rl->c, child[i]);
+
+	cs->list_length = 1;
+	enqueue(child_info, cs);
+    }
+    free(reply);
+
+done:
+    free(rl);
+}
+
 static void
-lookat(Display *dpy, Window root, Bool verbose, int maxcmdlen)
+lookat(xcb_connection_t *dpy, xcb_window_t root, int verbose, int maxcmdlen)
 {
-    Window dummy, *children = NULL, client;
-    unsigned int i, nchildren = 0;
+    root_list_state *rl = malloc(sizeof(*rl));
 
-    /*
-     * clients are not allowed to stomp on the root and ICCCM doesn't yet
-     * say anything about window managers putting stuff there; but, try
-     * anyway.
-     */
-    print_client_properties (dpy, root, verbose, maxcmdlen);
+    if (!rl)
+	return; /* TODO: OOM message */
 
     /*
-     * then, get the list of windows
+     * get the list of windows
      */
-    if (!XQueryTree (dpy, root, &dummy, &dummy, &children, &nchildren)) {
-	return;
-    }
 
-    for (i = 0; i < nchildren; i++) {
-	client = XmuClientWindow (dpy, children[i]);
-	if (client != None)
-	  print_client_properties (dpy, client, verbose, maxcmdlen);
-    }
+    rl->c = dpy;
+    rl->cookie = xcb_query_tree(dpy, root);
+    rl->verbose = verbose;
+    rl->maxcmdlen = maxcmdlen;
+    enqueue(root_list, rl);
 }
 
 static char *Nil = "(nil)";
 
+typedef struct {
+    xcb_connection_t *c;
+    xcb_get_property_cookie_t client_machine;
+    xcb_get_property_cookie_t command;
+    xcb_get_property_cookie_t name;
+    xcb_get_property_cookie_t icon_name;
+    xcb_get_property_cookie_t wm_class;
+    xcb_window_t w;
+    int verbose;
+    int maxcmdlen;
+} client_state;
+
 static void
-print_client_properties(Display *dpy, Window w, Bool verbose, int maxcmdlen)
+show_client_properties(void *closure)
 {
-    char **cliargv = NULL;
-    int i, cliargc;
-    XTextProperty nametp, machtp, tp;
-    int charsleft = maxcmdlen;
+    client_state *cs = closure;
+    xcb_get_property_reply_t *client_machine;
+    xcb_get_property_reply_t *command;
+    xcb_get_property_reply_t *name;
+    xcb_get_property_reply_t *icon_name;
+    xcb_get_property_reply_t *wm_class;
+    char *argv;
+    int charsleft = cs->maxcmdlen;
+    int i;
 
     /*
      * get the WM_MACHINE and WM_COMMAND list of strings
      */
-    if (!XGetWMClientMachine (dpy, w, &machtp)) {
-	machtp.value = NULL;
-	machtp.encoding = None;
+    client_machine = xcb_get_property_reply(cs->c, cs->client_machine, NULL);
+    command = xcb_get_property_reply(cs->c, cs->command, NULL);
+    if (cs->verbose) {
+	name = xcb_get_property_reply(cs->c, cs->name, NULL);
+	icon_name = xcb_get_property_reply(cs->c, cs->icon_name, NULL);
+	wm_class = xcb_get_property_reply(cs->c, cs->wm_class, NULL);
     }
 
-    if (!XGetCommand (dpy, w, &cliargv, &cliargc)) {
-	if (machtp.value) XFree ((char *) machtp.value);
-	return;
-    }
+    if (!command || !command->type)
+	goto done;
 
     /*
      * do header information
      */
-    if (verbose) {
-	printf ("Window 0x%lx:\n", w);
-	print_text_field (dpy, "  Machine:  ", &machtp);
-	if (XGetWMName (dpy, w, &nametp)) {
-	    print_text_field (dpy, "  Name:  ", &nametp);
-	    if (nametp.value) XFree ((char *) nametp.value);
-	}
+    if (cs->verbose) {
+	printf ("Window 0x%lx:\n", cs->w);
+	print_text_field (cs->c, "  Machine:  ", client_machine);
+	if (name && name->type)
+	    print_text_field (cs->c, "  Name:  ", name);
     } else {
-	print_text_field (dpy, NULL, &machtp);
+	print_text_field (cs->c, NULL, client_machine);
 	putchar (' ');
 	putchar (' ');
     }
-    if (machtp.value) XFree ((char *) machtp.value);
 
-    if (verbose) {
-	if (XGetWMIconName (dpy, w, &tp)) {
-	    print_text_field (dpy, "  Icon Name:  ", &tp);
-	    if (tp.value) XFree ((char *) tp.value);
-	}
-    }
+
+    if (cs->verbose)
+	if (icon_name && icon_name->type)
+	    print_text_field (cs->c, "  Icon Name:  ", icon_name);
 
 
     /*
      * do the command
      */
-    if (verbose) {
+    if (cs->verbose)
 	printf ("  Command:  ");
-    }
-    for (i = 0; i < cliargc && charsleft > 0; ) {
-	charsleft -= print_quoted_word (cliargv[i], charsleft);
-	i++;
-	if (i < cliargc  &&  charsleft > 0) {
-	    putchar (' '); charsleft--;
+    argv = xcb_get_property_value(command);
+    for (i = 0; i < command->value_len && charsleft > 0; ) {
+	charsleft -= print_quoted_word (argv + i, charsleft);
+	i += strnlen(argv + i, command->value_len - i) + 1;
+	if (i < command->value_len && charsleft > 0) {
+	    putchar (' ');
+	    charsleft--;
 	}
     }
     putchar ('\n');
-    XFreeStringList (cliargv);
 
 
     /*
      * do trailer information
      */
-    if (verbose) {
-	XClassHint clh;
-	if (XGetClassHint (dpy, w, &clh)) {
-	    printf ("  Instance/Class:  %s/%s",
-		    clh.res_name ? clh.res_name : Nil,
-		    clh.res_class ? clh.res_class : Nil);
-	    if (clh.res_name) XFree (clh.res_name);
-	    if (clh.res_class) XFree (clh.res_class);
+    if (cs->verbose) {
+	if (wm_class && wm_class->type) {
+	    char *res_name, *res_class;
+	    int name_len, class_len;
+	    res_name = xcb_get_property_value(wm_class);
+	    name_len = strnlen(res_name, wm_class->value_len) + 1;
+	    class_len = wm_class->value_len - name_len;
+	    if (class_len > 0) {
+		res_class = res_name + name_len;
+	    } else {
+		res_class = Nil;
+		class_len = strlen(res_class);
+	    }
+
+	    printf ("  Instance/Class:  %.*s/%.*s",
+		    name_len, res_name,
+		    class_len, res_class);
 	    putchar ('\n');
 	}
     }
+
+done:
+    if (client_machine)
+	free(client_machine);
+    if (command)
+	free(command);
+    if (cs->verbose) {
+	if (name)
+	    free(name);
+	if (icon_name)
+	    free(icon_name);
+	if (wm_class)
+	    free(wm_class);
+    }
+    free(cs);
 }
 
 static void
-print_text_field(Display *dpy, char *s, XTextProperty *tp)
+print_client_properties(xcb_connection_t *dpy, xcb_window_t w, int verbose, int maxcmdlen)
 {
-    if (tp->encoding == None || tp->format == 0) {
+    client_state *cs = malloc(sizeof(*cs));
+    if (!cs)
+	return; /* TODO: print OOM message */
+
+    cs->c = dpy;
+    cs->w = w;
+    cs->verbose = verbose;
+    cs->maxcmdlen = maxcmdlen;
+
+    /*
+     * get the WM_CLIENT_MACHINE and WM_COMMAND list of strings
+     */
+    cs->client_machine = xcb_get_property(dpy, 0, w,
+			    WM_CLIENT_MACHINE, XCB_GET_PROPERTY_TYPE_ANY,
+			    0, 1000000L);
+    cs->command = xcb_get_property(dpy, 0, w,
+			    WM_COMMAND, XCB_GET_PROPERTY_TYPE_ANY,
+			    0, 1000000L);
+
+    if (verbose) {
+	cs->name = xcb_get_property(dpy, 0, w,
+			    WM_NAME, XCB_GET_PROPERTY_TYPE_ANY,
+			    0, 1000000L);
+	cs->icon_name = xcb_get_property(dpy, 0, w,
+			    WM_ICON_NAME, XCB_GET_PROPERTY_TYPE_ANY,
+			    0, 1000000L);
+	cs->wm_class = xcb_get_property(dpy, 0, w,
+			    WM_CLASS, STRING,
+			    0, 1000000L);
+    }
+
+    enqueue(show_client_properties, cs);
+}
+
+static void
+print_text_field(xcb_connection_t *dpy, char *s, xcb_get_property_reply_t *tp)
+{
+    if (tp->type == XCB_NONE || tp->format == 0) {  /* Or XCB_ATOM_NONE after libxcb 1.5 */
 	printf ("''");
 	return;
     }
 
     if (s) printf ("%s", s);
-    if (tp->encoding == XA_STRING && tp->format == 8) {
-	printf ("%s", tp->value ? (char *) tp->value : Nil);
+    if (tp->type == STRING && tp->format == 8) {
+	printf ("%.*s", (int)tp->value_len, (char *)xcb_get_property_value(tp));
     } else {
-	unknown (dpy, tp->encoding, tp->format);
+	unknown (dpy, tp->type, tp->format);
     }
     if (s) putchar ('\n');
 }
@@ -303,18 +625,22 @@ print_quoted_word(char *s,
 }
 
 static void
-unknown(Display *dpy, Atom actual_type, int actual_format)
+unknown(xcb_connection_t *dpy, xcb_atom_t actual_type, int actual_format)
 {
-    char *s;
-
     printf ("<unknown type ");
-    if (actual_type == None) printf ("None");
-    else if ((s = XGetAtomName (dpy, actual_type)) != NULL) {
-	fputs (s, stdout);
-	XFree (s);
-    } else {
-	fputs (Nil, stdout);
+    if (actual_type == XCB_NONE)
+	printf ("None");
+    else {
+	/* This should happen so rarely as to make no odds. Eat a round-trip: */
+	xcb_get_atom_name_reply_t *atom =
+	    xcb_get_atom_name_reply(dpy,
+		xcb_get_atom_name(dpy, actual_type), NULL);
+	if (atom) {
+	    printf("%.*s", xcb_get_atom_name_name_length(atom),
+			  xcb_get_atom_name_name(atom));
+	    free(atom);
+	} else
+	    fputs (Nil, stdout);
     }
     printf (" (%ld) or format %d>", actual_type, actual_format);
 }
-