git-gui: More performance improvements to rescan logic.

Removed as much as possible from the merge_state proc, which is where
we spent most of our time before UI update.  This change makes our
running time match that of git status, except that we then need about
7 additional seconds to draw 6900 files on screen.

Apparently the [array names a -exact $v] operator in Tcl is O(n) rather
than O(1), which is really quite disappointing given that each array can
only have one entry for a given value.  Switching to a lookup with a
catch (whose error we ignore) runs in O(1) time and bought us most of
that improvement.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

git-gui

@@ -70,7 +70,7 @@ proc repository_state {hdvar ctvar} {
 proc update_status {{final Ready.}} {
 	global HEAD PARENT commit_type
 	global ui_index ui_other ui_status_value ui_comm
-	global status_active file_states
+	global status_active file_states status_start
 
 	if {$status_active || ![lock_index read]} return
 
@@ -84,6 +84,7 @@ proc update_status {{final Ready.}} {
 		set commit_type $new_type
 	}
 
+	set status_start [clock seconds]
 	array unset file_states
 	foreach w [list $ui_index $ui_other] {
 		$w conf -state normal
@@ -230,7 +231,7 @@ proc read_ls_others {fd final} {
 }
 
 proc status_eof {fd buf final} {
-	global status_active $buf
+	global status_active status_start $buf
 	global ui_fname_value ui_status_value file_states
 
 	if {[eof $fd]} {
@@ -240,8 +241,12 @@ proc status_eof {fd buf final} {
 		if {[incr status_active -1] == 0} {
 			unlock_index
 
-			set ui_status_value $final
+			set e1 [clock seconds]
 			display_all_files
+			set e2 [clock seconds]
+puts "TIME [expr $e1 - $status_start] + [expr $e2 - $e1] = [expr $e2 - $status_start]"
+
+			set ui_status_value $final
 
 			if {$ui_fname_value != {} && [array names file_states \
 				-exact $ui_fname_value] != {}}  {
@@ -664,11 +669,11 @@ proc push_to {remote} {
 ## ui helpers
 
 proc mapcol {state path} {
-	global all_cols
+	global all_cols ui_other
 
 	if {[catch {set r $all_cols($state)}]} {
 		puts "error: no column for state={$state} $path"
-		return o
+		return $ui_other
 	}
 	return $r
 }
@@ -716,31 +721,34 @@ proc bsearch {w path} {
 
 set next_icon_id 0
 
-proc merge_state {path state} {
+proc merge_state {path new_state} {
 	global file_states next_icon_id
 
-	if {[array names file_states -exact $path] == {}}  {
-		set m __
-		set s [list $m icon[incr next_icon_id]]
+	set s0 [string index $new_state 0]
+	set s1 [string index $new_state 1]
+
+	if {[catch {set info $file_states($path)}]} {
+		set state __
+		set icon n[incr next_icon_id]
 	} else {
-		set s $file_states($path)
-		set m [lindex $s 0]
+		set state [lindex $info 0]
+		set icon [lindex $info 1]
 	}
 
-	if {[string index $state 0] == {_}} {
-		set state [string index $m 0][string index $state 1]
-	} elseif {[string index $state 0] == {*}} {
-		set state _[string index $state 1]
+	if {$s0 == {_}} {
+		set s0 [string index $state 0]
+	} elseif {$s0 == {*}} {
+		set s0 _
 	}
 
-	if {[string index $state 1] == {_}} {
-		set state [string index $state 0][string index $m 1]
-	} elseif {[string index $state 1] == {*}} {
-		set state [string index $state 0]_
+	if {$s1 == {_}} {
+		set s1 [string index $state 1]
+	} elseif {$s1 == {*}} {
+		set s1 _
 	}
 
-	set file_states($path) [lreplace $s 0 0 $state]
-	return $m
+	set file_states($path) [list $s0$s1 $icon]
+	return $state
 }
 
 proc display_file {path state} {
@@ -750,19 +758,12 @@ proc display_file {path state} {
 	if {$status_active} return
 
 	set s $file_states($path)
+	set old_w [mapcol $old_m $path]
+	set new_w [mapcol $new_m $path]
 	set new_m [lindex $s 0]
-	set new_col [mapcol $new_m $path]
 	set new_ico [mapicon $new_m $path]
 
-	if {$new_col == {o}} {
-		set old_w $ui_index
-		set new_w $ui_other
-	} else {
-		set old_w $ui_other
-		set new_w $ui_index
-	}
-
-	if {$new_col != [mapcol $old_m $path]} {
+	if {$new_w != $old_w} {
 		set lno [bsearch $old_w $path]
 		if {$lno >= 0} {
 			incr lno
@@ -795,18 +796,12 @@ proc display_all_files {} {
 	foreach path [lsort [array names file_states]] {
 		set s $file_states($path)
 		set m [lindex $s 0]
-
-		if {[mapcol $m $path] == {o}} {
-			set aw $ui_other
-		} else {
-			set aw $ui_index
-		}
-
-		$aw image create end \
+		set w [mapcol $m $path]
+		$w image create end \
 			-align center -padx 5 -pady 1 \
 			-name [lindex $s 1] \
 			-image [mapicon $m $path]
-		$aw insert end "$path\n"
+		$w insert end "$path\n"
 	}
 
 	$ui_index conf -state disabled
@@ -1025,6 +1020,8 @@ static unsigned char file_merge_bits[] = {
    0xfa, 0x17, 0x02, 0x10, 0xfe, 0x1f};
 } -maskdata $filemask
 
+set ui_index .vpane.files.index.list
+set ui_other .vpane.files.other.list
 set max_status_desc 0
 foreach i {
 		{__ i plain    "Unmodified"}
@@ -1035,7 +1032,7 @@ foreach i {
 		{_O o plain    "Untracked"}
 		{A_ o fulltick "Added"}
 		{AM o parttick "Partially added"}
-		{AD o question  "Added (but now gone)"}
+		{AD o question "Added (but now gone)"}
 
 		{_D i question "Missing"}
 		{D_ i removed  "Removed"}
@@ -1048,7 +1045,11 @@ foreach i {
 	if {$max_status_desc < [string length [lindex $i 3]]} {
 		set max_status_desc [string length [lindex $i 3]]
 	}
-	set all_cols([lindex $i 0]) [lindex $i 1]
+	if {[lindex $i 1] == {i}} {
+		set all_cols([lindex $i 0]) $ui_index
+	} else {
+		set all_cols([lindex $i 0]) $ui_other
+	}
 	set all_icons([lindex $i 0]) file_[lindex $i 2]
 	set all_descs([lindex $i 0]) [lindex $i 3]
 }
@@ -1461,7 +1462,6 @@ panedwindow .vpane.files -orient horizontal
 pack .vpane -anchor n -side top -fill both -expand 1
 
 # -- Index File List
-set ui_index .vpane.files.index.list
 frame .vpane.files.index -height 100 -width 400
 label .vpane.files.index.title -text {Modified Files} \
 	-background green \
@@ -1479,7 +1479,6 @@ pack $ui_index -side left -fill both -expand 1
 .vpane.files add .vpane.files.index -sticky nsew
 
 # -- Other (Add) File List
-set ui_other .vpane.files.other.list
 frame .vpane.files.other -height 100 -width 100
 label .vpane.files.other.title -text {Untracked Files} \
 	-background red \