gitk: Implement date mode in the new framework

This restores date mode, which lists commits by date, as far as possible
given the constraint that parents come after all their children.  To
implement this in the new framework, we (1) only join a new commit onto
an existing arc if the arc is the last arc created, (2) treat arcs as
seeds unless they have a child arc that comes later, and (3) never
decrease the token value for an arc.

This means we get lots of "seeds", which exposed some quadratic behaviour
in adding and removing seeds.  To fix this, we add a vbackptr array, which
points to the arc whose vleftptr entry points to us, and a vlastins array,
which shows where in an arc's vdownptr/vleftptr list we last inserted a
parent, which acts as a hint of a good place to start looking for where to
insert a new child.

This also ensures the children array elements stay in sorted order at all
times.  We weren't resorting the children lists when reassigning tokens
in renumbervarc.  Since the children lists are now always sorted, we don't
have to search through all elements to find the one with the highest token;
we can just use the last element.
Signed-off-by: NPaul Mackerras <paulus@samba.org>

gitk

@@ -269,19 +269,21 @@ proc strrep {n} {
 # --topo-order) into the order for display.
 
 proc varcinit {view} {
-    global varcstart vupptr vdownptr vleftptr varctok varcrow
-    global vtokmod varcmod vrowmod varcix
+    global varcstart vupptr vdownptr vleftptr vbackptr varctok varcrow
+    global vtokmod varcmod vrowmod varcix vlastins
 
     set varcstart($view) {{}}
     set vupptr($view) {0}
     set vdownptr($view) {0}
     set vleftptr($view) {0}
+    set vbackptr($view) {0}
     set varctok($view) {{}}
     set varcrow($view) {{}}
     set vtokmod($view) {}
     set varcmod($view) 0
     set vrowmod($view) 0
     set varcix($view) {{}}
+    set vlastins($view) {0}
 }
 
 proc resetvarcs {view} {
@@ -306,13 +308,13 @@ proc resetvarcs {view} {
 }
 
 proc newvarc {view id} {
-    global varcid varctok parents children
-    global vupptr vdownptr vleftptr varcrow varcix varcstart
-    global commitdata commitinfo vseedcount varccommits
+    global varcid varctok parents children datemode
+    global vupptr vdownptr vleftptr vbackptr varcrow varcix varcstart
+    global commitdata commitinfo vseedcount varccommits vlastins
 
     set a [llength $varctok($view)]
     set vid $view,$id
-    if {[llength $children($vid)] == 0} {
+    if {[llength $children($vid)] == 0 || $datemode} {
 	if {![info exists commitinfo($id)]} {
 	    parsecommit $id $commitdata($id) 1
 	}
@@ -326,64 +328,61 @@ proc newvarc {view id} {
 	set c [incr vseedcount($view,$cdate)]
 	set cdate [expr {$cdate ^ 0xffffffff}]
 	set tok "s[strrep $cdate][strrep $c]"
-	lappend vupptr($view) 0
-	set ka [lindex $vdownptr($view) 0]
-	if {$ka == 0 ||
-	    [string compare $tok [lindex $varctok($view) $ka]] < 0} {
-	    lset vdownptr($view) 0 $a
-	    lappend vleftptr($view) $ka
-	} else {
-	    while {[set b [lindex $vleftptr($view) $ka]] != 0 &&
-		   [string compare $tok [lindex $varctok($view) $b]] >= 0} {
-		set ka $b
-	    }
-	    lset vleftptr($view) $ka $a
-	    lappend vleftptr($view) $b
-	}
     } else {
 	set tok {}
-	foreach k $children($vid) {
-	    set ka $varcid($view,$k)
-	    if {[string compare [lindex $varctok($view) $ka] $tok] > 0} {
-		set ki $k
-		set tok [lindex $varctok($view) $ka]
-	    }
+    }
+    set ka 0
+    if {[llength $children($vid)] > 0} {
+	set kid [lindex $children($vid) end]
+	set k $varcid($view,$kid)
+	if {[string compare [lindex $varctok($view) $k] $tok] > 0} {
+	    set ki $kid
+	    set ka $k
+	    set tok [lindex $varctok($view) $k]
 	}
-	set ka $varcid($view,$ki)
-	lappend vupptr($view) $ka
+    }
+    if {$ka != 0} {
 	set i [lsearch -exact $parents($view,$ki) $id]
 	set j [expr {[llength $parents($view,$ki)] - 1 - $i}]
-	set rsib 0
-	while {[incr i] < [llength $parents($view,$ki)]} {
-	    set bi [lindex $parents($view,$ki) $i]
-	    if {[info exists varcid($view,$bi)]} {
-		set b $varcid($view,$bi)
-		if {[lindex $vupptr($view) $b] == $ka} {
-		    set rsib $b
-		    lappend vleftptr($view) [lindex $vleftptr($view) $b]
-		    lset vleftptr($view) $b $a
-		    break
-		}
-	    }
-	}
-	if {$rsib == 0} {
-	    lappend vleftptr($view) [lindex $vdownptr($view) $ka]
-	    lset vdownptr($view) $ka $a
-	}
 	append tok [strrep $j]
     }
+    set c [lindex $vlastins($view) $ka]
+    if {$c == 0 || [string compare $tok [lindex $varctok($view) $c]] < 0} {
+	set c $ka
+	set b [lindex $vdownptr($view) $ka]
+    } else {
+	set b [lindex $vleftptr($view) $c]
+    }
+    while {$b != 0 && [string compare $tok [lindex $varctok($view) $b]] >= 0} {
+	set c $b
+	set b [lindex $vleftptr($view) $c]
+    }
+    if {$c == $ka} {
+	lset vdownptr($view) $ka $a
+	lappend vbackptr($view) 0
+    } else {
+	lset vleftptr($view) $c $a
+	lappend vbackptr($view) $c
+    }
+    lset vlastins($view) $ka $a
+    lappend vupptr($view) $ka
+    lappend vleftptr($view) $b
+    if {$b != 0} {
+	lset vbackptr($view) $b $a
+    }
     lappend varctok($view) $tok
     lappend varcstart($view) $id
     lappend vdownptr($view) 0
     lappend varcrow($view) {}
     lappend varcix($view) {}
     set varccommits($view,$a) {}
+    lappend vlastins($view) 0
     return $a
 }
 
 proc splitvarc {p v} {
     global varcid varcstart varccommits varctok
-    global vupptr vdownptr vleftptr varcix varcrow
+    global vupptr vdownptr vleftptr vbackptr varcix varcrow vlastins
 
     set oa $varcid($v,$p)
     set ac $varccommits($v,$oa)
@@ -405,6 +404,8 @@ proc splitvarc {p v} {
     lset vdownptr($v) $oa $na
     lappend vupptr($v) $oa
     lappend vleftptr($v) 0
+    lappend vbackptr($v) 0
+    lappend vlastins($v) 0
     for {set b [lindex $vdownptr($v) $na]} {$b != 0} {set b [lindex $vleftptr($v) $b]} {
 	lset vupptr($v) $b $na
     }
@@ -412,11 +413,12 @@ proc splitvarc {p v} {
 
 proc renumbervarc {a v} {
     global parents children varctok varcstart varccommits
-    global vupptr vdownptr vleftptr varcid vtokmod
+    global vupptr vdownptr vleftptr vbackptr vlastins varcid vtokmod datemode
 
     set t1 [clock clicks -milliseconds]
     set todo {}
     set isrelated($a) 1
+    set kidchanged($a) 1
     set ntot 0
     while {$a != 0} {
 	if {[info exists isrelated($a)]} {
@@ -440,26 +442,45 @@ proc renumbervarc {a v} {
 	set a $b
     }
     foreach a $todo {
+	if {![info exists kidchanged($a)]} continue
 	set id [lindex $varcstart($v) $a]
-	set tok {}
-	foreach k $children($v,$id) {
-	    set ka $varcid($v,$k)
-	    if {[string compare [lindex $varctok($v) $ka] $tok] > 0} {
-		set ki $k
-		set tok [lindex $varctok($v) $ka]
+	if {[llength $children($v,$id)] > 1} {
+	    set children($v,$id) [lsort -command [list vtokcmp $v] \
+				      $children($v,$id)]
+	}
+	set oldtok [lindex $varctok($v) $a]
+	if {!$datemode} {
+	    set tok {}
+	} else {
+	    set tok $oldtok
+	}
+	set ka 0
+	if {[llength $children($v,$id)] > 0} {
+	    set kid [lindex $children($v,$id) end]
+	    set k $varcid($v,$kid)
+	    if {[string compare [lindex $varctok($v) $k] $tok] > 0} {
+		set ki $kid
+		set ka $k
+		set tok [lindex $varctok($v) $k]
 	    }
 	}
-	if {$tok ne {}} {
-	    set ka $varcid($v,$ki)
+	if {$ka != 0} {
 	    set i [lsearch -exact $parents($v,$ki) $id]
 	    set j [expr {[llength $parents($v,$ki)] - 1 - $i}]
 	    append tok [strrep $j]
-	    set oldtok [lindex $varctok($v) $a]
-	    if {$tok eq $oldtok} continue
-	    lset varctok($v) $a $tok
-	} else {
-	    set ka 0
 	}
+	if {$tok eq $oldtok} {
+	    continue
+	}
+	set id [lindex $varccommits($v,$a) end]
+	foreach p $parents($v,$id) {
+	    if {[info exists varcid($v,$p)]} {
+		set kidchanged($varcid($v,$p)) 1
+	    } else {
+		set sortkids($p) 1
+	    }
+	}
+	lset varctok($v) $a $tok
 	set b [lindex $vupptr($v) $a]
 	if {$b != $ka} {
 	    if {[string compare [lindex $varctok($v) $ka] $vtokmod($v)] < 0} {
@@ -468,38 +489,48 @@ proc renumbervarc {a v} {
 	    if {[string compare [lindex $varctok($v) $b] $vtokmod($v)] < 0} {
 		modify_arc $v $b
 	    }
-	    set c [lindex $vdownptr($v) $b]
-	    if {$c == $a} {
-		lset vdownptr($v) $b [lindex $vleftptr($v) $a]
+	    set c [lindex $vbackptr($v) $a]
+	    set d [lindex $vleftptr($v) $a]
+	    if {$c == 0} {
+		lset vdownptr($v) $b $d
 	    } else {
-		set b $c
-		while {$b != 0 && [lindex $vleftptr($v) $b] != $a} {
-		    set b [lindex $vleftptr($v) $b]
-		}
-		if {$b != 0} {
-		    lset vleftptr($v) $b [lindex $vleftptr($v) $a]
-		} else {
-		    puts "oops couldn't find $a in chain for [lindex $vupptr($v) $a]"
-		}
+		lset vleftptr($v) $c $d
+	    }
+	    if {$d != 0} {
+		lset vbackptr($v) $d $c
 	    }
 	    lset vupptr($v) $a $ka
-	    set rsib 0
-	    while {[incr i] < [llength $parents($v,$ki)]} {
-		set bi [lindex $parents($v,$ki) $i]
-		if {[info exists varcid($v,$bi)]} {
-		    set b $varcid($v,$bi)
-		    if {[lindex $vupptr($v) $b] == $ka} {
-			set rsib $b
-			lset vleftptr($v) $a [lindex $vleftptr($v) $b]
-			lset vleftptr($v) $b $a
-			break
-		    }
-		}
+	    set c [lindex $vlastins($v) $ka]
+	    if {$c == 0 || \
+		    [string compare $tok [lindex $varctok($v) $c]] < 0} {
+		set c $ka
+		set b [lindex $vdownptr($v) $ka]
+	    } else {
+		set b [lindex $vleftptr($v) $c]
+	    }
+	    while {$b != 0 && \
+		      [string compare $tok [lindex $varctok($v) $b]] >= 0} {
+		set c $b
+		set b [lindex $vleftptr($v) $c]
 	    }
-	    if {$rsib == 0} {
-		lset vleftptr($v) $a [lindex $vdownptr($v) $ka]
-		lset vdownptr($v) $ka $a
+	    if {$c == $ka} {
+ 		lset vdownptr($v) $ka $a
+		lset vbackptr($v) $a 0
+	    } else {
+		lset vleftptr($v) $c $a
+		lset vbackptr($v) $a $c
+	    }
+	    lset vleftptr($v) $a $b
+	    if {$b != 0} {
+		lset vbackptr($v) $b $a
 	    }
+	    lset vlastins($v) $ka $a
+	}
+    }
+    foreach id [array names sortkids] {
+	if {[llength $children($v,$id)] > 1} {
+	    set children($v,$id) [lsort -command [list vtokcmp $v] \
+				      $children($v,$id)]
 	}
     }
     set t2 [clock clicks -milliseconds]
@@ -831,7 +862,7 @@ proc closevarcs {v} {
 
 proc getcommitlines {fd inst view}  {
     global cmitlisted commitinterest leftover
-    global commitidx commitdata
+    global commitidx commitdata datemode
     global parents children curview hlview
     global vnextroot idpending ordertok
     global varccommits varcid varctok vtokmod
@@ -946,12 +977,12 @@ proc getcommitlines {fd inst view}  {
 	set a 0
 	if {![info exists children($vid)]} {
 	    set children($vid) {}
-	} else {
-	    if {[llength $children($vid)] == 1} {
-		set k [lindex $children($vid) 0]
-		if {[llength $parents($view,$k)] == 1} {
-		    set a $varcid($view,$k)
-		}
+	} elseif {[llength $children($vid)] == 1} {
+	    set k [lindex $children($vid) 0]
+	    if {[llength $parents($view,$k)] == 1 &&
+		(!$datemode ||
+		 $varcid($view,$k) == [llength $varctok($view)] - 1)} {
+		set a $varcid($view,$k)
 	    }
 	}
 	if {$a == 0} {
@@ -974,9 +1005,9 @@ proc getcommitlines {fd inst view}  {
 					   $children($vp)]
 		    catch {unset ordertok}
 		}
-	    }
-	    if {[info exists varcid($view,$p)]} {
-		fix_reversal $p $a $view
+		if {[info exists varcid($view,$p)]} {
+		    fix_reversal $p $a $view
+		}
 	    }
 	    incr i
 	}
@@ -1033,7 +1064,7 @@ proc chewcommits {view} {
     if {$view == $curview} {
 	layoutmore
 	if {$viewcomplete($view)} {
-	    global commitidx
+	    global commitidx varctok
 	    global numcommits startmsecs
 	    global mainheadid commitinfo nullid
 
@@ -1044,6 +1075,7 @@ proc chewcommits {view} {
 	    if {$commitidx($curview) > 0} {
 		#set ms [expr {[clock clicks -milliseconds] - $startmsecs}]
 		#puts "overall $ms ms for $numcommits commits"
+		#puts "[llength $varctok($view)] arcs, $commitidx($view) commits"
 	    } else {
 		show_status "No commits selected"
 	    }