Artifact 00c265ebb6c2bf602a2ea5eb0db4be65bdd914b9
File
tools/cvs2fossil/lib/c2f_cyclebreaker.tcl
part of check-in
[f284847134]
- Reworked the dot export internals a bit to be more general regarding labeling and attribute writing. Updated the cycle breaker to define proper labels.
by
aku on
2007-11-22 07:22:38.
## -*- tcl -*-
# # ## ### ##### ######## ############# #####################
## Copyright (c) 2007 Andreas Kupries.
#
# This software is licensed as described in the file LICENSE, which
# you should have received as part of this distribution.
#
# This software consists of voluntary contributions made by many
# individuals. For exact contribution history, see the revision
# history and logs, available at http://fossil-scm.hwaci.com/fossil
# # ## ### ##### ######## ############# #####################
## This file provides a helper package for the passes 6 and 7 which
## contains the common code of the cycle breaking algorithm.
# # ## ### ##### ######## ############# #####################
## Requirements
package require Tcl 8.4 ; # Required runtime.
package require snit ; # OO system.
package require struct::graph ; # Graph handling.
package require struct::list ; # Higher order list operations.
package require vc::tools::dot ; # User feedback. DOT export.
package require vc::tools::log ; # User feedback.
package require vc::tools::trouble ; # Error reporting.
package require vc::tools::misc ; # Text formatting.
package require vc::fossil::import::cvs::project::rev ; # Project level changesets
package require vc::fossil::import::cvs::project::revlink ; # Cycle links.
# # ## ### ##### ######## ############# #####################
##
snit::type ::vc::fossil::import::cvs::cyclebreaker {
# # ## ### ##### ######## #############
## Public API
typemethod precmd {cmd} {
::variable myprecmd $cmd
return
}
typemethod savecmd {cmd} {
::variable mysavecmd $cmd
return
}
typemethod breakcmd {cmd} {
::variable mybreakcmd $cmd
return
}
# # ## ### ##### ######## #############
typemethod dotsto {path} {
::variable mydotdestination $path
return
}
typemethod dot {label changesets} {
::variable mydotprefix $label
::variable mydotid 0
set dg [Setup $changesets 0]
Mark $dg
$dg destroy
return
}
# # ## ### ##### ######## #############
typemethod run {label changesetcmd} {
::variable myat 0
::variable mydotprefix $label
::variable mydotid 0
# We create a graph of the revision changesets, using the file
# level dependencies to construct a first approximation of the
# dependencies at the project level. Then we look for cycles
# in that graph and break them.
# 1. Create nodes for all relevant changesets and a mapping
# from the revisions to their changesets/nodes.
set changesets [uplevel #0 $changesetcmd]
set dg [Setup $changesets]
# 3. Lastly we iterate the graph topologically. We mark off
# the nodes which have no predecessors, in order from
# oldest to youngest, saving and removing dependencies. If
# we find no nodes without predecessors we have a cycle,
# and work on breaking it.
log write 3 cyclebreaker {Now sorting the changesets, breaking cycles}
InitializeCandidates $dg
while {1} {
while {[WithoutPredecessor $dg n]} {
ProcessedHook $n $myat
$dg node delete $n
incr myat
ShowPendingNodes
}
if {![llength [dg nodes]]} break
BreakCycleHook $dg
InitializeCandidates $dg
}
$dg destroy
log write 3 cyclebreaker Done.
ClearHooks
# Reread the graph and dump its final form, if graph export
# was activated.
::variable mydotdestination
if {$mydotdestination eq ""} return
set dg [Setup [uplevel #0 $changesetcmd] 0]
Mark $dg -done
$dg destroy
return
}
# # ## ### ##### ######## #############
typemethod break {graph} {
BreakCycle $graph [FindCycle $graph]
return
}
typemethod replace {graph n replacements} {
Replace $graph $n $replacements
return
}
# # ## ### ##### ######## #############
## Internal methods
proc Setup {changesets {log 1}} {
if {$log} {
log write 3 cyclebreaker "Creating changeset graph, filling with nodes"
log write 3 cyclebreaker "Adding [nsp [llength $changesets] node]"
}
set dg [struct::graph dg]
foreach cset $changesets {
$dg node insert $cset
$dg node set $cset timerange [$cset timerange]
$dg node set $cset label [ID $cset]
}
# 2. Find for all relevant changeset their revisions and their
# dependencies. Map the latter back to changesets and
# construct the corresponding arcs.
if {$log} {
log write 3 cyclebreaker {Setting up node dependencies}
}
foreach cset $changesets {
foreach succ [$cset successors] {
# Changesets may have dependencies outside of the
# chosen set. These are ignored
if {![$dg node exists $succ]} continue
$dg arc insert $cset $succ
}
}
# Run the user hook to manipulate the graph before
# consummation.
if {$log} { Mark $dg -start }
PreHook $dg
return $dg
}
# Instead of searching the whole graph for the degree-0 nodes in
# each iteration we compute the list once to start, and then only
# update it incrementally based on the outgoing neighbours of the
# node chosen for commit.
proc InitializeCandidates {dg} {
# bottom = list (list (node, range min, range max))
::variable mybottom
foreach n [$dg nodes] {
if {[$dg node degree -in $n]} continue
lappend mybottom [linsert [$dg node get $n timerange] 0 $n]
}
set mybottom [lsort -index 1 -integer [lsort -index 2 -integer $mybottom]]
ShowPendingNodes
return
}
proc WithoutPredecessor {dg nv} {
::variable mybottom
upvar 1 $nv n
if {![llength $mybottom]} { return 0 }
set n [lindex [lindex $mybottom 0] 0]
set mybottom [lrange $mybottom 1 end]
set changed 0
# Update list of nodes without predecessor, based on the
# outgoing neighbours of the chosen node. This should be
# faster than iterating of the whole set of nodes, finding all
# without predecessors, sorting them by time, etc. pp.
foreach out [$dg nodes -out $n] {
if {[$dg node degree -in $out] > 1} continue
# Degree-1 neighbour, will have no predecessors after the
# removal of n. Put on the list.
lappend mybottom [linsert [$dg node get $out timerange] 0 $out]
set changed 1
}
if {$changed} {
set mybottom [lsort -index 1 -integer [lsort -index 2 -integer $mybottom]]
}
# We do not delete the node immediately, to allow the Save
# procedure to save the dependencies as well (encoded in the
# arcs).
return 1
}
proc ShowPendingNodes {} {
if {[log verbosity?] < 10} return
::variable mybottom
log write 10 cyclebreaker \
"Pending: [struct::list map $mybottom [myproc FormatPendingItem]]"
return
}
proc FormatPendingItem {item} { lreplace $item 0 0 <[[lindex $item 0] id]> }
proc FindCycle {dg} {
# This procedure is run if and only the graph is not empty and
# all nodes have predecessors. This means that each node is
# either part of a cycle or (indirectly) depending on a node
# in a cycle. We can start at an arbitrary node, follow its
# incoming edges to its predecessors until we see a node a
# second time. That node closes the cycle and the beginning is
# its first occurence. Note that we can choose an arbitrary
# predecessor of each node as well, we do not have to search.
# We record for each node the index of the first appearance in
# the path, making it easy at the end to cut the cycle from
# it.
# Choose arbitrary node to start our search at.
set start [lindex [$dg nodes] 0]
# Initialize state, path of seen nodes, and when seen.
set path {}
array set seen {}
while {1} {
# Stop searching when we have seen the current node
# already, the circle has been closed.
if {[info exists seen($start)]} break
lappend path $start
set seen($start) [expr {[llength $path]-1}]
# Choose arbitrary predecessor
set start [lindex [$dg nodes -in $start] 0]
}
return [struct::list reverse [lrange $path $seen($start) end]]
}
proc ID {cset} { return "<[$cset id]>" }
proc BreakCycle {dg cycle} {
# The cycle we have gotten is broken by breaking apart one or
# more of the changesets in the cycle. This causes us to
# create one or more changesets which are to be committed,
# added to the graph, etc. pp.
set cprint [join [struct::list map $cycle [myproc ID]] { }]
lappend cycle [lindex $cycle 0] [lindex $cycle 1]
set bestlink {}
set bestnode {}
foreach \
prev [lrange $cycle 0 end-2] \
cset [lrange $cycle 1 end-1] \
next [lrange $cycle 2 end] {
# Each triple PREV -> CSET -> NEXT of changesets, a
# 'link' in the cycle, is analysed and the best
# location where to at least weaken the cycle is
# chosen for further processing.
set link [project::revlink %AUTO% $prev $cset $next]
if {$bestlink eq ""} {
set bestlink $link
set bestnode $cset
} elseif {[$link betterthan $bestlink]} {
$bestlink destroy
set bestlink $link
set bestnode $cset
} else {
$link destroy
}
}
log write 5 cyclebreaker "Breaking cycle ($cprint) by splitting changeset <[$bestnode id]>"
set ID [$bestnode id]
Mark $dg -${ID}-before
set newcsets [$bestlink break]
$bestlink destroy
# At this point the old changeset (BESTNODE) is gone
# already. We remove it from the graph as well and then enter
# the fragments generated for it.
Replace $dg $bestnode $newcsets
Mark $dg -${ID}-after
return
}
# TODO: This should be a graph method.
proc HasArc {dg a b} {
#8.5: return [expr {$b in [$dg nodes -out $a]}]
if {[lsearch -exact [$dg nodes -out $a] $b] < 0} { return 0 }
return 1
}
proc Mark {dg {suffix {}}} {
::variable mydotdestination
if {$mydotdestination eq ""} return
::variable mydotprefix
::variable mydotid
set fname $mydotdestination/${mydotprefix}${mydotid}${suffix}.dot
file mkdir [file dirname $fname]
dot write $dg $mydotprefix$suffix $fname
incr mydotid
log write 5 cyclebreaker ".dot export $fname"
return
}
proc Replace {dg n replacements} {
# NOTE. We have to get the list of incoming neighbours and
# recompute their successors after the new nodes have been
# inserted. Their outgoing arcs will now go to one or both of
# the new nodes, and not redoing them may cause us to forget
# circles, leaving them in, unbroken.
set pre [$dg nodes -in $n]
$dg node delete $n
foreach cset $replacements {
$dg node insert $cset
$dg node set $cset timerange [$cset timerange]
}
foreach cset $replacements {
foreach succ [$cset successors] {
# The new changesets may have dependencies outside of
# the chosen set. These are ignored
if {![$dg node exists $succ]} continue
$dg arc insert $cset $succ
}
}
foreach cset $pre {
foreach succ [$cset successors] {
# Note that the arc may already exist in the graph. If
# so ignore it. The new changesets may have
# dependencies outside of the chosen set. These are
# ignored
if {![$dg node exists $succ]} continue
if {[HasArc $dg $cset $succ]} continue;# TODO should be graph method.
$dg arc insert $cset $succ
}
}
return
}
# # ## ### ##### ######## #############
## Callback invokation ...
proc PreHook {graph} {
# Give the user of the cycle breaker the opportunity to work
# with the graph between setup and consummation.
::variable myprecmd
if {![llength $myprecmd]} return
uplevel #0 [linsert $myprecmd end $graph]
Mark $graph -pre-done
return
}
proc ProcessedHook {cset pos} {
# Give the user of the cycle breaker the opportunity to work
# with the changeset before it is removed from the graph.
::variable mysavecmd
if {![llength $mysavecmd]} return
uplevel #0 [linsert $mysavecmd end $pos $cset]
return
}
proc BreakCycleHook {graph} {
# Call out to the chosen algorithm for cycle breaking. Finding
# a cycle if no breaker was chosen is an error.
::variable mybreakcmd
if {![llength $mybreakcmd]} {
trouble fatal "Found a cycle, expecting none."
exit 1
}
uplevel #0 [linsert $mybreakcmd end $graph]
return
}
proc ClearHooks {} {
::variable myprecmd {}
::variable mysavecmd {}
::variable mybreakcmd {}
return
}
# # ## ### ##### ######## #############
typevariable myat 0 ; # Counter for commit ids for the
# changesets.
typevariable mybottom {} ; # List of the candidate nodes for
# committing.
typevariable myprecmd {} ; # Callback, change graph before walk.
typevariable mysavecmd {} ; # Callback, for each processed node.
typevariable mybreakcmd {} ; # Callback, for each found cycle.
typevariable mydotdestination {} ; # Destination directory for the
# generated .dot files.
typevariable mydotprefix {} ; # Prefix for dot files when
# exporting the graphs.
typevariable mydotid 0 ; # Counter for dot file name
# generation.
# # ## ### ##### ######## #############
## Configuration
pragma -hasinstances no ; # singleton
pragma -hastypeinfo no ; # no introspection
pragma -hastypedestroy no ; # immortal
# # ## ### ##### ######## #############
}
namespace eval ::vc::fossil::import::cvs {
namespace export cyclebreaker
namespace eval cyclebreaker {
namespace eval project {
namespace import ::vc::fossil::import::cvs::project::rev
namespace import ::vc::fossil::import::cvs::project::revlink
}
namespace import ::vc::tools::misc::*
namespace import ::vc::tools::log
namespace import ::vc::tools::trouble
namespace import ::vc::tools::dot
log register cyclebreaker
}
}
# # ## ### ##### ######## ############# #####################
## Ready
package provide vc::fossil::import::cvs::cyclebreaker 1.0
return