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[Bug #1070] Calculate the critical path using a topological order

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Avoid exponential increase of calculations done, only visiting a node
when all their predecessors have already been processed. This
guarantees that the nodes are processed in a topological order, i.e.,
a node is not processed until their predecessors are processed.

FEA: ItEr74S04BugFixing
This commit is contained in:
Óscar González Fernández 2011-05-15 21:08:28 +02:00
parent f82b20bbd1
commit d733ba80a8
1 changed files with 35 additions and 6 deletions
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41
ganttzk/src/main/java/org/zkoss/ganttz/data/criticalpath/CriticalPathCalculator.java
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@ -68,6 +68,25 @@ public class CriticalPathCalculator<T, D extends IDependency<T>> {
private Map<T, Map<T, DependencyType>> dependencies; private Map<T, Map<T, DependencyType>> dependencies;
private class VisitorTracker {
private Map<T, Set<T>> visitorsOn = new HashMap<T, Set<T>>();
void visit(T visited, T visitor) {
if (!visitorsOn.containsKey(visited)) {
visitorsOn.put(visited, new HashSet<T>());
}
visitorsOn.get(visited).add(visitor);
}
boolean hasBeenVisitedByAll(T current,
Collection<? extends T> collection) {
return visitorsOn.containsKey(current)
&& visitorsOn.get(current).containsAll(collection);
}
}
public List<T> calculateCriticalPath(ICriticalPathCalculable<T> graph) { public List<T> calculateCriticalPath(ICriticalPathCalculable<T> graph) {
this.graph = graph; this.graph = graph;
@ -80,10 +99,10 @@ public class CriticalPathCalculator<T, D extends IDependency<T>> {
nodes = createGraphNodes(); nodes = createGraphNodes();
forward(bop, null); forward(bop, null, new VisitorTracker());
eop.updateLatestValues(); eop.updateLatestValues();
backward(eop, null); backward(eop, null, new VisitorTracker());
return getTasksOnCriticalPath(); return getTasksOnCriticalPath();
} }
@ -272,7 +291,8 @@ public class CriticalPathCalculator<T, D extends IDependency<T>> {
return DependencyType.END_START; return DependencyType.END_START;
} }
private void forward(Node<T, D> currentNode, T previousTask) { private void forward(Node<T, D> currentNode, T previousTask,
VisitorTracker visitorTracker) {
T currentTask = currentNode.getTask(); T currentTask = currentNode.getTask();
int earliestStart = currentNode.getEarliestStart(); int earliestStart = currentNode.getEarliestStart();
int earliestFinish = currentNode.getEarliestFinish(); int earliestFinish = currentNode.getEarliestFinish();
@ -284,6 +304,7 @@ public class CriticalPathCalculator<T, D extends IDependency<T>> {
int countStartStart = 0; int countStartStart = 0;
for (T task : nextTasks) { for (T task : nextTasks) {
visitorTracker.visit(task, currentTask);
if (graph.isContainer(currentTask)) { if (graph.isContainer(currentTask)) {
if (graph.contains(currentTask, previousTask)) { if (graph.contains(currentTask, previousTask)) {
if (graph.contains(currentTask, task)) { if (graph.contains(currentTask, task)) {
@ -312,7 +333,10 @@ public class CriticalPathCalculator<T, D extends IDependency<T>> {
break; break;
} }
forward(node, currentTask); if (visitorTracker.hasBeenVisitedByAll(task,
node.getPreviousTasks())) {
forward(node, currentTask, visitorTracker);
}
} }
if (nextTasks.size() == countStartStart) { if (nextTasks.size() == countStartStart) {
@ -357,7 +381,8 @@ public class CriticalPathCalculator<T, D extends IDependency<T>> {
return Constraint.coalesce(startConstraints); return Constraint.coalesce(startConstraints);
} }
private void backward(Node<T, D> currentNode, T nextTask) { private void backward(Node<T, D> currentNode, T nextTask,
VisitorTracker visitorTracker) {
T currentTask = currentNode.getTask(); T currentTask = currentNode.getTask();
int latestStart = currentNode.getLatestStart(); int latestStart = currentNode.getLatestStart();
int latestFinish = currentNode.getLatestFinish(); int latestFinish = currentNode.getLatestFinish();
@ -369,6 +394,7 @@ public class CriticalPathCalculator<T, D extends IDependency<T>> {
int countEndEnd = 0; int countEndEnd = 0;
for (T task : previousTasks) { for (T task : previousTasks) {
visitorTracker.visit(task, currentTask);
if (graph.isContainer(currentTask)) { if (graph.isContainer(currentTask)) {
if (graph.contains(currentTask, nextTask)) { if (graph.contains(currentTask, nextTask)) {
if (graph.contains(currentTask, task)) { if (graph.contains(currentTask, task)) {
@ -397,7 +423,10 @@ public class CriticalPathCalculator<T, D extends IDependency<T>> {
break; break;
} }
backward(node, currentTask); if (visitorTracker.hasBeenVisitedByAll(task,
node.getNextTasks())) {
backward(node, currentTask, visitorTracker);
}
} }
if (previousTasks.size() == countEndEnd) { if (previousTasks.size() == countEndEnd) {