hudson.model.ResourceList Maven / Gradle / Ivy
package hudson.model;
import java.util.Set;
import java.util.HashSet;
import java.util.Map;
import java.util.HashMap;
import java.util.Arrays;
import java.util.Collection;
import java.util.Map.Entry;
/**
* List of {@link Resource}s that an activity needs.
*
*
* There are two ways to access resources. Read and write.
* As with usual reader/writer pattern, multiple read accesses can
* co-exist concurrently, but write access requires exclusive access
* (the number of allowed concurrent write activity is determined by
* {@link Resource#numConcurrentWrite}.
*
* @author Kohsuke Kawaguchi
* @since 1.121
*/
public final class ResourceList {
/**
* All resources (R/W.)
*/
private final Set all = new HashSet();
/**
* Write accesses. Values are the # of write counts that this list uses.
*
* The values are mostly supposed to be 1, but when {@link ResourceController}
* uses a list to keep track of the union of all the activities, it can get larger.
*/
private final Map write = new HashMap();
private static final Integer MAX_INT = Integer.MAX_VALUE;
/**
* Creates union of all resources.
*/
public static ResourceList union(ResourceList... lists) {
return union(Arrays.asList(lists));
}
/**
* Creates union of all resources.
*/
public static ResourceList union(Collection lists) {
switch(lists.size()) {
case 0:
return EMPTY;
case 1:
return lists.iterator().next();
default:
ResourceList r = new ResourceList();
for (ResourceList l : lists) {
r.all.addAll(l.all);
for (Entry e : l.write.entrySet())
r.write.put(e.getKey(), unbox(r.write.get(e.getKey()))+e.getValue());
}
return r;
}
}
/**
* Adds a resource for read access.
*/
public ResourceList r(Resource r) {
all.add(r);
return this;
}
/**
* Adds a resource for write access.
*/
public ResourceList w(Resource r) {
all.add(r);
write.put(r, unbox(write.get(r))+1);
return this;
}
/**
* Checks if this resource list and that resource list has any conflicting
* resource access.
*/
public boolean isCollidingWith(ResourceList that) {
return getConflict(that)!=null;
}
/**
* Returns the resource in this list that's colliding with the given resource list.
*/
public Resource getConflict(ResourceList that) {
Resource r = _getConflict(this,that);
if(r!=null) return r;
return _getConflict(that,this);
}
private Resource _getConflict(ResourceList lhs, ResourceList rhs) {
for (Entry r : lhs.write.entrySet()) {
for (Resource l : rhs.all) {
Integer v = rhs.write.get(l);
if(v!=null) // this is write/write conflict.
v += r.getValue();
else // Otherwise set it to a very large value, since it's read/write conflict
v = MAX_INT;
if(r.getKey().isCollidingWith(l,unbox(v)))
return r.getKey();
}
}
return null;
}
public String toString() {
Map m = new HashMap();
for (Resource r : all)
m.put(r,"R");
for (Entry e : write.entrySet())
m.put(e.getKey(),"W"+e.getValue());
return m.toString();
}
/**
* {@link Integer} unbox operation that treats null as 0.
*/
private static int unbox(Integer x) {
return x==null ? 0 : x;
}
/**
* Empty resource list.
*/
public static final ResourceList EMPTY = new ResourceList();
}