org.apache.hadoop.yarn.webapp.Router Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.yarn.webapp;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
import static org.apache.hadoop.yarn.util.StringHelper.djoin;
import static org.apache.hadoop.yarn.util.StringHelper.join;
import static org.apache.hadoop.yarn.util.StringHelper.pjoin;
import java.lang.reflect.Method;
import java.util.EnumSet;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import java.util.regex.Pattern;
import org.apache.commons.lang.StringUtils;
import org.apache.hadoop.classification.InterfaceAudience;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.google.common.base.CharMatcher;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Maps;
/**
* Manages path info to controller#action routing.
*/
@InterfaceAudience.LimitedPrivate({"YARN", "MapReduce"})
class Router {
static final Logger LOG = LoggerFactory.getLogger(Router.class);
static final ImmutableList EMPTY_LIST = ImmutableList.of();
static final CharMatcher SLASH = CharMatcher.is('/');
static final Pattern controllerRe =
Pattern.compile("^/[A-Za-z_]\\w*(?:/.*)?");
static class Dest {
final String prefix;
final ImmutableList pathParams;
final Method action;
final Class controllerClass;
Class defaultViewClass;
final EnumSet methods;
Dest(String path, Method method, Class cls,
List pathParams, WebApp.HTTP httpMethod) {
prefix = checkNotNull(path);
action = checkNotNull(method);
controllerClass = checkNotNull(cls);
this.pathParams = pathParams != null ? ImmutableList.copyOf(pathParams)
: EMPTY_LIST;
methods = EnumSet.of(httpMethod);
}
}
Class hostClass; // starting point to look for default classes
final TreeMap routes = Maps.newTreeMap(); // path->dest
/**
* Add a route to the router.
* e.g., add(GET, "/foo/show", FooController.class, "show", [name...]);
* The name list is from /foo/show/:name/...
*/
synchronized Dest add(WebApp.HTTP httpMethod, String path,
Class cls,
String action, List names) {
LOG.debug("adding {}({})->{}#{}", new Object[]{path, names, cls, action});
Dest dest = addController(httpMethod, path, cls, action, names);
addDefaultView(dest);
return dest;
}
private Dest addController(WebApp.HTTP httpMethod, String path,
Class cls,
String action, List names) {
try {
// Look for the method in all public methods declared in the class
// or inherited by the class.
// Note: this does not distinguish methods with the same signature
// but different return types.
// TODO: We may want to deal with methods that take parameters in the future
Method method = cls.getMethod(action, null);
Dest dest = routes.get(path);
if (dest == null) {
method.setAccessible(true); // avoid any runtime checks
dest = new Dest(path, method, cls, names, httpMethod);
routes.put(path, dest);
return dest;
}
dest.methods.add(httpMethod);
return dest;
} catch (NoSuchMethodException nsme) {
throw new WebAppException(action + "() not found in " + cls);
} catch (SecurityException se) {
throw new WebAppException("Security exception thrown for " + action +
"() in " + cls);
}
}
private void addDefaultView(Dest dest) {
String controllerName = dest.controllerClass.getSimpleName();
if (controllerName.endsWith("Controller")) {
controllerName = controllerName.substring(0,
controllerName.length() - 10);
}
dest.defaultViewClass = find(View.class,
dest.controllerClass.getPackage().getName(),
join(controllerName + "View"));
}
void setHostClass(Class cls) {
hostClass = cls;
}
/**
* Resolve a path to a destination.
*/
synchronized Dest resolve(String httpMethod, String path) {
WebApp.HTTP method = WebApp.HTTP.valueOf(httpMethod); // can throw
Dest dest = lookupRoute(method, path);
if (dest == null) {
return resolveDefault(method, path);
}
return dest;
}
private Dest lookupRoute(WebApp.HTTP method, String path) {
String key = path;
do {
Dest dest = routes.get(key);
if (dest != null && methodAllowed(method, dest)) {
if ((Object)key == path) { // shut up warnings
LOG.debug("exact match for {}: {}", key, dest.action);
return dest;
} else if (isGoodMatch(dest, path)) {
LOG.debug("prefix match2 for {}: {}", key, dest.action);
return dest;
}
return resolveAction(method, dest, path);
}
Map.Entry lower = routes.lowerEntry(key);
if (lower == null) {
return null;
}
dest = lower.getValue();
if (prefixMatches(dest, path)) {
if (methodAllowed(method, dest)) {
if (isGoodMatch(dest, path)) {
LOG.debug("prefix match for {}: {}", lower.getKey(), dest.action);
return dest;
}
return resolveAction(method, dest, path);
}
// check other candidates
int slashPos = key.lastIndexOf('/');
key = slashPos > 0 ? path.substring(0, slashPos) : "/";
} else {
key = "/";
}
} while (true);
}
static boolean methodAllowed(WebApp.HTTP method, Dest dest) {
// Accept all methods by default, unless explicity configured otherwise.
return dest.methods.contains(method) || (dest.methods.size() == 1 &&
dest.methods.contains(WebApp.HTTP.GET));
}
static boolean prefixMatches(Dest dest, String path) {
LOG.debug("checking prefix {}{} for path: {}", new Object[]{dest.prefix,
dest.pathParams, path});
if (!path.startsWith(dest.prefix)) {
return false;
}
int prefixLen = dest.prefix.length();
if (prefixLen > 1 && path.length() > prefixLen &&
path.charAt(prefixLen) != '/') {
return false;
}
// prefix is / or prefix is path or prefix/...
return true;
}
static boolean isGoodMatch(Dest dest, String path) {
if (SLASH.countIn(dest.prefix) > 1) {
return true;
}
// We want to match (/foo, :a) for /foo/bar/blah and (/, :a) for /123
// but NOT / for /foo or (/, :a) for /foo or /foo/ because default route
// (FooController#index) for /foo and /foo/ takes precedence.
if (dest.prefix.length() == 1) {
return dest.pathParams.size() > 0 && !maybeController(path);
}
return dest.pathParams.size() > 0 || // /foo should match /foo/
(path.endsWith("/") && SLASH.countIn(path) == 2);
}
static boolean maybeController(String path) {
return controllerRe.matcher(path).matches();
}
// Assume /controller/action style path
private Dest resolveDefault(WebApp.HTTP method, String path) {
List parts = WebApp.parseRoute(path);
String controller = parts.get(WebApp.R_CONTROLLER);
String action = parts.get(WebApp.R_ACTION);
// NameController is encouraged default
Class cls = find(Controller.class,
join(controller, "Controller"));
if (cls == null) {
cls = find(Controller.class, controller);
}
if (cls == null) {
throw new WebAppException(join(path, ": controller for ", controller,
" not found"));
}
return add(method, defaultPrefix(controller, action), cls, action, null);
}
private String defaultPrefix(String controller, String action) {
if (controller.equals("default") && action.equals("index")) {
return "/";
}
if (action.equals("index")) {
return join('/', controller);
}
return pjoin("", controller, action);
}
private Class find(Class cls, String cname) {
String pkg = hostClass.getPackage().getName();
return find(cls, pkg, cname);
}
private Class find(Class cls, String pkg, String cname) {
String name = StringUtils.capitalize(cname);
Class found = load(cls, djoin(pkg, name));
if (found == null) {
found = load(cls, djoin(pkg, "webapp", name));
}
if (found == null) {
found = load(cls, join(hostClass.getName(), '$', name));
}
return found;
}
@SuppressWarnings("unchecked")
private Class load(Class cls, String className) {
LOG.debug("trying: {}", className);
try {
Class found = Class.forName(className);
if (cls.isAssignableFrom(found)) {
LOG.debug("found {}", className);
return (Class) found;
}
LOG.warn("found a {} but it's not a {}", className, cls.getName());
} catch (ClassNotFoundException e) {
// OK in this case.
}
return null;
}
// Dest may contain a candidate controller
private Dest resolveAction(WebApp.HTTP method, Dest dest, String path) {
if (dest.prefix.length() == 1) {
return null;
}
checkState(!isGoodMatch(dest, path), dest.prefix);
checkState(SLASH.countIn(path) > 1, path);
List parts = WebApp.parseRoute(path);
String controller = parts.get(WebApp.R_CONTROLLER);
String action = parts.get(WebApp.R_ACTION);
return add(method, pjoin("", controller, action), dest.controllerClass,
action, null);
}
}
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