org.apache.hadoop.fs.shell.find.Find 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.fs.shell.find;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Deque;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Set;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.shell.CommandFactory;
import org.apache.hadoop.fs.shell.CommandFormat;
import org.apache.hadoop.fs.shell.FsCommand;
import org.apache.hadoop.fs.shell.PathData;
@InterfaceAudience.Private
@InterfaceStability.Unstable
/**
* Implements a Hadoop find command.
*/
public class Find extends FsCommand {
/**
* Register the names for the count command
*
* @param factory the command factory that will instantiate this class
*/
public static void registerCommands(CommandFactory factory) {
factory.addClass(Find.class, "-find");
}
public static final String NAME = "find";
public static final String USAGE = " ... ...";
public static final String DESCRIPTION;
private static String[] HELP =
{ "Finds all files that match the specified expression and",
"applies selected actions to them. If no is specified",
"then defaults to the current working directory. If no",
"expression is specified then defaults to -print."
};
private static final String OPTION_FOLLOW_LINK = "L";
private static final String OPTION_FOLLOW_ARG_LINK = "H";
/** List of expressions recognized by this command. */
private static final Set> EXPRESSIONS =
new HashSet<>();
private static void addExpression(Class clazz) {
EXPRESSIONS.add(clazz.asSubclass(Expression.class));
}
static {
// Initialize the static variables.
// Operator Expressions
addExpression(And.class);
// Action Expressions
addExpression(Print.class);
// Navigation Expressions
// Matcher Expressions
addExpression(Name.class);
DESCRIPTION = buildDescription(ExpressionFactory.getExpressionFactory());
// Register the expressions with the expression factory.
registerExpressions(ExpressionFactory.getExpressionFactory());
}
/** Options for use in this command */
private FindOptions options;
/** Root expression for this instance of the command. */
private Expression rootExpression;
/** Set of path items returning a {@link Result#STOP} result. */
private HashSet stopPaths = new HashSet();
/** Register the expressions with the expression factory. */
private static void registerExpressions(ExpressionFactory factory) {
for (Class exprClass : EXPRESSIONS) {
factory.registerExpression(exprClass);
}
}
/** Build the description used by the help command. */
private static String buildDescription(ExpressionFactory factory) {
ArrayList operators = new ArrayList();
ArrayList primaries = new ArrayList();
for (Class exprClass : EXPRESSIONS) {
Expression expr = factory.createExpression(exprClass, null);
if (expr.isOperator()) {
operators.add(expr);
} else {
primaries.add(expr);
}
}
Collections.sort(operators, new Comparator() {
@Override
public int compare(Expression arg0, Expression arg1) {
return arg0.getClass().getName().compareTo(arg1.getClass().getName());
}
});
Collections.sort(primaries, new Comparator() {
@Override
public int compare(Expression arg0, Expression arg1) {
return arg0.getClass().getName().compareTo(arg1.getClass().getName());
}
});
StringBuilder sb = new StringBuilder();
for (String line : HELP) {
sb.append(line).append("\n");
}
sb.append("\n");
sb.append("The following primary expressions are recognised:\n");
for (Expression expr : primaries) {
for (String line : expr.getUsage()) {
sb.append(" ").append(line).append("\n");
}
for (String line : expr.getHelp()) {
sb.append(" ").append(line).append("\n");
}
sb.append("\n");
}
sb.append("The following operators are recognised:\n");
for (Expression expr : operators) {
for (String line : expr.getUsage()) {
sb.append(" ").append(line).append("\n");
}
for (String line : expr.getHelp()) {
sb.append(" ").append(line).append("\n");
}
sb.append("\n");
}
return sb.toString();
}
/** Default constructor for the Find command. */
public Find() {
setRecursive(true);
}
@Override
protected void processOptions(LinkedList args) throws IOException {
CommandFormat cf =
new CommandFormat(1, Integer.MAX_VALUE, OPTION_FOLLOW_LINK,
OPTION_FOLLOW_ARG_LINK, null);
cf.parse(args);
if (cf.getOpt(OPTION_FOLLOW_LINK)) {
getOptions().setFollowLink(true);
} else if (cf.getOpt(OPTION_FOLLOW_ARG_LINK)) {
getOptions().setFollowArgLink(true);
}
// search for first non-path argument (ie starts with a "-") and capture and
// remove the remaining arguments as expressions
LinkedList expressionArgs = new LinkedList();
Iterator it = args.iterator();
boolean isPath = true;
while (it.hasNext()) {
String arg = it.next();
if (isPath) {
if (arg.startsWith("-")) {
isPath = false;
}
}
if (!isPath) {
expressionArgs.add(arg);
it.remove();
}
}
if (args.isEmpty()) {
args.add(Path.CUR_DIR);
}
Expression expression = parseExpression(expressionArgs);
if (!expression.isAction()) {
Expression and = getExpression(And.class);
Deque children = new LinkedList();
children.add(getExpression(Print.class));
children.add(expression);
and.addChildren(children);
expression = and;
}
setRootExpression(expression);
}
/**
* Set the root expression for this find.
*
* @param expression
*/
@InterfaceAudience.Private
void setRootExpression(Expression expression) {
this.rootExpression = expression;
}
/**
* Return the root expression for this find.
*
* @return the root expression
*/
@InterfaceAudience.Private
Expression getRootExpression() {
return this.rootExpression;
}
/** Returns the current find options, creating them if necessary. */
@InterfaceAudience.Private
FindOptions getOptions() {
if (options == null) {
options = createOptions();
}
return options;
}
/** Create a new set of find options. */
private FindOptions createOptions() {
FindOptions options = new FindOptions();
options.setOut(out);
options.setErr(err);
options.setIn(System.in);
options.setCommandFactory(getCommandFactory());
options.setConfiguration(getConf());
return options;
}
/** Add the {@link PathData} item to the stop set. */
private void addStop(PathData item) {
stopPaths.add(item.path);
}
/** Returns true if the {@link PathData} item is in the stop set. */
private boolean isStop(PathData item) {
return stopPaths.contains(item.path);
}
/**
* Parse a list of arguments to to extract the {@link Expression} elements.
* The input Deque will be modified to remove the used elements.
*
* @param args arguments to be parsed
* @return list of {@link Expression} elements applicable to this command
* @throws IOException if list can not be parsed
*/
private Expression parseExpression(Deque args) throws IOException {
Deque primaries = new LinkedList();
Deque operators = new LinkedList();
Expression prevExpr = getExpression(And.class);
while (!args.isEmpty()) {
String arg = args.pop();
if ("(".equals(arg)) {
Expression expr = parseExpression(args);
primaries.add(expr);
prevExpr = new BaseExpression() {
@Override
public Result apply(PathData item, int depth) throws IOException {
return Result.PASS;
}
}; // stub the previous expression to be a non-op
} else if (")".equals(arg)) {
break;
} else if (isExpression(arg)) {
Expression expr = getExpression(arg);
expr.addArguments(args);
if (expr.isOperator()) {
while (!operators.isEmpty()) {
if (operators.peek().getPrecedence() >= expr.getPrecedence()) {
Expression op = operators.pop();
op.addChildren(primaries);
primaries.push(op);
} else {
break;
}
}
operators.push(expr);
} else {
if (!prevExpr.isOperator()) {
Expression and = getExpression(And.class);
while (!operators.isEmpty()) {
if (operators.peek().getPrecedence() >= and.getPrecedence()) {
Expression op = operators.pop();
op.addChildren(primaries);
primaries.push(op);
} else {
break;
}
}
operators.push(and);
}
primaries.push(expr);
}
prevExpr = expr;
} else {
throw new IOException("Unexpected argument: " + arg);
}
}
while (!operators.isEmpty()) {
Expression operator = operators.pop();
operator.addChildren(primaries);
primaries.push(operator);
}
return primaries.isEmpty() ? getExpression(Print.class) : primaries.pop();
}
/** Returns true if the target is an ancestor of the source. */
private boolean isAncestor(PathData source, PathData target) {
for (Path parent = source.path; (parent != null) && !parent.isRoot();
parent = parent.getParent()) {
if (parent.equals(target.path)) {
return true;
}
}
return false;
}
@Override
protected void recursePath(PathData item) throws IOException {
if (isStop(item)) {
// this item returned a stop result so don't recurse any further
return;
}
if (getDepth() >= getOptions().getMaxDepth()) {
// reached the maximum depth so don't got any further.
return;
}
if (item.stat.isSymlink() && getOptions().isFollowLink()) {
PathData linkedItem =
new PathData(item.stat.getSymlink().toString(), getConf());
if (isAncestor(item, linkedItem)) {
getOptions().getErr().println(
"Infinite loop ignored: " + item.toString() + " -> "
+ linkedItem.toString());
return;
}
if (linkedItem.exists) {
item = linkedItem;
}
}
if (item.stat.isDirectory()) {
super.recursePath(item);
}
}
@Override
protected boolean isPathRecursable(PathData item) throws IOException {
if (item.stat.isDirectory()) {
return true;
}
if (item.stat.isSymlink()) {
PathData linkedItem =
new PathData(item.fs.resolvePath(item.stat.getSymlink()).toString(),
getConf());
if (linkedItem.stat.isDirectory()) {
if (getOptions().isFollowLink()) {
return true;
}
if (getOptions().isFollowArgLink() && (getDepth() == 0)) {
return true;
}
}
}
return false;
}
@Override
protected void processPath(PathData item) throws IOException {
if (getOptions().isDepthFirst()) {
// depth first so leave until post processing
return;
}
applyItem(item);
}
@Override
protected void postProcessPath(PathData item) throws IOException {
if (!getOptions().isDepthFirst()) {
// not depth first so already processed
return;
}
applyItem(item);
}
private void applyItem(PathData item) throws IOException {
if (getDepth() >= getOptions().getMinDepth()) {
Result result = getRootExpression().apply(item, getDepth());
if (Result.STOP.equals(result)) {
addStop(item);
}
}
}
@Override
protected void processArguments(LinkedList args)
throws IOException {
Expression expr = getRootExpression();
expr.setOptions(getOptions());
expr.prepare();
super.processArguments(args);
expr.finish();
}
/** Gets a named expression from the factory. */
private Expression getExpression(String expressionName) {
return ExpressionFactory.getExpressionFactory().getExpression(
expressionName, getConf());
}
/** Gets an instance of an expression from the factory. */
private Expression getExpression(
Class expressionClass) {
return ExpressionFactory.getExpressionFactory().createExpression(
expressionClass, getConf());
}
/** Asks the factory whether an expression is recognized. */
private boolean isExpression(String expressionName) {
return ExpressionFactory.getExpressionFactory()
.isExpression(expressionName);
}
}
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