Github user xuanyuanking commented on a diff in the pull request:
https://github.com/apache/spark/pull/21618#discussion_r216588353
--- Diff: core/src/main/java/org/apache/hadoop/fs/SparkGlobber.java ---
@@ -0,0 +1,293 @@
+/**
+ * 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;
+
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.commons.lang3.StringUtils;
+import org.apache.commons.logging.LogFactory;
+import org.apache.commons.logging.Log;
+
+/**
+ * This is based on hadoop-common-2.7.2
+ * {@link org.apache.hadoop.fs.Globber}.
+ * This class exposes globWithThreshold which can be used glob path in
parallel.
+ */
+public class SparkGlobber {
+ public static final Log LOG =
LogFactory.getLog(SparkGlobber.class.getName());
+
+ private final FileSystem fs;
+ private final FileContext fc;
+ private final Path pathPattern;
+
+ public SparkGlobber(FileSystem fs, Path pathPattern) {
+ this.fs = fs;
+ this.fc = null;
+ this.pathPattern = pathPattern;
+ }
+
+ public SparkGlobber(FileContext fc, Path pathPattern) {
+ this.fs = null;
+ this.fc = fc;
+ this.pathPattern = pathPattern;
+ }
+
+ private FileStatus getFileStatus(Path path) throws IOException {
+ try {
+ if (fs != null) {
+ return fs.getFileStatus(path);
+ } else {
+ return fc.getFileStatus(path);
+ }
+ } catch (FileNotFoundException e) {
+ return null;
+ }
+ }
+
+ private FileStatus[] listStatus(Path path) throws IOException {
+ try {
+ if (fs != null) {
+ return fs.listStatus(path);
+ } else {
+ return fc.util().listStatus(path);
+ }
+ } catch (FileNotFoundException e) {
+ return new FileStatus[0];
+ }
+ }
+
+ private Path fixRelativePart(Path path) {
+ if (fs != null) {
+ return fs.fixRelativePart(path);
+ } else {
+ return fc.fixRelativePart(path);
+ }
+ }
+
+ /**
+ * Convert a path component that contains backslash ecape sequences to a
+ * literal string. This is necessary when you want to explicitly refer
to a
+ * path that contains globber metacharacters.
+ */
+ private static String unescapePathComponent(String name) {
+ return name.replaceAll("\\\\(.)", "$1");
+ }
+
+ /**
+ * Translate an absolute path into a list of path components.
+ * We merge double slashes into a single slash here.
+ * POSIX root path, i.e. '/', does not get an entry in the list.
+ */
+ private static List<String> getPathComponents(String path)
+ throws IOException {
+ ArrayList<String> ret = new ArrayList<String>();
+ for (String component : path.split(Path.SEPARATOR)) {
+ if (!component.isEmpty()) {
+ ret.add(component);
+ }
+ }
+ return ret;
+ }
+
+ private String schemeFromPath(Path path) throws IOException {
+ String scheme = path.toUri().getScheme();
+ if (scheme == null) {
+ if (fs != null) {
+ scheme = fs.getUri().getScheme();
+ } else {
+ scheme =
fc.getFSofPath(fc.fixRelativePart(path)).getUri().getScheme();
+ }
+ }
+ return scheme;
+ }
+
+ private String authorityFromPath(Path path) throws IOException {
+ String authority = path.toUri().getAuthority();
+ if (authority == null) {
+ if (fs != null) {
+ authority = fs.getUri().getAuthority();
+ } else {
+ authority =
fc.getFSofPath(fc.fixRelativePart(path)).getUri().getAuthority();
+ }
+ }
+ return authority ;
+ }
+
+ public FileStatus[] globWithThreshold(int threshold) throws IOException {
+ // First we get the scheme and authority of the pattern that was passed
+ // in.
+ String scheme = schemeFromPath(pathPattern);
+ String authority = authorityFromPath(pathPattern);
+
+ // Next we strip off everything except the pathname itself, and expand
all
+ // globs. Expansion is a process which turns "grouping" clauses,
+ // expressed as brackets, into separate path patterns.
+ String pathPatternString = pathPattern.toUri().getPath();
+ List<String> flattenedPatterns =
GlobExpander.expand(pathPatternString);
+
+ // Now loop over all flattened patterns. In every case, we'll be
trying to
+ // match them to entries in the filesystem.
+ ArrayList<FileStatus> results =
+ new ArrayList<FileStatus>(flattenedPatterns.size());
+ boolean sawWildcard = false;
+ for (String flatPattern : flattenedPatterns) {
+ // Get the absolute path for this flattened pattern. We couldn't do
+ // this prior to flattening because of patterns like {/,a}, where
which
+ // path you go down influences how the path must be made absolute.
+ Path absPattern = fixRelativePart(new Path(
+ flatPattern.isEmpty() ? Path.CUR_DIR : flatPattern));
+ // Now we break the flattened, absolute pattern into path components.
+ // For example, /a/*/c would be broken into the list [a, *, c]
+ List<String> components =
+ getPathComponents(absPattern.toUri().getPath());
+ // Starting out at the root of the filesystem, we try to match
+ // filesystem entries against pattern components.
+ ArrayList<FileStatus> candidates = new ArrayList<FileStatus>(1);
+ // To get the "real" FileStatus of root, we'd have to do an expensive
+ // RPC to the NameNode. So we create a placeholder FileStatus which
has
+ // the correct path, but defaults for the rest of the information.
+ // Later, if it turns out we actually want the FileStatus of root,
we'll
+ // replace the placeholder with a real FileStatus obtained from the
+ // NameNode.
+ FileStatus rootPlaceholder;
+ if (Path.WINDOWS && !components.isEmpty()
+ && Path.isWindowsAbsolutePath(absPattern.toUri().getPath(),
true)) {
+ // On Windows the path could begin with a drive letter, e.g.
/E:/foo.
+ // We will skip matching the drive letter and start from listing
the
+ // root of the filesystem on that drive.
+ String driveLetter = components.remove(0);
+ rootPlaceholder = new FileStatus(0, true, 0, 0, 0, new Path(scheme,
+ authority, Path.SEPARATOR + driveLetter + Path.SEPARATOR));
+ } else {
+ rootPlaceholder = new FileStatus(0, true, 0, 0, 0,
+ new Path(scheme, authority, Path.SEPARATOR));
+ }
+ candidates.add(rootPlaceholder);
+
+ for (int componentIdx = 0; componentIdx < components.size();
+ componentIdx++) {
+ ArrayList<FileStatus> newCandidates =
+ new ArrayList<FileStatus>(candidates.size());
+ GlobFilter globFilter = new
GlobFilter(components.get(componentIdx));
+ String component =
unescapePathComponent(components.get(componentIdx));
+ if (globFilter.hasPattern()) {
+ sawWildcard = true;
+ }
+ if (candidates.isEmpty() && sawWildcard) {
+ // Optimization: if there are no more candidates left, stop
examining
+ // the path components. We can only do this if we've already
seen
+ // a wildcard component-- otherwise, we still need to visit all
path
+ // components in case one of them is a wildcard.
+ break;
+ }
+ if ((componentIdx < components.size() - 1) &&
+ (!globFilter.hasPattern())) {
+ // Optimization: if this is not the terminal path component, and
we
+ // are not matching against a glob, assume that it exists. If it
+ // doesn't exist, we'll find out later when resolving a later
glob
+ // or the terminal path component.
+ for (FileStatus candidate : candidates) {
+ candidate.setPath(new Path(candidate.getPath(), component));
+ }
+ continue;
+ }
+ for (FileStatus candidate : candidates) {
+ if (globFilter.hasPattern()) {
+ FileStatus[] children = listStatus(candidate.getPath());
+ if (children.length == 1) {
+ // If we get back only one result, this could be either a
listing
+ // of a directory with one entry, or it could reflect the
fact
+ // that what we listed resolved to a file.
+ //
+ // Unfortunately, we can't just compare the returned paths to
+ // figure this out. Consider the case where you have /a/b,
where
+ // b is a symlink to "..". In that case, listing /a/b will
give
+ // back "/a/b" again. If we just went by returned pathname,
we'd
+ // incorrectly conclude that /a/b was a file and should not
match
+ // /a/*/*. So we use getFileStatus of the path we just
listed to
+ // disambiguate.
+ if (!getFileStatus(candidate.getPath()).isDirectory()) {
+ continue;
+ }
+ }
+ for (FileStatus child : children) {
+ if (componentIdx < components.size() - 1) {
+ // Don't try to recurse into non-directories. See
HADOOP-10957.
+ if (!child.isDirectory()) continue;
+ }
+ // Set the child path based on the parent path.
+ child.setPath(new Path(candidate.getPath(),
+ child.getPath().getName()));
+ if (globFilter.accept(child.getPath())) {
+ newCandidates.add(child);
+ }
+ }
+ } else {
+ // When dealing with non-glob components, use getFileStatus
+ // instead of listStatus. This is an optimization, but it also
+ // is necessary for correctness in HDFS, since there are some
+ // special HDFS directories like .reserved and .snapshot that
are
+ // not visible to listStatus, but which do exist. (See
HADOOP-9877)
+ FileStatus childStatus = getFileStatus(
+ new Path(candidate.getPath(), component));
+ if (childStatus != null) {
+ newCandidates.add(childStatus);
+ }
+ }
+ }
+ candidates = newCandidates;
+ // When size of candidates has reached the threshold, stop
expanding other
--- End diff --
Is it also necessary port the UT? I think maybe enough comment and limit
change is enough cause UT still has maintenance cost. What's your opinion?
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