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HADOOP-19052.Hadoop use Shell command to get the count of the hard link which takes a lot of time #6527

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HADOOP-19052.Hadoop use Shell command to get the count of the hard link which takes a lot of time #6527

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HADOOP-19052.Hadoop use Shell command to get the count of the hard li…
liangyu-1 Feb 5, 2024
fc72fe8
HADOOP-19052.Hadoop use Shell command to get the count of the hard li…
liangyu-1 Feb 23, 2024
f0b7a76
Merge branch 'apache:trunk' into HADOOP-19052
liangyu-1 Feb 23, 2024
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19 changes: 19 additions & 0 deletions hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/HardLink.java
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,8 @@
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.StringReader;
import java.nio.file.FileStore;
import java.nio.file.Files;

import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.util.Shell;
Expand Down Expand Up @@ -50,6 +52,10 @@ public class HardLink {
private static HardLinkCommandGetter getHardLinkCommand;

public final LinkStats linkStats; //not static

private static final String FileAttributeView = "unix";

private static final String FileAttribute = "unix:nlink";

//initialize the command "getters" statically, so can use their
//methods without instantiating the HardLink object
Expand Down Expand Up @@ -203,6 +209,15 @@ public static void createHardLinkMult(File parentDir, String[] fileBaseNames,
parentDir.toPath().resolve(name));
}
}
@VisibleForTesting
static boolean supportsHardLink(File f) {
try {
FileStore store = Files.getFileStore(f.toPath());
return store.supportsFileAttributeView(FileAttributeView);
} catch (IOException e) {
return false;
}
}

/**
* Retrieves the number of links to the specified file.
Expand All @@ -220,6 +235,10 @@ public static int getLinkCount(File fileName) throws IOException {
throw new FileNotFoundException(fileName + " not found.");
}

if (supportsHardLink(fileName)) {
return (int) Files.getAttribute(fileName.toPath(), FileAttribute);
}

// construct and execute shell command
String[] cmd = getHardLinkCommand.linkCount(fileName);
String inpMsg = null;
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14 changes: 14 additions & 0 deletions hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/TestHardLink.java
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Expand Up @@ -22,6 +22,8 @@
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.nio.file.FileStore;
import java.nio.file.Files;
import java.util.Arrays;

import org.apache.hadoop.test.GenericTestUtils;
Expand Down Expand Up @@ -204,6 +206,8 @@ private String fetchFileContents(File file)
char[] result = Arrays.copyOf(buf, cnt);
return new String(result);
}



/**
* Sanity check the simplest case of HardLink.getLinkCount()
Expand All @@ -219,6 +223,16 @@ public void testGetLinkCount() throws IOException {
assertEquals(1, getLinkCount(x3));
}

@Test
public void testGetLinkCountFromFileAttribute() throws IOException {
assertTrue(supportsHardLink(x1));
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@yangjiandan yangjiandan Feb 5, 2024

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supportsHardLink(x1) may be false if os is not unix style

assertEquals(1, getLinkCount(x1));
assertTrue(supportsHardLink(x2));
assertEquals(1, getLinkCount(x2));
assertTrue(supportsHardLink(x3));
assertEquals(1, getLinkCount(x3));
}

/**
* Test the single-file method HardLink.createHardLink().
* Also tests getLinkCount() with values greater than one.
Expand Down