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vfs: do not traverse all elements when building directory listing
Motivation: DirectoryStream accepts NavigableSet for directory listing to allow file system implementations to optimize the ordering and populate the listing in lazy fashion is required. However, PseudoFs#list method applies transformation and convert it into a collection, which enforces full iteration over provided listing. Moreover, the newly created collection is converted into TreeSet and re-sorted. Modification: Introduce DirectoryStream#transform method which returns a new DirectoryStream with lazy-transformed elements. The getEntries() method is removed. Result: faster directory listing on big directories with less memory consumption. On a directory with 100K files the ls operation is ~x10 faster! Fixes: #61 Acked-by: Dmitry Litvintsev Target: master, 0.17
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95 changes: 95 additions & 0 deletions
95
core/src/test/java/org/dcache/nfs/vfs/DirectoryStreamTest.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,95 @@ | ||
| package org.dcache.nfs.vfs; | ||
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| import com.google.common.primitives.Ints; | ||
| import java.util.NavigableSet; | ||
| import java.util.TreeSet; | ||
| import org.dcache.nfs.v4.xdr.verifier4; | ||
| import org.junit.Test; | ||
| import static org.junit.Assert.*; | ||
| import org.junit.Before; | ||
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| /** | ||
| * | ||
| */ | ||
| public class DirectoryStreamTest { | ||
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| private DirectoryStream stream; | ||
| @Before | ||
| public void setUp() { | ||
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| NavigableSet<DirectoryEntry> entries = new TreeSet<>(); | ||
| byte[] verifier = verifier4.valueOf(System.currentTimeMillis()).value; | ||
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| for (int i = 0; i < 10; i++) { | ||
| FileHandle fh = new FileHandle(0, 0, 0, Ints.toByteArray(i)); | ||
| Inode inode = new Inode(fh); | ||
| Stat stat = new Stat(); | ||
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| stat.setMode(Stat.S_IFDIR | 0755); | ||
| stat.setMTime(System.currentTimeMillis()); | ||
| stat.setATime(System.currentTimeMillis()); | ||
| stat.setCTime(System.currentTimeMillis()); | ||
| stat.setGeneration(1); | ||
| stat.setNlink(2); | ||
| stat.setUid(1); | ||
| stat.setGid(2); | ||
| stat.setDev(1); | ||
| stat.setFileid(i); | ||
| stat.setSize(512); | ||
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| entries.add(new DirectoryEntry(String.format("file-%d", i), inode, stat, i)); | ||
| } | ||
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| stream = new DirectoryStream(verifier, entries); | ||
| } | ||
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| @Test | ||
| public void testTail() { | ||
| DirectoryStream tail = stream.tail(3); | ||
| assertEquals(tail.iterator().next().getCookie(), 4); | ||
| assertArrayEquals(stream.getVerifier(), tail.getVerifier()); | ||
| } | ||
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| @Test | ||
| public void testTransform() { | ||
| DirectoryStream transformed = stream.transform(d -> new DirectoryEntry(d.getName().toUpperCase(), d.getInode(), d.getStat(), d.getCookie())); | ||
| assertArrayEquals(stream.getVerifier(), transformed.getVerifier()); | ||
| for (DirectoryEntry e : transformed) { | ||
| assertTrue(e.getName().startsWith("FILE")); | ||
| } | ||
| } | ||
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| @Test | ||
| public void testTransformAndTail() { | ||
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| DirectoryStream transformed = stream.transform(d -> new DirectoryEntry(d.getName().toUpperCase(), d.getInode(), d.getStat(), d.getCookie())); | ||
| DirectoryStream tail = transformed.tail(3); | ||
| DirectoryEntry next = tail.iterator().next(); | ||
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| assertEquals(next.getCookie(), 4); | ||
| assertEquals("FILE-4", next.getName()); | ||
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| } | ||
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| @Test | ||
| public void testMultipleTransformAndTail() { | ||
| DirectoryStream transformed = stream.transform(d -> new DirectoryEntry(d.getName().toUpperCase(), d.getInode(), d.getStat(), d.getCookie())); | ||
| DirectoryStream tail = transformed.tail(3).tail(5); | ||
| DirectoryEntry next = tail.iterator().next(); | ||
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| assertEquals(next.getCookie(), 6); | ||
| assertEquals("FILE-6", next.getName()); | ||
| } | ||
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| @Test | ||
| public void testMultipleTransform() { | ||
| DirectoryStream transformed = stream | ||
| .transform(d -> new DirectoryEntry(d.getName().toUpperCase(), d.getInode(), d.getStat(), d.getCookie())) | ||
| .transform(d -> new DirectoryEntry("a" + d.getName(), d.getInode(), d.getStat(), d.getCookie())); | ||
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| assertArrayEquals(stream.getVerifier(), transformed.getVerifier()); | ||
| for (DirectoryEntry e : transformed) { | ||
| assertTrue(e.getName().startsWith("aFILE")); | ||
| } | ||
| } | ||
| } |