package org.apache.lucene.index;
/*
* 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.
*/
import java.io.IOException;
import java.io.PrintStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import org.apache.lucene.codecs.Codec;
import org.apache.lucene.codecs.CodecUtil;
import org.apache.lucene.codecs.FieldInfosFormat;
import org.apache.lucene.codecs.LiveDocsFormat;
import org.apache.lucene.store.ChecksumIndexInput;
import org.apache.lucene.store.ChecksumIndexOutput;
import org.apache.lucene.store.DataOutput;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.IOContext;
import org.apache.lucene.store.IndexInput;
import org.apache.lucene.store.IndexOutput;
import org.apache.lucene.store.NoSuchDirectoryException;
import org.apache.lucene.util.IOUtils;
/**
* A collection of segmentInfo objects with methods for operating on
* those segments in relation to the file system.
* <p>
* The active segments in the index are stored in the segment info file,
* <tt>segments_N</tt>. There may be one or more <tt>segments_N</tt> files in the
* index; however, the one with the largest generation is the active one (when
* older segments_N files are present it's because they temporarily cannot be
* deleted, or, a writer is in the process of committing, or a custom
* {@link org.apache.lucene.index.IndexDeletionPolicy IndexDeletionPolicy}
* is in use). This file lists each segment by name and has details about the
* codec and generation of deletes.
* </p>
* <p>There is also a file <tt>segments.gen</tt>. This file contains
* the current generation (the <tt>_N</tt> in <tt>segments_N</tt>) of the index.
* This is used only as a fallback in case the current generation cannot be
* accurately determined by directory listing alone (as is the case for some NFS
* clients with time-based directory cache expiration). This file simply contains
* an {@link DataOutput#writeInt Int32} version header
* ({@link #FORMAT_SEGMENTS_GEN_CURRENT}), followed by the
* generation recorded as {@link DataOutput#writeLong Int64}, written twice.</p>
* <p>
* Files:
* <ul>
* <li><tt>segments.gen</tt>: GenHeader, Generation, Generation
* <li><tt>segments_N</tt>: Header, Version, NameCounter, SegCount,
* <SegName, SegCodec, DelGen, DeletionCount, FieldInfosGen, UpdatesFiles><sup>SegCount</sup>,
* CommitUserData, Checksum
* </ul>
* </p>
* Data types:
* <p>
* <ul>
* <li>Header --> {@link CodecUtil#writeHeader CodecHeader}</li>
* <li>GenHeader, NameCounter, SegCount, DeletionCount --> {@link DataOutput#writeInt Int32}</li>
* <li>Generation, Version, DelGen, Checksum, FieldInfosGen --> {@link DataOutput#writeLong Int64}</li>
* <li>SegName, SegCodec --> {@link DataOutput#writeString String}</li>
* <li>CommitUserData --> {@link DataOutput#writeStringStringMap Map<String,String>}</li>
* <li>UpdatesFiles --> {@link DataOutput#writeStringSet(Set) Set<String>}</li>
* </ul>
* </p>
* Field Descriptions:
* <p>
* <ul>
* <li>Version counts how often the index has been changed by adding or deleting
* documents.</li>
* <li>NameCounter is used to generate names for new segment files.</li>
* <li>SegName is the name of the segment, and is used as the file name prefix for
* all of the files that compose the segment's index.</li>
* <li>DelGen is the generation count of the deletes file. If this is -1,
* there are no deletes. Anything above zero means there are deletes
* stored by {@link LiveDocsFormat}.</li>
* <li>DeletionCount records the number of deleted documents in this segment.</li>
* <li>Checksum contains the CRC32 checksum of all bytes in the segments_N file up
* until the checksum. This is used to verify integrity of the file on opening the
* index.</li>
* <li>SegCodec is the {@link Codec#getName() name} of the Codec that encoded
* this segment.</li>
* <li>CommitUserData stores an optional user-supplied opaque
* Map<String,String> that was passed to
* {@link IndexWriter#setCommitData(java.util.Map)}.</li>
* <li>FieldInfosGen is the generation count of the fieldInfos file. If this is -1,
* there are no updates to the fieldInfos in that segment. Anything above zero
* means there are updates to fieldInfos stored by {@link FieldInfosFormat}.</li>
* <li>UpdatesFiles stores the list of files that were updated in that segment.</li>
* </ul>
* </p>
*
* @lucene.experimental
*/
public final class SegmentInfos implements Cloneable, Iterable<SegmentCommitInfo> {
/** The file format version for the segments_N codec header, up to 4.5. */
public static final int VERSION_40 = 0;
/** The file format version for the segments_N codec header, since 4.6+. */
public static final int VERSION_46 = 1;
/** Used for the segments.gen file only!
* Whenever you add a new format, make it 1 smaller (negative version logic)! */
public static final int FORMAT_SEGMENTS_GEN_CURRENT = -2;
/** Used to name new segments. */
public int counter;
/** Counts how often the index has been changed. */
public long version;
private long generation; // generation of the "segments_N" for the next commit
private long lastGeneration; // generation of the "segments_N" file we last successfully read
// or wrote; this is normally the same as generation except if
// there was an IOException that had interrupted a commit
/** Opaque Map<String, String> that user can specify during IndexWriter.commit */
public Map<String,String> userData = Collections.emptyMap();
private List<SegmentCommitInfo> segments = new ArrayList<>();
/**
* If non-null, information about loading segments_N files
* will be printed here. @see #setInfoStream.
*/
private static PrintStream infoStream = null;
/** Sole constructor. Typically you call this and then
* use {@link #read(Directory) or
* #read(Directory,String)} to populate each {@link
* SegmentCommitInfo}. Alternatively, you can add/remove your
* own {@link SegmentCommitInfo}s. */
public SegmentInfos() {
}
/** Returns {@link SegmentCommitInfo} at the provided
* index. */
public SegmentCommitInfo info(int i) {
return segments.get(i);
}
/**
* Get the generation of the most recent commit to the
* list of index files (N in the segments_N file).
*
* @param files -- array of file names to check
*/
public static long getLastCommitGeneration(String[] files) {
if (files == null) {
return -1;
}
long max = -1;
for (String file : files) {
if (file.startsWith(IndexFileNames.SEGMENTS) && !file.equals(IndexFileNames.SEGMENTS_GEN)) {
long gen = generationFromSegmentsFileName(file);
if (gen > max) {
max = gen;
}
}
}
return max;
}
/**
* Get the generation of the most recent commit to the
* index in this directory (N in the segments_N file).
*
* @param directory -- directory to search for the latest segments_N file
*/
public static long getLastCommitGeneration(Directory directory) throws IOException {
try {
return getLastCommitGeneration(directory.listAll());
} catch (NoSuchDirectoryException nsde) {
return -1;
}
}
/**
* Get the filename of the segments_N file for the most
* recent commit in the list of index files.
*
* @param files -- array of file names to check
*/
public static String getLastCommitSegmentsFileName(String[] files) {
return IndexFileNames.fileNameFromGeneration(IndexFileNames.SEGMENTS,
"",
getLastCommitGeneration(files));
}
/**
* Get the filename of the segments_N file for the most
* recent commit to the index in this Directory.
*
* @param directory -- directory to search for the latest segments_N file
*/
public static String getLastCommitSegmentsFileName(Directory directory) throws IOException {
return IndexFileNames.fileNameFromGeneration(IndexFileNames.SEGMENTS,
"",
getLastCommitGeneration(directory));
}
/**
* Get the segments_N filename in use by this segment infos.
*/
public String getSegmentsFileName() {
return IndexFileNames.fileNameFromGeneration(IndexFileNames.SEGMENTS,
"",
lastGeneration);
}
/**
* Parse the generation off the segments file name and
* return it.
*/
public static long generationFromSegmentsFileName(String fileName) {
if (fileName.equals(IndexFileNames.SEGMENTS)) {
return 0;
} else if (fileName.startsWith(IndexFileNames.SEGMENTS)) {
return Long.parseLong(fileName.substring(1+IndexFileNames.SEGMENTS.length()),
Character.MAX_RADIX);
} else {
throw new IllegalArgumentException("fileName \"" + fileName + "\" is not a segments file");
}
}
/**
* A utility for writing the {@link IndexFileNames#SEGMENTS_GEN} file to a
* {@link Directory}.
*
* <p>
* <b>NOTE:</b> this is an internal utility which is kept public so that it's
* accessible by code from other packages. You should avoid calling this
* method unless you're absolutely sure what you're doing!
*
* @lucene.internal
*/
public static void writeSegmentsGen(Directory dir, long generation) {
try {
IndexOutput genOutput = dir.createOutput(IndexFileNames.SEGMENTS_GEN, IOContext.READONCE);
try {
genOutput.writeInt(FORMAT_SEGMENTS_GEN_CURRENT);
genOutput.writeLong(generation);
genOutput.writeLong(generation);
} finally {
genOutput.close();
dir.sync(Collections.singleton(IndexFileNames.SEGMENTS_GEN));
}
} catch (Throwable t) {
// It's OK if we fail to write this file since it's
// used only as one of the retry fallbacks.
try {
dir.deleteFile(IndexFileNames.SEGMENTS_GEN);
} catch (Throwable t2) {
// Ignore; this file is only used in a retry
// fallback on init.
}
}
}
/**
* Get the next segments_N filename that will be written.
*/
public String getNextSegmentFileName() {
long nextGeneration;
if (generation == -1) {
nextGeneration = 1;
} else {
nextGeneration = generation+1;
}
return IndexFileNames.fileNameFromGeneration(IndexFileNames.SEGMENTS,
"",
nextGeneration);
}
/**
* Read a particular segmentFileName. Note that this may
* throw an IOException if a commit is in process.
*
* @param directory -- directory containing the segments file
* @param segmentFileName -- segment file to load
* @throws CorruptIndexException if the index is corrupt
* @throws IOException if there is a low-level IO error
*/
public final void read(Directory directory, String segmentFileName) throws IOException {
boolean success = false;
// Clear any previous segments:
this.clear();
generation = generationFromSegmentsFileName(segmentFileName);
lastGeneration = generation;
ChecksumIndexInput input = new ChecksumIndexInput(directory.openInput(segmentFileName, IOContext.READ));
try {
// NOTE: as long as we want to throw indexformattooold (vs corruptindexexception), we need
// to read the magic ourselves.
int magic = input.readInt();
if (magic != CodecUtil.CODEC_MAGIC) {
throw new IndexFormatTooOldException(input, magic, CodecUtil.CODEC_MAGIC, CodecUtil.CODEC_MAGIC);
}
// 4.0+
int format = CodecUtil.checkHeaderNoMagic(input, "segments", VERSION_40, VERSION_46);
version = input.readLong();
counter = input.readInt();
int numSegments = input.readInt();
if (numSegments < 0) {
throw new CorruptIndexException("invalid segment count: " + numSegments + " (resource: " + input + ")");
}
for (int seg = 0; seg < numSegments; seg++) {
String segName = input.readString();
Codec codec = Codec.forName(input.readString());
//System.out.println("SIS.read seg=" + seg + " codec=" + codec);
SegmentInfo info = codec.segmentInfoFormat().getSegmentInfoReader().read(directory, segName, IOContext.READ);
info.setCodec(codec);
long delGen = input.readLong();
int delCount = input.readInt();
if (delCount < 0 || delCount > info.getDocCount()) {
throw new CorruptIndexException("invalid deletion count: " + delCount + " (resource: " + input + ")");
}
long fieldInfosGen = -1;
if (format >= VERSION_46) {
fieldInfosGen = input.readLong();
}
SegmentCommitInfo siPerCommit = new SegmentCommitInfo(info, delCount, delGen, fieldInfosGen);
if (format >= VERSION_46) {
int numGensUpdatesFiles = input.readInt();
final Map<Long,Set<String>> genUpdatesFiles;
if (numGensUpdatesFiles == 0) {
genUpdatesFiles = Collections.emptyMap();
} else {
genUpdatesFiles = new HashMap<>(numGensUpdatesFiles);
for (int i = 0; i < numGensUpdatesFiles; i++) {
genUpdatesFiles.put(input.readLong(), input.readStringSet());
}
}
siPerCommit.setGenUpdatesFiles(genUpdatesFiles);
}
add(siPerCommit);
}
userData = input.readStringStringMap();
final long checksumNow = input.getChecksum();
final long checksumThen = input.readLong();
if (checksumNow != checksumThen) {
throw new CorruptIndexException("checksum mismatch in segments file (resource: " + input + ")");
}
success = true;
} finally {
if (!success) {
// Clear any segment infos we had loaded so we
// have a clean slate on retry:
this.clear();
IOUtils.closeWhileHandlingException(input);
} else {
input.close();
}
}
}
/** Find the latest commit ({@code segments_N file}) and
* load all {@link SegmentCommitInfo}s. */
public final void read(Directory directory) throws IOException {
generation = lastGeneration = -1;
new FindSegmentsFile(directory) {
@Override
protected Object doBody(String segmentFileName) throws IOException {
read(directory, segmentFileName);
return null;
}
}.run();
}
// Only non-null after prepareCommit has been called and
// before finishCommit is called
ChecksumIndexOutput pendingSegnOutput;
private void write(Directory directory) throws IOException {
String segmentFileName = getNextSegmentFileName();
// Always advance the generation on write:
if (generation == -1) {
generation = 1;
} else {
generation++;
}
ChecksumIndexOutput segnOutput = null;
boolean success = false;
try {
segnOutput = new ChecksumIndexOutput(directory.createOutput(segmentFileName, IOContext.DEFAULT));
CodecUtil.writeHeader(segnOutput, "segments", VERSION_46);
segnOutput.writeLong(version);
segnOutput.writeInt(counter); // write counter
segnOutput.writeInt(size()); // write infos
for (SegmentCommitInfo siPerCommit : this) {
SegmentInfo si = siPerCommit.info;
segnOutput.writeString(si.name);
segnOutput.writeString(si.getCodec().getName());
segnOutput.writeLong(siPerCommit.getDelGen());
segnOutput.writeInt(siPerCommit.getDelCount());
segnOutput.writeLong(siPerCommit.getFieldInfosGen());
final Map<Long,Set<String>> genUpdatesFiles = siPerCommit.getUpdatesFiles();
segnOutput.writeInt(genUpdatesFiles.size());
for (Entry<Long,Set<String>> e : genUpdatesFiles.entrySet()) {
segnOutput.writeLong(e.getKey());
segnOutput.writeStringSet(e.getValue());
}
assert si.dir == directory;
assert siPerCommit.getDelCount() <= si.getDocCount();
}
segnOutput.writeStringStringMap(userData);
pendingSegnOutput = segnOutput;
success = true;
} finally {
if (!success) {
// We hit an exception above; try to close the file
// but suppress any exception:
IOUtils.closeWhileHandlingException(segnOutput);
try {
// Try not to leave a truncated segments_N file in
// the index:
directory.deleteFile(segmentFileName);
} catch (Throwable t) {
// Suppress so we keep throwing the original exception
}
}
}
}
/**
* Returns a copy of this instance, also copying each
* SegmentInfo.
*/
@Override
public SegmentInfos clone() {
try {
final SegmentInfos sis = (SegmentInfos) super.clone();
// deep clone, first recreate all collections:
sis.segments = new ArrayList<>(size());
for(final SegmentCommitInfo info : this) {
assert info.info.getCodec() != null;
// dont directly access segments, use add method!!!
sis.add(info.clone());
}
sis.userData = new HashMap<>(userData);
return sis;
} catch (CloneNotSupportedException e) {
throw new RuntimeException("should not happen", e);
}
}
/**
* version number when this SegmentInfos was generated.
*/
public long getVersion() {
return version;
}
/** Returns current generation. */
public long getGeneration() {
return generation;
}
/** Returns last succesfully read or written generation. */
public long getLastGeneration() {
return lastGeneration;
}
/** If non-null, information about retries when loading
* the segments file will be printed to this.
*/
public static void setInfoStream(PrintStream infoStream) {
SegmentInfos.infoStream = infoStream;
}
/* Advanced configuration of retry logic in loading
segments_N file */
private static int defaultGenLookaheadCount = 10;
/**
* Advanced: set how many times to try incrementing the
* gen when loading the segments file. This only runs if
* the primary (listing directory) and secondary (opening
* segments.gen file) methods fail to find the segments
* file.
*
* @lucene.experimental
*/
public static void setDefaultGenLookaheadCount(int count) {
defaultGenLookaheadCount = count;
}
/**
* Returns the {@code defaultGenLookaheadCount}.
*
* @see #setDefaultGenLookaheadCount
*
* @lucene.experimental
*/
public static int getDefaultGenLookahedCount() {
return defaultGenLookaheadCount;
}
/**
* Returns {@code infoStream}.
*
* @see #setInfoStream
*/
public static PrintStream getInfoStream() {
return infoStream;
}
/**
* Prints the given message to the infoStream. Note, this method does not
* check for null infoStream. It assumes this check has been performed by the
* caller, which is recommended to avoid the (usually) expensive message
* creation.
*/
private static void message(String message) {
infoStream.println("SIS [" + Thread.currentThread().getName() + "]: " + message);
}
/**
* Utility class for executing code that needs to do
* something with the current segments file. This is
* necessary with lock-less commits because from the time
* you locate the current segments file name, until you
* actually open it, read its contents, or check modified
* time, etc., it could have been deleted due to a writer
* commit finishing.
*/
public abstract static class FindSegmentsFile {
final Directory directory;
/** Sole constructor. */
public FindSegmentsFile(Directory directory) {
this.directory = directory;
}
/** Locate the most recent {@code segments} file and
* run {@link #doBody} on it. */
public Object run() throws IOException {
return run(null);
}
/** Run {@link #doBody} on the provided commit. */
public Object run(IndexCommit commit) throws IOException {
if (commit != null) {
if (directory != commit.getDirectory())
throw new IOException("the specified commit does not match the specified Directory");
return doBody(commit.getSegmentsFileName());
}
String segmentFileName = null;
long lastGen = -1;
long gen = 0;
int genLookaheadCount = 0;
IOException exc = null;
int retryCount = 0;
boolean useFirstMethod = true;
// Loop until we succeed in calling doBody() without
// hitting an IOException. An IOException most likely
// means a commit was in process and has finished, in
// the time it took us to load the now-old infos files
// (and segments files). It's also possible it's a
// true error (corrupt index). To distinguish these,
// on each retry we must see "forward progress" on
// which generation we are trying to load. If we
// don't, then the original error is real and we throw
// it.
// We have three methods for determining the current
// generation. We try the first two in parallel (when
// useFirstMethod is true), and fall back to the third
// when necessary.
while(true) {
if (useFirstMethod) {
// List the directory and use the highest
// segments_N file. This method works well as long
// as there is no stale caching on the directory
// contents (NOTE: NFS clients often have such stale
// caching):
String[] files = null;
long genA = -1;
files = directory.listAll();
if (files != null) {
genA = getLastCommitGeneration(files);
}
if (infoStream != null) {
message("directory listing genA=" + genA);
}
// Also open segments.gen and read its
// contents. Then we take the larger of the two
// gens. This way, if either approach is hitting
// a stale cache (NFS) we have a better chance of
// getting the right generation.
long genB = -1;
IndexInput genInput = null;
try {
genInput = directory.openInput(IndexFileNames.SEGMENTS_GEN, IOContext.READONCE);
} catch (IOException e) {
if (infoStream != null) {
message("segments.gen open: IOException " + e);
}
}
if (genInput != null) {
try {
int version = genInput.readInt();
if (version == FORMAT_SEGMENTS_GEN_CURRENT) {
long gen0 = genInput.readLong();
long gen1 = genInput.readLong();
if (infoStream != null) {
message("fallback check: " + gen0 + "; " + gen1);
}
if (gen0 == gen1) {
// The file is consistent.
genB = gen0;
}
} else {
throw new IndexFormatTooNewException(genInput, version, FORMAT_SEGMENTS_GEN_CURRENT, FORMAT_SEGMENTS_GEN_CURRENT);
}
} catch (IOException err2) {
// rethrow any format exception
if (err2 instanceof CorruptIndexException) throw err2;
} finally {
genInput.close();
}
}
if (infoStream != null) {
message(IndexFileNames.SEGMENTS_GEN + " check: genB=" + genB);
}
// Pick the larger of the two gen's:
gen = Math.max(genA, genB);
if (gen == -1) {
// Neither approach found a generation
throw new IndexNotFoundException("no segments* file found in " + directory + ": files: " + Arrays.toString(files));
}
}
if (useFirstMethod && lastGen == gen && retryCount >= 2) {
// Give up on first method -- this is 3rd cycle on
// listing directory and checking gen file to
// attempt to locate the segments file.
useFirstMethod = false;
}
// Second method: since both directory cache and
// file contents cache seem to be stale, just
// advance the generation.
if (!useFirstMethod) {
if (genLookaheadCount < defaultGenLookaheadCount) {
gen++;
genLookaheadCount++;
if (infoStream != null) {
message("look ahead increment gen to " + gen);
}
} else {
// All attempts have failed -- throw first exc:
throw exc;
}
} else if (lastGen == gen) {
// This means we're about to try the same
// segments_N last tried.
retryCount++;
} else {
// Segment file has advanced since our last loop
// (we made "progress"), so reset retryCount:
retryCount = 0;
}
lastGen = gen;
segmentFileName = IndexFileNames.fileNameFromGeneration(IndexFileNames.SEGMENTS,
"",
gen);
try {
Object v = doBody(segmentFileName);
if (infoStream != null) {
message("success on " + segmentFileName);
}
return v;
} catch (IOException err) {
// Save the original root cause:
if (exc == null) {
exc = err;
}
if (infoStream != null) {
message("primary Exception on '" + segmentFileName + "': " + err + "'; will retry: retryCount=" + retryCount + "; gen = " + gen);
}
if (gen > 1 && useFirstMethod && retryCount == 1) {
// This is our second time trying this same segments
// file (because retryCount is 1), and, there is
// possibly a segments_(N-1) (because gen > 1).
// So, check if the segments_(N-1) exists and
// try it if so:
String prevSegmentFileName = IndexFileNames.fileNameFromGeneration(IndexFileNames.SEGMENTS,
"",
gen-1);
final boolean prevExists;
prevExists = directory.fileExists(prevSegmentFileName);
if (prevExists) {
if (infoStream != null) {
message("fallback to prior segment file '" + prevSegmentFileName + "'");
}
try {
Object v = doBody(prevSegmentFileName);
if (infoStream != null) {
message("success on fallback " + prevSegmentFileName);
}
return v;
} catch (IOException err2) {
if (infoStream != null) {
message("secondary Exception on '" + prevSegmentFileName + "': " + err2 + "'; will retry");
}
}
}
}
}
}
}
/**
* Subclass must implement this. The assumption is an
* IOException will be thrown if something goes wrong
* during the processing that could have been caused by
* a writer committing.
*/
protected abstract Object doBody(String segmentFileName) throws IOException;
}
// Carry over generation numbers from another SegmentInfos
void updateGeneration(SegmentInfos other) {
lastGeneration = other.lastGeneration;
generation = other.generation;
}
final void rollbackCommit(Directory dir) {
if (pendingSegnOutput != null) {
// Suppress so we keep throwing the original exception
// in our caller
IOUtils.closeWhileHandlingException(pendingSegnOutput);
pendingSegnOutput = null;
// Must carefully compute fileName from "generation"
// since lastGeneration isn't incremented:
final String segmentFileName = IndexFileNames.fileNameFromGeneration(IndexFileNames.SEGMENTS,
"",
generation);
// Suppress so we keep throwing the original exception
// in our caller
IOUtils.deleteFilesIgnoringExceptions(dir, segmentFileName);
}
}
/** Call this to start a commit. This writes the new
* segments file, but writes an invalid checksum at the
* end, so that it is not visible to readers. Once this
* is called you must call {@link #finishCommit} to complete
* the commit or {@link #rollbackCommit} to abort it.
* <p>
* Note: {@link #changed()} should be called prior to this
* method if changes have been made to this {@link SegmentInfos} instance
* </p>
**/
final void prepareCommit(Directory dir) throws IOException {
if (pendingSegnOutput != null) {
throw new IllegalStateException("prepareCommit was already called");
}
write(dir);
}
/** Returns all file names referenced by SegmentInfo
* instances matching the provided Directory (ie files
* associated with any "external" segments are skipped).
* The returned collection is recomputed on each
* invocation. */
public Collection<String> files(Directory dir, boolean includeSegmentsFile) throws IOException {
HashSet<String> files = new HashSet<>();
if (includeSegmentsFile) {
final String segmentFileName = getSegmentsFileName();
if (segmentFileName != null) {
files.add(segmentFileName);
}
}
final int size = size();
for(int i=0;i<size;i++) {
final SegmentCommitInfo info = info(i);
assert info.info.dir == dir;
if (info.info.dir == dir) {
files.addAll(info.files());
}
}
return files;
}
final void finishCommit(Directory dir) throws IOException {
if (pendingSegnOutput == null) {
throw new IllegalStateException("prepareCommit was not called");
}
boolean success = false;
try {
pendingSegnOutput.finishCommit();
success = true;
} finally {
if (!success) {
// Closes pendingSegnOutput & deletes partial segments_N:
rollbackCommit(dir);
} else {
success = false;
try {
pendingSegnOutput.close();
success = true;
} finally {
if (!success) {
// Closes pendingSegnOutput & deletes partial segments_N:
rollbackCommit(dir);
} else {
pendingSegnOutput = null;
}
}
}
}
// NOTE: if we crash here, we have left a segments_N
// file in the directory in a possibly corrupt state (if
// some bytes made it to stable storage and others
// didn't). But, the segments_N file includes checksum
// at the end, which should catch this case. So when a
// reader tries to read it, it will throw a
// CorruptIndexException, which should cause the retry
// logic in SegmentInfos to kick in and load the last
// good (previous) segments_N-1 file.
final String fileName = IndexFileNames.fileNameFromGeneration(IndexFileNames.SEGMENTS, "", generation);
success = false;
try {
dir.sync(Collections.singleton(fileName));
success = true;
} finally {
if (!success) {
try {
dir.deleteFile(fileName);
} catch (Throwable t) {
// Suppress so we keep throwing the original exception
}
}
}
lastGeneration = generation;
writeSegmentsGen(dir, generation);
}
/** Writes & syncs to the Directory dir, taking care to
* remove the segments file on exception
* <p>
* Note: {@link #changed()} should be called prior to this
* method if changes have been made to this {@link SegmentInfos} instance
* </p>
**/
final void commit(Directory dir) throws IOException {
prepareCommit(dir);
finishCommit(dir);
}
/** Returns readable description of this segment. */
public String toString(Directory directory) {
StringBuilder buffer = new StringBuilder();
buffer.append(getSegmentsFileName()).append(": ");
final int count = size();
for(int i = 0; i < count; i++) {
if (i > 0) {
buffer.append(' ');
}
final SegmentCommitInfo info = info(i);
buffer.append(info.toString(directory, 0));
}
return buffer.toString();
}
/** Return {@code userData} saved with this commit.
*
* @see IndexWriter#commit()
*/
public Map<String,String> getUserData() {
return userData;
}
void setUserData(Map<String,String> data) {
if (data == null) {
userData = Collections.<String,String>emptyMap();
} else {
userData = data;
}
}
/** Replaces all segments in this instance, but keeps
* generation, version, counter so that future commits
* remain write once.
*/
void replace(SegmentInfos other) {
rollbackSegmentInfos(other.asList());
lastGeneration = other.lastGeneration;
}
/** Returns sum of all segment's docCounts. Note that
* this does not include deletions */
public int totalDocCount() {
int count = 0;
for(SegmentCommitInfo info : this) {
count += info.info.getDocCount();
}
return count;
}
/** Call this before committing if changes have been made to the
* segments. */
public void changed() {
version++;
}
/** applies all changes caused by committing a merge to this SegmentInfos */
void applyMergeChanges(MergePolicy.OneMerge merge, boolean dropSegment) {
final Set<SegmentCommitInfo> mergedAway = new HashSet<>(merge.segments);
boolean inserted = false;
int newSegIdx = 0;
for (int segIdx = 0, cnt = segments.size(); segIdx < cnt; segIdx++) {
assert segIdx >= newSegIdx;
final SegmentCommitInfo info = segments.get(segIdx);
if (mergedAway.contains(info)) {
if (!inserted && !dropSegment) {
segments.set(segIdx, merge.info);
inserted = true;
newSegIdx++;
}
} else {
segments.set(newSegIdx, info);
newSegIdx++;
}
}
// the rest of the segments in list are duplicates, so don't remove from map, only list!
segments.subList(newSegIdx, segments.size()).clear();
// Either we found place to insert segment, or, we did
// not, but only because all segments we merged becamee
// deleted while we are merging, in which case it should
// be the case that the new segment is also all deleted,
// we insert it at the beginning if it should not be dropped:
if (!inserted && !dropSegment) {
segments.add(0, merge.info);
}
}
List<SegmentCommitInfo> createBackupSegmentInfos() {
final List<SegmentCommitInfo> list = new ArrayList<>(size());
for(final SegmentCommitInfo info : this) {
assert info.info.getCodec() != null;
list.add(info.clone());
}
return list;
}
void rollbackSegmentInfos(List<SegmentCommitInfo> infos) {
this.clear();
this.addAll(infos);
}
/** Returns an <b>unmodifiable</b> {@link Iterator} of contained segments in order. */
// @Override (comment out until Java 6)
@Override
public Iterator<SegmentCommitInfo> iterator() {
return asList().iterator();
}
/** Returns all contained segments as an <b>unmodifiable</b> {@link List} view. */
public List<SegmentCommitInfo> asList() {
return Collections.unmodifiableList(segments);
}
/** Returns number of {@link SegmentCommitInfo}s. */
public int size() {
return segments.size();
}
/** Appends the provided {@link SegmentCommitInfo}. */
public void add(SegmentCommitInfo si) {
segments.add(si);
}
/** Appends the provided {@link SegmentCommitInfo}s. */
public void addAll(Iterable<SegmentCommitInfo> sis) {
for (final SegmentCommitInfo si : sis) {
this.add(si);
}
}
/** Clear all {@link SegmentCommitInfo}s. */
public void clear() {
segments.clear();
}
/** Remove the provided {@link SegmentCommitInfo}.
*
* <p><b>WARNING</b>: O(N) cost */
public void remove(SegmentCommitInfo si) {
segments.remove(si);
}
/** Remove the {@link SegmentCommitInfo} at the
* provided index.
*
* <p><b>WARNING</b>: O(N) cost */
void remove(int index) {
segments.remove(index);
}
/** Return true if the provided {@link
* SegmentCommitInfo} is contained.
*
* <p><b>WARNING</b>: O(N) cost */
boolean contains(SegmentCommitInfo si) {
return segments.contains(si);
}
/** Returns index of the provided {@link
* SegmentCommitInfo}.
*
* <p><b>WARNING</b>: O(N) cost */
int indexOf(SegmentCommitInfo si) {
return segments.indexOf(si);
}
}