/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 2002-2006
* Sleepycat Software. All rights reserved.
*
* $Id: FileSummaryLN.java,v 1.1 2006/05/06 09:00:13 ckaestne Exp $
*/
package com.sleepycat.je.tree;
import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import com.sleepycat.je.DatabaseException;
import com.sleepycat.je.cleaner.FileSummary;
import com.sleepycat.je.cleaner.PackedOffsets;
import com.sleepycat.je.cleaner.TrackedFileSummary;
import com.sleepycat.je.dbi.DatabaseImpl;
import com.sleepycat.je.log.LogEntryType;
import com.sleepycat.je.log.LogException;
import com.sleepycat.je.log.LogUtils;
import com.sleepycat.je.log.LoggableObject;
/**
* A FileSummaryLN represents a Leaf Node in the UtilizationProfile database.
*
* <p>The contents of the FileSummaryLN are not fixed until the moment at which
* the LN is added to the log. A base summary object contains the summary last
* added to the log. A tracked summary object contains live summary info being
* updated in real time. The tracked summary is added to the base summary just
* before logging it, and then the tracked summary is reset. This ensures that
* the logged summary will accurately reflect the totals calculated at the
* point in the log where the LN is added.</p>
*
* <p>This is all done in the writeToLog method, which operates under the log
* write latch. All utilization tracking must be done under the log write
* latch.</p>
*
* <p>In record version 1, obsolete offset tracking was added and multiple
* records are stored for a single file rather than a single record. Each
* record contains the offsets that were tracked since the last record was
* written.
*
* <p>The key is 8 bytes: 4 bytes for the file number followed by 4 bytes for
* the sequence number. The lowest valued key for a given file contains the
* most recent summary information, while to get a complete list of obsolete
* offsets all records for the file must be read. A range search using just
* the first 4 bytes can be used to find the most recent record -- this is
* possible because the sequence number values are decreasing over time for a
* given file. Here are example keys for three summary records in file 1:</p>
*
* <pre>
* (file=1, sequence=Integer.MAX_VALUE - 300)
* (file=1, sequence=Integer.MAX_VALUE - 200)
* (file=1, sequence=Integer.MAX_VALUE - 100)
* </pre>
*
* <p>The sequence number is the number of obsolete entries counted so far,
* subtracted from Integer.MAX_VALUE to cause the latest written record to have
* the lowest key.</p>
*
* <h3>Log version information</h3>
* <p>Version 0: Keys are old format strings. No obsolete detail is
* present.</p>
* <p>Version 1: Keys are two 4 byte integers: {file, sequence}. Obsolete
* detail is present. Some offsets may be invalid if RMW was used.</p>
* <p>Version 2: The RMW problem with invalid offsets was corrected. There is
* no data format change; all versions of JE 2.0.x can read version 1.</p>
*
* @see com.sleepycat.je.cleaner.UtilizationProfile
*/
public final class FileSummaryLN extends LN {
private static final String BEGIN_TAG = "<fileSummaryLN>";
private static final String END_TAG = "</fileSummaryLN>";
private FileSummary baseSummary;
private TrackedFileSummary trackedSummary;
private PackedOffsets obsoleteOffsets;
private boolean needOffsets;
private byte logVersion;
/**
* Creates a new LN with a given base summary.
*/
public FileSummaryLN(FileSummary baseSummary) {
super(new byte[0]);
assert baseSummary != null;
this.baseSummary = baseSummary;
obsoleteOffsets = new PackedOffsets();
logVersion = -1;
}
/**
* Creates an empty LN to be filled in from the log.
*/
public FileSummaryLN()
throws DatabaseException {
baseSummary = new FileSummary();
obsoleteOffsets = new PackedOffsets();
}
/**
* Sets the live summary object that will be added to the base summary at
* the time the LN is logged.
*/
public void setTrackedSummary(TrackedFileSummary trackedSummary) {
this.trackedSummary = trackedSummary;
needOffsets = true;
}
/**
* Returns the tracked summary, or null if setTrackedSummary was not
* called.
*/
public TrackedFileSummary getTrackedSummary() {
return trackedSummary;
}
/**
* Returns the base summary for the file that is stored in the LN.
*/
public FileSummary getBaseSummary() {
return baseSummary;
}
/**
* Returns the obsolete offsets for the file.
*/
public PackedOffsets getObsoleteOffsets() {
return obsoleteOffsets;
}
/**
* Returns true if the given key for this LN is a String file number key.
* For the old version of the LN there will be a single record per file.
*
* If this is a version 0 log entry, the key is a string. However, such an
* LN may be migrated by the cleaner, in which case the version will be 1
* or greater [#13061]. In the latter case, we can distinguish a string
* key by:
*
* 1) If the key is not 8 bytes long, it has to be a string key.
*
* 2) If the key is 8 bytes long, but bytes[4] is ascii "0" to "9", then it
* must be a string key. bytes[4] to bytes[7] are a sequence number that
* is the number of log entries counted. For this number to be greater
* than 0x30000000, the binary value of 4 digits starting with ascii "0",
* over 400 million log entries would have to occur in a single file; this
* should never happen.
*
* Note that having to rely on method (2) is unlikely. A string key will
* only be 8 bytes if the file number reach 8 decimal digits (10,000,000 to
* 99,999,999). This is a very large file number and unlikely to have
* occurred using JE 1.7.1 or earlier.
*
* In summary, the only time the algorithm here could fail is if there were
* more than 400 million log entries per file, and more than 10 million
* were written with JE 1.7.1 or earlier.
*/
public boolean hasStringKey(byte[] bytes) {
if (logVersion == 0 || bytes.length != 8) {
return true;
} else {
return (bytes[4] >= '0' && bytes[4] <= '9');
}
}
/**
* Convert a FileSummaryLN key from a byte array to a long. The file
* number is the first 4 bytes of the key.
*/
public long getFileNumber(byte[] bytes) {
if (hasStringKey(bytes)) {
try {
return Long.valueOf(new String(bytes, "UTF-8")).longValue();
} catch (UnsupportedEncodingException shouldNeverHappen) {
assert false: shouldNeverHappen;
return 0;
}
} else {
ByteBuffer buf = ByteBuffer.wrap(bytes);
return LogUtils.readIntMSB(buf) & 0xFFFFFFFFL;
}
}
/**
* Returns the first 4 bytes of the key for the given file number. This
* can be used to do a range search to find the first LN for the file.
*/
public static byte[] makePartialKey(long fileNum) {
byte[] bytes = new byte[4];
ByteBuffer buf = ByteBuffer.wrap(bytes);
LogUtils.writeIntMSB(buf, (int) fileNum);
return bytes;
}
/**
* Returns the full two-part key for a given file number and unique
* sequence. This can be used to insert a new LN.
*
* @param sequence is a unique identifier for the LN for the given file,
* and must be greater than the last sequence.
*/
public static byte[] makeFullKey(long fileNum, int sequence) {
assert sequence >= 0;
byte[] bytes = new byte[8];
ByteBuffer buf = ByteBuffer.wrap(bytes);
/*
* The sequence is subtracted from MAX_VALUE so that increasing values
* will be sorted first. This allows a simple range search to find the
* most recent value.
*/
LogUtils.writeIntMSB(buf, (int) fileNum);
LogUtils.writeIntMSB(buf, Integer.MAX_VALUE - sequence);
return bytes;
}
/**
* Initialize a node that has been faulted in from the log. If this FSLN
* contains version 1 offsets that can be incorrect when RMW was used, and
* if je.cleaner.rmwFix is enabled, discard the offsets. [#13158]
*/
public void postFetchInit(DatabaseImpl db, long sourceLsn)
throws DatabaseException {
super.postFetchInit(db, sourceLsn);
if (logVersion == 1 &&
db.getDbEnvironment().getUtilizationProfile().isRMWFixEnabled()) {
obsoleteOffsets = new PackedOffsets();
}
}
/*
* Dumping
*/
public String toString() {
return dumpString(0, true);
}
public String beginTag() {
return BEGIN_TAG;
}
public String endTag() {
return END_TAG;
}
public String dumpString(int nSpaces, boolean dumpTags) {
StringBuffer sb = new StringBuffer();
sb.append(super.dumpString(nSpaces, dumpTags));
sb.append('\n');
if (!isDeleted()) {
sb.append(baseSummary.toString());
sb.append(obsoleteOffsets.toString());
}
return sb.toString();
}
/**
* Dump additional fields. Done this way so the additional info can
* be within the XML tags defining the dumped log entry.
*/
protected void dumpLogAdditional(StringBuffer sb, boolean verbose) {
if (!isDeleted()) {
baseSummary.dumpLog(sb, true);
if (verbose) {
obsoleteOffsets.dumpLog(sb, true);
}
}
}
/*
* Logging
*/
/**
* Log type for transactional entries.
*/
protected LogEntryType getTransactionalLogType() {
assert false : "Txnl access to UP db not allowed";
return LogEntryType.LOG_FILESUMMARYLN;
}
/**
* @see LN#getLogType
*/
public LogEntryType getLogType() {
return LogEntryType.LOG_FILESUMMARYLN;
}
/**
* @see LoggableObject#marshallOutsideWriteLatch
* FileSummaryLNs must be marshalled within the log write latch, because
* that critical section is used to guarantee that all previous log
* entries are reflected in the summary.
*/
public boolean marshallOutsideWriteLatch() {
return false;
}
/**
* @see LoggableObject#countAsObsoleteWhenLogged
*/
public boolean countAsObsoleteWhenLogged() {
return false;
}
/**
* @see LN#getLogSize
*/
public int getLogSize() {
int size = super.getLogSize();
if (!isDeleted()) {
size += baseSummary.getLogSize();
getOffsets();
size += obsoleteOffsets.getLogSize();
}
return size;
}
/**
* @see LN#writeToLog
*/
public void writeToLog(ByteBuffer logBuffer) {
/*
* Add the tracked (live) summary to the base summary before writing it
* to the log, and reset the tracked summary. Do this even when
* deleting the LN, so that the tracked summary is cleared.
*/
if (trackedSummary != null) {
baseSummary.add(trackedSummary);
if (!isDeleted()) {
getOffsets();
}
/* Reset the totals to zero and clear the tracked offsets. */
trackedSummary.reset();
}
super.writeToLog(logBuffer);
if (!isDeleted()) {
baseSummary.writeToLog(logBuffer);
obsoleteOffsets.writeToLog(logBuffer);
}
}
/**
* @see LN#readFromLog
*/
public void readFromLog(ByteBuffer itemBuffer, byte entryTypeVersion)
throws LogException {
super.readFromLog(itemBuffer, entryTypeVersion);
logVersion = entryTypeVersion;
if (!isDeleted()) {
baseSummary.readFromLog(itemBuffer, entryTypeVersion);
if (entryTypeVersion > 0) {
obsoleteOffsets.readFromLog(itemBuffer, entryTypeVersion);
}
}
}
/**
* If tracked offsets may be present, get them so they are ready to be
* written to the log.
*/
private void getOffsets() {
if (needOffsets) {
long[] offsets = trackedSummary.getObsoleteOffsets();
if (offsets != null) {
obsoleteOffsets.pack(offsets);
}
needOffsets = false;
}
}
}