[Jrobin-commits] src/org/jrobin/core RrdSafeFileBackend.java,NONE,1.1 RrdSafeFileBackendFactory.java

SourceForge Headquarters 1320 Columbia Street Suite 310 San Diego, CA 92101 +1 (858) 422-6466

Update of /cvsroot/jrobin/src/org/jrobin/core
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv12665/org/jrobin/core

Modified Files:
	Archive.java Datasource.java Header.java 
	RrdBackendFactory.java RrdDouble.java RrdDoubleArray.java 
	RrdInt.java RrdLong.java RrdPrimitive.java RrdString.java 
Added Files:
	RrdSafeFileBackend.java RrdSafeFileBackendFactory.java 
Log Message:
Major core update: added one more backend type (SAFE - basically it's a FILE, but with RRD file locking and minimal in-memory caching). Could be useful when RRD files are used by two JVMs running at the same time.

Index: RrdPrimitive.java
===================================================================
RCS file: /cvsroot/jrobin/src/org/jrobin/core/RrdPrimitive.java,v
retrieving revision 1.9
retrieving revision 1.10
diff -C2 -d -r1.9 -r1.10
*** RrdPrimitive.java	8 Nov 2004 11:18:49 -0000	1.9
--- RrdPrimitive.java	9 Nov 2004 11:36:53 -0000	1.10
***************
*** 36,48 ****
  	private int byteCount;
  	private final long pointer;

! 	RrdPrimitive(RrdUpdater updater, int type) throws IOException {
! 		this(updater, type, 1);
  	}

! 	RrdPrimitive(RrdUpdater updater, int type, int count) throws IOException {
  		this.backend = updater.getRrdBackend();
  		this.byteCount = RRD_PRIM_SIZES[type] * count;
  		this.pointer = updater.getRrdAllocator().allocate(byteCount);
  	}

--- 36,50 ----
  	private int byteCount;
  	private final long pointer;
+ 	private final boolean cachingAllowed;

! 	RrdPrimitive(RrdUpdater updater, int type, boolean isConstant) throws IOException {
! 		this(updater, type, 1, isConstant);
  	}

! 	RrdPrimitive(RrdUpdater updater, int type, int count, boolean isConstant) throws IOException {
  		this.backend = updater.getRrdBackend();
  		this.byteCount = RRD_PRIM_SIZES[type] * count;
  		this.pointer = updater.getRrdAllocator().allocate(byteCount);
+ 		this.cachingAllowed = isConstant || backend.isCachingAllowed();
  	}

***************
*** 111,115 ****

  	final boolean isCachingAllowed() {
! 		return backend.isCachingAllowed();
  	}
  }
--- 113,117 ----

  	final boolean isCachingAllowed() {
! 		return cachingAllowed;
  	}
  }

Index: Header.java
===================================================================
RCS file: /cvsroot/jrobin/src/org/jrobin/core/Header.java,v
retrieving revision 1.7
retrieving revision 1.8
diff -C2 -d -r1.7 -r1.8
*** Header.java	22 Jul 2004 09:34:10 -0000	1.7
--- Header.java	9 Nov 2004 11:36:53 -0000	1.8
***************
*** 52,59 ****
  		boolean shouldInitialize = rrdDef != null;
  		this.parentDb = parentDb;
! 		signature = new RrdString(this);
! 		step = new RrdLong(this);
! 		dsCount = new RrdInt(this);
! 		arcCount = new RrdInt(this);
  		lastUpdateTime = new RrdLong(this);
  		if(shouldInitialize) {
--- 52,59 ----
  		boolean shouldInitialize = rrdDef != null;
  		this.parentDb = parentDb;
! 		signature = new RrdString(this, true); 		// constant, may be cached
! 		step = new RrdLong(this, true); 			// constant, may be cached
! 		dsCount = new RrdInt(this, true); 			// constant, may be cached
! 		arcCount = new RrdInt(this, true); 			// constant, may be cached
  		lastUpdateTime = new RrdLong(this);
  		if(shouldInitialize) {

Index: Archive.java
===================================================================
RCS file: /cvsroot/jrobin/src/org/jrobin/core/Archive.java,v
retrieving revision 1.18
retrieving revision 1.19
diff -C2 -d -r1.18 -r1.19
*** Archive.java	21 Sep 2004 08:42:09 -0000	1.18
--- Archive.java	9 Nov 2004 11:36:53 -0000	1.19
***************
*** 52,59 ****
  		boolean shouldInitialize = arcDef != null;
  		this.parentDb = parentDb;
! 		consolFun = new RrdString(this);
  		xff = new RrdDouble(this);
! 		steps = new RrdInt(this);
! 		rows = new RrdInt(this);
  		if(shouldInitialize) {
  			consolFun.set(arcDef.getConsolFun());
--- 52,59 ----
  		boolean shouldInitialize = arcDef != null;
  		this.parentDb = parentDb;
! 		consolFun = new RrdString(this, true);  // constant, may be cached
  		xff = new RrdDouble(this);
! 		steps = new RrdInt(this, true);			// constant, may be cached
! 		rows = new RrdInt(this, true);			// constant, may be cached
  		if(shouldInitialize) {
  			consolFun.set(arcDef.getConsolFun());

Index: RrdInt.java
===================================================================
RCS file: /cvsroot/jrobin/src/org/jrobin/core/RrdInt.java,v
retrieving revision 1.10
retrieving revision 1.11
diff -C2 -d -r1.10 -r1.11
*** RrdInt.java	8 Nov 2004 11:18:48 -0000	1.10
--- RrdInt.java	9 Nov 2004 11:36:53 -0000	1.11
***************
*** 32,39 ****
  	private boolean cached = false;

  	RrdInt(RrdUpdater updater) throws IOException {
! 		super(updater,  RrdPrimitive.RRD_INT);
  	}
! 	
  	void set(int value) throws IOException {
  		if(!isCachingAllowed()) {
--- 32,43 ----
  	private boolean cached = false;

+ 	RrdInt(RrdUpdater updater, boolean isConstant) throws IOException {
+ 		super(updater,  RrdPrimitive.RRD_INT, isConstant);
+ 	}
+ 
  	RrdInt(RrdUpdater updater) throws IOException {
! 		this(updater, false);
  	}
! 
  	void set(int value) throws IOException {
  		if(!isCachingAllowed()) {

Index: RrdDouble.java
===================================================================
RCS file: /cvsroot/jrobin/src/org/jrobin/core/RrdDouble.java,v
retrieving revision 1.10
retrieving revision 1.11
diff -C2 -d -r1.10 -r1.11
*** RrdDouble.java	8 Nov 2004 11:18:48 -0000	1.10
--- RrdDouble.java	9 Nov 2004 11:36:53 -0000	1.11
***************
*** 32,37 ****
  	private boolean cached = false;

  	RrdDouble(RrdUpdater updater) throws IOException {
! 		super(updater, RrdDouble.RRD_DOUBLE);
  	}

--- 32,41 ----
  	private boolean cached = false;

+ 	RrdDouble(RrdUpdater updater, boolean isConstant) throws IOException {
+ 		super(updater, RrdDouble.RRD_DOUBLE, isConstant);
+ 	}
+ 
  	RrdDouble(RrdUpdater updater) throws IOException {
! 		super(updater, RrdDouble.RRD_DOUBLE, false);
  	}

Index: RrdString.java
===================================================================
RCS file: /cvsroot/jrobin/src/org/jrobin/core/RrdString.java,v
retrieving revision 1.10
retrieving revision 1.11
diff -C2 -d -r1.10 -r1.11
*** RrdString.java	8 Nov 2004 11:18:49 -0000	1.10
--- RrdString.java	9 Nov 2004 11:36:53 -0000	1.11
***************
*** 31,36 ****
  	private String cache;

  	RrdString(RrdUpdater updater) throws IOException {
! 		super(updater, RrdPrimitive.RRD_STRING);
  	}

--- 31,40 ----
  	private String cache;

+ 	RrdString(RrdUpdater updater, boolean isConstant) throws IOException {
+ 		super(updater, RrdPrimitive.RRD_STRING, isConstant);
+ 	}
+ 
  	RrdString(RrdUpdater updater) throws IOException {
! 		this(updater, false);
  	}

Index: RrdLong.java
===================================================================
RCS file: /cvsroot/jrobin/src/org/jrobin/core/RrdLong.java,v
retrieving revision 1.10
retrieving revision 1.11
diff -C2 -d -r1.10 -r1.11
*** RrdLong.java	8 Nov 2004 11:18:48 -0000	1.10
--- RrdLong.java	9 Nov 2004 11:36:53 -0000	1.11
***************
*** 32,37 ****
  	private boolean cached = false;

  	RrdLong(RrdUpdater updater) throws IOException {
! 		super(updater, RrdPrimitive.RRD_LONG);
  	}

--- 32,41 ----
  	private boolean cached = false;

+ 	RrdLong(RrdUpdater updater, boolean isConstant) throws IOException {
+ 		super(updater, RrdPrimitive.RRD_LONG, isConstant);
+ 	}
+ 
  	RrdLong(RrdUpdater updater) throws IOException {
! 		this(updater, false);
  	}

Index: RrdBackendFactory.java
===================================================================
RCS file: /cvsroot/jrobin/src/org/jrobin/core/RrdBackendFactory.java,v
retrieving revision 1.7
retrieving revision 1.8
diff -C2 -d -r1.7 -r1.8
*** RrdBackendFactory.java	13 Jul 2004 18:42:19 -0000	1.7
--- RrdBackendFactory.java	9 Nov 2004 11:36:53 -0000	1.8
***************
*** 37,41 ****
   * Each factory creates unlimited number of specific backend objects.
   *
!  * JRobin supports three different backend types (backend factories) out of the box:<p>
   * <ul>
   * <li>{@link RrdFileBackend}: objects of this class are created from the
--- 37,41 ----
   * Each factory creates unlimited number of specific backend objects.
   *
!  * JRobin supports four different backend types (backend factories) out of the box:<p>
   * <ul>
   * <li>{@link RrdFileBackend}: objects of this class are created from the
***************
*** 44,47 ****
--- 44,55 ----
   * RRD data in files on the disk.
   *
+  * <li>{@link RrdSafeFileBackend}: objects of this class are created from the
+  * {@link RrdSafeFileBackendFactory} class. It uses java.io.* package and RandomAccessFile class to store
+  * RRD data in files on the disk. This backend is SAFE:
+  * it locks the underlying RRD file during update/fetch operations, and caches only static
+  * parts of a RRD file in memory. Therefore, this backend is safe to be used when RRD files should
+  * be shared <b>between several JVMs</b> at the same time. However, this backend is *slow* since it does
+  * not use fast java.nio.* package (it's still based on the RandomAccessFile class).
+  *
   * <li>{@link RrdNioBackend}: objects of this class are created from the
   * {@link RrdNioBackendFactory} class. The backend uses java.io.* and java.nio.*
***************
*** 72,75 ****
--- 80,85 ----
  			RrdNioBackendFactory nioFactory = new RrdNioBackendFactory();
  			registerFactory(nioFactory);
+ 			RrdSafeFileBackendFactory safeFactory = new RrdSafeFileBackendFactory();
+ 			registerFactory(safeFactory);

  			// Here is the default backend factory
***************
*** 87,90 ****
--- 97,104 ----
  	 * <li><b>FILE</b>: Default factory which creates backends based on the
  	 * java.io.* package. RRD data is stored in files on the disk
+ 	 * <li><b>SAFE</b>: Default factory which creates backends based on the
+ 	 * java.io.* package. RRD data is stored in files on the disk. This backend
+ 	 * is "safe". Being safe means that RRD files can be safely shared between
+ 	 * several JVM's.
  	 * <li><b>NIO</b>: Factory which creates backends based on the
  	 * java.nio.* package. RRD data is stored in files on the disk
***************
*** 149,155 ****
  	 * Replaces the default backend factory with a new one. This method must be called before
  	 * the first RRD gets created. <p>
! 	 * @param factoryName Name of the default factory. Out of the box, JRobin supports three
! 	 * different RRD backends: "FILE" (java.io.* based), "NIO" (java.nio.* based) and "MEMORY"
! 	 * (byte[] based).
  	 * @throws RrdException Thrown if invalid factory name is supplied or not called before
  	 * the first RRD is created.
--- 163,170 ----
  	 * Replaces the default backend factory with a new one. This method must be called before
  	 * the first RRD gets created. <p>
! 	 * @param factoryName Name of the default factory. Out of the box, JRobin supports four
! 	 * different RRD backends: "FILE" (java.io.* based), "SAFE" (java.io.* based - use this
! 	 * backend if RRD files may be accessed from several JVMs at the same time),
! 	 * "NIO" (java.nio.* based) and "MEMORY" (byte[] based).
  	 * @throws RrdException Thrown if invalid factory name is supplied or not called before
  	 * the first RRD is created.

--- NEW FILE: RrdSafeFileBackendFactory.java ---
package org.jrobin.core;

import java.io.IOException;

/**
 * Factory class which creates actual {@link RrdSafeFileBackend} objects.
 */
public class RrdSafeFileBackendFactory extends RrdFileBackendFactory {
	/** factory name, "SAFE" */
	public static final String NAME = "SAFE";

	/**
	 * Creates RrdSafeFileBackend object for the given file path.
	 * @param path File path
	 * @param readOnly True, if the file should be accessed in read/only mode.
	 * False otherwise.
	 * @param lockMode This parameter is ignored since this backend implements its own
	 * locking mechanism.
	 * @return RrdSafeFileBackend object which handles all I/O operations for the given file path
	 * @throws IOException Thrown in case of I/O error.
	 */
	protected RrdBackend open(String path, boolean readOnly, int lockMode) throws IOException {
		return new RrdSafeFileBackend(path, readOnly, lockMode);
	}

	/**
	 * Returns the name of this factory.
	 * @return Factory name (equals to string "SAFE")
	 */
	public String getFactoryName() {
		return NAME;
	}
}

--- NEW FILE: RrdSafeFileBackend.java ---
package org.jrobin.core;

import java.io.IOException;
import java.nio.channels.FileLock;

/**
 * JRobin backend which is used to store RRD data to ordinary files on the disk. This backend
 * is SAFE: it locks the underlying RRD file during update/fetch operations, and caches only static 
 * parts of a RRD file in memory. Therefore, this backend is safe to be used when RRD files should
 * be shared between several JVMs at the same time. However, this backend is *slow* since it does
 * not use fast java.nio.* package (it's still based on the RandomAccessFile class).
 */
public class RrdSafeFileBackend extends RrdFileBackend {
	/** Number of locking retries. This backend will not give up if the first locking request fails. */
	public static final int LOCK_RETRY_COUNT = 40;
	/**	Number of milliseconds between locking retries */
	public static final int LOCK_RETRY_DELAY = 50; // milliseconds

	private FileLock lock;

	/**
	 * Creates RrdFileBackend object for the given file path, backed by RandomAccessFile object.
	 * @param path Path to a file
	 * @param readOnly True, if file should be open in a read-only mode. False otherwise
	 * @param lockMode Ignored, since this backend implements its own locking mechanism
	 * @throws IOException Thrown in case of I/O error
	 */
	public RrdSafeFileBackend(String path, boolean readOnly, int lockMode) throws IOException {
		// this backend implements its own locking mechanism - we'll simply ignore the suggested lockMode
		super(path, readOnly, RrdDb.NO_LOCKS);
	}

	private void lockFile() throws IOException {
		if(lock != null) {
			// lock already obtained
			return;
		}
		for(int i = 0; i < LOCK_RETRY_COUNT; i++) {
			lock = channel.tryLock();
			if(lock != null) {
				return;
			}
			try {
				Thread.sleep(LOCK_RETRY_DELAY);
			}
			catch (InterruptedException e) {
				// NOP
			}
		}
		throw new IOException("Could not obtain lock on file: " + getPath() +
				"] after " + LOCK_RETRY_COUNT + " consecutive retries");
	}

	private void unlockFile() throws IOException {
		if(lock != null) {
			lock.release();
			lock = null;
		}
	}

	/**
	 * Defines the caching policy for this backend.
	 * @return <code>false</code>
	 */
	protected boolean isCachingAllowed() {
		return false;
	}

	/**
	 * Locks the underlying RRD file just before the next RRD update operation.
	 * @throws IOException Thrown if the file lock could not be obtained.
	 */
	protected void beforeUpdate() throws IOException {
		super.beforeUpdate();
		lockFile();
	}

	/**
	 * Unlocks the underlying RRD file just after the RRD update operation.
	 * @throws IOException Thrown if the lock could not be released.
	 */
	protected void afterUpdate() throws IOException {
		unlockFile();
		super.afterUpdate();
	}

	/**
	 * Locks the underlying RRD file just before the next RRD fetch operation.
	 * @throws IOException Thrown if the file lock could not be obtained.
	 */
	protected void beforeFetch() throws IOException {
		super.beforeFetch();
		lockFile();
	}

	/**
	 * Unlocks the underlying RRD file just after the RRD fetch operation.
	 * @throws IOException Thrown if the lock could not be released.
	 */
	protected void afterFetch() throws IOException {
		unlockFile();
		super.afterFetch();
	}

	/**
	 * Releases the file lock before closing the RRD file (if not already released).
	 * @throws IOException Thrown if the lock could not be released.
	 */
	protected void beforeClose() throws IOException {
		// just in case
		unlockFile();
		super.beforeClose();
	}
}

Index: Datasource.java
===================================================================
RCS file: /cvsroot/jrobin/src/org/jrobin/core/Datasource.java,v
retrieving revision 1.9
retrieving revision 1.10
diff -C2 -d -r1.9 -r1.10
*** Datasource.java	21 Sep 2004 08:42:09 -0000	1.9
--- Datasource.java	9 Nov 2004 11:36:53 -0000	1.10
***************
*** 54,59 ****
  		boolean shouldInitialize = dsDef != null;
  		this.parentDb = parentDb;
! 		dsName = new RrdString(this);
! 		dsType = new RrdString(this);
  		heartbeat = new RrdLong(this);
  		minValue = new RrdDouble(this);
--- 54,59 ----
  		boolean shouldInitialize = dsDef != null;
  		this.parentDb = parentDb;
! 		dsName = new RrdString(this, true); 	// constant, may be cached
! 		dsType = new RrdString(this, true);		// constant, may be cached
  		heartbeat = new RrdLong(this);
  		minValue = new RrdDouble(this);

Index: RrdDoubleArray.java
===================================================================
RCS file: /cvsroot/jrobin/src/org/jrobin/core/RrdDoubleArray.java,v
retrieving revision 1.6
retrieving revision 1.7
diff -C2 -d -r1.6 -r1.7
*** RrdDoubleArray.java	20 May 2004 10:29:33 -0000	1.6
--- RrdDoubleArray.java	9 Nov 2004 11:36:53 -0000	1.7
***************
*** 32,36 ****

  	RrdDoubleArray(RrdUpdater updater, int length) throws IOException {
! 		super(updater, RrdPrimitive.RRD_DOUBLE, length);
  		this.length = length;
  	}
--- 32,36 ----

  	RrdDoubleArray(RrdUpdater updater, int length) throws IOException {
! 		super(updater, RrdPrimitive.RRD_DOUBLE, length, false);
  		this.length = length;
  	}