Use Mutex to avoid parallel FTP directory queries

rse/plugins/org.eclipse.rse.services.files.ftp/src/org/eclipse/rse/services/files/ftp/FTPService.java

@@ -36,6 +36,7 @@ import java.util.ArrayList;
 import java.util.List;
 
 import org.eclipse.core.runtime.IProgressMonitor;
+import org.eclipse.rse.services.Mutex;
 import org.eclipse.rse.services.clientserver.NamePatternMatcher;
 import org.eclipse.rse.services.clientserver.messages.SystemMessageException;
 import org.eclipse.rse.services.files.AbstractFileService;
@@ -50,6 +51,9 @@ import sun.net.ftp.FtpClient;
 public class FTPService extends AbstractFileService implements IFileService, IFTPService
 {
 	private FTPClientService _ftpClient;
+	private Mutex _mutex = new Mutex();
+	private long _mutexTimeout = 5000; //max.5 seconds to obtain dir channel 
+
 	private String    _userHome;
 	private IFTPDirectoryListingParser _ftpPropertiesUtil;
 	
@@ -151,6 +155,7 @@ public class FTPService extends AbstractFileService implements IFileService, IFT
 	
 	public IHostFile getFile(IProgressMonitor monitor, String remoteParent, String fileName)
 	{
+		//No Mutex lock needed here because internalFetch() does the lock
 		IHostFile[] matches = internalFetch(monitor, remoteParent, fileName, FILE_TYPE_FILES_AND_FOLDERS);
 		if (matches != null && matches.length > 0)
 		{
@@ -174,6 +179,8 @@ public class FTPService extends AbstractFileService implements IFileService, IFT
 		}
 		NamePatternMatcher filematcher = new NamePatternMatcher(fileFilter, true, true);
 		List results = new ArrayList();
+		if (_mutex.waitForLock(monitor, _mutexTimeout))
+		{
 			try
 			{
 				FtpClient ftp = getFTPClient();
@@ -212,6 +219,11 @@ public class FTPService extends AbstractFileService implements IFileService, IFT
 			{			
 				e.printStackTrace();
 			}
+			finally
+			{
+				_mutex.release();
+			}
+		}
 		return (IHostFile[])results.toArray(new IHostFile[results.size()]);
 	}
 	
@@ -271,9 +283,11 @@ public class FTPService extends AbstractFileService implements IFileService, IFT
 	
 	public boolean download(IProgressMonitor monitor, String remoteParent, String remoteFile, File localFile, boolean isBinary, String hostEncoding)
 	{
-		FtpClient ftp = getFTPClient();
+		if (_mutex.waitForLock(monitor, _mutexTimeout))
+		{
 			try
 			{
+				FtpClient ftp = getFTPClient();
 				ftp.cd(remoteParent);
 				/*
 				if (isBinary)
@@ -308,13 +322,18 @@ public class FTPService extends AbstractFileService implements IFileService, IFT
 				      totalWrote += readCount;
 				 }
 				 bos.close();
-	
+				 return true;
 			}
 			catch (Exception e)
 			{			
 				e.printStackTrace();
 			}
-		return true;
+			finally
+			{
+				_mutex.release();
+			}
+		}
+		return false;
 	}
 	
 	public IHostFile getUserHome()
@@ -336,14 +355,20 @@ public class FTPService extends AbstractFileService implements IFileService, IFT
 	 */
 	public boolean delete(IProgressMonitor monitor, String remoteParent, String fileName) {
 		boolean hasSucceeded = false;
+		if (_mutex.waitForLock(monitor, _mutexTimeout)) {
 			try {
 				getFTPClient().cd(remoteParent);
 				int returnedValue = getFTPClient().sendCommand("DELE " + fileName);
 				hasSucceeded = (returnedValue > 0);
-		} catch (IOException e) {
+			}
+			catch (IOException e) {			
 				// Changing folder raised an exception
 				hasSucceeded = false;
 			}
+			finally {
+				_mutex.release();
+			}
+		}
 		return hasSucceeded;
 	}
 
@@ -352,11 +377,18 @@ public class FTPService extends AbstractFileService implements IFileService, IFT
 	 */
 	public boolean rename(IProgressMonitor monitor, String remoteParent, String oldName, String newName) {
 		boolean hasSucceeded = false;
+		if (_mutex.waitForLock(monitor, _mutexTimeout)) {
+			try {
 				int returnedValue = getFTPClient().sendCommand("RNFR " + remoteParent + getSeparator() + oldName);
 				if (returnedValue > 0) {
 					returnedValue = getFTPClient().sendCommand("RNTO " + remoteParent + getSeparator() + newName);
 					hasSucceeded = (returnedValue > 0);
 				}
+			}
+			finally {
+				_mutex.release();
+			}
+		}
 		return hasSucceeded;
 	}
 	
@@ -365,11 +397,18 @@ public class FTPService extends AbstractFileService implements IFileService, IFT
 	 */
 	public boolean rename(IProgressMonitor monitor, String remoteParent, String oldName, String newName, IHostFile oldFile) {
 		boolean hasSucceeded = false;
+		if (_mutex.waitForLock(monitor, _mutexTimeout)) {
+			try {
 				int returnedValue = getFTPClient().sendCommand("RNFR " + remoteParent + getSeparator() + oldName);
 				if (returnedValue > 0) {
 					returnedValue = getFTPClient().sendCommand("RNTO " + remoteParent + getSeparator() + newName);
 					hasSucceeded = (returnedValue > 0);
 				}
+			}
+			finally {
+				_mutex.release();
+			}
+		}
 		return hasSucceeded;
 	}
 
@@ -378,11 +417,18 @@ public class FTPService extends AbstractFileService implements IFileService, IFT
 	 */
 	public boolean move(IProgressMonitor monitor, String srcParent, String srcName, String tgtParent, String tgtName) {
 		boolean hasSucceeded = false;
+		if (_mutex.waitForLock(monitor, _mutexTimeout)) {
+			try {
 				int returnedValue = getFTPClient().sendCommand("RNFR " + srcParent + getSeparator() + srcName);
 				if (returnedValue > 0) {
 					returnedValue = getFTPClient().sendCommand("RNTO " + tgtParent + getSeparator() + tgtName);
 					hasSucceeded = (returnedValue > 0);
 				}
+			}
+			finally {
+				_mutex.release();
+			}
+		}
 		return hasSucceeded;
 	}
 
@@ -390,6 +436,8 @@ public class FTPService extends AbstractFileService implements IFileService, IFT
 	 * @see org.eclipse.rse.services.files.IFileService#createFolder(org.eclipse.core.runtime.IProgressMonitor, java.lang.String, java.lang.String)
 	 */
 	public IHostFile createFolder(IProgressMonitor monitor, String remoteParent, String folderName) 
+	{
+		if (_mutex.waitForLock(monitor, _mutexTimeout))
 		{
 			try
 			{
@@ -401,6 +449,15 @@ public class FTPService extends AbstractFileService implements IFileService, IFT
 			{			
 				e.printStackTrace();
 			}
+			finally
+			{
+				_mutex.release();
+			}
+		}
+		//TODO getFile() will acquire the lock again after having released it
+		//For optimization, Mutex should notice when the _same_ thread tries 
+		//to acquire a lock that it already holds again. To do so, the current
+		//locking thread would need to be remembered.
 		return getFile(monitor, remoteParent, folderName);
 	}
 
@@ -408,13 +465,19 @@ public class FTPService extends AbstractFileService implements IFileService, IFT
      * @see org.eclipse.rse.services.files.IFileService#createFile(org.eclipse.core.runtime.IProgressMonitor, java.lang.String, java.lang.String)
      */
     public IHostFile createFile(IProgressMonitor monitor, String remoteParent, String fileName) {
+		if (_mutex.waitForLock(monitor, _mutexTimeout)) {
 			try {
 				File tempFile = File.createTempFile("ftp", "temp");
 				tempFile.deleteOnExit();
 				upload(monitor, tempFile, remoteParent, fileName, true, null, null);
-		} catch (Exception e) {
+			}
+			catch (Exception e) {			
 				e.printStackTrace();
 			}
+			finally {
+				_mutex.release();
+			}
+		}
 		return getFile(monitor, remoteParent, fileName);
 	}