-/**
- *
- */
-package uk.ac.vamsas.client.simpleclient;
-
-import java.io.File;
-
-
-/**
- * Watches a particular file for its creation, deletion, or
- * modification. The watcher is thread safe and different
- * instances watching the state of a particular file carry
- * their own state record for the file.
- */
-public class FileWatcher {
-
- private File subject = null;
-
- private long lastStat[];
- boolean waslocked=false;
- boolean exists = false;
- /**
- * transient lock on subject - can be passed back to calling class
- * to preserve new state of file for immediate reading.
- */
- private Lock subjectLock = null;
- /**
- * clear local locks on subject.
- *
- */
- private void clearLock() {
- if (subjectLock!=null)
- subjectLock.release();
- subjectLock=null;
- }
- /**
- *
- * @return true if subject exists and is locked by another process.
- */
- private boolean checkLock() {
- if (subject!=null && subject.exists()) {
- if (subjectLock!=null) {
- subjectLock.release();
- }
- subjectLock = LockFactory.tryLock(subject);
- if (subjectLock.isLocked()) {
- return false;
- }
- clearLock();
- return true;
- }
- return false;
- }
-
- private long[] getStat(File subject) {
- return new long[] { subject.lastModified(), subject.length() };
- }
- private boolean compStat(long[] stat, long[] newstat) {
- if (stat[0]!=newstat[0] || stat[1]!=newstat[1])
- return false;
- return true;
- }
- /**
- * Detect changes in file state and release of any
- * lock in place during change.
- * @return true if file state has changed. Leaves lock in subjectLock (ready to be passed to caller)
- */
- private boolean check() {
- if (subject != null) {
- if (!subject.exists()) {
- if (exists) {
- if (!waslocked) {
- // !checkLock()) {
-
- exists = false;
- // waslocked=false;
- return true;
- }
- }
- // locked - state change registered after lock is released
- return false;
- } else {
- long[] newStat = getStat(subject); // subject.lastModified();
- if (!checkLock()) {
- // file is free to access, return state change
- if (!exists || !compStat(lastStat, newStat)) {
- waslocked=false;
- exists=true;
- lastStat=newStat;
- return true;
- }
- // no change
- return false;
- } else {
- waslocked=true;
- return false;
- }
- }
- }
- return false;
- }
- /**
- * updates internal record of file state when caller has intentionally
- * modified subject. (ignores locked-state of subject)
- */
- public void setState() {
- if (subject!=null) {
- if (exists = subject.exists()) {
- lastStat = getStat(subject);
- waslocked = false;
- }
- }
- }
-
- /**
- * Make a watcher for a particular file. If the file doesn't exist, the
- * watcher will watch for its creation (and indicate a change of state)
- * For locked files, the removal of a lock constitutes a change of
- * state if the file was modified.
- *
- * @param subject
- */
-
- public FileWatcher(File subject) {
- this.subject = subject;
- setState();
- }
- /**
- * Test for change in file state. Only indicates a change
- * after any lock on a file has been released.
- * @return true if file has been modified.
- */
- public boolean hasChanged() {
- boolean res = check();
- clearLock();
- return res;
- }
- /**
- * passes lock back to caller if hasChanged returned true.
- * @return
- */
- public Lock getChangedState() {
- boolean res = check();
- if (res)
- return subjectLock;
- else {
- clearLock();
- return null;
- }
- }
- /**
- * safely? getting current state of the watched file
- * @return
- */
- public long[] getCurrentState() {
- return getStat(subject);
- }
- /**
- * safely compare an externally recorded state with the current state
- * for significant modifications.
- * @param a
- * @param b
- * @return
- */
- public boolean diffState(long[] a, long[] b) {
- return compStat(a,b);
- }
- /**
- * @return the subject
- */
- public File getSubject() {
- return subject;
- }
-}
+/*\r
+ * This file is part of the Vamsas Client version 0.1. \r
+ * Copyright 2009 by Jim Procter, Iain Milne, Pierre Marguerite, \r
+ * Andrew Waterhouse and Dominik Lindner.\r
+ * \r
+ * Earlier versions have also been incorporated into Jalview version 2.4 \r
+ * since 2008, and TOPALi version 2 since 2007.\r
+ * \r
+ * The Vamsas Client is free software: you can redistribute it and/or modify\r
+ * it under the terms of the GNU Lesser General Public License as published by\r
+ * the Free Software Foundation, either version 3 of the License, or\r
+ * (at your option) any later version.\r
+ * \r
+ * The Vamsas Client is distributed in the hope that it will be useful,\r
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of\r
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the\r
+ * GNU Lesser General Public License for more details.\r
+ * \r
+ * You should have received a copy of the GNU Lesser General Public License\r
+ * along with the Vamsas Client. If not, see <http://www.gnu.org/licenses/>.\r
+ */\r
+package uk.ac.vamsas.client.simpleclient;\r
+\r
+import java.io.File;\r
+\r
+/**\r
+ * Watches a particular file for its creation, deletion, or modification. The\r
+ * watcher is thread safe and different instances watching the state of a\r
+ * particular file carry their own state record for the file.\r
+ */\r
+public class FileWatcher {\r
+\r
+ private File subject = null;\r
+\r
+ private long lastStat[];\r
+\r
+ boolean waslocked = false;\r
+\r
+ boolean exists = false;\r
+\r
+ /**\r
+ * transient lock on subject - can be passed back to calling class to preserve\r
+ * new state of file for immediate reading.\r
+ */\r
+ private Lock subjectLock = null;\r
+\r
+ /**\r
+ * clear local locks on subject.\r
+ * \r
+ */\r
+ private void clearLock() {\r
+ if (subjectLock != null)\r
+ subjectLock.release();\r
+ subjectLock = null;\r
+ }\r
+\r
+ /**\r
+ * \r
+ * @return true if subject exists and is locked by another process.\r
+ */\r
+ private boolean checkLock() {\r
+ if (subject != null && subject.exists()) {\r
+ if (subjectLock != null) {\r
+ subjectLock.release();\r
+ }\r
+ subjectLock = LockFactory.tryLock(subject);\r
+ if (subjectLock.isLocked()) {\r
+ return false;\r
+ }\r
+ clearLock();\r
+ return true;\r
+ }\r
+ return false;\r
+ }\r
+\r
+ private long[] getStat(File subject) {\r
+ return new long[] { subject.lastModified(), subject.length() };\r
+ }\r
+\r
+ private boolean compStat(long[] stat, long[] newstat) {\r
+ if (stat[0] != newstat[0] || stat[1] != newstat[1])\r
+ return false;\r
+ return true;\r
+ }\r
+\r
+ /**\r
+ * Detect changes in file state and release of any lock in place during\r
+ * change.\r
+ * \r
+ * @return true if file state has changed. Leaves lock in subjectLock (ready\r
+ * to be passed to caller)\r
+ */\r
+ private boolean check() {\r
+ if (subject != null) {\r
+ if (!subject.exists()) {\r
+ if (exists) {\r
+ if (!waslocked) {\r
+ // !checkLock()) {\r
+\r
+ exists = false;\r
+ // waslocked=false;\r
+ return true;\r
+ }\r
+ }\r
+ // locked - state change registered after lock is released\r
+ return false;\r
+ } else {\r
+ long[] newStat = getStat(subject); // subject.lastModified();\r
+ if (!checkLock()) {\r
+ // file is free to access, return state change\r
+ if (!exists || !compStat(lastStat, newStat)) {\r
+ waslocked = false;\r
+ exists = true;\r
+ lastStat = newStat;\r
+ return true;\r
+ }\r
+ // no change\r
+ return false;\r
+ } else {\r
+ waslocked = true;\r
+ return false;\r
+ }\r
+ }\r
+ }\r
+ return false;\r
+ }\r
+\r
+ /**\r
+ * updates internal record of file state when caller has intentionally\r
+ * modified subject. (ignores locked-state of subject)\r
+ */\r
+ public void setState() {\r
+ if (subject != null) {\r
+ if (exists = subject.exists()) {\r
+ lastStat = getStat(subject);\r
+ waslocked = false;\r
+ }\r
+ }\r
+ }\r
+\r
+ /**\r
+ * Make a watcher for a particular file. If the file doesn't exist, the\r
+ * watcher will watch for its creation (and indicate a change of state) For\r
+ * locked files, the removal of a lock constitutes a change of state if the\r
+ * file was modified.\r
+ * \r
+ * @param subject\r
+ */\r
+\r
+ public FileWatcher(File subject) {\r
+ this.subject = subject;\r
+ setState();\r
+ }\r
+\r
+ /**\r
+ * Test for change in file state. Only indicates a change after any lock on a\r
+ * file has been released.\r
+ * \r
+ * @return true if file has been modified.\r
+ */\r
+ public boolean hasChanged() {\r
+ boolean res = check();\r
+ clearLock();\r
+ return res;\r
+ }\r
+\r
+ /**\r
+ * passes lock back to caller if hasChanged returned true.\r
+ * \r
+ * @return\r
+ */\r
+ public Lock getChangedState() {\r
+ boolean res = check();\r
+ if (res)\r
+ return subjectLock;\r
+ else {\r
+ clearLock();\r
+ return null;\r
+ }\r
+ }\r
+\r
+ /**\r
+ * safely? getting current state of the watched file\r
+ * \r
+ * @return\r
+ */\r
+ public long[] getCurrentState() {\r
+ return getStat(subject);\r
+ }\r
+\r
+ /**\r
+ * safely compare an externally recorded state with the current state for\r
+ * significant modifications.\r
+ * \r
+ * @param a\r
+ * @param b\r
+ * @return\r
+ */\r
+ public boolean diffState(long[] a, long[] b) {\r
+ return compStat(a, b);\r
+ }\r
+\r
+ /**\r
+ * @return the subject\r
+ */\r
+ public File getSubject() {\r
+ return subject;\r
+ }\r
+}\r
git://source.jalview.org / vamsas.git / blobdiff