java - Watchservice in windows 7 does not work -
this code works fine in linux not in windows 7: file contents update have click on output file. trick?
i using windows 7 prof, netbeans ide 8.0 rc1 (build 201402242200) updated version netbeans 8.0 patch 1.1, jdk 1.8
package watchfilethreadmod; import java.io.filenotfoundexception; import java.io.ioexception; import java.io.randomaccessfile; import java.nio.file.files; import static java.nio.file.linkoption.nofollow_links; import java.nio.file.path; import java.nio.file.paths; import static java.nio.file.standardwatcheventkinds.*; import java.nio.file.watchevent; import java.nio.file.watchkey; import java.nio.file.watchservice; import java.util.arraylist; import java.util.list; import java.util.logging.level; import java.util.logging.logger; public class watchfilethreadmod { static class watchfile { string filename; long lastfilepos; randomaccessfile file; public watchfile(string _filename, randomaccessfile _file) { filename = _filename; lastfilepos = 0; file = _file; } } public static void shutdownlistener(thread thread) { thread thr = thread; if (thr != null) { thr.interrupt(); } } private static class mywatchqueuereader implements runnable { /** * watchservice passed in above */ private watchservice mywatcher; public arraylist<watchfile> threadfiletowatch; public string dirpath; public mywatchqueuereader(string _dirpath, watchservice mywatcher, arraylist<watchfile> _threadfiletowatch) { this.mywatcher = mywatcher; this.threadfiletowatch = _threadfiletowatch; this.dirpath = _dirpath; } private void openfile(watchfile obj) { try { system.out.println("open file "+obj.filename); obj.file = new randomaccessfile(dirpath + "/" + obj.filename, "r"); } catch (filenotfoundexception e) { obj.file = null; system.out.println("filename " + obj.filename + " non trovato"); } obj.lastfilepos = 0; } private void process(watchevent evt) { string thisline; arraylist<watchfile> auxlist = threadfiletowatch; (watchfile obj : auxlist) { if (obj.filename.equals(evt.context().tostring())) { if (obj.file == null) { openfile(obj); } try { obj.file.seek(obj.lastfilepos); } catch (ioexception e) { system.err.println("seek error: " + e); } try { thisline = obj.file.readline(); if ((thisline == null)&&(evt.kind() == entry_modify)) { system.out.printf("---> thisline == null received %s event file: %s\n", evt.kind(), evt.context()); obj.file.close(); system.out.println("close file "+obj.filename); openfile(obj); thisline = obj.file.readline(); } while (thisline != null) { // while loop begins here if (thisline.length() > 0) { if (thisline.substring(thisline.length() - 1).equals("*")) { obj.lastfilepos = obj.file.getfilepointer(); system.out.println(obj.filename + ": " + thisline); } } thisline = obj.file.readline(); } // end while } // end try catch (ioexception e) { system.err.println("error: " + e); } } } } /** * in order implement file watcher, loop forever ensuring * requesting take next item file watchers queue. */ @override public void run() { try { // first event before looping watchkey key = mywatcher.take(); while (key != null) { // have polled event, traverse , // receive states (watchevent event : key.pollevents()) { watchevent.kind eventtype = event.kind(); if (eventtype == overflow) { continue; } process(event); } key.reset(); key = mywatcher.take(); } } catch (interruptedexception e) { arraylist<watchfile> auxlist = threadfiletowatch; (watchfile obj : auxlist) { if (obj.file != null) { try { obj.file.close(); system.out.println("chiusura file " + obj.filename); } catch (ioexception ex) { system.out.println("errore in chiusura file"); logger.getlogger(watchfilethreadmod.class.getname()).log(level.severe, null, ex); } } } //e.printstacktrace(); } system.out.println("stopping thread"); } } public static void main(string[] args) throws exception { // directory want watch, using paths singleton class //path towatch = paths.get(directory_to_watch); arraylist<watchfile> filetowatch = new arraylist<>(); string filename; randomaccessfile file; filetowatch.add(new watchfile("eurusd.rlt", new randomaccessfile(args[0] + "/eurusd.rlt", "r"))); filename = "eurchf2.rlt"; try { file = new randomaccessfile(args[0] + "/" + filename, "r"); } catch (filenotfoundexception e) { file = null; system.out.println("filename " + filename + " non trovato"); } filetowatch.add(new watchfile(filename, file)); filetowatch = filetowatch; path towatch = paths.get(args[0]); if (towatch == null) { throw new unsupportedoperationexception("directory not found"); } // sanity check - check if path folder try { boolean isfolder = (boolean) files.getattribute(towatch, "basic:isdirectory", nofollow_links); if (!isfolder) { throw new illegalargumentexception("path: " + towatch + " not folder"); } } catch (ioexception ioe) { // folder not exists ioe.printstacktrace(); } // make new watch service can register interest in // directories , files with. watchservice mywatcher = towatch.getfilesystem().newwatchservice(); // start file watcher thread below mywatchqueuereader filewatcher = new mywatchqueuereader(args[0], mywatcher, filetowatch); thread processingthread = new thread(filewatcher, "filewatcher"); processingthread.start(); towatch.register(mywatcher, entry_create, entry_modify); } } edit: reduced code requested.
edit 2: file path
edit 3: metatrader code using write data
#property strict int file_handle; string inpfilename = _symbol + ".rlt"; // file name input string inpdirectoryname = "data"; // folder name int oninit() { resetlasterror(); file_handle = fileopen(inpdirectoryname + "//" + inpfilename, file_share_read|file_write|file_txt|file_ansi); if(file_handle == invalid_handle) { printformat("failed open %s file, error code = %d", inpfilename, getlasterror()); expertremove(); } return init_succeeded; } void ontick() { // file_handle = fileopen(inpdirectoryname + "//" + inpfilename, file_share_read|file_write|file_txt|file_ansi); // datetime), bid, volume // string s = fileread() string s = timetostr(timegmt()) + "|" + bid + "|" + volume[0]; filewritestring(file_handle, s + "|*\r\n"); fileflush(file_handle); //fileclose(file_handle); } void ondeinit(const int reason) { fileclose(file_handle); } edit 4: screencast better show issue: data updates when click on output file
first of all, premise : i'm answering question future users of watchservice, (like me) experience problem (i.e. on systems events signaled way after occur).
the problem implementation of feature in java native, platform-dependant (take @ https://docs.oracle.com/javase/7/docs/api/java/nio/file/watchservice.html, under section 'platform dependencies').
in particular, on windows 7 (and macosx afaict) implementation uses polling retrieve changes filesystem, can't rely on 'liveliness' of notifications watchservice. notifications signaled, there no guarantees on when happen. don't have rigorous solution problem, after lot of trial , error can describe works me :
first, when writing file registered (i.e. 'watched'), try flush content every time can , update 'last modified' attribute on file, e.g. :
try (filewriter writer = new filewriter(outputfile)) { writer.write("the string write"); outputfile.setlastmodified(system.currenttimemillis()); writer.flush(); } second, try 'trigger' refresh code (i know it's not code, in case, i'm happy works 99% of time)
thread.sleep(2000); // in case i've created file , i'm watching entry_create event on outputdir outputdir.list(); or (if watching entry_modify on particular file in outputdir)
thread.sleep(2000); outputfile.length(); in both cases, sleep call 'gives time' mechanism underlying watchservice trigger, though 2 seconds lot more needed.
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