Looking at this Java example, about the key state, Oracle says:
Ready indicates that the key is ready to accept events. When first created, a key is in the ready state.
Signaled indicates that one or more events are queued. Once the key has been signaled, it is no longer in the ready state until the reset method is invoked.
In WatchKey javadoc:
Events detected while the key is in the signaled state are queued but do not cause the key to be re-queued for retrieval from the watch service
The documentation doesn't say what happens to events generated between key.pollEvents() and key.reset()? It is assumed that events will be buffered until the key is reset, and the key will be signaled immediately after the reset. This seems supported by the test below.
Could you point me to some official documentation? or to a discussion about the lack of documentation?
Path dir = Paths.get("test");
WatchService watcher = dir.getFileSystem().newWatchService();
dir.register(watcher, CREATE, DELETE, MODIFY);
while (true) {
WatchKey key = watcher.take();
System.out.println("polling.");
for (WatchEvent<?> event : key.pollEvents()) {
... (details removed) ...
System.out.format(" Event %s in [%s] for entry [%s]%n",
event.kind().name(), registeredDir, childPath);
try { Thread.sleep(20000); } catch (InterruptedException e) { ; }
}
System.out.println("resetting.");
key.reset();
}
... within the 20s allowed by the sleep(), I did:
- Create a file,
- Edit it, save it,
- Rename it,
- Edit it, save it,
- Delete it
Output:
polling.
Event ENTRY_CREATE in [test] for entry [test\file1.txt]
resetting.
polling.
Event ENTRY_MODIFY in [test] for entry [test\file1.txt]
Event ENTRY_DELETE in [test] for entry [test\file1.txt]
Event ENTRY_CREATE in [test] for entry [test\file2.txt]
Event ENTRY_MODIFY in [test] for entry [test\file2.txt]
Event ENTRY_DELETE in [test] for entry [test\file2.txt]
resetting.
Tks.
