file system event watching fixes

base/exports.jl

@@ -1077,6 +1077,7 @@ export
     truncate,
     UV_READABLE,
     UV_WRITABLE,
+    watch_file,
     WindowsRawSocket,
     write,
     writecsv,

base/poll.jl

@@ -24,8 +24,12 @@ function close(t::FileMonitor)
     end
 end
 
+# Polling event flags
 const UV_READABLE = 1
 const UV_WRITABLE = 2
+# Non-polling event flags
+const UV_RENAME = 1
+const UV_CHANGE = 2
 
 convert(::Type{Int32},fd::RawFD) = fd.fd 
 
@@ -237,14 +241,14 @@ function stop_watching(t::PollingFileWatcher)
 end
 
 function _uv_hook_fseventscb(t::FileMonitor,filename::Ptr,events::Int32,status::Int32)
+    fname = bytestring(convert(Ptr{Uint8},filename)) # seems broken at the moment - got NULL
     if isa(t.cb,Function)
-        # bytestring(convert(Ptr{Uint8},filename)) - seems broken at the moment - got NULL
-        t.cb(status, events, status)
-        if status == -1
-            notify_error(t.notify,UVError("FileMonitor",status))
-        else
-            notify(t.notify,events)
-        end
+        t.cb(fname, events, status)
+    end
+    if status < 0
+        notify_error(t.notify,(UVError("FileMonitor",status), fname, events))
+    else
+        notify(t.notify,(status, fname, events))
     end
 end
 
@@ -282,6 +286,7 @@ function poll_file(s, interval_seconds::Real, seconds::Real)
     wait(wt) == :poll
 end
 
+watch_file(s; poll=false) = watch_file(false, s, poll=poll)
 function watch_file(cb, s; poll=false)
     if poll
         pfw = PollingFileWatcher(cb,s)

doc/stdlib/base.rst

@@ -1429,6 +1429,10 @@ Network I/O
    Create a TcpServer on any port, using hint as a starting point. Returns a tuple of the actual port that the server
    was created on and the server itself. 
 
+.. function:: watch_file(cb=false, s; poll=false)
+
+   Watch file or directory ``s`` and run callback ``cb`` when ``s`` is modified. The ``poll`` parameter specifies whether to use file system event monitoring or polling. The callback function ``cb`` should accept 3 arguments: ``(filename, events, status)`` where ``filename`` is the name of file that was modified, ``events`` can be ``UV_CHANGE`` or ``UV_RENAME`` when using file system event monitoring, or ``UV_READABLE`` or ``UV_WRITABLE`` when using polling, and ``status`` is always 0. Pass ``false`` for ``cb`` to not use a callback function.
+
 .. function:: poll_fd(fd, seconds::Real; readable=false, writable=false)
 
    Poll a file descriptor fd for changes in the read or write availability and with a timeout given by the second argument.

test/file.jl

@@ -90,13 +90,27 @@ function test_monitor(slval)
     close(fm)
 end
 
+function test_monitor_wait(tval)
+    fm = watch_file(file)
+    @async begin
+        sleep(tval/10_000)
+        f = open(file,"a")
+        write(f,"Hello World\n")
+        close(f)
+    end
+    fname, events = wait(fm)
+    @test fname == basename(file)
+    @test events == Base.UV_CHANGE
+end
+
 # Commented out the tests below due to issues 3015, 3016 and 3020 
 test_timeout(0.1)
 test_timeout(1)
 test_touch(0.1)
 test_touch(1)
 test_monitor(1)
 test_monitor(0.1)
+test_monitor_wait(0.1)
 
 ##########
 #  mmap  #