fs: make fs.watchFile() work on windows

lib/fs.js

@@ -876,7 +876,13 @@ function StatWatcher() {
   var self = this;
   this._handle = new binding.StatWatcher();
 
-  this._handle.onchange = function(current, previous) {
+  // uv_fs_poll is a little more powerful than ev_stat but we curb it for
+  // the sake of backwards compatibility
+  var oldStatus = -1;
+
+  this._handle.onchange = function(current, previous, newStatus) {
+    if (oldStatus == -1 && newStatus == -1) return;
+    oldStatus = newStatus;
     self.emit('change', current, previous);
   };
 
@@ -905,10 +911,6 @@ function inStatWatchers(filename) {
 
 
 fs.watchFile = function(filename) {
-  if (isWindows) {
-    throw new Error('use fs.watch api instead');
-  }
-
   var stat;
   var options;
   var listener;

node.gyp

@@ -82,6 +82,7 @@
         'src/node_main.cc',
         'src/node_os.cc',
         'src/node_script.cc',
+        'src/node_stat_watcher.cc',
         'src/node_string.cc',
         'src/node_zlib.cc',
         'src/pipe_wrap.cc',
@@ -208,7 +209,6 @@
           'defines': [ '__POSIX__' ],
           'sources': [
             'src/node_signal_watcher.cc',
-            'src/node_stat_watcher.cc',
             'src/node_io_watcher.cc',
           ]
         }],

src/node.cc

@@ -69,7 +69,6 @@ typedef int mode_t;
 #include "node_http_parser.h"
 #ifdef __POSIX__
 # include "node_signal_watcher.h"
-# include "node_stat_watcher.h"
 #endif
 #include "node_constants.h"
 #include "node_javascript.h"

src/node_file.cc

@@ -22,9 +22,7 @@
 #include "node.h"
 #include "node_file.h"
 #include "node_buffer.h"
-#ifdef __POSIX__
-# include "node_stat_watcher.h"
-#endif
+#include "node_stat_watcher.h"
 #include "req_wrap.h"
 
 #include <fcntl.h>
@@ -984,9 +982,7 @@ void InitFs(Handle<Object> target) {
 
   oncomplete_sym = NODE_PSYMBOL("oncomplete");
 
-#ifdef __POSIX__
   StatWatcher::Initialize(target);
-#endif
 }
 
 }  // end namespace node

src/node_stat_watcher.cc

@@ -25,6 +25,11 @@
 #include <string.h>
 #include <stdlib.h>
 
+// Poll interval in milliseconds. 5007 is what libev used to use. It's a little
+// on the slow side but let's stick with it for now, keep behavioral changes to
+// a minimum.
+#define DEFAULT_POLL_INTERVAL 5007
+
 namespace node {
 
 using namespace v8;
@@ -33,6 +38,7 @@ Persistent<FunctionTemplate> StatWatcher::constructor_template;
 static Persistent<String> onchange_sym;
 static Persistent<String> onstop_sym;
 
+
 void StatWatcher::Initialize(Handle<Object> target) {
   HandleScope scope;
 
@@ -48,18 +54,24 @@ void StatWatcher::Initialize(Handle<Object> target) {
 }
 
 
-void StatWatcher::Callback(EV_P_ ev_stat *watcher, int revents) {
-  assert(revents == EV_STAT);
-  StatWatcher *handler = static_cast<StatWatcher*>(watcher->data);
-  assert(watcher == &handler->watcher_);
+void StatWatcher::Callback(uv_fs_poll_t* handle,
+                           int status,
+                           const uv_statbuf_t* prev,
+                           const uv_statbuf_t* curr) {
+  StatWatcher* wrap = container_of(handle, StatWatcher, watcher_);
+  assert(handle == &wrap->watcher_);
   HandleScope scope;
-  Local<Value> argv[2];
-  argv[0] = BuildStatsObject(&watcher->attr);
-  argv[1] = BuildStatsObject(&watcher->prev);
+  Local<Value> argv[3];
+  argv[0] = BuildStatsObject(curr);
+  argv[1] = BuildStatsObject(prev);
+  argv[2] = Integer::New(status);
+  if (status == -1) {
+    SetErrno(uv_last_error(wrap->watcher_.loop));
+  }
   if (onchange_sym.IsEmpty()) {
     onchange_sym = NODE_PSYMBOL("onchange");
   }
-  MakeCallback(handler->handle_, onchange_sym, ARRAY_SIZE(argv), argv);
+  MakeCallback(wrap->handle_, onchange_sym, ARRAY_SIZE(argv), argv);
 }
 
 
@@ -69,7 +81,7 @@ Handle<Value> StatWatcher::New(const Arguments& args) {
   }
 
   HandleScope scope;
-  StatWatcher *s = new StatWatcher();
+  StatWatcher* s = new StatWatcher();
   s->Wrap(args.Holder());
   return args.This();
 }
@@ -82,27 +94,23 @@ Handle<Value> StatWatcher::Start(const Arguments& args) {
     return ThrowException(Exception::TypeError(String::New("Bad arguments")));
   }
 
-  StatWatcher *handler = ObjectWrap::Unwrap<StatWatcher>(args.Holder());
+  StatWatcher* wrap = ObjectWrap::Unwrap<StatWatcher>(args.Holder());
   String::Utf8Value path(args[0]);
 
-  assert(handler->path_ == NULL);
-  handler->path_ = strdup(*path);
-
-  ev_tstamp interval = 0.;
-  if (args[2]->IsInt32()) {
-    interval = NODE_V8_UNIXTIME(args[2]);
+  uint32_t interval = DEFAULT_POLL_INTERVAL;
+  if (args[2]->IsUint32()) {
+    interval = args[2]->Uint32Value();
   }
 
-  ev_stat_set(&handler->watcher_, handler->path_, interval);
-  ev_stat_start(EV_DEFAULT_UC_ &handler->watcher_);
+  uv_fs_poll_start(&wrap->watcher_, Callback, *path, interval);
 
-  handler->persistent_ = args[1]->IsTrue();
+  wrap->persistent_ = args[1]->IsTrue();
 
-  if (!handler->persistent_) {
-    ev_unref(EV_DEFAULT_UC);
+  if (!wrap->persistent_) {
+    uv_unref(reinterpret_cast<uv_handle_t*>(&wrap->watcher_));
   }
 
-  handler->Ref();
+  wrap->Ref();
 
   return Undefined();
 }
@@ -110,24 +118,20 @@ Handle<Value> StatWatcher::Start(const Arguments& args) {
 
 Handle<Value> StatWatcher::Stop(const Arguments& args) {
   HandleScope scope;
-  StatWatcher *handler = ObjectWrap::Unwrap<StatWatcher>(args.Holder());
+  StatWatcher* wrap = ObjectWrap::Unwrap<StatWatcher>(args.Holder());
   if (onstop_sym.IsEmpty()) {
     onstop_sym = NODE_PSYMBOL("onstop");
   }
-  MakeCallback(handler->handle_, onstop_sym, 0, NULL);
-  handler->Stop();
+  MakeCallback(wrap->handle_, onstop_sym, 0, NULL);
+  wrap->Stop();
   return Undefined();
 }
 
 
 void StatWatcher::Stop () {
-  if (watcher_.active) {
-    if (!persistent_) ev_ref(EV_DEFAULT_UC);
-    ev_stat_stop(EV_DEFAULT_UC_ &watcher_);
-    free(path_);
-    path_ = NULL;
-    Unref();
-  }
+  if (!uv_is_active(reinterpret_cast<uv_handle_t*>(&watcher_))) return;
+  uv_fs_poll_stop(&watcher_);
+  Unref();
 }
 
 

src/node_stat_watcher.h

@@ -23,7 +23,7 @@
 #define NODE_STAT_WATCHER_H_
 
 #include "node.h"
-#include "uv-private/ev.h"
+#include "uv.h"
 
 namespace node {
 
@@ -36,14 +36,11 @@ class StatWatcher : ObjectWrap {
 
   StatWatcher() : ObjectWrap() {
     persistent_ = false;
-    path_ = NULL;
-    ev_init(&watcher_, StatWatcher::Callback);
-    watcher_.data = this;
+    uv_fs_poll_init(uv_default_loop(), &watcher_);
   }
 
   ~StatWatcher() {
     Stop();
-    assert(path_ == NULL);
   }
 
   static v8::Handle<v8::Value> New(const v8::Arguments& args);
@@ -51,13 +48,15 @@ class StatWatcher : ObjectWrap {
   static v8::Handle<v8::Value> Stop(const v8::Arguments& args);
 
  private:
-  static void Callback(EV_P_ ev_stat *watcher, int revents);
+  static void Callback(uv_fs_poll_t* handle,
+                       int status,
+                       const uv_statbuf_t* prev,
+                       const uv_statbuf_t* curr);
 
   void Stop();
 
-  ev_stat watcher_;
+  uv_fs_poll_t watcher_;
   bool persistent_;
-  char *path_;
 };
 
 }  // namespace node

test/pummel/test-fs-watch-file.js

@@ -19,12 +19,6 @@
 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 // USE OR OTHER DEALINGS IN THE SOFTWARE.
 
-// fs.watchFile is not available on Windows
-if (process.platform === 'win32') {
-  process.exit(0);
-}
-
-
 var common = require('../common');
 var assert = require('assert');
 var path = require('path');

test/pummel/test-watch-file.js

@@ -19,11 +19,6 @@
 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 // USE OR OTHER DEALINGS IN THE SOFTWARE.
 
-// fs.watchFile is not available on Windows
-if (process.platform === 'win32') {
-  process.exit(0);
-}
-
 var common = require('../common');
 var assert = require('assert');