From b35823b9126e83e990b085aec90145d2cf408d9f Mon Sep 17 00:00:00 2001
From: Corey Johnson & Nathan Sobo <cj+nathan@github.com>
Date: Wed, 25 Apr 2012 17:38:25 -0600
Subject: [PATCH] PathWatcher no longer opens multiple file descriptors for the
 same path and other :lipstick:

---
 Atom/src/PathWatcher.h |  1 +
 Atom/src/PathWatcher.m | 63 +++++++++++++++++++++++++++---------------
 2 files changed, 42 insertions(+), 22 deletions(-)

diff --git a/Atom/src/PathWatcher.h b/Atom/src/PathWatcher.h
index 0f51d6e8e..00fdd302c 100644
--- a/Atom/src/PathWatcher.h
+++ b/Atom/src/PathWatcher.h
@@ -4,6 +4,7 @@ typedef void (^WatchCallback)(NSArray *);
 
 @interface PathWatcher : NSObject {
   int _kq;
+  NSMutableDictionary *_fileDescriptorsByPath;
   NSMutableDictionary *_callbacksByFileDescriptor;
 }
 
diff --git a/Atom/src/PathWatcher.m b/Atom/src/PathWatcher.m
index fdcee6dd6..c4ee49c1b 100644
--- a/Atom/src/PathWatcher.m
+++ b/Atom/src/PathWatcher.m
@@ -6,6 +6,7 @@
 
 @interface PathWatcher ()
 - (void)watchPath:(NSString *)path callback:(WatchCallback)callback;
+- (void)watchFileDescriptor:(int)fd;
 @end
 
 @implementation PathWatcher
@@ -29,6 +30,7 @@
   self = [super init];
   
   _callbacksByFileDescriptor = [[NSMutableDictionary alloc] init];
+  _fileDescriptorsByPath = [[NSMutableDictionary alloc] init];
   _kq = kqueue();
   
   if (_kq == -1) {
@@ -39,33 +41,47 @@
   return self;
 }
 
-- (void)watchPath:(NSString *)path callback:(WatchCallback)callback {
-  struct timespec timeout = { 0, 0 };
-  struct kevent event;
-  int fd = open([path fileSystemRepresentation], O_EVTONLY, 0);
+- (void)watchPath:(NSString *)path callback:(WatchCallback)callback {  
+  NSLog(@"Watching path %@", path);
   
-  if (fd >= 0) {
-    int filter = EVFILT_VNODE;
-    int flags = EV_ADD | EV_ENABLE | EV_CLEAR;
-    int filterFlags = NOTE_ATTRIB | NOTE_WRITE | NOTE_EXTEND | NOTE_RENAME | NOTE_DELETE;
-    
-    EV_SET(&event, fd, filter, flags, filterFlags, 0, (void *)path);    
-    
-    @synchronized(self) {
-      NSNumber *fdNumber = [NSNumber numberWithInt:fd];
-      NSMutableArray *callbacks = [_callbacksByFileDescriptor objectForKey:fdNumber];
-      if (!callbacks) {
-        callbacks = [NSMutableArray array];
-        [_callbacksByFileDescriptor setObject:callbacks forKey:fdNumber];
-      }
-      [callbacks addObject:callback];
-      
-      kevent(_kq, &event, 1, NULL, 0, &timeout);
+  path = [path stringByStandardizingPath];
+  
+  @synchronized(self) {
+    NSNumber *fdNumber = [_fileDescriptorsByPath objectForKey:path];    
+    if (!fdNumber) {
+      int fd = open([path fileSystemRepresentation], O_EVTONLY, 0);      
+      if (fd < 0) return; // TODO: Decide what to do here
+      [self watchFileDescriptor:fd];
+
+      fdNumber = [NSNumber numberWithInt:fd];
+      [_fileDescriptorsByPath setObject:fdNumber forKey:path];
     }
+    
+    NSMutableArray *callbacks = [_callbacksByFileDescriptor objectForKey:fdNumber];
+    if (!callbacks) {      
+      callbacks = [NSMutableArray array];
+      [_callbacksByFileDescriptor setObject:callbacks forKey:fdNumber];      
+    }
+    
+    [callbacks addObject:callback];
   }
 }
 
-- (void)watch {
+- (void)watchFileDescriptor:(int)fd {
+  NSLog(@"Watching fd %d", fd);
+  
+  struct timespec timeout = { 0, 0 };
+  struct kevent event;
+  int filter = EVFILT_VNODE;
+  int flags = EV_ADD | EV_ENABLE | EV_CLEAR;
+  int filterFlags = NOTE_WRITE;
+  EV_SET(&event, fd, filter, flags, filterFlags, 0, 0);
+  kevent(_kq, &event, 1, NULL, 0, &timeout);
+}
+
+- (void)watch {  
+  NSLog(@"kicking off watch");
+  
   @autoreleasepool {
     struct kevent event;    
     struct timespec timeout = { 5, 0 }; // 5 seconds timeout.
@@ -82,12 +98,15 @@
 
       NSMutableArray *eventFlags = [NSMutableArray array];
 
+      NSLog(@"flags are: %d, fd is: %d", event.fflags, (int)event.ident);
+      
       if (event.fflags & NOTE_WRITE) {
         [eventFlags addObject:@"modified"];
       }
       
       @synchronized(self) {
         NSNumber *fdNumber = [NSNumber numberWithInt:event.ident];
+        
         for (WatchCallback callback in [_callbacksByFileDescriptor objectForKey:fdNumber]) {
           dispatch_async(dispatch_get_main_queue(), ^{
             callback(eventFlags);