Add FileSystemWatcher class to dart:io.

runtime/bin/file_system_watcher_macos.cc

Index: runtime/bin/file_system_watcher_macos.cc
diff --git a/runtime/bin/file_system_watcher_macos.cc b/runtime/bin/file_system_watcher_macos.cc
new file mode 100644
index 0000000000000000000000000000000000000000..f1eec2e5018981c0f71a0d3b02947cbafe261fda
--- /dev/null
+++ b/runtime/bin/file_system_watcher_macos.cc
@@ -0,0 +1,244 @@
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include "platform/globals.h"
+#if defined(TARGET_OS_MACOS)
+
+#include "bin/file_system_watcher.h"
+
+#include <errno.h>  // NOLINT
+#include <fcntl.h>  // NOLINT
+#include <unistd.h>  // NOLINT
+#include <CoreServices/CoreServices.h>  // NOLINT
+
+#include "bin/eventhandler.h"
+#include "bin/fdutils.h"
+#include "bin/socket.h"
+#include "bin/thread.h"
+
+
+namespace dart {
+namespace bin {
+
+static Mutex* watcher_mutex = new Mutex();
+static Monitor* watcher_monitor = new Monitor();
+
+class FSEventsWatcher;
+static FSEventsWatcher* watcher = NULL;
+
+union FSEvent {
+  struct {
+    uint32_t flags;
+    char path[PATH_MAX];
+  } data;
+  uint8_t bytes[PATH_MAX + 4];
+};
+
+class FSEventsWatcher {

[Søren Gjesse, 2013/08/23 07:47:45]

Please rename this to FileSystemEventsWatcher. The name starting with FS is
confusing in code with Mac OS API names also starting with FS.

+ public:
+  class Node {
+   public:
+    Node(FSEventStreamRef ref, int fds[2])
+      : ref_(ref) {
+      fds_[0] = fds[0];
+      fds_[1] = fds[1];
+    }
+    ~Node() {
+      close(fds_[1]);
+      FSEventStreamInvalidate(ref_);
+      FSEventStreamRelease(ref_);
+    }
+
+    void Start() {
+      FSEventStreamStart(ref_);
+    }
+
+    void Stop() {
+      FSEventStreamStop(ref_);
+    }
+
+    int read_fd() const { return fds_[0]; }
+
+   private:
+    FSEventStreamRef ref_;
+    int fds_[2];

[Søren Gjesse, 2013/08/23 07:47:45]

Use two named members

read_fd_
write_fd_

+  };
+
+  FSEventsWatcher() : run_loop_(0), users_(0) {
+    Thread::Start(Run, reinterpret_cast<uword>(this));
+  }
+
+  static void TimerCallback(CFRunLoopTimerRef timer, void* context) {
+    // Dummy callback to keep RunLoop alive.
+  }
+
+  static void Run(uword arg) {
+    FSEventsWatcher* watcher = reinterpret_cast<FSEventsWatcher*>(arg);
+    watcher->run_loop_ = CFRunLoopGetCurrent();
+
+    // Notify, as the run-loop is set.
+    watcher_monitor->Notify();
+
+    CFRunLoopTimerRef timer = CFRunLoopTimerCreate(
+        NULL,
+        CFAbsoluteTimeGetCurrent() + 1,
+        1,
+        0,
+        0,
+        TimerCallback,
+        NULL);
+
+    CFRunLoopAddTimer(watcher->run_loop_, timer, kCFRunLoopCommonModes);
+
+    CFRunLoopRun();
+  }
+
+  void Increment() {
+    users_++;
+  }
+
+  void Decrement() {
+    ASSERT(users_ > 0);
+    users_--;
+    if (users_ == 0) {
+      CFRunLoopStop(run_loop_);
+      watcher = NULL;
+      delete this;
+    }
+  }
+
+  Node* AddPath(const char* path, int events) {
+    int fds[2];
+    VOID_TEMP_FAILURE_RETRY(pipe(fds));
+    Socket::SetNonBlocking(fds[0]);
+    Socket::SetBlocking(fds[1]);

[Søren Gjesse, 2013/08/23 07:47:45]

SetCloseOnExec on both fds?

+
+    CFStringRef path_ref = CFStringCreateWithCString(
+        NULL, path, kCFStringEncodingUTF8);
+
+    FSEventStreamContext context;
+    context.version = 0;
+    context.info = reinterpret_cast<void*>(fds[1]);
+    context.retain = NULL;
+    context.release = NULL;
+    context.copyDescription = NULL;
+    FSEventStreamRef ref = FSEventStreamCreate(
+        NULL,
+        Callback,
+        &context,
+        CFArrayCreate(NULL, reinterpret_cast<const void**>(&path_ref), 1, NULL),
+        kFSEventStreamEventIdSinceNow,
+        0.10,
+        kFSEventStreamCreateFlagFileEvents);

[Søren Gjesse, 2013/08/23 07:47:45]

Two blank lines.

+
+
+    FSEventStreamScheduleWithRunLoop(
+        ref,
+        run_loop_,
+        kCFRunLoopDefaultMode);
+
+    return new Node(ref, fds);
+  }
+
+ private:
+  static void Callback(ConstFSEventStreamRef ref,
+                       void* client,
+                       size_t num_events,
+                       void* event_paths,
+                       const FSEventStreamEventFlags event_flags[],
+                       const FSEventStreamEventId event_ids[]) {
+    int fd = reinterpret_cast<int>(client);
+    for (size_t i = 0; i < num_events; i++) {
+      char *path = reinterpret_cast<char**>(event_paths)[i];
+      FSEvent event;
+      event.data.flags = event_flags[i];
+      memmove(event.data.path, path, strlen(path) + 1);
+      write(fd, event.bytes, sizeof(event));
+    }
+  }
+
+  CFRunLoopRef run_loop_;
+  int users_;
+};
+
+intptr_t FileSystemWatcher::Init() {
+  MutexLocker lock(watcher_mutex);
+  if (watcher == NULL) {
+    watcher = new FSEventsWatcher();
+    watcher_monitor->Enter();
+    watcher_monitor->Wait(Monitor::kNoTimeout);
+    watcher_monitor->Exit();
+  }
+  watcher->Increment();
+  return 0;
+}
+
+
+void FileSystemWatcher::Stop(intptr_t id) {
+  MutexLocker lock(watcher_mutex);
+  watcher->Decrement();
+}
+
+
+intptr_t FileSystemWatcher::GetSocketId(intptr_t id, intptr_t path_id) {
+  if (path_id == -1) return -1;
+  FSEventsWatcher::Node* node =
+      reinterpret_cast<FSEventsWatcher::Node*>(path_id);
+  return node->read_fd();
+}
+
+
+intptr_t FileSystemWatcher::AddPath(intptr_t id, const char* path, int events) {
+  FSEventsWatcher::Node* node = watcher->AddPath(path, events);
+  node->Start();
+  return reinterpret_cast<intptr_t>(node);
+}
+
+
+bool FileSystemWatcher::RemovePath(intptr_t id, intptr_t path_id) {
+  FSEventsWatcher::Node* node =
+      reinterpret_cast<FSEventsWatcher::Node*>(path_id);
+  node->Stop();
+  delete node;
+  return true;
+}
+
+
+intptr_t FileSystemWatcher::ReadEvents(intptr_t id,
+                                       intptr_t path_id,
+                                       Event** events) {
+  intptr_t fd = GetSocketId(id, path_id);
+  intptr_t avail = FDUtils::AvailableBytes(fd);
+  int count = avail / sizeof(FSEvent);
+  if (count <= 0) return 0;
+  *events = new Event[count];
+  FSEvent e;
+  for (int i = 0; i < count; i++) {
+    intptr_t bytes = TEMP_FAILURE_RETRY(read(fd, e.bytes, sizeof(e)));
+    if (bytes < 0) return -1;
+    Event* event = *events + i;
+    event->event = 0;
+    event->path_id = id;
+    event->link = 1;
+    int flags = e.data.flags;
+    if (flags & kFSEventStreamEventFlagItemModified) {
+      event->event |= kModifyContent;
+    }
+    if (flags & kFSEventStreamEventFlagItemRenamed) event->event |= kMove;
+    if (flags & kFSEventStreamEventFlagItemXattrMod) {
+      event->event |= kModefyAttribute;
+    }
+    if (flags & kFSEventStreamEventFlagItemCreated) event->event |= kCreate;
+    if (flags & kFSEventStreamEventFlagItemRemoved) event->event |= kDelete;
+    event->filename = strdup(e.data.path);
+  }
+  return count;
+}
+
+}  // namespace bin
+}  // namespace dart
+
+#endif  // defined(TARGET_OS_MACOS)
+
+