Add FileSystemWatcher class to dart:io.

runtime/bin/file_system_watcher_macos.cc

+// 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 {
+ public:
+  class Node {
+   public:
+    Node(intptr_t base_path_length, int read_fd, int write_fd, bool recursive)
+      : base_path_length_(base_path_length),
+        read_fd_(read_fd),
+        write_fd_(write_fd),
+        recursive_(recursive),
+        ref_(NULL) {}
+
+    ~Node() {
+      close(write_fd_);
+      FSEventStreamInvalidate(ref_);
+      FSEventStreamRelease(ref_);
+    }
+
+    void set_ref(FSEventStreamRef ref) {
+      ref_ = ref;
+    }
+
+    void Start() {
+      FSEventStreamStart(ref_);
+    }
+
+    void Stop() {
+      FSEventStreamStop(ref_);
+    }
+
+    intptr_t base_path_length() const { return base_path_length_; }
+    int read_fd() const { return read_fd_; }
+    int write_fd() const { return write_fd_; }
+    bool recursive() const { return recursive_; }
+
+   private:
+    intptr_t base_path_length_;
+    int read_fd_;
+    int write_fd_;
+    bool recursive_;
+    FSEventStreamRef ref_;
+  };
+
+  FSEventsWatcher() : run_loop_(0), users_(0) {
+    Thread::Start(Run, reinterpret_cast<uword>(this));
+  }
+
+  ~FSEventsWatcher() {
+    CFRunLoopStop(run_loop_);
+  }
+
+  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();
+  }
+
+  static void Increment() {
+    if (watcher == NULL) {
+      watcher = new FSEventsWatcher();
+      watcher_monitor->Enter();
+      watcher_monitor->Wait(Monitor::kNoTimeout);
+      watcher_monitor->Exit();
+    }
+    watcher->users_++;
+  }
+
+  static void Decrement() {
+    ASSERT(watcher->users_ > 0);
+    watcher->users_--;
+    if (watcher->users_ == 0) {
+      delete watcher;
+      watcher = NULL;
+    }
+  }
+
+  Node* AddPath(const char* path, int events, bool recursive) {
+    int fds[2];
+    VOID_TEMP_FAILURE_RETRY(pipe(fds));
+    Socket::SetNonBlocking(fds[0]);
+    Socket::SetBlocking(fds[1]);
+
+    char base_path[PATH_MAX];
+    realpath(path, base_path);
+    CFStringRef path_ref = CFStringCreateWithCString(
+        NULL, base_path, kCFStringEncodingUTF8);
+
+    Node* node = new Node(strlen(base_path), fds[0], fds[1], recursive);
+
+    FSEventStreamContext context;
+    context.version = 0;
+    context.info = reinterpret_cast<void*>(node);
+    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);
+
+    node->set_ref(ref);
+
+    FSEventStreamScheduleWithRunLoop(
+        ref,
+        run_loop_,
+        kCFRunLoopDefaultMode);
+
+    return node;
+  }
+
+ private:
+  static void Callback(ConstFSEventStreamRef ref,
+                       void* client,
+                       size_t num_events,
+                       void* event_paths,
+                       const FSEventStreamEventFlags event_flags[],
+                       const FSEventStreamEventId event_ids[]) {
+    Node* node = reinterpret_cast<Node*>(client);
+    for (size_t i = 0; i < num_events; i++) {
+      char *path = reinterpret_cast<char**>(event_paths)[i];
+      path += node->base_path_length() + 1;
+      if (!node->recursive() && strstr(path, "/") != NULL) continue;
+      FSEvent event;
+      event.data.flags = event_flags[i];
+      memmove(event.data.path, path, strlen(path) + 1);
+      write(node->write_fd(), event.bytes, sizeof(event));
+    }
+  }
+
+  CFRunLoopRef run_loop_;
+  int users_;
+};
+
+
+intptr_t FileSystemWatcher::WatchPath(const char* path,
+                                      int events,
+                                      bool recursive) {
+  MutexLocker lock(watcher_mutex);
+  FSEventsWatcher::Increment();
+
+  FSEventsWatcher::Node* node = watcher->AddPath(path, events, recursive);
+  node->Start();
+  return reinterpret_cast<intptr_t>(node);
+}
+
+
+void FileSystemWatcher::UnwatchPath(intptr_t id) {
+  MutexLocker lock(watcher_mutex);
+
+  FSEventsWatcher::Node* node = reinterpret_cast<FSEventsWatcher::Node*>(id);
+  node->Stop();
+  delete node;
+
+  FSEventsWatcher::Decrement();
+}
+
+
+intptr_t FileSystemWatcher::GetSocketId(intptr_t id) {
+  return reinterpret_cast<FSEventsWatcher::Node*>(id)->read_fd();
+}
+
+
+Dart_Handle FileSystemWatcher::ReadEvents(intptr_t id) {
+  intptr_t fd = GetSocketId(id);
+  intptr_t avail = FDUtils::AvailableBytes(fd);
+  int count = avail / sizeof(FSEvent);
+  if (count <= 0) return Dart_NewList(0);
+  Dart_Handle events = Dart_NewList(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 DartUtils::NewDartOSError();
+    }
+    Dart_Handle event = Dart_NewList(3);
+    int flags = e.data.flags;
+    int mask = 0;
+    if (flags & kFSEventStreamEventFlagItemModified) mask |= kModifyContent;
+    if (flags & kFSEventStreamEventFlagItemRenamed) mask |= kMove;
+    if (flags & kFSEventStreamEventFlagItemXattrMod) mask |= kModefyAttribute;
+    if (flags & kFSEventStreamEventFlagItemCreated) mask |= kCreate;
+    if (flags & kFSEventStreamEventFlagItemRemoved) mask |= kDelete;
+    Dart_ListSetAt(event, 0, Dart_NewInteger(mask));
+    Dart_ListSetAt(event, 1, Dart_NewInteger(1));
+    Dart_ListSetAt(event, 2, Dart_NewStringFromUTF8(
+        reinterpret_cast<uint8_t*>(e.data.path), strlen(e.data.path)));
+    Dart_ListSetAt(events, i, event);
+  }
+  return events;
+}
+
+}  // namespace bin
+}  // namespace dart
+
+#endif  // defined(TARGET_OS_MACOS)
+
+