Refactor PollEventDriverWatchers.

- Better encapsulates the mutex protection inside PollingThread
- Uses mallocT/freeT to allocate snapshot nodes

source/eventcore/drivers/posix/watchers.d

@@ -3,7 +3,7 @@ module eventcore.drivers.posix.watchers;
 
 import eventcore.driver;
 import eventcore.drivers.posix.driver;
-import eventcore.internal.utils : nogc_assert;
+import eventcore.internal.utils : mallocT, freeT, nogc_assert;
 
 
 final class InotifyEventDriverWatchers(Events : EventDriverEvents) : EventDriverWatchers
@@ -313,42 +313,40 @@ final class PollEventDriverWatchers(Events : EventDriverEvents) : EventDriverWat
 
 	private void onEvent(EventID evt)
 	{
-		import std.algorithm.mutation : swap;
-
 		auto pt = evt in m_pollers;
 		if (!pt) return;
 
 		m_events.wait(evt, &onEvent);
 
-		FileChange[] changes;
+		foreach (ref ch; pt.readChanges())
-		try synchronized (pt.m_changesMutex)
-			swap(changes, pt.m_changes);
-		catch (Exception e) assert(false, "Failed to acquire mutex: "~e.msg);
-
-		foreach (ref ch; changes)
 			pt.m_callback(cast(WatcherID)evt, ch);
 	}
 
 
 	private final class PollingThread : Thread {
-		int refCount = 1;
-		EventID changesEvent;
-
 		private {
 			shared(Events) m_eventsDriver;
 			Mutex m_changesMutex;
-			/*shared*/ FileChange[] m_changes;
+			/*shared*/ FileChange[] m_changes; // protected by m_changesMutex
+			EventID m_changesEvent; // protected by m_changesMutex
 			immutable string m_basePath;
 			immutable bool m_recursive;
 			immutable FileChangesCallback m_callback;
-			size_t m_entryCount;
 
-			struct Entry {
+			final static class Entry {
-				Entry* parent;
+				Entry parent;
 				string name;
 				ulong size;
 				long lastChange;
 
+				this(Entry parent, string name, ulong size, long lastChange)
+				{
+					this.parent = parent;
+					this.name = name;
+					this.size = size;
+					this.lastChange = lastChange;
+				}
+
 				string path()
 				{
 					import std.path : buildPath;
@@ -361,11 +359,13 @@ final class PollEventDriverWatchers(Events : EventDriverEvents) : EventDriverWat
 			}
 
 			struct Key {
-				Entry* parent;
+				Entry parent;
 				string name;
 			}
 
-			Entry*[Key] m_entries;
+			// used only within the polling thread
+			Entry[Key] m_entries;
+			size_t m_entryCount;
 		}
 
 		this(shared(Events) event_driver, EventID event, string path, bool recursive, FileChangesCallback callback)
@@ -374,7 +374,7 @@ final class PollEventDriverWatchers(Events : EventDriverEvents) : EventDriverWat
 
 			m_changesMutex = new Mutex;
 			m_eventsDriver = event_driver;
-			changesEvent = event;
+			m_changesEvent = event;
 			m_basePath = path;
 			m_recursive = recursive;
 			m_callback = callback;
@@ -387,10 +387,21 @@ final class PollEventDriverWatchers(Events : EventDriverEvents) : EventDriverWat
 		void dispose()
 		nothrow {
 			try synchronized (m_changesMutex) {
-				changesEvent = EventID.invalid;
+				m_changesEvent = EventID.invalid;
 			} catch (Exception e) assert(false, e.msg);
 		}
 
+		FileChange[] readChanges()
+		nothrow {
+			import std.algorithm.mutation : swap;
+
+			FileChange[] changes;
+			try synchronized (m_changesMutex)
+				swap(changes, m_changes);
+			catch (Exception e) assert(false, "Failed to acquire mutex: "~e.msg);
+			return changes;
+		}
+
 		private void run()
 		nothrow @trusted {
 			import core.time : msecs;
@@ -401,7 +412,7 @@ final class PollEventDriverWatchers(Events : EventDriverEvents) : EventDriverWat
 				auto timeout = Clock.currTime(UTC()) + min(m_entryCount, 60000).msecs + 1000.msecs;
 				while (true) {
 					try synchronized (m_changesMutex) {
-						if (changesEvent == EventID.invalid) return;
+						if (m_changesEvent == EventID.invalid) return;
 					} catch (Exception e) assert(false, "Mutex lock failed: "~e.msg);
 					auto remaining = timeout - Clock.currTime(UTC());
 					if (remaining <= 0.msecs) break;
@@ -411,9 +422,9 @@ final class PollEventDriverWatchers(Events : EventDriverEvents) : EventDriverWat
 				scan(true);
 
 				try synchronized (m_changesMutex) {
-					if (changesEvent == EventID.invalid) return;
+					if (m_changesEvent == EventID.invalid) return;
 					if (m_changes.length)
-						m_eventsDriver.trigger(changesEvent, false);
+						m_eventsDriver.trigger(m_changesEvent, false);
 				} catch (Exception e) assert(false, "Mutex lock failed: "~e.msg);
 			} catch (Throwable th) {
 				import core.stdc.stdio : fprintf, stderr;
@@ -435,8 +446,8 @@ final class PollEventDriverWatchers(Events : EventDriverEvents) : EventDriverWat
 		@trusted nothrow {
 			import std.algorithm.mutation : swap;
 
-			Entry*[Key] new_entries;
+			Entry[Key] new_entries;
-			Entry*[] added;
+			Entry[] added;
 			size_t ec = 0;
 
 			scan(null, generate_changes, new_entries, added, ec);
@@ -445,12 +456,9 @@ final class PollEventDriverWatchers(Events : EventDriverEvents) : EventDriverWat
 				if (!e.key.parent || Key(e.key.parent.parent, e.key.parent.name) !in m_entries) {
 					if (generate_changes)
 						addChange(FileChangeKind.removed, e.key, e.value.isDir);
+					try freeT(e.value);
+					catch (Exception e) assert(false, e.msg);
 				}
-
-				static if (__VERSION__ >= 2079) {
-					import core.memory : __delete;
-					__delete(e.value);
-				} else mixin("delete e.value;");
 			}
 
 			foreach (e; added)
@@ -460,7 +468,7 @@ final class PollEventDriverWatchers(Events : EventDriverEvents) : EventDriverWat
 			m_entryCount = ec;
 		}
 
-		private void scan(Entry* parent, bool generate_changes, ref Entry*[Key] new_entries, ref Entry*[] added, ref size_t ec)
+		private void scan(Entry parent, bool generate_changes, ref Entry[Key] new_entries, ref Entry[] added, ref size_t ec)
 		@trusted nothrow {
 			import std.file : SpanMode, dirEntries;
 			import std.path : buildPath, baseName;
@@ -486,7 +494,7 @@ final class PollEventDriverWatchers(Events : EventDriverEvents) : EventDriverWat
 					ec++;
 					m_entries.remove(key);
 				} else {
-					auto e = new Entry(parent, key.name, de.isDir ? ulong.max : de.size, modified_time);
+					auto e = mallocT!Entry(parent, key.name, de.isDir ? ulong.max : de.size, modified_time);
 					new_entries[key] = e;
 					ec++;
 					if (generate_changes) added ~= e;