Fixed #100 (some pesky FS drivers can send paths with and without trailing slashes, now the code accounts for that). Improved the datastructures in FSEventsDirUpdateImpl - less mallocs, less caches trashing. Added logging as well. (#108)

Author: mikekazakov

Source/Utility/Utility.xcodeproj/project.pbxproj

@@ -67,6 +67,7 @@
 		CF52C39B22B974280043E825 /* UTIImpl_UT.cpp in Sources */ = {isa = PBXBuildFile; fileRef = CF52C39922B974210043E825 /* UTIImpl_UT.cpp */; };
 		CF5D1DC72B52B9E900750174 /* Tags.cpp in Sources */ = {isa = PBXBuildFile; fileRef = CF5D1DC62B52B9E900750174 /* Tags.cpp */; };
 		CF5D1DC92B52B9FA00750174 /* Tags_UT.mm in Sources */ = {isa = PBXBuildFile; fileRef = CF5D1DC82B52B9FA00750174 /* Tags_UT.mm */; };
+		CF5D1E442B652AA900750174 /* FSEventsDirUpdateImpl.cpp in Sources */ = {isa = PBXBuildFile; fileRef = CF5D1E432B652AA900750174 /* FSEventsDirUpdateImpl.cpp */; };
 		CF61F305264048F6009FF900 /* FSEventsFileUpdate.cpp in Sources */ = {isa = PBXBuildFile; fileRef = CF61F304264048F6009FF900 /* FSEventsFileUpdate.cpp */; };
 		CF61F30B26404962009FF900 /* FSEventsFileUpdateImpl.h in Headers */ = {isa = PBXBuildFile; fileRef = CF61F30A26404962009FF900 /* FSEventsFileUpdateImpl.h */; };
 		CF61F30F26404971009FF900 /* FSEventsFileUpdateImpl.cpp in Sources */ = {isa = PBXBuildFile; fileRef = CF61F30E26404971009FF900 /* FSEventsFileUpdateImpl.cpp */; };
@@ -159,6 +160,8 @@
 		CF5D1DC52B52B9D900750174 /* Tags.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = Tags.h; path = include/Utility/Tags.h; sourceTree = "<group>"; };
 		CF5D1DC62B52B9E900750174 /* Tags.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = Tags.cpp; path = source/Tags.cpp; sourceTree = "<group>"; };
 		CF5D1DC82B52B9FA00750174 /* Tags_UT.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; name = Tags_UT.mm; path = tests/Tags_UT.mm; sourceTree = "<group>"; };
+		CF5D1E422B652A9A00750174 /* FSEventsDirUpdateImpl.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = FSEventsDirUpdateImpl.h; path = include/Utility/FSEventsDirUpdateImpl.h; sourceTree = "<group>"; };
+		CF5D1E432B652AA900750174 /* FSEventsDirUpdateImpl.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = FSEventsDirUpdateImpl.cpp; path = source/FSEventsDirUpdateImpl.cpp; sourceTree = "<group>"; };
 		CF614AA81F9D871D0005F2DB /* ByteCountFormatter_UT.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; name = ByteCountFormatter_UT.mm; path = tests/ByteCountFormatter_UT.mm; sourceTree = SOURCE_ROOT; };
 		CF614AA91F9D871D0005F2DB /* Encodings_UT.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; name = Encodings_UT.mm; path = tests/Encodings_UT.mm; sourceTree = SOURCE_ROOT; };
 		CF614AAA1F9D871D0005F2DB /* Info.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; name = Info.plist; path = tests/Info.plist; sourceTree = SOURCE_ROOT; };
@@ -361,6 +364,7 @@
 				CFD62BD91C9A6BE30021EE7F /* FontExtras.h */,
 				CFD62BE71C9A709C0021EE7F /* FPSLimitedDrawer.h */,
 				CFD62C111C9AB47F0021EE7F /* FSEventsDirUpdate.h */,
+				CF5D1E422B652A9A00750174 /* FSEventsDirUpdateImpl.h */,
 				CF61F303264048EA009FF900 /* FSEventsFileUpdate.h */,
 				CF61F30A26404962009FF900 /* FSEventsFileUpdateImpl.h */,
 				CF09392F1D10214200D67AC6 /* FunctionKeysPass.h */,
@@ -425,6 +429,7 @@
 				CFD62C001C9A87170021EE7F /* FontExtras.mm */,
 				CFD62BE91C9A70A40021EE7F /* FPSLimitedDrawer.mm */,
 				CFD62C0F1C9AB4770021EE7F /* FSEventsDirUpdate.cpp */,
+				CF5D1E432B652AA900750174 /* FSEventsDirUpdateImpl.cpp */,
 				CF61F304264048F6009FF900 /* FSEventsFileUpdate.cpp */,
 				CF61F30E26404971009FF900 /* FSEventsFileUpdateImpl.cpp */,
 				CF0939311D10214D00D67AC6 /* FunctionKeysPass.mm */,
@@ -611,6 +616,7 @@
 				CF71BCE32932389100997E0F /* SpdLogWindow.mm in Sources */,
 				CF46015C256125E50095FC73 /* NativeFSManager.mm in Sources */,
 				CF460149256125E50095FC73 /* FPSLimitedDrawer.mm in Sources */,
+				CF5D1E442B652AA900750174 /* FSEventsDirUpdateImpl.cpp in Sources */,
 				CF460143256125E50095FC73 /* NativeFSManagerVolumeLookup.cpp in Sources */,
 				CF460158256125E50095FC73 /* VerticallyCenteredTextFieldCell.mm in Sources */,
 				CF460164256125E50095FC73 /* SystemInformation.mm in Sources */,

Source/Utility/include/Utility/FSEventsDirUpdate.h

@@ -1,10 +1,9 @@
-// Copyright (C) 2013-2020 Michael Kazakov. Subject to GNU General Public License version 3.
+// Copyright (C) 2013-2024 Michael Kazakov. Subject to GNU General Public License version 3.
 #pragma once
 
 #include <stdint.h>
 #include <string>
 #include <functional>
-#include <memory>
 
 namespace nc::utility {
 
@@ -13,25 +12,25 @@ class NativeFSManagerImpl;
 class FSEventsDirUpdate
 {
 public:
-    static FSEventsDirUpdate &Instance();
- 
-    // zero returned value means error. any others - valid observation tickets
-    uint64_t AddWatchPath(const char *_path, std::function<void()> _handler);
-    
-    // it's better to use this method
-    void RemoveWatchPathWithTicket(uint64_t _ticket);
+    virtual ~FSEventsDirUpdate() = default;
+
+    // Registers _handler as a watch callback for any changes of the directory '_path' (but not its children)
+    // Zero will be returned to indicate an error.
+    // Any other values represent observation tickets.
+    virtual uint64_t AddWatchPath(const char *_path, std::function<void()> _handler) = 0;
+
+    // Deregisters the watcher identified by _ticket.
+    virtual void RemoveWatchPathWithTicket(uint64_t _ticket) = 0;
+
+    static FSEventsDirUpdate &Instance() noexcept;
 
     static inline const uint64_t no_ticket = 0;
-    
+
 private:
     friend class nc::utility::NativeFSManagerImpl;
-    
-    // called exclusevily by NativeFSManager
-    void OnVolumeDidUnmount(const std::string &_on_path);
-    
-    FSEventsDirUpdate();
-    struct Impl;
-    std::unique_ptr<Impl>   me;
+
+    // called exclusively by NativeFSManager
+    virtual void OnVolumeDidUnmount(const std::string &_on_path) = 0;
 };
 
-}
+} // namespace nc::utility

Source/Utility/include/Utility/FSEventsDirUpdateImpl.h

@@ -0,0 +1,51 @@
+// Copyright (C) 2013-2024 Michael Kazakov. Subject to GNU General Public License version 3.
+#pragma once
+#include "FSEventsDirUpdate.h"
+#include <DiskArbitration/DiskArbitration.h>
+#include <CoreServices/CoreServices.h>
+#include <Base/spinlock.h>
+#include <filesystem>
+#include <Base/RobinHoodUtil.h>
+
+namespace nc::utility {
+
+class FSEventsDirUpdateImpl : public FSEventsDirUpdate
+{
+public:
+    uint64_t AddWatchPath(const char *_path, std::function<void()> _handler) override;
+
+    void RemoveWatchPathWithTicket(uint64_t _ticket) override;
+
+    // Implementation detail exposed for testability
+    static bool ShouldFire(std::string_view _watched_path,
+                           size_t _num_events,
+                           const char *_event_paths[],
+                           const FSEventStreamEventFlags _event_flags[]) noexcept;
+
+private:
+    struct WatchData {
+        std::string_view path; // canonical fs representation, should include a trailing slash. points into hashmap
+        FSEventStreamRef stream = nullptr;
+        std::vector<std::pair<uint64_t, std::function<void()>>> handlers;
+    };
+
+    using WatchesT = robin_hood::
+        unordered_node_map<std::string, WatchData, RHTransparentStringHashEqual, RHTransparentStringHashEqual>;
+
+    void OnVolumeDidUnmount(const std::string &_on_path) override;
+
+    static void DiskDisappeared(DADiskRef disk, void *context);
+    static void FSEventsDirUpdateCallback(ConstFSEventStreamRef streamRef,
+                                          void *userData,
+                                          size_t numEvents,
+                                          void *eventPaths,
+                                          const FSEventStreamEventFlags eventFlags[],
+                                          const FSEventStreamEventId eventIds[]);
+    static FSEventStreamRef CreateEventStream(const std::string &path, void *context);
+
+    spinlock m_Lock;
+    WatchesT m_Watches;                // path -> watch data;
+    std::atomic_ulong m_LastTicket{1}; // no #0 ticket, it's an error code
+};
+
+} // namespace nc::utility