incremental dehydrate (#921)

- Feature: Incremental CAS-based hydration/dehydration replacing the previous full-copy approach
- Feature: S3 hydration backend with multipart upload/download support
- Feature: Configurable thread pools for hub instance provisioning and hydration
  `--hub-instance-provision-threads` defaults to `max(cpu_count / 4, 2)`. Set to 0 for synchronous operation.
  `--hub-hydration-threads` defaults to `max(cpu_count / 4, 2)`. Set to 0 for synchronous operation.
- Improvement: Hub triggers GC on instance before deprovisioning to compact storage before dehydration
- Improvement: GC status now reports pending triggers as running
- Improvement: S3 client debug logging gated behind verbose mode to reduce log noise at default verbosity
- Improvement: Hub dashboard Resources tile now shows total memory
- Improvement: `filesystemutils` moved from `zenremotestore` to `zenutil` for broader reuse
- Improvement: Hub uses separate provision and hydration worker pools to avoid deadlocks
- Improvement: Hibernate/wake/deprovision on non-existent or already-in-target-state modules are idempotent
- Improvement: `ScopedTemporaryDirectory` with empty path now creates a temporary directory instead of asserting

1 files changed, 18 insertions, 4 deletions

diff --git a/src/zencore/filesystem.cpp b/src/zencore/filesystem.cpp
index a63594be9..cae6ba5d4 100644
--- a/src/zencore/filesystem.cpp
+++ b/src/zencore/filesystem.cpp
@@ -114,6 +114,20 @@ struct ScopedFd
 
 	explicit operator bool() const { return Fd >= 0; }
 };
+#	if ZEN_PLATFORM_LINUX
+inline uint64_t
+StatMtime100Ns(const struct stat& S)
+{
+	return uint64_t(S.st_mtim.tv_sec) * 10'000'000ULL + uint64_t(S.st_mtim.tv_nsec) / 100;
+}
+#	elif ZEN_PLATFORM_MAC
+inline uint64_t
+StatMtime100Ns(const struct stat& S)
+{
+	return uint64_t(S.st_mtimespec.tv_sec) * 10'000'000ULL + uint64_t(S.st_mtimespec.tv_nsec) / 100;
+}
+#	endif
+
 #endif	// ZEN_PLATFORM_LINUX || ZEN_PLATFORM_MAC
 
 #if ZEN_PLATFORM_WINDOWS
@@ -2123,7 +2137,7 @@ FileSystemTraversal::TraverseFileSystem(const std::filesystem::path& RootDir, Tr
 		}
 		else if (S_ISREG(Stat.st_mode))
 		{
-			Visitor.VisitFile(RootDir, FileName, Stat.st_size, gsl::narrow<uint32_t>(Stat.st_mode), gsl::narrow<uint64_t>(Stat.st_mtime));
+			Visitor.VisitFile(RootDir, FileName, Stat.st_size, gsl::narrow<uint32_t>(Stat.st_mode), StatMtime100Ns(Stat));
 		}
 		else
 		{
@@ -2507,7 +2521,7 @@ GetModificationTickFromHandle(void* NativeHandle, std::error_code& Ec)
 	struct stat Stat;
 	if (0 == fstat(Fd, &Stat))
 	{
-		return gsl::narrow<uint64_t>(Stat.st_mtime);
+		return StatMtime100Ns(Stat);
 	}
 #endif
 	Ec = MakeErrorCodeFromLastError();
@@ -2546,7 +2560,7 @@ GetModificationTickFromPath(const std::filesystem::path& Filename)
 	{
 		ThrowLastError(fmt::format("Failed to get mode of file {}", Filename));
 	}
-	return gsl::narrow<uint64_t>(Stat.st_mtime);
+	return StatMtime100Ns(Stat);
 #endif
 }
 
@@ -2589,7 +2603,7 @@ TryGetFileProperties(const std::filesystem::path& Path,
 	{
 		return false;
 	}
-	OutModificationTick		  = gsl::narrow<uint64_t>(Stat.st_mtime);
+	OutModificationTick		  = StatMtime100Ns(Stat);
 	OutSize					  = size_t(Stat.st_size);
 	OutNativeModeOrAttributes = (uint32_t)Stat.st_mode;
 	return true;