FolderWatch

A watch on folders, as the platform reports changes to them.

In the namespace platform::filesystem. Declared in src/libs/libplatform/platform/FileSystem.hpp.

Detailed description

Linux: one inotify instance, one watch descriptor per folder. Events are read without blocking from descriptor, which a QSocketNotifier can wait on. Windows: one recursive ReadDirectoryChangesW per root, each change reported against the folder the caller added, and descriptor is an event handle a QWinEventNotifier waits on. Android hosts: not provided; create says so and the caller lives without a watcher, as build-graph §KN-BG5a allows.

Not a Qt QFileSystemWatcher: that one hides overflow, which is the one thing the graph must know about.