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Explainer https://github.com/whatwg/fs/blob/main/proposals/MultipleReadersWriters.md Specification https://github.com/whatwg/fs/pull/151 Summary Currently, only one FileSystemSyncAccessHandle may be open at a time per file, preventing an origin from reading and writing to the same file from multiple tabs easily. Conversely, multiple FileSystemWritableFileStreams can be simultaneously open, letting multiple writers clobber each other. Introducing new locking modes for FileSystemSyncAccessHandle and FileSystemWritableFileStream allows opening either multiple readers/writers or an exclusive writer to a file entry, depending on the application's use case. ``` handle.createSyncAccessHandle({ mode: 'read-only' }); handle.createSyncAccessHandle({ mode: 'readwrite-unsafe' }); handle.createWritable({ mode: 'exclusive' }); ``` Blink component Blink>Storage>FileSystem <https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink%3EStorage%3EFileSystem> TAG review https://github.com/w3ctag/design-reviews/issues/845 TAG review status Issues addressed Origin Trial documentation link https://developer.chrome.com/blog/new-dev-trial-for-multiple-readers-and-writers/ Risks Interoperability and Compatibility Gecko: Positive (https://github.com/mozilla/standards-positions/issues/861) WebKit: No Signal (https://github.com/WebKit/standards-positions/issues/238) Web developers: Positive (https://github.com/whatwg/fs/issues/34) Other signals: Emscripten plans to utilize multiple readers and writers for performance improvement, and sites using Emscripten will be able to take advantage of this integration. WebView application risks Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications? None Debuggability Feature is web exposed through WebIDL changes. No additional implementation effort is required. Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, Chrome OS, Android, and Android WebView)? Yes Is this feature fully tested by web-platform-tests <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md> ? WPTs have been added that fully test the behavior of the new locking modes. They additionally test the interactions between combinations of primitives, their different modes, and file handle operations. https://wpt.fyi/results/fs/FileSystemFileHandle-cross-primitive-locking.https.tentative.worker.html?label=experimental&label=master&aligned https://wpt.fyi/results/fs/FileSystemFileHandle-sync-access-handle-lock-modes.https.tentative.worker.html?label=experimental&label=master&aligned https://wpt.fyi/results/fs/FileSystemFileHandle-writable-file-stream-lock-modes.https.tentative.worker.html?label=experimental&label=master&aligned Flag name on chrome://flags file-system-access-locking-scheme Finch feature name FileSystemAccessLockingScheme Requires code in //chrome? False Tracking bug https://bugs.chromium.org/p/chromium/issues/detail?id=1382215 Launch bug https://launch.corp.google.com/launch/4261043 Estimated milestones Shipping on desktop 121 Anticipated spec changes Discussion: https://github.com/whatwg/fs/issues/34 No open issues that introduce web compat/interop risk. Link to entry on the Chrome Platform Status https://chromestatus.com/feature/5172892632875008 Links to previous Intent discussions Intent to prototype: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAPscNz5Oi-z6-%2BvTVyf9BNgvVnLZeQo5nfzyRhEZ_F400tTP3w%40mail.gmail.com -- You received this message because you are subscribed to the Google Groups "blink-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to blink-dev+unsubscr...@chromium.org. To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAO4d-Ss1eT-GU98ysscmpzbw5cJDGjSxRBMBhwweir7Q%2B1Q8RQ%40mail.gmail.com.
