diff options
Diffstat (limited to '')
-rw-r--r-- | dom/docs/navigation/BrowsingContext.rst | 149 | ||||
-rw-r--r-- | dom/docs/navigation/embedding.rst | 92 | ||||
-rw-r--r-- | dom/docs/navigation/index.rst | 9 | ||||
-rw-r--r-- | dom/docs/navigation/nav_replace.rst | 119 |
4 files changed, 369 insertions, 0 deletions
diff --git a/dom/docs/navigation/BrowsingContext.rst b/dom/docs/navigation/BrowsingContext.rst new file mode 100644 index 0000000000..213b2fcce5 --- /dev/null +++ b/dom/docs/navigation/BrowsingContext.rst @@ -0,0 +1,149 @@ +BrowsingContext and WindowContext +================================= + +The ``BrowsingContext`` is the Gecko representation of the spec-defined +`Browsing Context`_ object. + +.. _Browsing Context: https://html.spec.whatwg.org/multipage/browsers.html#browsing-context + + +The Browsing Context Tree +------------------------- + +``BrowsingContext`` and ``WindowContext`` objects form a tree, corresponding +to the tree of frame elements which was used to construct them. + + +Example +^^^^^^^ + +Loading the HTML documents listed here, would end up creating a set of BrowsingContexts and WindowContexts forming the tree. + +.. code-block:: html + + <!-- http://example.com/top.html --> + <iframe src="frame1.html"></iframe> + <iframe src="http://mozilla.org/"></iframe> + + <!-- http://example.com/frame1.html --> + <iframe src="http://example.com/frame2.html"></iframe> + + <!-- http://mozilla.org --> + <iframe></iframe> + <iframe></iframe> + +.. digraph:: browsingcontext + + node [shape=rectangle] + + "BC1" [label="BrowsingContext A"] + "BC2" [label="BrowsingContext B"] + "BC3" [label="BrowsingContext C"] + "BC4" [label="BrowsingContext D"] + "BC5" [label="BrowsingContext E"] + "BC6" [label="BrowsingContext F"] + + "WC1" [label="WindowContext\n(http://example.com/top.html)"] + "WC2" [label="WindowContext\n(http://example.com/frame1.html)"] + "WC3" [label="WindowContext\n(http://mozilla.org)"] + "WC4" [label="WindowContext\n(http://example.com/frame2.html)"] + "WC5" [label="WindowContext\n(about:blank)"] + "WC6" [label="WindowContext\n(about:blank)"] + + "BC1" -> "WC1"; + "WC1" -> "BC2"; + "WC1" -> "BC3"; + "BC2" -> "WC2"; + "BC3" -> "WC3"; + "WC2" -> "BC4"; + "BC4" -> "WC4"; + "WC3" -> "BC5"; + "BC5" -> "WC5"; + "WC3" -> "BC6"; + "BC6" -> "WC6"; + + +Synced Fields +------------- + +WIP - In-progress documentation at `<https://wiki.mozilla.org/Project_Fission/BrowsingContext>`_. + + +API Documentation +----------------- + +.. cpp:class:: BrowsingContext + + .. hlist:: + :columns: 3 + + * `header (searchfox) <https://searchfox.org/mozilla-central/source/docshell/base/BrowsingContext.h>`_ + * `source (searchfox) <https://searchfox.org/mozilla-central/source/docshell/base/BrowsingContext.cpp>`_ + * `html spec <https://html.spec.whatwg.org/multipage/browsers.html#browsing-context>`_ + + This is a synced-context type. Instances of it will exist in every + "relevant" content process for the navigation. + + Instances of :cpp:class:`BrowsingContext` created in the parent processes + will be :cpp:class:`CanonicalBrowsingContext`. + + .. cpp:function:: WindowContext* GetParentWindowContext() + + Get the parent ``WindowContext`` embedding this context, or ``nullptr``, + if this is the toplevel context. + + .. cpp:function:: WindowContext* GetTopWindowContext() + + Get the toplevel ``WindowContext`` embedding this context, or ``nullptr`` + if this is the toplevel context. + + This is equivalent to repeatedly calling ``GetParentWindowContext()`` + until it returns nullptr. + + .. cpp:function:: BrowsingContext* GetParent() + + .. cpp:function:: BrowsingContext* Top() + + .. cpp:function:: static already_AddRefed<BrowsingContext> Get(uint64_t aId) + + Look up a specific ``BrowsingContext`` by it's unique ID. Callers should + check if the returned context has already been discarded using + ``IsDiscarded`` before using it. + +.. cpp:class:: CanonicalBrowsingContext : public BrowsingContext + + .. hlist:: + :columns: 3 + + * `header (searchfox) <https://searchfox.org/mozilla-central/source/docshell/base/CanonicalBrowsingContext.h>`_ + * `source (searchfox) <https://searchfox.org/mozilla-central/source/docshell/base/CanonicalBrowsingContext.cpp>`_ + + When a :cpp:class:`BrowsingContext` is constructed in the parent process, + it is actually an instance of :cpp:class:`CanonicalBrowsingContext`. + + Due to being in the parent process, more information about the context is + available from a ``CanonicalBrowsingContext``. + +.. cpp:class:: WindowContext + + .. hlist:: + :columns: 3 + + * `header (searchfox) <https://searchfox.org/mozilla-central/source/docshell/base/WindowContext.h>`_ + * `source (searchfox) <https://searchfox.org/mozilla-central/source/docshell/base/WindowContext.cpp>`_ + +.. cpp:class:: WindowGlobalParent : public WindowContext, public WindowGlobalActor, public PWindowGlobalParent + + .. hlist:: + :columns: 3 + + * `header (searchfox) <https://searchfox.org/mozilla-central/source/dom/ipc/WindowGlobalParent.h>`_ + * `source (searchfox) <https://searchfox.org/mozilla-central/source/dom/ipc/WindowGlobalParent.cpp>`_ + +.. cpp:class:: WindowGlobalChild : public WindowGlobalActor, public PWindowGlobalChild + + .. hlist:: + :columns: 3 + + * `header (searchfox) <https://searchfox.org/mozilla-central/source/dom/ipc/WindowGlobalChild.h>`_ + * `source (searchfox) <https://searchfox.org/mozilla-central/source/dom/ipc/WindowGlobalChild.cpp>`_ diff --git a/dom/docs/navigation/embedding.rst b/dom/docs/navigation/embedding.rst new file mode 100644 index 0000000000..a42aabc6f5 --- /dev/null +++ b/dom/docs/navigation/embedding.rst @@ -0,0 +1,92 @@ +Browsing Context Embedding +========================== + +Embedder Element to nsDocShell +------------------------------ + +In order to render the contents of a ``BrowsingContext``, the embedding +element needs to be able to communicate with the ``nsDocShell`` which is +currently being used to host it's content. This is done in 3 different ways +depending on which combination of processes is in-use. + +- *in-process*: The ``nsFrameLoader`` directly embeds the ``nsDocShell``. +- *remote tab*: The parent process is the embedder, and uses a ``PBrowser``, + via a ``BrowserHost``. The ``BrowserChild`` actor holds the actual + ``nsDocShell`` alive. +- *remote subframe*: A content process is the embedder, and uses a + ``PBrowserBridge``, via a ``BrowserBridgeHost`` to communicate with the + parent process. The parent process then uses a ``BrowserParent``, as in the + *remote tab* case, to communicate with the ``nsDocShell``. + +Diagram +^^^^^^^ + +.. digraph:: embedding + + node [shape=rectangle] + + subgraph cluster_choice { + color=transparent; + node [shape=none]; + + "In-Process"; + "Remote Tab"; + "Remote Subframe"; + } + + "nsFrameLoaderOwner" [label="nsFrameLoaderOwner\ne.g. <iframe>, <xul:browser>, <embed>"] + + "nsFrameLoaderOwner" -> "nsFrameLoader"; + + "nsFrameLoader" -> "In-Process" [dir=none]; + "nsFrameLoader" -> "Remote Tab" [dir=none]; + "nsFrameLoader" -> "Remote Subframe" [dir=none]; + + "In-Process" -> "nsDocShell"; + "Remote Tab" -> "BrowserHost"; + "Remote Subframe" -> "BrowserBridgeHost"; + + "BrowserHost" -> "BrowserParent"; + "BrowserParent" -> "BrowserChild" [label="PBrowser" style=dotted]; + "BrowserChild" -> "nsDocShell"; + + "BrowserBridgeHost" -> "BrowserBridgeChild"; + "BrowserBridgeChild" -> "BrowserBridgeParent" [label="PBrowserBridge", style=dotted]; + "BrowserBridgeParent" -> "BrowserParent"; + +nsDocShell to Document +---------------------- + +Embedding an individual document within a ``nsDocShell`` is done within the +content process, which has that docshell. + + +Diagram +^^^^^^^ + +This diagram shows the objects involved in a content process which is being +used to host a given ``BrowsingContext``, along with rough relationships +between them. Dotted lines represent a "current" relationship, whereas solid +lines are a stronger lifetime relationship. + +.. graph:: document + + node [shape=rectangle] + + "BrowsingContext" -- "nsDocShell" [style=dotted]; + "nsDocShell" -- "nsGlobalWindowOuter"; + "nsGlobalWindowOuter" -- "nsGlobalWindowInner" [style=dotted]; + "nsGlobalWindowInner" -- "Document" [style=dotted]; + + "nsDocShell" -- "nsDocumentViewer" [style=dotted]; + "nsDocumentViewer" -- "Document"; + "nsDocumentViewer" -- "PresShell"; + + "nsGlobalWindowInner" -- "WindowGlobalChild"; + "BrowsingContext" -- "WindowContext" [style=dotted]; + "WindowContext" -- "nsGlobalWindowInner"; + + subgraph cluster_synced { + label = "Synced Contexts"; + "BrowsingContext" "WindowContext"; + } diff --git a/dom/docs/navigation/index.rst b/dom/docs/navigation/index.rst new file mode 100644 index 0000000000..b322855eb6 --- /dev/null +++ b/dom/docs/navigation/index.rst @@ -0,0 +1,9 @@ +DOM Navigation +============== + +.. toctree:: + :maxdepth: 1 + + embedding + BrowsingContext + nav_replace diff --git a/dom/docs/navigation/nav_replace.rst b/dom/docs/navigation/nav_replace.rst new file mode 100644 index 0000000000..6e2c710e28 --- /dev/null +++ b/dom/docs/navigation/nav_replace.rst @@ -0,0 +1,119 @@ +Objects Replaced by Navigations +=============================== + +There are 3 major types of navigations, each of which can cause different +objects to be replaced. The general rules look something like this: + +.. csv-table:: objects replaced or preserved across navigations + :header: "Class/Id", ":ref:`in-process navigations <in-process navigations>`", ":ref:`cross-process navigations <cross-process navigations>`", ":ref:`cross-group navigations <cross-group navigations>`" + + "BrowserId [#bid]_", |preserve|, |preserve|, |preserve| + "BrowsingContextWebProgress", |preserve|, |preserve|, |preserve| + "BrowsingContextGroup", |preserve|, |preserve|, |replace| + "BrowsingContext", |preserve|, |preserve|, |replace| + "nsFrameLoader", |preserve|, |replace|, |replace| + "RemoteBrowser", |preserve|, |replace|, |replace| + "Browser{Parent,Child}", |preserve|, |replace|, |replace| + "nsDocShell", |preserve|, |replace|, |replace| + "nsGlobalWindowOuter", |preserve|, |replace|, |replace| + "nsGlobalWindowInner", "|replace| [#inner]_", |replace|, |replace| + "WindowContext", "|replace| [#inner]_", |replace|, |replace| + "WindowGlobal{Parent,Child}", "|replace| [#inner]_", |replace|, |replace| + "Document", "|replace|", |replace|, |replace| + + +.. |replace| replace:: ❌ replaced +.. |preserve| replace:: ✔️ preserved + +.. [#bid] + + The BrowserId is a unique ID on each ``BrowsingContext`` object, obtained + using ``GetBrowserId``, not a class. This ID will persist even when a + ``BrowsingContext`` is replaced (e.g. due to + ``Cross-Origin-Opener-Policy``). + +.. [#inner] + + When navigating from the initial ``about:blank`` document to a same-origin + document, the same ``nsGlobalWindowInner``, ``WindowContext`` and + ``WindowGlobal{Parent,Child}`` may be used. This initial ``about:blank`` + document is the one created when synchronously accessing a newly-created + pop-up window from ``window.open``, or a newly-created document in an + ``<iframe>``. + +Types of Navigations +-------------------- + +.. _in-process navigations: + +in-process navigations +^^^^^^^^^^^^^^^^^^^^^^ + +An in-process navigation is the traditional type of navigation, and the most +common type of navigation when :ref:`Fission` is not enabled. + +These navigations are used when no process switching or BrowsingContext +replacement is required, which includes most navigations with Fission +disabled, and most same site-origin navigations when Fission is enabled. + +.. _cross-process navigations: + +cross-process navigations +^^^^^^^^^^^^^^^^^^^^^^^^^ + +A cross-process navigation is used when a navigation requires a process +switch to occur, and no BrowsingContext replacement is required. This is a +common type of load when :ref:`Fission` is enabled, though it is also used +for navigations to and from special URLs like ``file://`` URIs when +Fission is disabled. + +These process changes are triggered by ``DocumentLoadListener`` when it +determines that a process switch is required. See that class's documentation +for more details. + +.. _cross-group navigations: + +cross-group navigations +^^^^^^^^^^^^^^^^^^^^^^^ + +A cross-group navigation is used when the navigation's `response requires +a browsing context group switch +<https://html.spec.whatwg.org/multipage/origin.html#browsing-context-group-switches-due-to-cross-origin-opener-policy>`_. + +These types of switches may or may not cause the process to change, but will +finish within a different ``BrowsingContextGroup`` than they started with. +Like :ref:`cross-process navigations`, these navigations are triggered using +the process switching logic in ``DocumentLoadListener``. + +As the parent of a content browsing context cannot change due to a navigation, +only toplevel content browsing contexts can cross-group navigate. Navigations in +chrome browsing contexts [#chromebc]_ or content subframes only experience +either in-process or cross-process navigations. + +As of the time of this writing, we currently trigger a cross-group navigation +in the following circumstances, though this may change in the future: + +- If the `Cross-Origin-Opener-Policy + <https://html.spec.whatwg.org/multipage/origin.html#the-cross-origin-opener-policy-header>`_ + header is specified, and a mismatch is detected. +- When switching processes between the parent process, and a content process. +- When loading an extension document in a toplevel browsing context. +- When navigating away from a preloaded ``about:newtab`` document. +- When putting a ``BrowsingContext`` into BFCache for the session history + in-parent BFCache implementation. This will happen on most toplevel + navigations without opener relationships when the ``fission.bfcacheInParent`` + pref is enabled. + +State which needs to be saved over cross-group navigations on +``BrowsingContext`` instances is copied in the +``CanonicalBrowsingContext::ReplacedBy`` method. + +.. [#chromebc] + + A chrome browsing context does **not** refer to pages with the system + principal loaded in the content area such as ``about:preferences``. + Chrome browsing contexts are generally used as the root context in a chrome + window, such where ``browser.xhtml`` is loaded for a browser window. + + All chrome browsing contexts exclusively load in the parent process and + cannot process switch when navigating. |