forked from mirrors/gecko-dev
2707a3d1f2
Some background information on why we want to flush writes: we're currently working on a "fast shutdown" project, which will simply call _exit(0) once a certain phase (controlled via pref) in shutdown is hit. This will allow us to skip a lot of ceremony, like freeing memory, removing listeners on observer notifications, etc. However, we don't want to be cavalier about data loss, so for the time being we want to ensure that all file writes which we previously had some assurance would complete will continue to complete. This means explicitly calling them immediately before a fast shutdown. We also want to call these before we turn on late write checking, which we control via another pref. This late write checking surfaces writes via telemetry which we didn't notice with local testing. However we want to ensure that we flush our writes before this point so we don't have lots of noise in the telemetry. Lina I'm requesting review from you since it looks like you did the reviews on most of the initial code. However, please let me know if there's someone more suitable. Depends on D75389 Differential Revision: https://phabricator.services.mozilla.com/D75572
108 lines
4.3 KiB
C++
108 lines
4.3 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
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#include "mozilla/ClearOnShutdown.h"
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#include "mozilla/StaticPtr.h"
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#include "mozilla/XULStore.h"
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#include "nsCOMPtr.h"
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namespace mozilla {
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// The XULStore API is implemented in Rust and exposed to C++ via a set of
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// C functions with the "xulstore_" prefix. We declare them in this anonymous
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// namespace to prevent C++ code outside this file from accessing them,
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// as they are an internal implementation detail, and C++ code should use
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// the mozilla::XULStore::* functions and mozilla::XULStoreIterator class
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// declared in XULStore.h.
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namespace {
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extern "C" {
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void xulstore_new_service(nsIXULStore** result);
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nsresult xulstore_set_value(const nsAString* doc, const nsAString* id,
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const nsAString* attr, const nsAString* value);
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nsresult xulstore_has_value(const nsAString* doc, const nsAString* id,
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const nsAString* attr, bool* has_value);
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nsresult xulstore_get_value(const nsAString* doc, const nsAString* id,
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const nsAString* attr, nsAString* value);
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nsresult xulstore_remove_value(const nsAString* doc, const nsAString* id,
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const nsAString* attr);
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XULStoreIterator* xulstore_get_ids(const nsAString* doc, nsresult* result);
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XULStoreIterator* xulstore_get_attrs(const nsAString* doc, const nsAString* id,
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nsresult* result);
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bool xulstore_iter_has_more(const XULStoreIterator*);
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nsresult xulstore_iter_get_next(XULStoreIterator*, nsAString* value);
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void xulstore_iter_free(XULStoreIterator* iterator);
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nsresult xulstore_shutdown();
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}
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// A static reference to the nsIXULStore singleton that JS uses to access
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// the store. Retrieved via mozilla::XULStore::GetService().
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static StaticRefPtr<nsIXULStore> sXULStore;
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} // namespace
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bool XULStoreIterator::HasMore() const { return xulstore_iter_has_more(this); }
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nsresult XULStoreIterator::GetNext(nsAString* item) {
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return xulstore_iter_get_next(this, item);
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}
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void DefaultDelete<XULStoreIterator>::operator()(XULStoreIterator* ptr) const {
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xulstore_iter_free(ptr);
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}
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namespace XULStore {
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already_AddRefed<nsIXULStore> GetService() {
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nsCOMPtr<nsIXULStore> xulStore;
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if (sXULStore) {
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xulStore = sXULStore;
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} else {
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xulstore_new_service(getter_AddRefs(xulStore));
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sXULStore = xulStore;
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mozilla::ClearOnShutdown(&sXULStore);
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}
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return xulStore.forget();
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}
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nsresult SetValue(const nsAString& doc, const nsAString& id,
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const nsAString& attr, const nsAString& value) {
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return xulstore_set_value(&doc, &id, &attr, &value);
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}
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nsresult HasValue(const nsAString& doc, const nsAString& id,
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const nsAString& attr, bool& has_value) {
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return xulstore_has_value(&doc, &id, &attr, &has_value);
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}
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nsresult GetValue(const nsAString& doc, const nsAString& id,
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const nsAString& attr, nsAString& value) {
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return xulstore_get_value(&doc, &id, &attr, &value);
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}
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nsresult RemoveValue(const nsAString& doc, const nsAString& id,
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const nsAString& attr) {
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return xulstore_remove_value(&doc, &id, &attr);
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}
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nsresult GetIDs(const nsAString& doc, UniquePtr<XULStoreIterator>& iter) {
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// We assign the value of the iter here in C++ via a return value
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// rather than in the Rust function via an out parameter in order
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// to ensure that any old value is deleted, since the UniquePtr's
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// assignment operator won't delete the old value if the assignment
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// happens in Rust.
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nsresult result;
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iter.reset(xulstore_get_ids(&doc, &result));
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return result;
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}
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nsresult GetAttrs(const nsAString& doc, const nsAString& id,
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UniquePtr<XULStoreIterator>& iter) {
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// We assign the value of the iter here in C++ via a return value
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// rather than in the Rust function via an out parameter in order
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// to ensure that any old value is deleted, since the UniquePtr's
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// assignment operator won't delete the old value if the assignment
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// happens in Rust.
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nsresult result;
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iter.reset(xulstore_get_attrs(&doc, &id, &result));
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return result;
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}
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nsresult Shutdown() { return xulstore_shutdown(); }
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}; // namespace XULStore
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}; // namespace mozilla
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