forked from mirrors/gecko-dev
68124009fc
This patch replaces the large -intPrefs/-boolPrefs/-stringPrefs flags with
a short-lived, anonymous, shared memory segment that is used to pass the early
prefs.
Removing the bloat from the command line is nice, but more important is the
fact that this will let us pass more prefs at content process start-up, which
will allow us to remove the early/late prefs split (bug 1436911).
Although this mechanism is only used for prefs, it's conceivable that it could
be used for other data that must be received very early by children, and for
which the command line isn't ideal.
Notable details:
- Much of the patch deals with the various platform-specific ways of passing
handles/fds to children.
- Linux and Mac: we use a fixed fd (8) in combination with the new
GeckoChildProcessHost::AddFdToRemap() function (which ensures the child
won't close the fd).
- Android: like Linux and Mac, but the handles get passed via "parcels" and
we use the new SetPrefsFd() function instead of the fixed fd.
- Windows: there is no need to duplicate the handle because Windows handles
are system-wide. But we do use the new
GeckoChildProcessHost::AddHandleToShare() function to add it to the list of
inheritable handles. We also ensure that list is processed on all paths
(MOZ_SANDBOX with sandbox, MOZ_SANDBOX without sandbox, non-MOZ_SANDBOX) so
that the handles are marked as inheritable. The handle is passed via the
-prefsHandle flag.
The -prefsLen flag is used on all platforms to indicate the size of the
shared memory segment.
- The patch also moves the serialization/deserialization of the prefs in/out of
the shared memory into libpref, which is a better spot for it. (This means
Preferences::MustSendToContentProcesses() can be removed.)
MozReview-Commit-ID: 8fREEBiYFvc
--HG--
extra : rebase_source : 7e4c8ebdbcd7d74d6bd2ab3c9e75a6a17dbd8dfe
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