This doesn't change the way C++ code uses static prefs. But it does slightly
change how Rust code uses static prefs, specifically the name generated by
bindgen is slightly different.
The commit also improves some comments.
Differential Revision: https://phabricator.services.mozilla.com/D35764
--HG--
extra : rebase_source : 13cf215aeb713e188103ef0cd04d094aa150853e
Static VarCache prefs have setters. These are dangerous because they can
violate the primary invariant of VarCache prefs, which is that the global
variable always matches the pref value in the table.
Fortunately they are only used in tests, and we can use vanilla pref setters
instead, and get rid of the VarCache setters.
Differential Revision: https://phabricator.services.mozilla.com/D35632
--HG--
extra : moz-landing-system : lando
We can initialize the StaticPrefs as soon as the SharedMap object is created outside the parent process.
Additionally when resetting the preferences to their default values, we no longer modify the `Once` StaticPrefs as they are immutable, only the underlying preference.
Differential Revision: https://phabricator.services.mozilla.com/D35263
--HG--
extra : moz-landing-system : lando
When testing, the Preference behing a `Once` StaticPrefs should never get modified as this indicate that this StaticPrefs should have a `Live` policy instead.
This is placed behind the preferences.check.once.policy which will get enabled during automated testing.
Differential Revision: https://phabricator.services.mozilla.com/D34107
--HG--
extra : moz-landing-system : lando
Rather than attempting to determine when the Once policy StaticPrefs should be set we initialize them when one of the getter gets called. They become immutable after that.
In a future change we will prevent those values to ever be changed once they have been initialized.
Differential Revision: https://phabricator.services.mozilla.com/D33440
--HG--
extra : moz-landing-system : lando
When we create the SharedPreferenceMap we store the value of the Once pref in it. All child processes will now read the Once pref from the read-only SharedPreferenceMap.
This makes the Once prefs immutable once we start the first child process.
Differential Revision: https://phabricator.services.mozilla.com/D33421
--HG--
extra : moz-landing-system : lando
This allows for an entry to not show in about:config.
This will be used to store Once StaticPrefs once they become immutable.
Differential Revision: https://phabricator.services.mozilla.com/D33420
--HG--
extra : moz-landing-system : lando
And set the underlying preference. StaticPrefs::Set becomes a convenience access to the original preference which is what gfxPrefs was actually doing.
Differential Revision: https://phabricator.services.mozilla.com/D31749
--HG--
extra : moz-landing-system : lando
And set the underlying preference. StaticPrefs::Set becomes a convenience access to the original preference which is what gfxPrefs was actually doing.
Differential Revision: https://phabricator.services.mozilla.com/D31749
--HG--
extra : moz-landing-system : lando
And set the underlying preference. StaticPrefs::Set becomes a convenience access to the original preference which is what gfxPrefs was actually doing.
Differential Revision: https://phabricator.services.mozilla.com/D31749
--HG--
extra : moz-landing-system : lando
Mechanical change from Matcher::match(...) to Matcher::operator()(...).
This will now permit the use of generic lambdas, and facilitate the
implementation of multi-lambda match.
Differential Revision: https://phabricator.services.mozilla.com/D24889
--HG--
extra : moz-landing-system : lando
We want to publish a multi-architecture AAR for GeckoView which includes
a single omni.ja, but we archicture-specific changes in greprefs.js that
prevent this from working. This patch causes us to try to read an
architecture-specific greprefs.js first, which will be provided by the
packaging process for the fat AAR.
Differential Revision: https://phabricator.services.mozilla.com/D22526
--HG--
extra : moz-landing-system : lando
This will be used by GeckoView to set initial pref values that would
normally come from prefs.js or similar on desktop and Fennec.
Differential Revision: https://phabricator.services.mozilla.com/D9820
Everything that goes in a PLDHashtable (and its derivatives, like
nsTHashtable) needs to inherit from PLDHashEntryHdr. But through a lack
of enforcement, copy constructors for these derived classes didn't
explicitly invoke the copy constructor for PLDHashEntryHdr (and the
compiler didn't invoke the copy constructor for us). Instead,
PLDHashTable explicitly copied around the bits that the copy constructor
would have.
The current setup has two problems:
1) Derived classes should be using move construction, not copy
construction, since anything that's shuffling hash table keys/entries
around will be using move construction.
2) Derived classes should take responsibility for transferring bits of
superclass state around, and not rely on something else to handle that.
The second point is not a huge problem for PLDHashTable (PLDHashTable
only has to copy PLDHashEntryHdr's bits in a single place), but future
hash table implementations that might move entries around more
aggressively would have to insert compensation code all over the
place. Additionally, if moving entries is implemented via memcpy (which
is quite common), PLDHashTable copying around bits *again* is
inefficient.
Let's fix all these problems in one go, by:
1) Explicitly declaring the set of constructors that PLDHashEntryHdr
implements (and does not implement). In particular, the copy
constructor is deleted, so any derived classes that attempt to make
themselves copyable will be detected at compile time: the compiler
will complain that the superclass type is not copyable.
This change on its own will result in many compiler errors, so...
2) Change any derived classes to implement move constructors instead of
copy constructors. Note that some of these move constructors are,
strictly speaking, unnecessary, since the relevant classes are moved
via memcpy in nsTHashtable and its derivatives.
In order to avoid the overhead of doing a full pref lookup for every static
var cache at content process startup, we currently assume that the default
value of any static varcache pref will always match the default value of its
database entry (as long as the pref isn't locked). This lets us only perform
lookups for preferences which have a user value, or are locked.
If the default values of those preferences are changed in a bundled preference
file, though, the varcache value will be correct in the parent process, but
not in child processes. Since this is an easy mistake to make, we should
assert that it doesn't happen.
Note: This change only affects applications which use e10s. Applications like
Thunderbird can still override default values of any static pref with
impunity. Repacks and distributors can only do so by changing user values or
locking the preference after the change (which is the standard practice for
enterprise deployments).
MozReview-Commit-ID: JMHQBrp9HN
--HG--
extra : source : 1b389b00030ed38cdb3543aa5d1a67795be47565
extra : amend_source : 16f2dccf40664db9daa42a6edaabb933acbc6204
In order to avoid the overhead of doing a full pref lookup for every static
var cache at content process startup, we currently assume that the default
value of any static varcache pref will always match the default value of its
database entry (as long as the pref isn't locked). This lets us only perform
lookups for preferences which have a user value, or are locked.
If the default values of those preferences are changed in a bundled preference
file, though, the varcache value will be correct in the parent process, but
not in child processes. Since this is an easy mistake to make, we should
assert that it doesn't happen.
Note: This change only affects applications which use e10s. Applications like
Thunderbird can still override default values of any static pref with
impunity. Repacks and distributors can only do so by changing user values or
locking the preference after the change (which is the standard practice for
enterprise deployments).
MozReview-Commit-ID: JMHQBrp9HN
--HG--
extra : rebase_source : 2f51295def52cbca316227f202158cb22656441a
Preference callbacks consume a non-trivial amount of memory, which adds up
fast given the number of callbacks we register.
Many of our consumers, however, register a large number of callbacks with the
same function and closure object, but different preference names or prefixes.
Since our callback matching is nothing more complicated than iteration over
all of our registered callbacks, there's nothing that prevents us from
combining all of these into a single callback, with an array of preferences
rather than a single string.
And since we already allocate an extra 8 bytes for each callback object, we
can add a variant tag without increasing our allocation size.
MozReview-Commit-ID: I497lWfMUp3
--HG--
extra : rebase_source : bac374d9a590c325728551d1669ebc6ef8ca3884
The preference storage in the shared memory snapshot is much more compact than
the dynamic hashtable, and is already mapped in memory, so there's no need to
keep the full hashtable in memory in the parent process after the snapshot is
created.
This patch empties the hashtable and the name string arena after the snapshot.
It also removes the accounting for preferences which have changed after init,
since those are, by definition, exactly the set of entries in the dynamic
hashtable.
MozReview-Commit-ID: L6VGq2z4foH
--HG--
extra : intermediate-source : 6c72dc1bff88e81f6c754b0971a44b9592d17ee1
extra : absorb_source : 321a2ac3a2d26bbe089c2183e25fccc85d8689f3
extra : source : 599895de063ef005dbd34847db9ee555410a878f
extra : histedit_source : 5905f462ea3d1c935addbe847e53a7d8589f6f38
With the parent sending a snapshot of its preference state at content process
startup, we're guaranteed to have the full set of built-in preferences in the
shared map at initialization time, so there's no need to load them again.
This also applies to static preference default values, so we skip setting
those, as well.
However, we do need to make sure that we update static preference cache
entries whose default values don't match the value in the shared map, since
they may have been changed by user preference files. In order to deal with
that, we iterate over all preferences in the map, and dispatch callbacks for
any that have user values.
MozReview-Commit-ID: DlRUbg7Qor3
--HG--
extra : intermediate-source : 7f4cc96fae1212cb2220770ac7311b9cc51af744
extra : absorb_source : 7c71a5994c26c2a1e34b291947a49ac5b3d633cb
extra : source : dc7ec17179d1961d91b897cec9f409786363ec9e
extra : histedit_source : f7c7a935e72af65446c2abc502744a066a6e2ae5%2C5cd3235724af3e5f22b772de171cea735ec4c047
This patch changes our preference look-up behavior to first check the dynamic
hashtable, and then fall back to the shared map.
In order for this to work, we need to make several other changes as well:
- Attempts to modify a preference that only exists in the shared table
requires that we copy it to the dynamic table, and change the value of the
new entry.
- Attempts to clear a user preference with no default value, but which also
exists in the shared map, requires that we keep an entry in the dynamic
table to mask the shared entry. To make this work, we change the type of
these entries to None, and ignore them during look-ups and iteration.
- Iteration needs to take both hashtables into consideration. The
serialization iterator for changed preferences only needs to care about
dynamic values, so it remains unchanged. Most of the others need to use
PrefsIter() instead.
MozReview-Commit-ID: 9PWmSZxoC9Z
--HG--
extra : intermediate-source : b4f9178f132de2b5f7064df9a9e1b489ea6576c3
extra : absorb_source : 57fd90ea8195adff9d314b813e94dc643fd085e4
extra : source : 5051f15fc2005667cfe76ccae0afb1fb0657c103
extra : histedit_source : 2ebf0e90a5e1b65795b20e9269def7cbbf2d1f11
Since lookups in the snapshotted hashtable are currently O(log n) rather than
O(1), they're expected to be slightly more expensive than the previous
purely-dynamic lookups.
In general, I expect this not to be a major issue. The main concern is pref
cache lookups while initializing the database. Initialization in the parent
process will still always use only a dynamic hashtable, so the performance
characteristics there won't change.
In the child process, though, we'll still need to notify observers of
preferences in the snapshot when they have user values, which could require
any number of lookups at startup (though in practice probably will not).
This patch solves that problem by caching the wrapper for the current known
preference value when dispatching callbacks, and optimizing lookups for that
value when it is present.
MozReview-Commit-ID: 2CAn0rM0bE9
--HG--
extra : intermediate-source : 8eff817d2f7e07409269899c048a9091220dec07
extra : absorb_source : 2609b4d9d1d994e19f884de1d1fba38347d35729
extra : source : faef4df47b2089592df7637f5b8f4ae193e98046
extra : histedit_source : b8a1e41ac70ad3eea354c375fb5f6813c0284a0d
For memory efficiency in content processes, we need to be able to store
changed preferences in a separate dynamic hashtable when their values don't
match the snapshot values.
That makes iteration over the full set of preferences somewhat more
complicated, since not only do we need to iterate over two tables, but we also
need to ignore preferences in the snapshot table if they also exist in the
dynamic hashtable.
This patch solves that problem by adding an iterator helper which iterates
over values in both tables, and skips values in the static table if they also
exist in the dynamic table.
In order to support completely deleting preferences that exist in the base
table, it also ignores all dynamic entries with the None type, so that they
can completely mask deleted base table values.
MozReview-Commit-ID: LCIwyPJMByj
--HG--
extra : intermediate-source : f9362cf1add47c2f62529e42764ed6088d274170
extra : absorb_source : fdaf890e85af43271cffd2371cf6fbf408c6cc50
extra : source : d344247b870668f53fa645e72bda4bb4309346c8
extra : histedit_source : 6cd565727eff617eeba386b563477ce4d4bfbd0a
The in-memory format of shared-memory preferences is significantly different
from the format used by dynamic preferences, which means that we need
different classes to access their properties.
Virtual classes would be a potential solution to this problem, but I don't
think the performance characteristics would be acceptable for preferences
code. And since the wrapper classes used for static prefs are temporary, they
would add the additional snag of figuring out how to keep a valid pointer
alive.
So, instead, this patch adds a wrapper class that can access either type of
preference, based on known type flags in a Variant. It also moves some of the
logic for deciding which preference value to return to the wrapper, so that it
doesn't need to be duplicated for each representation.
MozReview-Commit-ID: LameIIbYcD3
--HG--
extra : intermediate-source : ce379eaab17905f39f1665c3e40f683ebd3f8824
extra : absorb_source : eb5ed3380613e070eff5f9c9501e2640a6d398f9
extra : source : 83d98ea5ebaccded8a20929c0f3316e5618f1f76
extra : histedit_source : 634d033608f72294f6fc34d4449fe0f003758c74
This is based on the SharedStringMap that's currently used for shared memory
string bundles.
When the parent process is ready to launch its first content process, it
creates a snapshot of the current state of the preference database, maps that
as read-only, and shares it with each content process. Look-ups in the
snapshotted map are done entirely using data in the shared memory region. It
doesn't require any additional per-process state data.
MozReview-Commit-ID: BdTUhak7dmS
--HG--
extra : intermediate-source : 434106f1b75e3ba900912f261bd22a1b7f5c931d
extra : absorb_source : 647ad37590448ad3c1eb8eb512bf671f262fa96e
extra : source : 68bb03c63b3cee1d47cbddfd3abf919f5783c04b
extra : histedit_source : 2228a9f8395929f5072a3c5ebda6ae3221e4a62d
Once the majority of preferences are stored in a read-only shared map, it
won't be possible to modify the access counts in their entries. Which means we
need a separate map for the access counts.
Fortunately, this code is only active in debug builds, so it shouldn't affect
release users. And the net impact on memory usage of this patchset will still
be decidedly downward.
MozReview-Commit-ID: EuLXlMQJP1M
--HG--
extra : intermediate-source : c490838c8329f6b0c21fa57ef078c44bf7a9ba8d
extra : absorb_source : 37a0f7a5fecba6c28bd6ce30644543c6d60ac823
extra : source : 4a8fbb472c91f13554cac3d0ea638cf9f368ff11
extra : histedit_source : 0e5a5f1cded97bcc959be15aa7194c017fd7efcc%2Cc0ae2011b9b40e6445ee366303f8ec4bb10cc87b
The preference storage in the shared memory snapshot is much more compact than
the dynamic hashtable, and is already mapped in memory, so there's no need to
keep the full hashtable in memory in the parent process after the snapshot is
created.
This patch empties the hashtable and the name string arena after the snapshot.
It also removes the accounting for preferences which have changed after init,
since those are, by definition, exactly the set of entries in the dynamic
hashtable.
MozReview-Commit-ID: L6VGq2z4foH
--HG--
extra : source : 599895de063ef005dbd34847db9ee555410a878f
extra : histedit_source : a3bcc573e29a60a61abaa1b2cc6daa87d6b1a946
With the parent sending a snapshot of its preference state at content process
startup, we're guaranteed to have the full set of built-in preferences in the
shared map at initialization time, so there's no need to load them again.
This also applies to static preference default values, so we skip setting
those, as well.
However, we do need to make sure that we update static preference cache
entries whose default values don't match the value in the shared map, since
they may have been changed by user preference files. In order to deal with
that, we iterate over all preferences in the map, and dispatch callbacks for
any that have user values.
MozReview-Commit-ID: DlRUbg7Qor3
--HG--
extra : source : dc7ec17179d1961d91b897cec9f409786363ec9e
extra : histedit_source : 285a99038c6731fed427cd8bc783b65f56e34ebb
This patch changes our preference look-up behavior to first check the dynamic
hashtable, and then fall back to the shared map.
In order for this to work, we need to make several other changes as well:
- Attempts to modify a preference that only exists in the shared table
requires that we copy it to the dynamic table, and change the value of the
new entry.
- Attempts to clear a user preference with no default value, but which also
exists in the shared map, requires that we keep an entry in the dynamic
table to mask the shared entry. To make this work, we change the type of
these entries to None, and ignore them during look-ups and iteration.
- Iteration needs to take both hashtables into consideration. The
serialization iterator for changed preferences only needs to care about
dynamic values, so it remains unchanged. Most of the others need to use
PrefsIter() instead.
MozReview-Commit-ID: 9PWmSZxoC9Z
--HG--
extra : source : 5051f15fc2005667cfe76ccae0afb1fb0657c103
extra : histedit_source : 28f2216b8c1e9d08ed9b2c03910d4b8434e55421
Since lookups in the snapshotted hashtable are currently O(log n) rather than
O(1), they're expected to be slightly more expensive than the previous
purely-dynamic lookups.
In general, I expect this not to be a major issue. The main concern is pref
cache lookups while initializing the database. Initialization in the parent
process will still always use only a dynamic hashtable, so the performance
characteristics there won't change.
In the child process, though, we'll still need to notify observers of
preferences in the snapshot when they have user values, which could require
any number of lookups at startup (though in practice probably will not).
This patch solves that problem by caching the wrapper for the current known
preference value when dispatching callbacks, and optimizing lookups for that
value when it is present.
MozReview-Commit-ID: 2CAn0rM0bE9
--HG--
extra : source : faef4df47b2089592df7637f5b8f4ae193e98046
extra : histedit_source : 3af498eac94f481523e86c31b9c2b3e55b3cd1fb
For memory efficiency in content processes, we need to be able to store
changed preferences in a separate dynamic hashtable when their values don't
match the snapshot values.
That makes iteration over the full set of preferences somewhat more
complicated, since not only do we need to iterate over two tables, but we also
need to ignore preferences in the snapshot table if they also exist in the
dynamic hashtable.
This patch solves that problem by adding an iterator helper which iterates
over values in both tables, and skips values in the static table if they also
exist in the dynamic table.
In order to support completely deleting preferences that exist in the base
table, it also ignores all dynamic entries with the None type, so that they
can completely mask deleted base table values.
MozReview-Commit-ID: LCIwyPJMByj
--HG--
extra : source : d344247b870668f53fa645e72bda4bb4309346c8
extra : histedit_source : bb670afc815f3953ccadebddd04962836569b281
The in-memory format of shared-memory preferences is significantly different
from the format used by dynamic preferences, which means that we need
different classes to access their properties.
Virtual classes would be a potential solution to this problem, but I don't
think the performance characteristics would be acceptable for preferences
code. And since the wrapper classes used for static prefs are temporary, they
would add the additional snag of figuring out how to keep a valid pointer
alive.
So, instead, this patch adds a wrapper class that can access either type of
preference, based on known type flags in a Variant. It also moves some of the
logic for deciding which preference value to return to the wrapper, so that it
doesn't need to be duplicated for each representation.
MozReview-Commit-ID: LameIIbYcD3
--HG--
extra : source : 83d98ea5ebaccded8a20929c0f3316e5618f1f76
extra : histedit_source : b3fc33ea04357e15323c7bcb1d02e73c1a9b0c76
This is based on the SharedStringMap that's currently used for shared memory
string bundles.
When the parent process is ready to launch its first content process, it
creates a snapshot of the current state of the preference database, maps that
as read-only, and shares it with each content process. Look-ups in the
snapshotted map are done entirely using data in the shared memory region. It
doesn't require any additional per-process state data.
MozReview-Commit-ID: BdTUhak7dmS
--HG--
extra : source : 68bb03c63b3cee1d47cbddfd3abf919f5783c04b
Once the majority of preferences are stored in a read-only shared map, it
won't be possible to modify the access counts in their entries. Which means we
need a separate map for the access counts.
Fortunately, this code is only active in debug builds, so it shouldn't affect
release users. And the net impact on memory usage of this patchset will still
be decidedly downward.
MozReview-Commit-ID: EuLXlMQJP1M
--HG--
extra : source : 4a8fbb472c91f13554cac3d0ea638cf9f368ff11
The preference storage in the shared memory snapshot is much more compact than
the dynamic hashtable, and is already mapped in memory, so there's no need to
keep the full hashtable in memory in the parent process after the snapshot is
created.
This patch empties the hashtable and the name string arena after the snapshot.
It also removes the accounting for preferences which have changed after init,
since those are, by definition, exactly the set of entries in the dynamic
hashtable.
MozReview-Commit-ID: L6VGq2z4foH
--HG--
extra : rebase_source : d4ba3b6a0ae3d46cf797fd6aaf4502d7a74f49c9
extra : absorb_source : e8b2648578a880d43a5a3a075e60ce1433c737ce
With the parent sending a snapshot of its preference state at content process
startup, we're guaranteed to have the full set of built-in preferences in the
shared map at initialization time, so there's no need to load them again.
This also applies to static preference default values, so we skip setting
those, as well.
However, we do need to make sure that we update static preference cache
entries whose default values don't match the value in the shared map, since
they may have been changed by user preference files. In order to deal with
that, we iterate over all preferences in the map, and dispatch callbacks for
any that have user values.
MozReview-Commit-ID: DlRUbg7Qor3
--HG--
extra : rebase_source : 93cad19e27d3aaf5d4cad358cdebd6d80b76f668
extra : absorb_source : 06cb8911c92b66f8863b5e184d88b923cdbd6adc
This patch changes our preference look-up behavior to first check the dynamic
hashtable, and then fall back to the shared map.
In order for this to work, we need to make several other changes as well:
- Attempts to modify a preference that only exists in the shared table
requires that we copy it to the dynamic table, and change the value of the
new entry.
- Attempts to clear a user preference with no default value, but which also
exists in the shared map, requires that we keep an entry in the dynamic
table to mask the shared entry. To make this work, we change the type of
these entries to None, and ignore them during look-ups and iteration.
- Iteration needs to take both hashtables into consideration. The
serialization iterator for changed preferences only needs to care about
dynamic values, so it remains unchanged. Most of the others need to use
PrefsIter() instead.
MozReview-Commit-ID: 9PWmSZxoC9Z
--HG--
extra : rebase_source : 054f4dcd534b41da889304c3c6d3365d56e8edda
extra : absorb_source : de81199e174f2d3604c803a5c016ba2f3baf3558
Since lookups in the snapshotted hashtable are currently O(log n) rather than
O(1), they're expected to be slightly more expensive than the previous
purely-dynamic lookups.
In general, I expect this not to be a major issue. The main concern is pref
cache lookups while initializing the database. Initialization in the parent
process will still always use only a dynamic hashtable, so the performance
characteristics there won't change.
In the child process, though, we'll still need to notify observers of
preferences in the snapshot when they have user values, which could require
any number of lookups at startup (though in practice probably will not).
This patch solves that problem by caching the wrapper for the current known
preference value when dispatching callbacks, and optimizing lookups for that
value when it is present.
MozReview-Commit-ID: 2CAn0rM0bE9
--HG--
extra : rebase_source : 4a7e9611efe5b554309df18f7b18ba9c807b72b2
extra : absorb_source : 185442bd69d616c2d2512df954dde7d1b54f2c30
For memory efficiency in content processes, we need to be able to store
changed preferences in a separate dynamic hashtable when their values don't
match the snapshot values.
That makes iteration over the full set of preferences somewhat more
complicated, since not only do we need to iterate over two tables, but we also
need to ignore preferences in the snapshot table if they also exist in the
dynamic hashtable.
This patch solves that problem by adding an iterator helper which iterates
over values in both tables, and skips values in the static table if they also
exist in the dynamic table.
In order to support completely deleting preferences that exist in the base
table, it also ignores all dynamic entries with the None type, so that they
can completely mask deleted base table values.
MozReview-Commit-ID: LCIwyPJMByj
--HG--
extra : rebase_source : 833abea0620f75410f9922e5d4b5cf36b84e9e50
extra : absorb_source : 89690c674120eb99ad25804408b1c3864c7b1fc8
The in-memory format of shared-memory preferences is significantly different
from the format used by dynamic preferences, which means that we need
different classes to access their properties.
Virtual classes would be a potential solution to this problem, but I don't
think the performance characteristics would be acceptable for preferences
code. And since the wrapper classes used for static prefs are temporary, they
would add the additional snag of figuring out how to keep a valid pointer
alive.
So, instead, this patch adds a wrapper class that can access either type of
preference, based on known type flags in a Variant. It also moves some of the
logic for deciding which preference value to return to the wrapper, so that it
doesn't need to be duplicated for each representation.
MozReview-Commit-ID: LameIIbYcD3
--HG--
extra : rebase_source : bf986b6008123661547949f615c8416403321835
extra : absorb_source : e86aae959325a9c3198e0259468a47a656739278
This is based on the SharedStringMap that's currently used for shared memory
string bundles.
When the parent process is ready to launch its first content process, it
creates a snapshot of the current state of the preference database, maps that
as read-only, and shares it with each content process. Look-ups in the
snapshotted map are done entirely using data in the shared memory region. It
doesn't require any additional per-process state data.
MozReview-Commit-ID: BdTUhak7dmS
--HG--
extra : rebase_source : e7cb96dd52380f2ed2fbd79b4e157e4efab65cb0
extra : absorb_source : ed95ed85388875353458eb65e41727e606ebf097
Once the majority of preferences are stored in a read-only shared map, it
won't be possible to modify the access counts in their entries. Which means we
need a separate map for the access counts.
Fortunately, this code is only active in debug builds, so it shouldn't affect
release users. And the net impact on memory usage of this patchset will still
be decidedly downward.
MozReview-Commit-ID: EuLXlMQJP1M
--HG--
extra : rebase_source : 6a32f03c37622093c67e7ee7a0e935d1e63c4fc8
This reduced the additional string duplication that we currently do every time
we add a preference observer.
It changes the string that we store in the observer objects to be absolute,
rather than relative to the branch, but keeps the semantics the same, by
resolving the full preference name in the places we were previously matching
by relative string.
This actually has the effect of simplifying a lot of code, since the absolute
preference name is usually what we want.
MozReview-Commit-ID: 10WjHb0tNGB
--HG--
extra : rebase_source : b3cb0ba103fc239e42459e77cd389db0b5ecde18
Most preference callbacks use literal strings for their domain filters, which
means that there's no need to make copies of them at all. Currently, however,
every preference observer node makes a separate heap-allocated copy of its
domain string.
This patch switches the domain string storage to nsCString instances, which
dramatically reduces the amount of unnecessary copies, at the expense of
making the callback nodes slightly larger.
MozReview-Commit-ID: 8NA3t2JS2UI
--HG--
extra : rebase_source : 628ad9af65cec16fb8be0c8dddc608b5ee5602e2
Some of the definitions are needed for the headers removal in
following patches.
MozReview-Commit-ID: BCj7U7RgBLj
--HG--
extra : rebase_source : e8e437f76c4db6ec930ea0481b6c1a38129a5477
extra : source : a1c42220e5070fa4beea438859ab0daec3f3fe7b
This removes our ability to detect when an unnecessary override is occurring,
but it's necessary for Thunderbird to work.
MozReview-Commit-ID: GZYLnEEVuvd
--HG--
extra : rebase_source : ff3f7163252176d78ecf11589cebeae99f987985
