This change moves almost everything in the `upb/` directory up one level, so
that for example `upb/upb/generated_code_support.h` becomes just
`upb/generated_code_support.h`. The only exceptions I made to this were that I
left `upb/cmake` and `upb/BUILD` where they are, mostly because that avoids
conflict with other files and the current locations seem reasonable for now.
The `python/` directory is a little bit of a challenge because we had to merge
the existing directory there with `upb/python/`. I made `upb/python/BUILD` into
the BUILD file for the merged directory, and it effectively loads the contents
of the other BUILD file via `python/build_targets.bzl`, but I plan to clean
this up soon.
PiperOrigin-RevId: 568651768
Remove message/message.h as a hdr from :message_internal
Lock down the visibility of :message_types to upb-only
message/types.h is not an internal header because the definitions there are part of the public surface. But the fact that it needs to exist is an implementation detail that should remain opaque, so make it a private dep.
PiperOrigin-RevId: 558960776
At some point, the typedef for upb_MiniTable, upb_MiniTableEnum and upb_MiniTableExtension were moved out of the internal headers and into the public ones, which requires usages of internal/file.h to import / resolve those public headers before it.
PiperOrigin-RevId: 548836379
pkg_files() has some odd quirks, like breaking if a filename exists in multiple directories. filegroup() does everything we need, without these quirks.
PiperOrigin-RevId: 547523447
This will move us towards keeping all these encapsulation breaks in a common place.
This also removes the IFTTT blocks. Keeping IFTTT blocks for each language would become unmanageable, but going forward we will know to look in `//third_party/upb/bits` whenever the internal data structures in upb change.
PiperOrigin-RevId: 547494495
After this change, `mini_table` only has MiniTable definitions themselves. Everything having to do with the MiniDescriptor wire format is in `mini_descriptor`.
Also rearranged some of the files in mini_table to have better structure for `internal/`.
This CL contains no functional change.
PiperOrigin-RevId: 543529112
`upb_MiniTableField_CType()` was directly checking the `descriptortype` in `upb_MiniTableField`, without taking `field->mode` into account -- which can indicate that an int32 is actually an enum, or that bytes is really a string.
PiperOrigin-RevId: 537975302
The `kUpb_DecodeOption_ExperimentalAllowUnlinked` flag to the decoder will enable the new behavior. When that flag is not passed, tree shaking with the old model will still be possible.
"Dynamic tree shaking" in upb is a feature that allows messages to be parsed even if the MiniTables have not been fully linked. Unlinked sub-message fields can be parsed by preserving their data in the unknown fields. If the application later discovers that the message field is actually needed, the MiniTable can be patched to properly link that field, and existing message instances can "promote" the data from the unknown fields to an actual message of the correct type.
Before this change, dynamic tree shaking stored unparsed message data in the unknown fields of the *parent*. In effect, we were treating the field as if it did not exist at all. This meant that parsing an unlinked field did not affect the hasbits or oneof cases of the parent, nor did it create a `upb_Array` or `upb_Map` for array/map fields. Only when a message was linked and promoted did any of these things occur.
While this model had some amount of conceptual simplicity, it caused significant problems with oneofs. When multiple fields inside a single oneof are parsed from the wire, order matters, because later oneof fields must overwrite earlier ones. Dynamic tree shaking can mean that some fields in a oneof are linked while others are not. It is essential that we preserve this ordering semantic even when dynamic tree shaking is being used, but it is difficult to do if the oneof's data can be split between linked fields (which have been reified into parsed field data) and unlinked fields (whose data lives in the unknown fields of the parent).
To solve this problem, this CL changes the representation for unlinked fields. Instead of being placed in the parent's unknown fields, we create an actual message instance for each unlinked message we parse, but we use a placeholder "empty message" MiniTable as the message's type. All of the message's data will therefore be placed into the "empty message's" unknown fields. But unlike before, this "empty message" is actually present according to the hasbits, oneof case, and `upb_Array`/`upb_Map` of the parent. This means that all of the oneof presence logic works as normal.
Since the MiniTable can be patched at any time, we need a bit in the message instance itself to signal whether a pointer to a sub-message is an "empty message" or not. When dynamic tree shaking is in use, all users must be capable of recognizing an empty message and acting accordingly (promoting, etc) even if the MiniTable itself says that the field is linked.
Because dynamic tree shaking imposes this extra requirement on users, we require that users pass an extra option to the decoder to allow parsing of unlinked sub-messages. Many existing users of upb (Ruby, PHP, Python, etc) will always have fully-linked MiniTables, so there is no reason for them to add extra logic to handle empty messages. By omitting the `kUpb_DecodeOption_ExperimentalAllowUnlinked` option, they will be relieved of the duty to check the tagged pointer that would indicate an empty, unlinked message.
For existing users of dynamic tree shaking, there are three main changes:
1. The APIs in message/promote.h have changed, and users will need to update to the new interfaces.
2. The model for maps has changed slightly. Before, we required that map entries always had their values linked; for dynamic tree shaking to apply to maps, we required that the *entry* was left unlinked, not the entry's value. In the new model, that is reversed: map entries must always be linked, but a map entry's value can be unlinked.
3. The presence model for unlinked fields has changed. Unlinked fields will now register as "present" from the perspective of hasbits, oneof cases, and array/map entries. Users must test the tagged pointer to know if a message is of the correct, linked type or whether it is a placeholder "empty" message. There is a new function `upb_Message_GetTaggedMessagePtr()`, as well as a new accessor `upb_MessageValue.tagged_msg_val` that can be used to read and test the tagged pointer directly.
PiperOrigin-RevId: 535288031
Prior to this change, all sub-messages and sub-enums were initialized to NULL. Going forward, sub-messages will need to be initialized differently than sub-enums.
To facilitate this, we change the order of subs, so that sub-messages always come before sub-enums. Then when we allocate the subs, we can initialize them in two separate loops.
This unfortunately requires one extra iteration over the fields if any closed enums are present, to adjust the `submsg_index` according to how many sub-messages were seen.
This CL is the first step towards changing how we handle unlinked sub-messages.
PiperOrigin-RevId: 529100966
The fields of upb_MiniTableField are intended to be internal-only, accessed only through public functions like `upb_MiniTable_GetSubMessageTable()`. But over time, clients have started accessing many of these fields directly. This is an easy mistake to make, as there is no clear signal that the fields should not be used in applications. This makes the implementation difficult to change without breaking users.
The new `UPB_PRIVATE()` macro appends an unpredictable string to each private symbol. This makes it very difficult to accidentally use a private symbol, since users would need to write something like `field->submsg_index_dont_copy_me__upb_internal_use_only`. This is still possible to do, but it leaves a clear wart in the code showing that an an encapsulation break has occurred. The `UPB_PRIVATE()` macro itself is defined in `port/def.inc`, which users cannot include directly.
Once we land this, more such CLs will follow for the other fields of `upb_MiniTable*`. We will add inline functions as needed to provide the semantic functionality needed by users.
PiperOrigin-RevId: 523166901
The new API upb_MiniTable_Link() links all sub-messages and sub-enums at a single time, by accepting an array of sub-tables and sub-enums. The order of these sub-tables can be queried using a separate function `upb_MiniTable_GetSubList()`, and this information is added to `CodeGeneratorRequest` as part of the upb-specific info.
PiperOrigin-RevId: 513970874
The upb convention is that "_Build()" means to also allocate, which this function does not do, so rename it as "_Init()" to free up the name for a future function that does allocate.
PiperOrigin-RevId: 510282736
According to https://en.cppreference.com/w/c/program/setjmp automatic variables
modified in a function calling setjmp can have indeterminate values. Instead,
refactor all functions calling setjmp so that the function calling setjmp
doesn’t have any local variables.
Part II: Mini table decoder.
PiperOrigin-RevId: 509644446
Eric Salo
Protobuf Team Bot
Adam Cozzette
Joshua Haberman
Mike Kruskal