|
|
|
|
// Protocol Buffers - Google's data interchange format
|
|
|
|
|
// Copyright 2023 Google LLC. All rights reserved.
|
|
|
|
|
//
|
|
|
|
|
// Use of this source code is governed by a BSD-style
|
|
|
|
|
// license that can be found in the LICENSE file or at
|
|
|
|
|
// https://developers.google.com/open-source/licenses/bsd
|
|
|
|
|
|
|
|
|
|
#ifndef UPB_MESSAGE_ACCESSORS_H_
|
|
|
|
|
#define UPB_MESSAGE_ACCESSORS_H_
|
|
|
|
|
|
|
|
|
|
#include <stddef.h>
|
|
|
|
|
#include <stdint.h>
|
|
|
|
|
#include <string.h>
|
|
|
|
|
|
|
|
|
|
#include "upb/base/descriptor_constants.h"
|
|
|
|
|
#include "upb/base/string_view.h"
|
|
|
|
|
#include "upb/mem/arena.h"
|
|
|
|
|
#include "upb/message/array.h"
|
|
|
|
|
#include "upb/message/internal/accessors.h"
|
|
|
|
|
#include "upb/message/internal/array.h"
|
|
|
|
|
#include "upb/message/internal/map.h"
|
|
|
|
|
#include "upb/message/internal/message.h"
|
|
|
|
|
#include "upb/message/internal/tagged_ptr.h"
|
|
|
|
|
#include "upb/message/map.h"
|
|
|
|
|
#include "upb/message/message.h"
|
|
|
|
|
#include "upb/message/tagged_ptr.h"
|
|
|
|
|
#include "upb/message/value.h"
|
|
|
|
|
#include "upb/mini_table/enum.h"
|
|
|
|
|
#include "upb/mini_table/extension.h"
|
|
|
|
|
#include "upb/mini_table/field.h"
|
|
|
|
|
#include "upb/mini_table/internal/field.h"
|
|
|
|
|
#include "upb/mini_table/internal/message.h"
|
|
|
|
|
#include "upb/mini_table/message.h"
|
|
|
|
|
#include "upb/mini_table/sub.h"
|
|
|
|
|
|
|
|
|
|
// Must be last.
|
|
|
|
|
#include "upb/port/def.inc"
|
|
|
|
|
|
|
|
|
|
#ifdef __cplusplus
|
|
|
|
|
extern "C" {
|
|
|
|
|
#endif
|
|
|
|
|
|
|
|
|
|
// Functions ending in BaseField() take a (upb_MiniTableField*) argument
|
|
|
|
|
// and work only on non-extension fields.
|
|
|
|
|
//
|
|
|
|
|
// Functions ending in Extension() take a (upb_MiniTableExtension*) argument
|
|
|
|
|
// and work only on extensions.
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE void upb_Message_Clear(upb_Message* msg, const upb_MiniTable* m);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE void upb_Message_ClearBaseField(upb_Message* msg,
|
|
|
|
|
const upb_MiniTableField* f);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE void upb_Message_ClearExtension(upb_Message* msg,
|
|
|
|
|
const upb_MiniTableExtension* e);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE bool upb_Message_HasBaseField(const upb_Message* msg,
|
|
|
|
|
const upb_MiniTableField* f);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE bool upb_Message_HasExtension(const upb_Message* msg,
|
|
|
|
|
const upb_MiniTableExtension* e);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE void upb_Message_SetBaseField(upb_Message* msg,
|
|
|
|
|
const upb_MiniTableField* f,
|
|
|
|
|
const void* val);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE bool upb_Message_SetExtension(upb_Message* msg,
|
|
|
|
|
const upb_MiniTableExtension* e,
|
|
|
|
|
const void* val, upb_Arena* a);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE upb_MessageValue
|
|
|
|
|
upb_Message_GetField(const upb_Message* msg, const upb_MiniTableField* f,
|
|
|
|
|
upb_MessageValue default_val);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE const upb_Array* upb_Message_GetArray(
|
|
|
|
|
const upb_Message* msg, const upb_MiniTableField* f);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE bool upb_Message_GetBool(const upb_Message* msg,
|
|
|
|
|
const upb_MiniTableField* f,
|
|
|
|
|
bool default_val);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE double upb_Message_GetDouble(const upb_Message* msg,
|
|
|
|
|
const upb_MiniTableField* field,
|
|
|
|
|
double default_val);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE float upb_Message_GetFloat(const upb_Message* msg,
|
|
|
|
|
const upb_MiniTableField* f,
|
|
|
|
|
float default_val);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE int32_t upb_Message_GetInt32(const upb_Message* msg,
|
|
|
|
|
const upb_MiniTableField* f,
|
|
|
|
|
int32_t default_val);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE int64_t upb_Message_GetInt64(const upb_Message* msg,
|
|
|
|
|
const upb_MiniTableField* f,
|
|
|
|
|
int64_t default_val);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE const upb_Map* upb_Message_GetMap(const upb_Message* msg,
|
|
|
|
|
const upb_MiniTableField* f);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE upb_Array* upb_Message_GetMutableArray(
|
|
|
|
|
upb_Message* msg, const upb_MiniTableField* f);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE upb_Map* upb_Message_GetMutableMap(upb_Message* msg,
|
|
|
|
|
const upb_MiniTableField* f);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE upb_Array* upb_Message_GetOrCreateMutableArray(
|
|
|
|
|
upb_Message* msg, const upb_MiniTableField* f, upb_Arena* arena);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE upb_Map* upb_Message_GetOrCreateMutableMap(
|
|
|
|
|
upb_Message* msg, const upb_MiniTable* map_entry_mini_table,
|
|
|
|
|
const upb_MiniTableField* f, upb_Arena* arena);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE upb_Message* upb_Message_GetOrCreateMutableMessage(
|
|
|
|
|
upb_Message* msg, const upb_MiniTable* mini_table,
|
|
|
|
|
const upb_MiniTableField* f, upb_Arena* arena);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE upb_StringView
|
|
|
|
|
upb_Message_GetString(const upb_Message* msg, const upb_MiniTableField* field,
|
|
|
|
|
upb_StringView default_val);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE uint32_t upb_Message_GetUInt32(const upb_Message* msg,
|
|
|
|
|
const upb_MiniTableField* f,
|
|
|
|
|
uint32_t default_val);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE uint64_t upb_Message_GetUInt64(const upb_Message* msg,
|
|
|
|
|
const upb_MiniTableField* f,
|
|
|
|
|
uint64_t default_val);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE bool upb_Message_SetBool(upb_Message* msg,
|
|
|
|
|
const upb_MiniTableField* f, bool value,
|
|
|
|
|
upb_Arena* a);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE void upb_Message_SetClosedEnum(
|
|
|
|
|
upb_Message* msg, const upb_MiniTable* msg_mini_table,
|
|
|
|
|
const upb_MiniTableField* f, int32_t value);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE bool upb_Message_SetDouble(upb_Message* msg,
|
|
|
|
|
const upb_MiniTableField* f,
|
|
|
|
|
double value, upb_Arena* a);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE bool upb_Message_SetFloat(upb_Message* msg,
|
|
|
|
|
const upb_MiniTableField* f,
|
|
|
|
|
float value, upb_Arena* a);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE bool upb_Message_SetInt32(upb_Message* msg,
|
|
|
|
|
const upb_MiniTableField* f,
|
|
|
|
|
int32_t value, upb_Arena* a);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE bool upb_Message_SetInt64(upb_Message* msg,
|
|
|
|
|
const upb_MiniTableField* f,
|
|
|
|
|
int64_t value, upb_Arena* a);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE bool upb_Message_SetString(upb_Message* msg,
|
|
|
|
|
const upb_MiniTableField* f,
|
|
|
|
|
upb_StringView value, upb_Arena* a);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE bool upb_Message_SetUInt32(upb_Message* msg,
|
|
|
|
|
const upb_MiniTableField* f,
|
|
|
|
|
uint32_t value, upb_Arena* a);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE bool upb_Message_SetUInt64(upb_Message* msg,
|
|
|
|
|
const upb_MiniTableField* f,
|
|
|
|
|
uint64_t value, upb_Arena* a);
|
|
|
|
|
|
Added a new dynamic tree shaking model to upb, with the intention of removing the old model once YouTube has migrated.
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
2 years ago
|
|
|
UPB_API_INLINE upb_TaggedMessagePtr upb_Message_GetTaggedMessagePtr(
|
|
|
|
|
const upb_Message* msg, const upb_MiniTableField* field,
|
|
|
|
|
upb_Message* default_val) {
|
|
|
|
|
UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Message);
|
|
|
|
|
UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
|
Refactored message accessors to share a common set of functions instead of duplicating logic.
Prior to this CL, there were several different code paths for reading/writing message data. Generated code, MiniTable accessors, and reflection all performed direct manipulation of the bits and bytes in a message, but they all had distinct implementations that did not share much of any code. This divergence meant that they could easily have different behavior, bugs could creep into one but not another, and we would need three different sets of tests to get full test coverage. This also made it very difficult to change the internal representation in any way, since it would require updating many places in the code.
With this CL, the three different APIs for accessing message data now all share a common set of functions. The common functions all take a `upb_MiniTableField` as the canonical description of a field's type and layout. The lowest-level functions are very branchy, as they must test for every possible variation in the field type (field vs oneof, hasbit vs no-hasbit, different field sizes, whether a nonzero default value exists, extension vs. regular field), however these functions are declared inline and designed to be very optimizable when values are known at compile time.
In generated accessors, for example, we can declare constant `upb_MiniTableField` instances so that all values can constant-propagate, and we can get fully specialized code even though we are calling a generic function. On the other hand, when we use the generic functions from reflection, we get runtime branches since values are not known at compile time. But even the function is written to still be as efficient as possible even when used from reflection. For example, we use memcpy() calls with constant length so that the compiler can optimize these into inline loads/stores without having to make an out-of-line call to memcpy().
In this way, this CL should be a benefit to both correctness and performance. It will also make it easier to change the message representation, for example to optimize the encoder by giving hasbits to all fields.
Note that we have not completely consolidated all access in this CL:
1. Some functions outside of get/set such as clear and hazzers are not yet unified.
2. The encoder and decoder still touch the message without going through the common functions. The encoder and decoder require a bit more specialized code to get good performance when reading/writing fields en masse.
PiperOrigin-RevId: 490016095
2 years ago
|
|
|
UPB_SIZE(kUpb_FieldRep_4Byte, kUpb_FieldRep_8Byte));
|
|
|
|
|
UPB_ASSUME(upb_MiniTableField_IsScalar(field));
|
Added a new dynamic tree shaking model to upb, with the intention of removing the old model once YouTube has migrated.
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
2 years ago
|
|
|
upb_TaggedMessagePtr tagged;
|
|
|
|
|
_upb_Message_GetNonExtensionField(msg, field, &default_val, &tagged);
|
|
|
|
|
return tagged;
|
|
|
|
|
}
|
|
|
|
|
|
Added a new dynamic tree shaking model to upb, with the intention of removing the old model once YouTube has migrated.
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
2 years ago
|
|
|
UPB_API_INLINE const upb_Message* upb_Message_GetMessage(
|
|
|
|
|
const upb_Message* msg, const upb_MiniTableField* field) {
|
Added a new dynamic tree shaking model to upb, with the intention of removing the old model once YouTube has migrated.
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
2 years ago
|
|
|
upb_TaggedMessagePtr tagged =
|
|
|
|
|
upb_Message_GetTaggedMessagePtr(msg, field, NULL);
|
Added a new dynamic tree shaking model to upb, with the intention of removing the old model once YouTube has migrated.
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
2 years ago
|
|
|
return upb_TaggedMessagePtr_GetNonEmptyMessage(tagged);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE upb_Message* upb_Message_GetMutableMessage(
|
|
|
|
|
upb_Message* msg, const upb_MiniTableField* field) {
|
|
|
|
|
return (upb_Message*)upb_Message_GetMessage(msg, field);
|
|
|
|
|
}
|
|
|
|
|
|
Added a new dynamic tree shaking model to upb, with the intention of removing the old model once YouTube has migrated.
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
2 years ago
|
|
|
// For internal use only; users cannot set tagged messages because only the
|
|
|
|
|
// parser and the message copier are allowed to directly create an empty
|
|
|
|
|
// message.
|
|
|
|
|
UPB_INLINE void UPB_PRIVATE(_upb_Message_SetTaggedMessagePtr)(
|
|
|
|
|
struct upb_Message* msg, const upb_MiniTable* mini_table,
|
|
|
|
|
const upb_MiniTableField* f, upb_TaggedMessagePtr sub_message) {
|
|
|
|
|
UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Message);
|
|
|
|
|
UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) ==
|
Refactored message accessors to share a common set of functions instead of duplicating logic.
Prior to this CL, there were several different code paths for reading/writing message data. Generated code, MiniTable accessors, and reflection all performed direct manipulation of the bits and bytes in a message, but they all had distinct implementations that did not share much of any code. This divergence meant that they could easily have different behavior, bugs could creep into one but not another, and we would need three different sets of tests to get full test coverage. This also made it very difficult to change the internal representation in any way, since it would require updating many places in the code.
With this CL, the three different APIs for accessing message data now all share a common set of functions. The common functions all take a `upb_MiniTableField` as the canonical description of a field's type and layout. The lowest-level functions are very branchy, as they must test for every possible variation in the field type (field vs oneof, hasbit vs no-hasbit, different field sizes, whether a nonzero default value exists, extension vs. regular field), however these functions are declared inline and designed to be very optimizable when values are known at compile time.
In generated accessors, for example, we can declare constant `upb_MiniTableField` instances so that all values can constant-propagate, and we can get fully specialized code even though we are calling a generic function. On the other hand, when we use the generic functions from reflection, we get runtime branches since values are not known at compile time. But even the function is written to still be as efficient as possible even when used from reflection. For example, we use memcpy() calls with constant length so that the compiler can optimize these into inline loads/stores without having to make an out-of-line call to memcpy().
In this way, this CL should be a benefit to both correctness and performance. It will also make it easier to change the message representation, for example to optimize the encoder by giving hasbits to all fields.
Note that we have not completely consolidated all access in this CL:
1. Some functions outside of get/set such as clear and hazzers are not yet unified.
2. The encoder and decoder still touch the message without going through the common functions. The encoder and decoder require a bit more specialized code to get good performance when reading/writing fields en masse.
PiperOrigin-RevId: 490016095
2 years ago
|
|
|
UPB_SIZE(kUpb_FieldRep_4Byte, kUpb_FieldRep_8Byte));
|
|
|
|
|
UPB_ASSUME(upb_MiniTableField_IsScalar(f));
|
|
|
|
|
upb_Message_SetBaseField(msg, f, &sub_message);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
// Sets the value of a message-typed field. The `mini_table` and `field`
|
|
|
|
|
// parameters belong to `msg`, not `sub_message`. The mini_tables of `msg` and
|
|
|
|
|
// `sub_message` must have been linked for this to work correctly.
|
Added a new dynamic tree shaking model to upb, with the intention of removing the old model once YouTube has migrated.
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
2 years ago
|
|
|
UPB_API_INLINE void upb_Message_SetMessage(upb_Message* msg,
|
|
|
|
|
const upb_MiniTable* mini_table,
|
|
|
|
|
const upb_MiniTableField* field,
|
|
|
|
|
upb_Message* sub_message) {
|
|
|
|
|
UPB_PRIVATE(_upb_Message_SetTaggedMessagePtr)
|
|
|
|
|
(msg, mini_table, field,
|
|
|
|
|
UPB_PRIVATE(_upb_TaggedMessagePtr_Pack)(sub_message, false));
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE void* upb_Message_ResizeArrayUninitialized(
|
|
|
|
|
upb_Message* msg, const upb_MiniTableField* f, size_t size,
|
|
|
|
|
upb_Arena* arena);
|
|
|
|
|
|
|
|
|
|
UPB_API_INLINE uint32_t upb_Message_WhichOneofFieldNumber(
|
|
|
|
|
const upb_Message* message, const upb_MiniTableField* oneof_field);
|
|
|
|
|
|
|
|
|
|
// Updates a map entry given an entry message.
|
|
|
|
|
bool upb_Message_SetMapEntry(upb_Map* map, const upb_MiniTable* mini_table,
|
|
|
|
|
const upb_MiniTableField* field,
|
|
|
|
|
upb_Message* map_entry_message, upb_Arena* arena);
|
|
|
|
|
|
|
|
|
|
#ifdef __cplusplus
|
|
|
|
|
} /* extern "C" */
|
|
|
|
|
#endif
|
|
|
|
|
|
|
|
|
|
#include "upb/port/undef.inc"
|
|
|
|
|
|
|
|
|
|
#endif // UPB_MESSAGE_ACCESSORS_H_
|
