diff options
Diffstat (limited to 'upb_msg.h')
| -rw-r--r-- | upb_msg.h | 74 |
1 files changed, 36 insertions, 38 deletions
@@ -4,8 +4,11 @@ * Copyright (c) 2009 Joshua Haberman. See LICENSE for details. * * upb_msg contains a full description of a message as defined in a .proto file. - * This allows for run-time reflection over .proto types, but also defines an - * in-memory byte-level format for storing protobufs. + * It supports many features and operations for dealing with proto messages: + * - reflection over .proto types at runtime (list fields, get names, etc). + * - an in-memory byte-level format for efficiently storing and accessing msgs. + * - serializing and deserializing from the in-memory format to a protobuf. + * - optional memory management for handling strings, arrays, and submessages. * * The in-memory format is very much like a C struct that you can define at * run-time, but also supports reflection. Like C structs it supports @@ -25,9 +28,12 @@ * this format. This format is designed to allow the fastest possible random * access of individual fields. * - * Note that no memory management is defined, which should make it easier to - * integrate this format with existing memory-management schemes. Any memory - * management semantics can be used with the format as defined here. + * Note that clients need not use the memory management facilities defined here. + * They are for convenience only -- clients wishing to do their own memory + * management may do so (allowing clients to perform advanced techniques like + * reference-counting, garbage collection, and string references). Different + * clients can read each others messages regardless of what memory management + * scheme each is using. */ #ifndef UPB_MSG_H_ @@ -49,13 +55,13 @@ extern "C" { struct google_protobuf_DescriptorProto; struct google_protobuf_FieldDescriptorProto; -/* Structure definition. ******************************************************/ +/* Message definition. ********************************************************/ /* Structure that describes a single field in a message. */ struct upb_msg_field { - struct google_protobuf_FieldDescriptorProto *descriptor; uint32_t byte_offset; /* Where to find the data. */ uint16_t field_index; /* Indexes upb_msg.fields. Also indicates set bit */ + upb_field_type_t type; /* Copied from descriptor for cache-friendliness. */ union upb_symbol_ref ref; }; @@ -69,62 +75,53 @@ struct upb_msg { struct upb_inttable fields_by_num; struct upb_strtable fields_by_name; struct upb_msg_field *fields; + struct google_protobuf_FieldDescriptorProto **field_descriptors; }; /* The num->field and name->field maps in upb_msg allow fast lookup of fields * by number or name. These lookups are in the critical path of parsing and * field lookup, so they must be as fast as possible. To make these more - * cache-friendly, we put the data in the table by value, but use only an - * abbreviated set of data (ie. not all the data in upb_msg_field). Notably, - * we don't include the pointer to the field descriptor. But the upb_msg_field - * can be retrieved in its entirety using the function below.*/ - -struct upb_abbrev_msg_field { - uint32_t byte_offset; /* Where to find the data. */ - uint16_t field_index; /* Indexes upb_msg.fields. Also indicates set bit */ - upb_field_type_t type; /* Copied from descriptor for cache-friendliness. */ - union upb_symbol_ref ref; -}; + * cache-friendly, we put the data in the table by value. */ struct upb_fieldsbynum_entry { struct upb_inttable_entry e; - struct upb_abbrev_msg_field f; + struct upb_msg_field f; }; struct upb_fieldsbyname_entry { struct upb_strtable_entry e; - struct upb_abbrev_msg_field f; + struct upb_msg_field f; }; -INLINE struct upb_msg_field *upb_get_msg_field( - struct upb_abbrev_msg_field *f, struct upb_msg *m) { - return &m->fields[f->field_index]; +/* Can be used to retrieve a field descriptor given the upb_msg_field ref. */ +INLINE struct google_protobuf_FieldDescriptorProto *upb_msg_field_descriptor( + struct upb_msg_field *f, struct upb_msg *m) { + return m->field_descriptors[f->field_index]; } /* Initialize and free a upb_msg. Caller retains ownership of d, but the msg * will contain references to it, so it must outlive the msg. Note that init - * does not resolve upb_msg_field.ref -- that is left to the caller. */ + * does not resolve upb_msg_field.ref -- the caller should do that + * post-initialization by calling upb_msg_ref() below. */ bool upb_msg_init(struct upb_msg *m, struct google_protobuf_DescriptorProto *d); void upb_msg_free(struct upb_msg *m); /* Clients use this function on a previously initialized upb_msg to resolve the - * "ref" field in the upb_msg_field and upb_abbrev_msg_field. Since messages - * can refer to each other in mutually-recursive ways, this step must be - * separated from initialization. The function is necessary because there are - * multiple internal maps in which the ref appears. */ + * "ref" field in the upb_msg_field. Since messages can refer to each other in + * mutually-recursive ways, this step must be separated from initialization. */ void upb_msg_ref(struct upb_msg *m, struct upb_msg_field *f, union upb_symbol_ref ref); /* While these are written to be as fast as possible, it will still be faster * to cache the results of this lookup if possible. These return NULL if no * such field is found. */ -INLINE struct upb_abbrev_msg_field *upb_msg_fieldbynum(struct upb_msg *m, - uint32_t number) { +INLINE struct upb_msg_field *upb_msg_fieldbynum(struct upb_msg *m, + uint32_t number) { struct upb_fieldsbynum_entry *e = upb_inttable_lookup( &m->fields_by_num, number, sizeof(struct upb_fieldsbynum_entry)); return e ? &e->f : NULL; } -INLINE struct upb_abbrev_msg_field *upb_msg_fieldbyname(struct upb_msg *m, - struct upb_string *name) { +INLINE struct upb_msg_field *upb_msg_fieldbyname(struct upb_msg *m, + struct upb_string *name) { struct upb_fieldsbyname_entry *e = upb_strtable_lookup(&m->fields_by_name, name); return e ? &e->f : NULL; @@ -179,7 +176,7 @@ UPB_DEFINE_PRIMITIVE_ARRAY(bool, bool) /* For each primitive type we define a set of six functions: * - * // For fetching out of a struct (s points to the raw struct data). + * // For fetching out of a msg (s points to the raw msg data). * int32_t *upb_msg_get_int32_ptr(void *s, struct upb_msg_field *f); * int32_t upb_msg_get_int32(void *s, struct upb_msg_field *f); * void upb_msg_set_int32(void *s, struct upb_msg_field *f, int32_t val); @@ -232,9 +229,11 @@ UPB_DEFINE_ALL_ACCESSORS(uint64_t, uint64, INLINE) UPB_DEFINE_ALL_ACCESSORS(bool, bool, INLINE) UPB_DEFINE_ALL_ACCESSORS(struct upb_string*, bytes, INLINE) UPB_DEFINE_ALL_ACCESSORS(struct upb_string*, string, INLINE) -UPB_DEFINE_ALL_ACCESSORS(void*, substruct, INLINE) +UPB_DEFINE_ALL_ACCESSORS(void*, submsg, INLINE) UPB_DEFINE_ACCESSORS(struct upb_array*, array, INLINE) +/* "Set" flag reading and writing. *******************************************/ + INLINE size_t upb_isset_offset(uint32_t field_index) { return field_index / 8; } @@ -243,10 +242,9 @@ INLINE uint8_t upb_isset_mask(uint32_t field_index) { return 1 << (field_index % 8); } -/* Functions for reading and writing the "set" flags in the pbstruct. Note - * that these do not perform any memory management associated with any dynamic - * memory these fields may be referencing; that is the client's responsibility. - * These *only* set and test the flags. */ +/* Functions for reading and writing the "set" flags in the msg. Note that + * these do not perform memory management associated with any dynamic memory + * these fields may be referencing. These *only* set and test the flags. */ INLINE void upb_msg_set(void *s, struct upb_msg_field *f) { ((char*)s)[upb_isset_offset(f->field_index)] |= upb_isset_mask(f->field_index); |