protobuf/ruby/ext/google/protobuf_c/protobuf.c

// Protocol Buffers - Google's data interchange format
// Copyright 2014 Google Inc.  All rights reserved.
// https://developers.google.com/protocol-buffers/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include "protobuf.h"

#include <ruby/version.h>

#include "defs.h"
#include "map.h"
#include "message.h"
#include "repeated_field.h"

VALUE cError;
VALUE cTypeError;

const upb_fielddef* map_field_key(const upb_fielddef* field) {
  const upb_msgdef *entry = upb_fielddef_msgsubdef(field);
  return upb_msgdef_itof(entry, 1);
}

const upb_fielddef* map_field_value(const upb_fielddef* field) {
  const upb_msgdef *entry = upb_fielddef_msgsubdef(field);
  return upb_msgdef_itof(entry, 2);
}

// -----------------------------------------------------------------------------
// StringBuilder, for inspect
// -----------------------------------------------------------------------------

struct StringBuilder {
  size_t size;
  size_t cap;
  char *data;
};

typedef struct StringBuilder StringBuilder;

static size_t StringBuilder_SizeOf(size_t cap) {
  return sizeof(StringBuilder) + cap;
}

StringBuilder* StringBuilder_New() {
  const size_t cap = 128;
  StringBuilder* builder = malloc(sizeof(*builder));
  builder->size = 0;
  builder->cap = cap;
  builder->data = malloc(builder->cap);
  return builder;
}

void StringBuilder_Free(StringBuilder* b) {
  free(b->data);
  free(b);
}

void StringBuilder_Printf(StringBuilder* b, const char *fmt, ...) {
  size_t have = b->cap - b->size;
  size_t n;
  va_list args;

  va_start(args, fmt);
  n = vsnprintf(&b->data[b->size], have, fmt, args);
  va_end(args);

  if (have <= n) {
    while (have <= n) {
      b->cap *= 2;
      have = b->cap - b->size;
    }
    b->data = realloc(b->data, StringBuilder_SizeOf(b->cap));
    va_start(args, fmt);
    n = vsnprintf(&b->data[b->size], have, fmt, args);
    va_end(args);
    PBRUBY_ASSERT(n < have);
  }

  b->size += n;
}

VALUE StringBuilder_ToRubyString(StringBuilder* b) {
  VALUE ret = rb_str_new(b->data, b->size);
  rb_enc_associate(ret, rb_utf8_encoding());
  return ret;
}

static void StringBuilder_PrintEnum(StringBuilder* b, int32_t val,
                                    const upb_enumdef* e) {
  const char *name = upb_enumdef_iton(e, val);
  if (name) {
    StringBuilder_Printf(b, ":%s", name);
  } else {
    StringBuilder_Printf(b, "%" PRId32, val);
  }
}

void StringBuilder_PrintMsgval(StringBuilder* b, upb_msgval val,
                               TypeInfo info) {
  switch (info.type) {
    case UPB_TYPE_BOOL:
      StringBuilder_Printf(b, "%s", val.bool_val ? "true" : "false");
      break;
    case UPB_TYPE_FLOAT: {
      VALUE str = rb_inspect(DBL2NUM(val.float_val));
      StringBuilder_Printf(b, "%s", RSTRING_PTR(str));
      break;
    }
    case UPB_TYPE_DOUBLE: {
      VALUE str = rb_inspect(DBL2NUM(val.double_val));
      StringBuilder_Printf(b, "%s", RSTRING_PTR(str));
      break;
    }
    case UPB_TYPE_INT32:
      StringBuilder_Printf(b, "%" PRId32, val.int32_val);
      break;
    case UPB_TYPE_UINT32:
      StringBuilder_Printf(b, "%" PRIu32, val.uint32_val);
      break;
    case UPB_TYPE_INT64:
      StringBuilder_Printf(b, "%" PRId64, val.int64_val);
      break;
    case UPB_TYPE_UINT64:
      StringBuilder_Printf(b, "%" PRIu64, val.uint64_val);
      break;
    case UPB_TYPE_STRING:
      StringBuilder_Printf(b, "\"%.*s\"", (int)val.str_val.size, val.str_val.data);
      break;
    case UPB_TYPE_BYTES:
      StringBuilder_Printf(b, "\"%.*s\"", (int)val.str_val.size, val.str_val.data);
      break;
    case UPB_TYPE_ENUM:
      StringBuilder_PrintEnum(b, val.int32_val, info.def.enumdef);
      break;
    case UPB_TYPE_MESSAGE:
      Message_PrintMessage(b, val.msg_val, info.def.msgdef);
      break;
  }
}

// -----------------------------------------------------------------------------
// Arena
// -----------------------------------------------------------------------------

void Arena_free(void* data) { upb_arena_free(data); }

static VALUE cArena;

const rb_data_type_t Arena_type = {
  "Google::Protobuf::Internal::Arena",
  { NULL, Arena_free, NULL },
};

static VALUE Arena_alloc(VALUE klass) {
  upb_arena *arena = upb_arena_new();
  return TypedData_Wrap_Struct(klass, &Arena_type, arena);
}

upb_arena *Arena_get(VALUE _arena) {
  upb_arena *arena;
  TypedData_Get_Struct(_arena, upb_arena, &Arena_type, arena);
  return arena;
}

VALUE Arena_new() {
  return Arena_alloc(cArena);
}

void Arena_register(VALUE module) {
  VALUE internal = rb_define_module_under(module, "Internal");
  VALUE klass = rb_define_class_under(internal, "Arena", rb_cObject);
  rb_define_alloc_func(klass, Arena_alloc);
  rb_gc_register_address(&cArena);
  cArena = klass;
}

// -----------------------------------------------------------------------------
// Object Cache
// -----------------------------------------------------------------------------

// A pointer -> Ruby Object cache that keeps references to Ruby wrapper
// objects.  This allows us to look up any Ruby wrapper object by the address
// of the object it is wrapping. That way we can avoid ever creating two
// different wrapper objects for the same C object, which saves memory and
// preserves object identity.
//
// We use Hash and/or WeakMap for the cache. WeakMap is faster overall
// (probably due to removal being integrated with GC) but doesn't work for Ruby
// <2.7 (see note below). We need Hash for Ruby <2.7 and for cases where we
// need to GC-root the object (notably when the object has been frozen).

#if RUBY_API_VERSION_CODE >= 20700
#define USE_WEAK_MAP 1
#else
#define USE_WEAK_MAP 0
#endif

static VALUE ObjectCache_GetKey(const void* key) {
  char buf[sizeof(key)];
  memcpy(&buf, &key, sizeof(key));
  intptr_t key_int = (intptr_t)key;
  PBRUBY_ASSERT((key_int & 3) == 0);
  return LL2NUM(key_int >> 2);
}

// Strong object cache, uses regular Hash and GC-roots objects.
// - For Ruby <2.7, used for all objects.
// - For Ruby >=2.7, used only for frozen objects, so we preserve the "frozen"
//   bit (since this information is not preserved at the upb level).

VALUE strong_obj_cache = Qnil;

static void StrongObjectCache_Init() {
  rb_gc_register_address(&strong_obj_cache);
  strong_obj_cache = rb_hash_new();
}

static void StrongObjectCache_Remove(void* key) {
  VALUE key_rb = ObjectCache_GetKey(key);
  PBRUBY_ASSERT(rb_hash_lookup(strong_obj_cache, key_rb) != Qnil);
  rb_hash_delete(strong_obj_cache, key_rb);
}

static VALUE StrongObjectCache_Get(const void* key) {
  VALUE key_rb = ObjectCache_GetKey(key);
  return rb_hash_lookup(strong_obj_cache, key_rb);
}

static void StrongObjectCache_Add(const void* key, VALUE val,
                                  upb_arena* arena) {
  PBRUBY_ASSERT(StrongObjectCache_Get(key) == Qnil);
  VALUE key_rb = ObjectCache_GetKey(key);
  rb_hash_aset(strong_obj_cache, key_rb, val);
  upb_arena_addcleanup(arena, (void*)key, StrongObjectCache_Remove);
}

// Weak object cache. This speeds up the test suite significantly, so we
// presume it speeds up real code also. However we can only use it in Ruby
// >=2.7 due to:
//   https://bugs.ruby-lang.org/issues/16035

#if USE_WEAK_MAP

VALUE weak_obj_cache = Qnil;

static void WeakObjectCache_Init() {
  rb_gc_register_address(&weak_obj_cache);
  VALUE klass = rb_eval_string("ObjectSpace::WeakMap");
  weak_obj_cache = rb_class_new_instance(0, NULL, klass);
}

static VALUE WeakObjectCache_Get(const void* key) {
  VALUE key_rb = ObjectCache_GetKey(key);
  VALUE ret = rb_funcall(weak_obj_cache, rb_intern("[]"), 1, key_rb);
  return ret;
}

static void WeakObjectCache_Add(const void* key, VALUE val) {
  PBRUBY_ASSERT(WeakObjectCache_Get(key) == Qnil);
  VALUE key_rb = ObjectCache_GetKey(key);
  rb_funcall(weak_obj_cache, rb_intern("[]="), 2, key_rb, val);
  PBRUBY_ASSERT(WeakObjectCache_Get(key) == val);
}

#endif

// Public ObjectCache API.

static void ObjectCache_Init() {
  StrongObjectCache_Init();
#if USE_WEAK_MAP
  WeakObjectCache_Init();
#endif
}

void ObjectCache_Add(const void* key, VALUE val, upb_arena *arena) {
#if USE_WEAK_MAP
  (void)arena;
  WeakObjectCache_Add(key, val);
#else
  StrongObjectCache_Add(key, val, arena);
#endif
}

// Returns the cached object for this key, if any. Otherwise returns Qnil.
VALUE ObjectCache_Get(const void* key) {
#if USE_WEAK_MAP
  return WeakObjectCache_Get(key);
#else
  return StrongObjectCache_Get(key);
#endif
}

void ObjectCache_Pin(const void* key, VALUE val, upb_arena *arena) {
#if USE_WEAK_MAP
  PBRUBY_ASSERT(WeakObjectCache_Get(key) == val);
  // This will GC-root the object, but we'll still use the weak map for
  // actual lookup.
  StrongObjectCache_Add(key, val, arena);
#else
  // Value is already pinned, nothing to do.
#endif
}

/*
 * call-seq:
 *     Google::Protobuf.discard_unknown(msg)
 *
 * Discard unknown fields in the given message object and recursively discard
 * unknown fields in submessages.
 */
static VALUE Google_Protobuf_discard_unknown(VALUE self, VALUE msg_rb) {
  const upb_msgdef *m;
  upb_msg *msg = Message_GetMutable(msg_rb, &m);
  if (!upb_msg_discardunknown(msg, m, 128)) {
    rb_raise(rb_eRuntimeError, "Messages nested too deeply.");
  }

  return Qnil;
}

/*
 * call-seq:
 *     Google::Protobuf.deep_copy(obj) => copy_of_obj
 *
 * Performs a deep copy of a RepeatedField instance, a Map instance, or a
 * message object, recursively copying its members.
 */
VALUE Google_Protobuf_deep_copy(VALUE self, VALUE obj) {
  VALUE klass = CLASS_OF(obj);
  if (klass == cRepeatedField) {
    return RepeatedField_deep_copy(obj);
  } else if (klass == cMap) {
    return Map_deep_copy(obj);
  } else {
    VALUE new_arena_rb = Arena_new();
    upb_arena *new_arena = Arena_get(new_arena_rb);
    const upb_msgdef *m;
    const upb_msg *msg = Message_Get(obj, &m);
    upb_msg* new_msg = Message_deep_copy(msg, m, new_arena);
    return Message_GetRubyWrapper(new_msg, m, new_arena_rb);
  }
}

// -----------------------------------------------------------------------------
// Initialization/entry point.
// -----------------------------------------------------------------------------

// This must be named "Init_protobuf_c" because the Ruby module is named
// "protobuf_c" -- the VM looks for this symbol in our .so.
__attribute__ ((visibility ("default")))
void Init_protobuf_c() {
  ObjectCache_Init();

  VALUE google = rb_define_module("Google");
  VALUE protobuf = rb_define_module_under(google, "Protobuf");

  Arena_register(protobuf);
  Defs_register(protobuf);
  RepeatedField_register(protobuf);
  Map_register(protobuf);
  Message_register(protobuf);

  cError = rb_const_get(protobuf, rb_intern("Error"));
  cTypeError = rb_const_get(protobuf, rb_intern("TypeError"));

  rb_define_singleton_method(protobuf, "discard_unknown",
                             Google_Protobuf_discard_unknown, 1);
  rb_define_singleton_method(protobuf, "deep_copy",
                             Google_Protobuf_deep_copy, 1);
}