tor-browser

hb-object.hh (8295B)

---

/*
* Copyright © 2007  Chris Wilson
* Copyright © 2009,2010  Red Hat, Inc.
* Copyright © 2011,2012  Google, Inc.
*
*  This is part of HarfBuzz, a text shaping library.
*
* Permission is hereby granted, without written agreement and without
* license or royalty fees, to use, copy, modify, and distribute this
* software and its documentation for any purpose, provided that the
* above copyright notice and the following two paragraphs appear in
* all copies of this software.
*
* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*
* Contributor(s):
*	Chris Wilson <chris@chris-wilson.co.uk>
* Red Hat Author(s): Behdad Esfahbod
* Google Author(s): Behdad Esfahbod
*/

#ifndef HB_OBJECT_HH
#define HB_OBJECT_HH

#include "hb.hh"
#include "hb-atomic.hh"
#include "hb-mutex.hh"
#include "hb-vector.hh"


/*
* Lockable set
*/

template <typename item_t, typename lock_t>
struct hb_lockable_set_t
{
 hb_vector_t<item_t> items;

 void init () { items.init (); }

 template <typename T>
 item_t *replace_or_insert (T v, lock_t &l, bool replace)
 {
   l.lock ();
   item_t *item = items.lsearch (v);
   if (item) {
     if (replace) {
item_t old = *item;
*item = v;
l.unlock ();
old.fini ();
     }
     else {
item = nullptr;
l.unlock ();
     }
   } else {
     item = items.push (v);
     l.unlock ();
   }
   return items.in_error () ? nullptr : item;
 }

 template <typename T>
 void remove (T v, lock_t &l)
 {
   l.lock ();
   item_t *item = items.lsearch (v);
   if (item)
   {
     item_t old = *item;
     *item = std::move (items.tail ());
     items.pop ();
     l.unlock ();
     old.fini ();
   } else {
     l.unlock ();
   }
 }

 template <typename T>
 bool find (T v, item_t *i, lock_t &l)
 {
   l.lock ();
   item_t *item = items.lsearch (v);
   if (item)
     *i = *item;
   l.unlock ();
   return !!item;
 }

 template <typename T>
 item_t *find_or_insert (T v, lock_t &l)
 {
   l.lock ();
   item_t *item = items.find (v);
   if (!item) {
     item = items.push (v);
   }
   l.unlock ();
   return item;
 }

 void fini (lock_t &l)
 {
   if (!items.length)
   {
     /* No need to lock. */
     items.fini ();
     return;
   }
   l.lock ();
   while (items.length)
   {
     item_t old = items.tail ();
     items.pop ();
     l.unlock ();
     old.fini ();
     l.lock ();
   }
   items.fini ();
   l.unlock ();
 }

};


/*
* Reference-count.
*/

struct hb_reference_count_t
{
 mutable hb_atomic_t<int> ref_count;

 void init (int v = 1) { ref_count = v; }
 int get_relaxed () const { return ref_count; }
 int inc () const { return ref_count.inc (); }
 int dec () const { return ref_count.dec (); }
 void fini () { ref_count = -0x0000DEAD; }

 bool is_inert () const { return !ref_count; }
 bool is_valid () const { return ref_count > 0; }
};


/* user_data */

struct hb_user_data_array_t
{
 struct hb_user_data_item_t {
   hb_user_data_key_t *key;
   void *data;
   hb_destroy_func_t destroy;

   bool operator == (const hb_user_data_key_t *other_key) const { return key == other_key; }
   bool operator == (const hb_user_data_item_t &other) const { return key == other.key; }

   void fini () { if (destroy) destroy (data); }
 };

 hb_mutex_t lock;
 hb_lockable_set_t<hb_user_data_item_t, hb_mutex_t> items;

 void init () { lock.init (); items.init (); }

 void fini () { items.fini (lock); lock.fini (); }

 bool set (hb_user_data_key_t *key,
    void *              data,
    hb_destroy_func_t   destroy,
    hb_bool_t           replace)
 {
   if (!key)
     return false;

   if (replace) {
     if (!data && !destroy) {
items.remove (key, lock);
return true;
     }
   }
   hb_user_data_item_t item = {key, data, destroy};
   bool ret = !!items.replace_or_insert (item, lock, (bool) replace);

   return ret;
 }

 void *get (hb_user_data_key_t *key)
 {
   hb_user_data_item_t item = {nullptr, nullptr, nullptr};

   return items.find (key, &item, lock) ? item.data : nullptr;
 }
};


/*
* Object header
*/

struct hb_object_header_t
{
 hb_reference_count_t ref_count;
 mutable hb_atomic_t<bool> writable = false;
 hb_atomic_t<hb_user_data_array_t *> user_data;

 bool is_inert () const { return !ref_count.get_relaxed (); }
};
#define HB_OBJECT_HEADER_STATIC {}


/*
* Object
*/

template <typename Type>
static inline void hb_object_trace (const Type *obj, const char *function)
{
 DEBUG_MSG (OBJECT, (void *) obj,
     "%s refcount=%d",
     function,
     obj ? obj->header.ref_count.get_relaxed () : 0);
}

template <typename Type, typename ...Ts>
static inline Type *hb_object_create (Ts... ds)
{
 Type *obj = (Type *) hb_calloc (1, sizeof (Type));

 if (unlikely (!obj))
   return obj;

 new (obj) Type (std::forward<Ts> (ds)...);

 hb_object_init (obj);
 hb_object_trace (obj, HB_FUNC);

 return obj;
}
template <typename Type>
static inline void hb_object_init (Type *obj)
{
 obj->header.ref_count.init ();
 obj->header.writable = true;
 obj->header.user_data.init ();
}
template <typename Type>
static inline bool hb_object_is_valid (const Type *obj)
{
 return likely (obj->header.ref_count.is_valid ());
}
template <typename Type>
static inline bool hb_object_is_immutable (const Type *obj)
{
 return !obj->header.writable;
}
template <typename Type>
static inline void hb_object_make_immutable (const Type *obj)
{
 obj->header.writable = false;
}
template <typename Type>
static inline Type *hb_object_reference (Type *obj)
{
 hb_object_trace (obj, HB_FUNC);
 if (unlikely (!obj || obj->header.is_inert ()))
   return obj;
 assert (hb_object_is_valid (obj));
 obj->header.ref_count.inc ();
 return obj;
}
template <typename Type>
static inline bool hb_object_destroy (Type *obj)
{
 hb_object_trace (obj, HB_FUNC);
 if (unlikely (!obj || obj->header.is_inert ()))
   return false;
 assert (hb_object_is_valid (obj));
 if (obj->header.ref_count.dec () != 1)
   return false;

 hb_object_fini (obj);

 if (!std::is_trivially_destructible<Type>::value)
   obj->~Type ();

 return true;
}
template <typename Type>
static inline void hb_object_fini (Type *obj)
{
 obj->header.ref_count.fini (); /* Do this before user_data */
 hb_user_data_array_t *user_data = obj->header.user_data.get_acquire ();
 if (user_data)
 {
   user_data->fini ();
   hb_free (user_data);
   obj->header.user_data.set_relaxed (nullptr);
 }
}
template <typename Type>
static inline bool hb_object_set_user_data (Type               *obj,
				    hb_user_data_key_t *key,
				    void *              data,
				    hb_destroy_func_t   destroy,
				    hb_bool_t           replace)
{
 if (unlikely (!obj || obj->header.is_inert ()))
   return false;
 assert (hb_object_is_valid (obj));

retry:
 hb_user_data_array_t *user_data = obj->header.user_data.get_acquire ();
 if (unlikely (!user_data))
 {
   user_data = (hb_user_data_array_t *) hb_calloc (1, sizeof (hb_user_data_array_t));
   if (unlikely (!user_data))
     return false;
   user_data->init ();
   if (unlikely (!obj->header.user_data.cmpexch (nullptr, user_data)))
   {
     user_data->fini ();
     hb_free (user_data);
     goto retry;
   }
 }

 return user_data->set (key, data, destroy, replace);
}

template <typename Type>
static inline void *hb_object_get_user_data (Type               *obj,
				     hb_user_data_key_t *key)
{
 if (unlikely (!obj || obj->header.is_inert ()))
   return nullptr;
 assert (hb_object_is_valid (obj));
 hb_user_data_array_t *user_data = obj->header.user_data.get_acquire ();
 if (!user_data)
   return nullptr;
 return user_data->get (key);
}


#endif /* HB_OBJECT_HH */