eina: add some documentation for Eina_Cow.

src/lib/eina/eina_cow.h

@@ -19,27 +19,122 @@
 #ifndef EINA_COW_H_
 #define EINA_COW_H_
 
+
+/**
+ * @addtogroup Eina_Tools_Group Tools
+ *
+ * @{
+ */
+
+/**
+ * @defgroup Eina_Cow_Group Lock
+ *
+ * @brief These functions provide some helper for a pseudo Copy On Write mechanism.
+ *
+ * Eina_Cow will return const memory pointer to some default value that you will
+ * be able to change only by requesting a writable pointer. Later on a garbage collector
+ * can come online and try to merge back some of those pointer.
+ *
+ * @since 1.8.0
+ *
+ * @{
+ */
+
+/**
+ * @typedef Eina_Cow
+ * Type for Eina_Cow pool
+ */
 typedef struct _Eina_Cow Eina_Cow;
+/**
+ * @typedef Eina_Cow_Data
+ * Type of the returned pointer to simplify some reading.
+ */
 typedef void Eina_Cow_Data;
 
+/**
+ * @brief Instantiate a new Eina_Cow pool.
+ *
+ * @param name The name of this pool, used for debug.
+ * @param struct_size The size of the object from this pool.
+ * @param step How many object to allocate when the pool get empty.
+ * @param default_value The default value returned by this pool.
+ * @return a valid new Eina_Cow or @c NULL on error.
+ */
 EAPI Eina_Cow *eina_cow_add(const char *name, unsigned int struct_size, unsigned int step, const void *default_value) EINA_WARN_UNUSED_RESULT;
+
+/**
+ * @brief Destroy an Eina_Cow pool and all the allocated memory
+ *
+ * @param cow The pool to destroy
+ */
 EAPI void eina_cow_del(Eina_Cow *cow);
 
+/**
+ * @brief Return a initialized pointer to the pool.
+ * @param cow The pool to take things from.
+ */
 EAPI const Eina_Cow_Data *eina_cow_alloc(Eina_Cow *cow) EINA_WARN_UNUSED_RESULT;
+
+/**
+ * @brief Free a pointer from the pool.
+ * @param cow The pool to gave back memory to.
+ */
 EAPI void eina_cow_free(Eina_Cow *cow, const Eina_Cow_Data *data);
 
+/**
+ * @brief Get a writable pointer from a const pointer.
+ * @param cow The pool the pointer come from.
+ * @param src The pointer you want to write to.
+ *
+ * NOTE: this function is not thread safe, be careful.
+ */
 EAPI void *eina_cow_write(Eina_Cow *cow,
 			  const Eina_Cow_Data * const *src) EINA_WARN_UNUSED_RESULT;
+/**
+ * @brief Set back a pointer into read only.
+ * @param cow The pool the pointer come from.
+ * @param src The read only version of the pointer.
+ * @param data The pointer to which data where written to.
+ *
+ * NOTE: this function is not thread safe, be careful.
+ */
 EAPI void eina_cow_done(Eina_Cow *cow,
 			const Eina_Cow_Data * const *dst,
 			const void *data,
 			Eina_Bool needed_gc);
+/**
+ * @brief Make the destination contain the same thing as the source pointer.
+ * @param cow The pool the pointers come from.
+ * @param dst The destination to update.
+ * @param src The source of information to copy.
+ */
 EAPI void eina_cow_memcpy(Eina_Cow *cow,
 			  const Eina_Cow_Data * const *dst,
 			  const Eina_Cow_Data *src);
 
+/**
+ * @brief Try to find entry that do have the same content and update them.
+ * @param cow The cow to try to compact.
+ * @return EINA_TRUE if something was compacted, EINA_FALSE if nothing was.
+ *
+ * There is no guaranty in the time it will require, but should remain low.
+ * It does run a hash function on all possible common structure trying to
+ * find the one that match and merge then into one pointer.
+ */
 EAPI Eina_Bool eina_cow_gc(Eina_Cow *cow);
 
+/**
+ * @def EINA_COW_WRITE_BEGIN
+ * @brief This macro setup a writable pointer from a const one.
+ * @param Cow The Eina_Cow where the const pointer come from.
+ * @param Read The const pointer to get a writable handler from.
+ * @param Write_Type The type of the pointer you want to write to.
+ * @param Write The name of the variable where to put the writeable pointer to.
+ * @since 1.8.0
+ *
+ * Be careful this macro open a C scope that it expect to be closed by
+ * EINA_COW_WRITE_END().
+ */
 #define EINA_COW_WRITE_BEGIN(Cow, Read, Write_Type, Write)		\
   do									\
     {									\
@@ -47,10 +142,28 @@ EAPI Eina_Bool eina_cow_gc(Eina_Cow *cow);
       									\
       Write = eina_cow_write(Cow, ((const Eina_Cow_Data**)&(Read)));
 
+/**
+ * @def EINA_COW_WRITE_END
+ * @brief This macro close the writable pointer.
+ * @param Cow The Eina_Cow where the const pointer come from.
+ * @param Read The const pointer to get a writable handler from.
+ * @param Write The name of the variable where to put the writeable pointer to.
+ * @since 1.8.0
+ *
+ * Be careful this macro close the scope opened by EINA_COW_WRITE_BEGIN().
+ */
 #define EINA_COW_WRITE_END(Cow, Read, Write)				\
       eina_cow_done(Cow, ((const Eina_Cow_Data**)&(Read)), Write,	\
 		    EINA_TRUE);						\
     }									\
   while (0);
 
+/**
+ * @}
+ */
+
+/**
+ * @}
+ */
+
 #endif