jeyzu pushed a commit to branch master.
commit a9e69d519cd5240320e278cdc4efa8b1723a5fa1
Author: Jérémy Zurcher <[email protected]>
Date: Thu May 16 10:55:32 2013 +0200
eo ptr ind: mostly cosmetic
- add and use SHIFT_* macros
- rename queue into fifo
- try to clarify the structure top table -> mid table -> table[entry]
---
src/lib/eo/eo_ptr_indirection.c | 216 +++++++++++++++++++++-------------------
1 file changed, 111 insertions(+), 105 deletions(-)
diff --git a/src/lib/eo/eo_ptr_indirection.c b/src/lib/eo/eo_ptr_indirection.c
index 74a3926..47c5295 100644
--- a/src/lib/eo/eo_ptr_indirection.c
+++ b/src/lib/eo/eo_ptr_indirection.c
@@ -17,14 +17,16 @@
* the Eo object to supply a better memory management by preventing bad usage
* of the pointers.
*
- * Eo * is no more a pointer but an index to an entry into a ids table.
- * For a better memory usage, we don't allocate all the tables at the
beginning,
- * but only when needed (i.e no more empty entries in allocated tables.
- * In addition, tables are composed of intermediate tables, this for memory
- * optimizations. Finding the different table, intermediate table and relative
- * entry is done by bits manipulation of the id:
+ * Eo * is no more a pointer but indexes to an entry into an ids table.
+ * For a better memory usage:
+ * - a tree structure is used, composed of a top level table pointing at
+ * mid tables pointing at tables composed of entries.
+ * - tables are allocated when needed (i.e no more empty entries in allocated
tables.
+ * For now there is no mechanism to free empty tables.
*
- * id = Table | Inter_table | Entry | Generation
+ * An Eo id is contructed by bits manipulation of table indexes and a
generation.
+ *
+ * id = Mid Table | Table | Entry | Generation
*
* Generation helps finding abuse of ids. When an entry is assigned to an
* object, a generation is inserted into the id. If the developer uses this id
@@ -32,69 +34,73 @@
* entry of the table, the generation will be different and an error will
* occur when accessing with the old id.
*
- * Each table is composed of:
- * - an index 'start' indicating which entry is the next one to use.
- * - 2 indexes 'queue_head' and 'queue_tail' defining a queue (fifo),
+ * Each Table is composed of:
+ * - an index 'start' indicating which free entry is the next one to use.
+ * - 2 indexes 'fifo_head' and 'fifo_tail' defining a fifo,
* that will help us to store the entries to be reused. It stores only the
* entries that have been used at least one time. The entries that have
* never been used are "pointed" by the start parameter.
* - entries composed of:
* - a pointer to the object
+ * - an index 'next_in_fifo' used to chain the free entries in the fifo
* - a flag indicating if the entry is active
* - a generation assigned to the object
- * - an index 'next_in_queue' used to chain the entries in the queue
*
* When an entry is searched into a table, we first use one of the entries that
- * has never been used. If there is none, we try to pop from the queue.
+ * has never been used. If there is none, we try to pop from the fifo.
+ * If a such entry doesn't exist, we pass to the next table.
+ * When an entry is found, we reserve it to the object pointer
+ * then contruct and return the related Eo id.
+ *
* Assigning all the entries of a table before trying to reuse them from
* the fifo ensures that we are not going to soon recycle a released entry,
* thus minimize the risks of an aggressive del() then use() on a single entry.
- * If a such entry doesn't exist, we pass to the next table.
- * When an entry is found, we reserve it to the object pointer and create
- * the id with the table id, the intermediate table id, the entry and a
- * generation.
+ *
* The indexes and a reference to the last table which served an entry is kept
* and is reused prior to the others untill it is full.
* When an object is freed, the entry into the table is released by appending
- * it to the queue.
+ * it to the fifo.
*/
#if SIZEOF_UINTPTR_T == 4
/* 32 bits */
-# define BITS_FOR_IDS_TABLE 5
-# define BITS_FOR_IDS_INTER_TABLE 5
-# define BITS_FOR_ID_IN_TABLE 12
-# define BITS_FOR_GENERATION_COUNTER 10
+# define BITS_MID_TABLE_ID 5
+# define BITS_TABLE_ID 5
+# define BITS_ENTRY_ID 12
+# define BITS_GENERATION_COUNTER 10
typedef int16_t Table_Index;
typedef uint16_t Generation_Counter;
#else
/* 64 bits */
-# define BITS_FOR_IDS_TABLE 11
-# define BITS_FOR_IDS_INTER_TABLE 11
-# define BITS_FOR_ID_IN_TABLE 12
-# define BITS_FOR_GENERATION_COUNTER 30
+# define BITS_MID_TABLE_ID 11
+# define BITS_TABLE_ID 11
+# define BITS_ENTRY_ID 12
+# define BITS_GENERATION_COUNTER 30
typedef int16_t Table_Index;
typedef uint32_t Generation_Counter;
#endif
/* Shifts macros to manipulate the Eo id */
-#define SHIFT_FOR_IDS_TABLE \
- (BITS_FOR_IDS_INTER_TABLE + BITS_FOR_ID_IN_TABLE +
BITS_FOR_GENERATION_COUNTER)
-
-#define SHIFT_FOR_IDS_INTER_TABLE \
- (BITS_FOR_ID_IN_TABLE + BITS_FOR_GENERATION_COUNTER)
-
-#define SHIFT_FOR_ID_IN_TABLE (BITS_FOR_GENERATION_COUNTER)
+#define SHIFT_MID_TABLE_ID (BITS_TABLE_ID + \
+ BITS_ENTRY_ID + BITS_GENERATION_COUNTER)
+#define SHIFT_TABLE_ID (BITS_ENTRY_ID + BITS_GENERATION_COUNTER)
+#define SHIFT_ENTRY_ID (BITS_GENERATION_COUNTER)
/* Maximum ranges */
-#define MAX_IDS_TABLES (1 << BITS_FOR_IDS_TABLE)
-#define MAX_IDS_INTER_TABLES (1 << BITS_FOR_IDS_INTER_TABLE)
-#define MAX_IDS_PER_TABLE (1 << BITS_FOR_ID_IN_TABLE)
-#define MAX_GENERATIONS (1 << BITS_FOR_GENERATION_COUNTER)
+#define MAX_MID_TABLE_ID (1 << BITS_MID_TABLE_ID)
+#define MAX_TABLE_ID (1 << BITS_TABLE_ID)
+#define MAX_ENTRY_ID (1 << BITS_ENTRY_ID)
+#define MAX_GENERATIONS (1 << BITS_GENERATION_COUNTER)
+
+/* Masks */
+#define MASK_MID_TABLE_ID (MAX_MID_TABLE_ID - 1)
+#define MASK_TABLE_ID (MAX_TABLE_ID - 1)
+#define MASK_ENTRY_ID (MAX_ENTRY_ID - 1)
+#define MASK_GENERATIONS (MAX_GENERATIONS - 1)
-#define MEM_HEADER_SIZE 16
-#define MEM_PAGE_SIZE 4096
-#define MEM_MAGIC 0x3f61ec8a
+#define MEM_HEADER_SIZE 16
+#define MEM_PAGE_SIZE 4096
+#define MEM_MAGIC 0x3f61ec8a
typedef struct _Mem_Header
{
@@ -159,26 +165,26 @@ typedef struct
{
/* Pointer to the object */
_Eo *ptr;
+ /* Indicates where to find the next entry to recycle */
+ Table_Index next_in_fifo;
/* Active flag */
unsigned int active : 1;
/* Generation */
- unsigned int generation : BITS_FOR_GENERATION_COUNTER;
- /* Indicates where to find the next entry to recycle */
- Table_Index next_in_queue;
+ unsigned int generation : BITS_GENERATION_COUNTER;
} _Eo_Id_Entry;
/* Table */
typedef struct
{
- /* Entries of the table holding real pointers and generations */
- _Eo_Id_Entry entries[MAX_IDS_PER_TABLE];
/* Indicates where start the "never used" entries */
Table_Index start;
/* Indicates where to find the next entry to recycle */
- Table_Index queue_head;
+ Table_Index fifo_head;
/* Indicates where to add an entry to recycle */
- Table_Index queue_tail;
+ Table_Index fifo_tail;
+ /* Entries of the table holding real pointers and generations */
+ _Eo_Id_Entry entries[MAX_ENTRY_ID];
} _Eo_Ids_Table;
/* Table Info */
@@ -186,14 +192,14 @@ typedef struct
{
/* Table pointer */
_Eo_Ids_Table *table;
- /* Top table index */
+ /* Index of mid table in top table */
+ Table_Index mid_table_id;
+ /* Index of table in mid table */
Table_Index table_id;
- /* Intermediate table index */
- Table_Index int_table_id;
} _Eo_Table_Info;
/* Tables handling pointers indirection */
-static _Eo_Ids_Table **_eo_ids_tables[MAX_IDS_TABLES] = { NULL };
+static _Eo_Ids_Table **_eo_ids_tables[MAX_MID_TABLE_ID] = { NULL };
/* Current table used for following allocations */
static _Eo_Table_Info current_table = { NULL, 0, 0 };
@@ -202,21 +208,21 @@ static _Eo_Table_Info current_table = { NULL, 0, 0 };
Generation_Counter _eo_generation_counter;
/* Macro used to compose an Eo id */
-#define EO_COMPOSE_ID(TABLE, INTER_TABLE, ENTRY, GENERATION)
\
- (((Eo_Id)(TABLE & (MAX_IDS_TABLES - 1)) << SHIFT_FOR_IDS_TABLE)
| \
- ((Eo_Id)(INTER_TABLE & (MAX_IDS_INTER_TABLES - 1)) <<
SHIFT_FOR_IDS_INTER_TABLE) | \
- ((ENTRY & (MAX_IDS_PER_TABLE - 1)) << SHIFT_FOR_ID_IN_TABLE)
| \
- (GENERATION & (MAX_GENERATIONS - 1) ))
+#define EO_COMPOSE_ID(TABLE, INTER_TABLE, ENTRY, GENERATION) \
+ (((Eo_Id)(TABLE & MASK_MID_TABLE_ID) << SHIFT_MID_TABLE_ID) | \
+ ((Eo_Id)(INTER_TABLE & MASK_TABLE_ID) << SHIFT_TABLE_ID) | \
+ ((ENTRY & MASK_ENTRY_ID) << SHIFT_ENTRY_ID) | \
+ (GENERATION & MASK_GENERATIONS ))
/* Macro to extract from an Eo id the indexes of the tables */
-#define EO_DECOMPOSE_ID(ID, TABLE, INTER_TABLE, ENTRY, GENERATION)
\
- TABLE = (ID >> SHIFT_FOR_IDS_TABLE) & (MAX_IDS_TABLES - 1);
\
- INTER_TABLE = (ID >> SHIFT_FOR_IDS_INTER_TABLE) & (MAX_IDS_INTER_TABLES -
1); \
- ENTRY = (ID >> SHIFT_FOR_ID_IN_TABLE) & (MAX_IDS_PER_TABLE - 1);
\
- GENERATION = ID & (MAX_GENERATIONS - 1);
\
+#define EO_DECOMPOSE_ID(ID, TABLE, INTER_TABLE, ENTRY, GENERATION) \
+ TABLE = (ID >> SHIFT_MID_TABLE_ID) & MASK_MID_TABLE_ID; \
+ INTER_TABLE = (ID >> SHIFT_TABLE_ID) & MASK_TABLE_ID; \
+ ENTRY = (ID >> SHIFT_ENTRY_ID) & MASK_ENTRY_ID; \
+ GENERATION = ID & MASK_GENERATIONS;
/* Macro used for readability */
-#define ID_TABLE _eo_ids_tables[table_id][int_table_id]
+#define TABLE_FROM_IDS _eo_ids_tables[mid_table_id][table_id]
_Eo *
_eo_obj_pointer_get(const Eo_Id obj_id)
@@ -224,14 +230,14 @@ _eo_obj_pointer_get(const Eo_Id obj_id)
#ifdef HAVE_EO_ID
_Eo_Id_Entry *entry;
Generation_Counter generation;
- Table_Index table_id, int_table_id, entry_id;
+ Table_Index mid_table_id, table_id, entry_id;
- EO_DECOMPOSE_ID(obj_id, table_id, int_table_id, entry_id, generation);
+ EO_DECOMPOSE_ID(obj_id, mid_table_id, table_id, entry_id, generation);
/* Checking the validity of the entry */
- if (_eo_ids_tables[table_id] && ID_TABLE)
+ if (_eo_ids_tables[mid_table_id] && TABLE_FROM_IDS)
{
- entry = &(ID_TABLE->entries[entry_id]);
+ entry = &(TABLE_FROM_IDS->entries[entry_id]);
if (entry && entry->active && (entry->generation == generation))
return entry->ptr;
}
@@ -250,20 +256,20 @@ _get_available_entry(_Eo_Ids_Table *table)
{
_Eo_Id_Entry *entry = NULL;
- if (table->start != MAX_IDS_PER_TABLE)
+ if (table->start != MAX_ENTRY_ID)
{
/* Serve never used entries first */
entry = &(table->entries[table->start]);
table->start++;
}
- else if (table->queue_head != -1)
+ else if (table->fifo_head != -1)
{
- /* Pop an unused entry from the queue */
- entry = &(table->entries[table->queue_head]);
- if (entry->next_in_queue == -1)
- table->queue_head = table->queue_tail = -1;
+ /* Pop a free entry from the fifo */
+ entry = &(table->entries[table->fifo_head]);
+ if (entry->next_in_fifo == -1)
+ table->fifo_head = table->fifo_tail = -1;
else
- table->queue_head = entry->next_in_queue;
+ table->fifo_head = entry->next_in_fifo;
}
return entry;
@@ -275,25 +281,25 @@ _search_tables()
_Eo_Ids_Table *table;
_Eo_Id_Entry *entry;
- for (Table_Index table_id = 1; table_id < MAX_IDS_TABLES; table_id++)
+ for (Table_Index mid_table_id = 1; mid_table_id < MAX_MID_TABLE_ID;
mid_table_id++)
{
- if (!_eo_ids_tables[table_id])
+ if (!_eo_ids_tables[mid_table_id])
{
/* Allocate a new intermediate table */
- _eo_ids_tables[table_id] =
_eo_id_mem_calloc(MAX_IDS_INTER_TABLES, sizeof(_Eo_Ids_Table*));
+ _eo_ids_tables[mid_table_id] = _eo_id_mem_calloc(MAX_TABLE_ID,
sizeof(_Eo_Ids_Table*));
}
- for (Table_Index int_table_id = 0; int_table_id <
MAX_IDS_INTER_TABLES; int_table_id++)
+ for (Table_Index table_id = 0; table_id < MAX_TABLE_ID; table_id++)
{
- table = ID_TABLE;
+ table = TABLE_FROM_IDS;
if (!table)
{
/* Allocate a new table and reserve the first entry */
table = _eo_id_mem_calloc(1, sizeof(_Eo_Ids_Table));
table->start = 1;
- table->queue_head = table->queue_tail = -1;
- ID_TABLE = table;
+ table->fifo_head = table->fifo_tail = -1;
+ TABLE_FROM_IDS = table;
entry = &(table->entries[0]);
}
else
@@ -303,8 +309,8 @@ _search_tables()
{
/* Store table info into current table */
current_table.table = table;
+ current_table.mid_table_id = mid_table_id;
current_table.table_id = table_id;
- current_table.int_table_id = int_table_id;
return entry;
}
}
@@ -337,8 +343,8 @@ _eo_id_allocate(const _Eo *obj)
entry->generation = _eo_generation_counter;
_eo_generation_counter++;
_eo_generation_counter %= MAX_GENERATIONS;
- return EO_COMPOSE_ID(current_table.table_id,
- current_table.int_table_id,
+ return EO_COMPOSE_ID(current_table.mid_table_id,
+ current_table.table_id,
(entry - current_table.table->entries),
entry->generation);
#else
@@ -353,27 +359,27 @@ _eo_id_release(const Eo_Id obj_id)
_Eo_Ids_Table *table;
_Eo_Id_Entry *entry;
Generation_Counter generation;
- Table_Index table_id, int_table_id, entry_id;
- EO_DECOMPOSE_ID(obj_id, table_id, int_table_id, entry_id, generation);
+ Table_Index mid_table_id, table_id, entry_id;
+ EO_DECOMPOSE_ID(obj_id, mid_table_id, table_id, entry_id, generation);
/* Checking the validity of the entry */
- if (_eo_ids_tables[table_id] && (table = ID_TABLE))
+ if (_eo_ids_tables[mid_table_id] && (table = TABLE_FROM_IDS))
{
entry = &(table->entries[entry_id]);
if (entry && entry->active && (entry->generation == generation))
{
/* Disable the entry */
entry->active = 0;
- entry->next_in_queue = -1;
- /* Push the entry into the queue */
- if (table->queue_tail == -1)
+ entry->next_in_fifo = -1;
+ /* Push the entry into the fifo */
+ if (table->fifo_tail == -1)
{
- table->queue_head = table->queue_tail = entry_id;
+ table->fifo_head = table->fifo_tail = entry_id;
}
else
{
- table->entries[table->queue_tail].next_in_queue = entry_id;
- table->queue_tail = entry_id;
+ table->entries[table->fifo_tail].next_in_fifo = entry_id;
+ table->fifo_tail = entry_id;
}
return;
}
@@ -388,20 +394,20 @@ _eo_id_release(const Eo_Id obj_id)
void
_eo_free_ids_tables()
{
- for (Table_Index table_id = 0; table_id < MAX_IDS_TABLES; table_id++)
+ for (Table_Index mid_table_id = 0; mid_table_id < MAX_MID_TABLE_ID;
mid_table_id++)
{
- if (_eo_ids_tables[table_id])
+ if (_eo_ids_tables[mid_table_id])
{
- for (Table_Index int_table_id = 0; int_table_id <
MAX_IDS_INTER_TABLES; int_table_id++)
+ for (Table_Index table_id = 0; table_id < MAX_TABLE_ID;
table_id++)
{
- if (ID_TABLE)
+ if (TABLE_FROM_IDS)
{
- _eo_id_mem_free(ID_TABLE);
+ _eo_id_mem_free(TABLE_FROM_IDS);
}
}
- _eo_id_mem_free(_eo_ids_tables[table_id]);
+ _eo_id_mem_free(_eo_ids_tables[mid_table_id]);
}
- _eo_ids_tables[table_id] = NULL;
+ _eo_ids_tables[mid_table_id] = NULL;
}
current_table.table = NULL;
}
@@ -412,22 +418,22 @@ _eo_print()
{
_Eo_Id_Entry *entry;
unsigned long obj_number = 0;
- for (Table_Index table_id = 0; table_id < MAX_IDS_TABLES; table_id++)
+ for (Table_Index mid_table_id = 0; mid_table_id < MAX_MID_TABLE_ID;
mid_table_id++)
{
- if (_eo_ids_tables[table_id])
+ if (_eo_ids_tables[mid_table_id])
{
- for (Table_Index int_table_id = 0; int_table_id <
MAX_IDS_INTER_TABLES; int_table_id++)
+ for (Table_Index table_id = 0; table_id < MAX_TABLE_ID;
table_id++)
{
- if (ID_TABLE)
+ if (TABLE_FROM_IDS)
{
- for (Table_Index entry_id = 0; entry_id <
MAX_IDS_PER_TABLE; entry_id++)
+ for (Table_Index entry_id = 0; entry_id < MAX_ENTRY_ID;
entry_id++)
{
- entry = &(ID_TABLE->entries[entry_id]);
+ entry = &(TABLE_FROM_IDS->entries[entry_id]);
if (entry->active)
{
printf("%ld: %p -> (%p, %p, %p, %p)\n",
obj_number++,
entry->ptr,
- (void *)table_id, (void *)int_table_id,
(void *)entry_id,
+ (void *)mid_table_id, (void *)table_id,
(void *)entry_id,
(void *)entry->generation);
}
}
--
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