feature: session pool support forearch session by index

src/session/session_pool.cpp

@@ -5,25 +5,28 @@
 
 struct session_pool
 {
-    uint64_t count;
+    uint64_t capacity;
+    uint64_t available;
     struct list_head free_queue;
 };
 
-struct session_pool *session_pool_new(uint64_t count)
+struct session_pool *session_pool_new(uint64_t capacity)
 {
-    struct session_pool *pool = (struct session_pool *)calloc(1, sizeof(struct session_pool) + count * sizeof(struct session));
+    struct session_pool *pool = (struct session_pool *)calloc(1, sizeof(struct session_pool) + capacity * sizeof(struct session));
     if (pool == NULL)
     {
         return NULL;
     }
+    pool->available = 0;
+    pool->capacity = capacity;
     INIT_LIST_HEAD(&pool->free_queue);
 
     struct session *array = (struct session *)(pool + 1);
-    for (uint64_t i = 0; i < count; i++)
+    for (uint64_t i = 0; i < capacity; i++)
     {
         struct session *sess = &array[i];
         list_add_tail(&sess->free, &pool->free_queue);
-        pool->count++;
+        pool->available++;
     }
 
     return pool;
@@ -37,7 +40,7 @@ void session_pool_free(struct session_pool *pool)
         {
             struct session *sess = list_first_entry(&pool->free_queue, struct session, free);
             list_del(&sess->free);
-            pool->count--;
+            pool->available--;
         }
 
         free(pool);
@@ -59,7 +62,7 @@ struct session *session_pool_pop(struct session_pool *pool)
 
     struct session *sess = list_first_entry(&pool->free_queue, struct session, free);
     list_del(&sess->free);
-    pool->count--;
+    pool->available--;
 
     return sess;
 }
@@ -72,15 +75,36 @@ void session_pool_push(struct session_pool *pool, struct session *sess)
     }
 
     list_add_tail(&sess->free, &pool->free_queue);
-    pool->count++;
+    pool->available++;
 }
 
-uint64_t session_pool_get_count(struct session_pool *pool)
+const struct session *session_pool_get0(const struct session_pool *pool, uint64_t idx)
+{
+    if (pool == NULL || idx >= pool->capacity)
+    {
+        return NULL;
+    }
+
+    struct session *array = (struct session *)(pool + 1);
+    return &array[idx];
+}
+
+uint64_t session_pool_available_num(const struct session_pool *pool)
 {
     if (pool == NULL)
     {
         return 0;
     }
 
-    return pool->count;
-}
+    return pool->available;
+}
+
+uint64_t session_pool_capacity_size(const struct session_pool *pool)
+{
+    if (pool == NULL)
+    {
+        return 0;
+    }
+
+    return pool->capacity;
+}