diff options
Diffstat (limited to 'sql/hash_filo.h')
| -rw-r--r-- | sql/hash_filo.h | 93 |
1 files changed, 76 insertions, 17 deletions
diff --git a/sql/hash_filo.h b/sql/hash_filo.h index b6068348d1d..abba4824c9e 100644 --- a/sql/hash_filo.h +++ b/sql/hash_filo.h @@ -1,4 +1,4 @@ -/* Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved. +/* Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -47,8 +47,11 @@ private: class hash_filo { - const uint size, key_offset, key_length; +private: + const uint key_offset, key_length; const my_hash_get_key get_key; + /** Size of this hash table. */ + uint m_size; my_hash_free_key free_element; bool init; CHARSET_INFO *hash_charset; @@ -61,9 +64,12 @@ public: hash_filo(uint size_arg, uint key_offset_arg , uint key_length_arg, my_hash_get_key get_key_arg, my_hash_free_key free_element_arg, CHARSET_INFO *hash_charset_arg) - :size(size_arg), key_offset(key_offset_arg), key_length(key_length_arg), - get_key(get_key_arg), free_element(free_element_arg),init(0), - hash_charset(hash_charset_arg) + :key_offset(key_offset_arg), key_length(key_length_arg), + get_key(get_key_arg), m_size(size_arg), + free_element(free_element_arg),init(0), + hash_charset(hash_charset_arg), + first_link(NULL), + last_link(NULL) { bzero((char*) &cache,sizeof(cache)); } @@ -86,32 +92,61 @@ public: } if (!locked) mysql_mutex_lock(&lock); + first_link= NULL; + last_link= NULL; (void) my_hash_free(&cache); - (void) my_hash_init(&cache,hash_charset,size,key_offset, + (void) my_hash_init(&cache,hash_charset,m_size,key_offset, key_length, get_key, free_element,0); if (!locked) mysql_mutex_unlock(&lock); - first_link=last_link=0; + } + + hash_filo_element *first() + { + mysql_mutex_assert_owner(&lock); + return first_link; + } + + hash_filo_element *last() + { + mysql_mutex_assert_owner(&lock); + return last_link; } hash_filo_element *search(uchar* key, size_t length) { + mysql_mutex_assert_owner(&lock); + hash_filo_element *entry=(hash_filo_element*) my_hash_search(&cache,(uchar*) key,length); if (entry) { // Found; link it first + DBUG_ASSERT(first_link != NULL); + DBUG_ASSERT(last_link != NULL); if (entry != first_link) { // Relink used-chain if (entry == last_link) - last_link=entry->prev_used; + { + last_link= last_link->prev_used; + /* + The list must have at least 2 elements, + otherwise entry would be equal to first_link. + */ + DBUG_ASSERT(last_link != NULL); + last_link->next_used= NULL; + } else { + DBUG_ASSERT(entry->next_used != NULL); + DBUG_ASSERT(entry->prev_used != NULL); entry->next_used->prev_used = entry->prev_used; entry->prev_used->next_used = entry->next_used; } - if ((entry->next_used= first_link)) - first_link->prev_used=entry; - first_link=entry; + entry->prev_used= NULL; + entry->next_used= first_link; + + first_link->prev_used= entry; + first_link=entry; } } return entry; @@ -119,10 +154,20 @@ public: bool add(hash_filo_element *entry) { - if (cache.records == size) + if (!m_size) return 1; + if (cache.records == m_size) { hash_filo_element *tmp=last_link; - last_link=last_link->prev_used; + last_link= last_link->prev_used; + if (last_link != NULL) + { + last_link->next_used= NULL; + } + else + { + /* Pathological case, m_size == 1 */ + first_link= NULL; + } my_hash_delete(&cache,(uchar*) tmp); } if (my_hash_insert(&cache,(uchar*) entry)) @@ -131,13 +176,27 @@ public: (*free_element)(entry); // This should never happen return 1; } - if ((entry->next_used=first_link)) - first_link->prev_used=entry; + entry->prev_used= NULL; + entry->next_used= first_link; + if (first_link != NULL) + first_link->prev_used= entry; else - last_link=entry; - first_link=entry; + last_link= entry; + first_link= entry; + return 0; } + + uint size() + { return m_size; } + + void resize(uint new_size) + { + mysql_mutex_lock(&lock); + m_size= new_size; + clear(true); + mysql_mutex_unlock(&lock); + } }; #endif |