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Diffstat (limited to 'netfs-sample/ncache.c')
| -rw-r--r-- | netfs-sample/ncache.c | 221 |
1 files changed, 0 insertions, 221 deletions
diff --git a/netfs-sample/ncache.c b/netfs-sample/ncache.c deleted file mode 100644 index 12462d31..00000000 --- a/netfs-sample/ncache.c +++ /dev/null @@ -1,221 +0,0 @@ -/*----------------------------------------------------------------------------*/ -/*ncache.h*/ -/*----------------------------------------------------------------------------*/ -/*The implementation of the cache of nodes*/ -/*----------------------------------------------------------------------------*/ -/*Based on the code of unionfs translator.*/ -/*----------------------------------------------------------------------------*/ -/*Copyright (C) 2001, 2002, 2005 Free Software Foundation, Inc. - Written by Sergiu Ivanov <unlimitedscolobb@gmail.com>. - - 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 the Free Software Foundation; either version 2 of the - License, or * (at your option) any later version. - - This program is distributed in the hope that it will be useful, but - WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - General Public License for more details. - - You should have received a copy of the GNU General Public License - along with this program; if not, write to the Free Software - Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 - USA.*/ -/*----------------------------------------------------------------------------*/ - -/*----------------------------------------------------------------------------*/ -#define _GNU_SOURCE 1 -/*----------------------------------------------------------------------------*/ -#include "ncache.h" -/*----------------------------------------------------------------------------*/ - -/*----------------------------------------------------------------------------*/ -/*--------Global Variables----------------------------------------------------*/ -/*The global cache chain*/ -ncache_t ncache; -/*----------------------------------------------------------------------------*/ -/*Cache size (may be overwritten by the user)*/ -int ncache_size = NCACHE_SIZE; -/*----------------------------------------------------------------------------*/ - -/*----------------------------------------------------------------------------*/ -/*--------Functions-----------------------------------------------------------*/ -/*Initializes the node cache*/ -void -ncache_init - ( - int size_max - ) - { - /*Reset the LRU and MRU ends of the list*/ - ncache.mru = ncache.lru = NULL; - - /*Set the maximal size according to the parameter*/ - ncache.size_max = size_max; - - /*The cache is empty so far; remark that*/ - ncache.size_current = 0; - - /*Init the lock*/ - mutex_init(&ncache.lock); - }/*ncache_init*/ -/*----------------------------------------------------------------------------*/ -/*Looks up the lnode and stores the result in `node`; creates a new entry - in the cache if the lookup fails*/ -error_t -ncache_node_lookup - ( - lnode_t * lnode, /*search for this*/ - node_t ** node /*put the result here*/ - ) - { - error_t err = 0; - - /*Obtain the pointer to the node corresponding to `lnode`*/ - node_t * n = lnode->node; - - /*If a node has already been created for the given lnode*/ - if(n != NULL) - { - /*count a new reference to 'n'*/ - netfs_nref(n); - } - else - { - /*create a new node for the given lnode and store the result in `n`*/ - err = node_create(lnode, &n); - } - - /*If no errors have occurred during the previous operations*/ - if(!err) - { - /*lock the mutex in the looked up node*/ - mutex_lock(&n->lock); - - /*store the lookup result in `node`*/ - *node = n; - } - - /*Return the result of operations*/ - return err; - }/*ncache_node_lookup*/ -/*----------------------------------------------------------------------------*/ -/*Removes the given node from the cache*/ -static -void -ncache_node_remove - ( - node_t * node - ) - { - /*Obtain the pointer to the netnode (this contains the information - specific of us)*/ - struct netnode * nn = node->nn; - - /*If there exists a successor of this node in the cache chain*/ - if(nn->ncache_next) - /*remove the reference in the successor*/ - nn->ncache_next->nn->ncache_prev = nn->ncache_prev; - /*If there exists a predecessor of this node in the cache chain*/ - if(nn->ncache_prev) - /*remove the reference in the predecessor*/ - nn->ncache_prev->nn->ncache_next = nn->ncache_next; - - /*If the node was located at the MRU end of the list*/ - if(ncache.mru == node) - /*shift the MRU end to the next node*/ - ncache.mru = nn->ncache_next; - /*If the node was located at the LRU end of the list*/ - if(ncache.lru == node) - /*shift the LRU end to the previous node*/ - ncache.lru = nn->ncache_prev; - - /*Invalidate the references inside the node*/ - nn->ncache_next = nn->ncache_prev = NULL; - - /*Count the removal of a node*/ - --ncache.size_current; - }/*ncache_node_remove*/ -/*----------------------------------------------------------------------------*/ -/*Resets the node cache*/ -void -ncache_reset(void) - { - /*The node being currently deleted*/ - node_t * node; - - /*Acquire a lock on the cache*/ - mutex_lock(&ncache.lock); - - /*Remove the whole cache chain*/ - for(node = ncache.mru; node != NULL; ncache_node_remove(node), node = ncache.mru); - - /*Release the lock*/ - mutex_unlock(&ncache.lock); - }/*ncache_reset*/ -/*----------------------------------------------------------------------------*/ -/*Adds the given node to the cache*/ -void -ncache_node_add - ( - node_t * node /*the node to add*/ - ) - { - /*Acquire a lock on the cache*/ - mutex_lock(&ncache.lock); - - /*If there already are some nodes in the cache and it is enabled*/ - if((ncache.size_max > 0) || (ncache.size_current > 0)) - { - /*If the node to be added is not at the MRU end already*/ - if(ncache.mru != node) - { - /*If the node is correctly integrated in the cache*/ - if((node->nn->ncache_next != NULL) && (node->nn->ncache_prev != NULL)) - /*remove the old entry*/ - ncache_node_remove(node); - else - /*add a new reference to the node*/ - netfs_nref(node); - - /*put the node at the MRU end of the cache chain*/ - node->nn->ncache_next = ncache.mru; - node->nn->ncache_prev = NULL; - - /*setup the pointer in the old MRU end, if it exists*/ - if(ncache.mru != NULL) - ncache.mru->nn->ncache_prev = node; - - /*setup the LRU end of the cache chain, if it did not exist previously*/ - if(ncache.lru == NULL) - ncache.lru = node; - - /*shift the MRU end to the new node*/ - ncache.mru = node; - - /*count the addition*/ - ++ncache.size_current; - } - } - - /*While the size of the cache is exceeding the maximal size*/ - node_t * old_lru; - for - ( - old_lru = ncache.lru; - ncache.size_current > ncache.size_max; - old_lru = ncache.lru - ) - { - /*remove the current LRU end of the list from the cache*/ - ncache_node_remove(old_lru); - - /*release the reference to the node owned by this thread*/ - netfs_nrele(old_lru); - } - - /*Release the lock on the cache*/ - mutex_unlock(&ncache.lock); - }/*ncache_node_add*/ -/*----------------------------------------------------------------------------*/ |