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cdfs-cache.c
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/*
2010, 2011 Stef Bon <[email protected]>
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.
*/
#include "global-defines.h"
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <stdbool.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <err.h>
#include <inttypes.h>
#include <ctype.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <fcntl.h>
#include <pthread.h>
#include <sqlite3.h>
#ifndef ENOATTR
#define ENOATTR ENODATA /* No such attribute */
#endif
#include <fuse/fuse_lowlevel.h>
#include "logging.h"
#include "cdfs.h"
#include "entry-management.h"
#include "cdfs-cache.h"
#include "cdfs-cdromutils.h"
extern struct cdfs_options_struct cdfs_options;
extern struct cdfs_device_struct cdfs_device;
struct read_result_struct *head_queue_read_results=NULL;
struct read_result_struct *tail_queue_read_results=NULL;
struct read_result_struct *unused_read_results=NULL;
struct cached_block_struct *unused_cached_blocks=NULL;
struct caching_data_struct *list_caching_data=NULL;
unsigned char results_lock=0;
pthread_mutex_t results_lockmutex;
pthread_cond_t results_lockcond;
//
// create a new read_result
//
// if there is an unused one, take that one
// otherwise create one
//
//
static struct read_result_struct *get_read_result()
{
struct read_result_struct *read_result;
if ( ! unused_read_results ) {
// no unused ones... : create a new one
read_result=malloc(sizeof(struct read_result_struct));
} else {
// take from list
read_result=unused_read_results;
unused_read_results=read_result->next;
if (unused_read_results) unused_read_results->prev=NULL;
}
if ( read_result ) {
read_result->startsector=0;
read_result->endsector=0;
read_result->read_call=NULL;
read_result->next=NULL;
read_result->prev=NULL;
}
return read_result;
}
static void move_read_result_to_unused_list(struct read_result_struct *read_result)
{
// remove first from the active list
if ( read_result->next ) read_result->next->prev=read_result->prev;
if ( read_result->prev ) read_result->prev->next=read_result->next;
// insert in unused list at beginning
if ( unused_read_results ) {
read_result->next=unused_read_results;
if ( read_result->next ) read_result->next->prev=read_result;
read_result->prev=NULL;
}
unused_read_results=read_result;
}
struct caching_data_struct *create_caching_data()
{
struct caching_data_struct *caching_data;
int nreturn=0;
caching_data=malloc(sizeof(struct caching_data_struct));
if ( caching_data ) {
caching_data->fd=0;
caching_data->startsector=0;
caching_data->endsector=0;
caching_data->sectorsread=0;
caching_data->tracknr=0;
caching_data->size=0;
pthread_mutex_init(&(caching_data->cachelockmutex), NULL);
pthread_cond_init(&(caching_data->cachelockcond), NULL);
caching_data->cachelock=0;
caching_data->nrreads=0;
caching_data->writelock=0;
caching_data->cached_block=NULL;
// insert in list
caching_data->next=list_caching_data;
if ( list_caching_data ) list_caching_data->prev=caching_data;
list_caching_data=caching_data;
caching_data->prev=NULL;
}
return caching_data;
}
//
// todo: lock the list
//
struct caching_data_struct *find_caching_data_by_tracknr(unsigned char tracknr)
{
struct caching_data_struct *caching_data=list_caching_data;
while ( caching_data ) {
if ( caching_data->tracknr == tracknr ) break;
caching_data=caching_data->next;
}
return caching_data;
}
//
//
// create a file in the cache
//
// do that by checking it exist already. If that's the case check it correct
// if it does not exist, create it
//
// additionally create list of "already decoded blocks"
//
//
// possibly start with a decoded "head" of 4096 (or any other default size) bytes standard
// return:
// <0 : error
// =0 : file does exist already
// =1 : file created
int create_cache_file(struct caching_data_struct *caching_data, const char *name)
{
struct stat st;
int res, nreturn=0;
// the cachefile is stored in the cachedirectory with the same name as the entry,,,, very simple
// here a wait loop for the hashcache to be set and ready
if ( cdfs_device.initready==0 ) {
// hash is not set....
nreturn=pthread_mutex_lock(&(cdfs_device.initmutex));
while ( cdfs_device.initready==0 ) {
nreturn=pthread_cond_wait(&(cdfs_device.initcond), &(cdfs_device.initmutex));
// if a timeout is used: handle ETIMEDOUT here
if ( nreturn!=0 ) {
nreturn=-abs(nreturn);
goto out;
}
}
nreturn=pthread_mutex_unlock(&(cdfs_device.initmutex));
}
snprintf(caching_data->path, PATH_MAX, "%s/%s/%s", cdfs_options.cache_directory, cdfs_options.cachehash, name);
res=stat(caching_data->path, &st);
if ( res==-1 ) {
// does exists already
res=mknod(caching_data->path, S_IFREG | S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH, 0);
if (res==-1) {
nreturn=-errno;
goto out;
}
logoutput2("set size to %zi", caching_data->size);
res=truncate(caching_data->path, caching_data->size);
if (res<0 ) {
nreturn=-errno;
goto out;
}
nreturn=1; /* file created */
}
out:
return nreturn;
}
//
// copy nbytes from buffer to offset on cached file
//
// admin a cached block list
//
int write_to_cached_file(struct caching_data_struct *caching_data, char *buffer, off_t offset, size_t size)
{
int nreturn=0;
int fd=0;
unsigned char openhere=0;
if ( ! buffer || size<=0 ) {
return 0;
} else if ( caching_data->fd==0 ) {
logoutput2("write_to_cached file: fd is zero");
fd=open(caching_data->path, O_WRONLY);
if ( fd<=0 ) goto out;
openhere=1;
} else {
fd=caching_data->fd;
}
logoutput2("write_to_cached file: writing %zi bytes to %"PRIu64" in file %s", size, offset, caching_data->path);
nreturn = pwrite(fd, buffer, size, offset);
if ( nreturn==-1 ) {
logoutput("error writing to file: %i", errno);
} else {
logoutput("write_to_cached file: %i bytes written", nreturn);
}
out:
if (openhere==1) close(fd);
return nreturn;
}
//
// create a new "cached" interval
//
// if there is an unused one, take that one
// otherwise create one
//
//
static struct cached_block_struct *get_cached_block()
{
struct cached_block_struct *cached_block;
if ( ! unused_cached_blocks ) {
// no unused ones... : create a new one
cached_block=malloc(sizeof(struct cached_block_struct));
} else {
// take from list
cached_block=unused_cached_blocks;
unused_cached_blocks=cached_block->next;
if (cached_block->next) unused_cached_blocks->prev=NULL;
}
if ( cached_block ) {
cached_block->startsector=0;
cached_block->endsector=0;
cached_block->tracknr=0;
cached_block->next=NULL;
cached_block->prev=NULL;
}
return cached_block;
}
static void move_cached_block_to_unused_list(struct cached_block_struct *cached_block)
{
// remove first from the active list
if ( cached_block->next ) cached_block->next->prev=cached_block->prev;
if ( cached_block->prev ) cached_block->prev->next=cached_block->next;
// insert in unused list at beginning
if ( unused_cached_blocks ) {
cached_block->next=unused_cached_blocks;
if ( cached_block->next ) cached_block->next->prev=cached_block;
cached_block->prev=NULL;
}
unused_cached_blocks=cached_block;
}
//
//
// get a read lock on caching data
//
// if the mutex is locked increase the number of reads just like a semaphore
//
//
int get_readlock_caching_data(struct caching_data_struct *caching_data)
{
int nreturn=0;
int nerror=0;
logoutput2("get_readlock_caching_data");
nreturn=pthread_mutex_lock(&(caching_data->cachelockmutex));
if ( nreturn!=0 ) {
nerror=-abs(nreturn);
goto out;
}
if ( caching_data->writelock>0 ) {
// wait for the writelock to become zero
// no timeout here: just wait (forever?)
while ( caching_data->writelock>0 ) {
nreturn=pthread_cond_wait(&(caching_data->cachelockcond), &(caching_data->cachelockmutex));
// if a timeout is used: handle ETIMEDOUT here
if ( nreturn!=0 ) {
nerror=-abs(nreturn);
goto out;
}
}
}
// here: got lock
// increase the number of reads
caching_data->nrreads++;
nreturn=1;
nreturn=pthread_mutex_unlock(&(caching_data->cachelockmutex));
if ( nreturn!=0 ) {
nerror=-abs(nreturn);
goto out;
}
out:
logoutput2("get_readlock_caching_data: error: %i return %i", nerror, nreturn);
return (nerror!=0 ) ? nerror : 1;
}
//
// release read lock
//
// just like a semaphore decrease the number of reads
//
int release_readlock_caching_data(struct caching_data_struct *caching_data)
{
int nreturn=0;
int nerror=0;
logoutput2("release_readlock_caching_data_internal");
nreturn=pthread_mutex_lock(&(caching_data->cachelockmutex));
if ( nreturn!=0 ) {
nerror=-abs(nreturn);
goto out;
}
// here: got lock
// decrease the number of reads
caching_data->nrreads--;
if ( caching_data->writelock>0 ) {
if ( caching_data->nrreads==0 ) {
// signal waiting threads which want a writelock
// do this only when there is one (writelock>0 ) and there are no reads anymore...
// (this has been the latest)
nreturn=pthread_cond_broadcast(&(caching_data->cachelockcond));
if ( nreturn!=0 ) {
nerror=-abs(nreturn);
goto out;
}
}
}
// unlock
nreturn=pthread_mutex_unlock(&(caching_data->cachelockmutex));
if ( nreturn!=0 ) {
nerror=-abs(nreturn);
goto out;
}
out:
logoutput2("release_readlock_caching_data: error: %i return %i", nerror, nreturn);
return (nerror!=0 ) ? nerror : nreturn;
}
//
// get a write lock on caching data
//
// TODO: some stepping down from another write lock ?
//
int get_writelock_caching_data(struct caching_data_struct *caching_data)
{
int nreturn=0;
int nerror=0;
logoutput2("get_writelock_caching_data");
nreturn=pthread_mutex_lock(&(caching_data->cachelockmutex));
if ( nreturn!=0 ) {
nerror=-abs(nreturn);
goto out;
}
// wait for the writelock to become zero or one
// no timeout here: just wait (forever?)
if ( caching_data->writelock==2 ) {
while ( caching_data->writelock==2 ) {
nreturn=pthread_cond_wait(&(caching_data->cachelockcond), &(caching_data->cachelockmutex));
// if a timeout is used: handle ETIMEDOUT here
if ( nreturn!=0 ) {
nerror=-abs(nreturn);
goto out;
} else if ( caching_data->writelock==1 || caching_data->writelock==0 ) {
break;
}
}
}
//
// here: got the mutex lock
//
if ( caching_data->writelock==1 ) {
// got it from another write lock which is releasing
caching_data->writelock=2;
} else {
// set it to 1 to prevent new reads
caching_data->writelock=1;
// wait for read locks to be released
if ( caching_data->nrreads>0 ) {
while ( caching_data->nrreads>0 ) {
nreturn=pthread_cond_wait(&(caching_data->cachelockcond), &(caching_data->cachelockmutex));
}
}
caching_data->writelock=2;
}
nreturn=pthread_mutex_unlock(&(caching_data->cachelockmutex));
if ( nreturn!=0 ) {
nerror=-abs(nreturn);
goto out;
}
out:
logoutput2("get_writelock_caching_data: error: %i return %i", nerror, nreturn);
return (nerror!=0 ) ? nerror : 1;
}
//
// release write lock
//
int release_writelock_caching_data(struct caching_data_struct *caching_data)
{
int nreturn=0;
int nerror=0;
logoutput2("release_writelock_caching_data");
nreturn=pthread_mutex_lock(&(caching_data->cachelockmutex));
if ( nreturn!=0 ) {
nerror=-abs(nreturn);
goto out;
}
// here: got mutex lock
// two steps: first get down to 1 to enable other waiting threads for a write lock
// to get this lock
//
// first step down to 1
//
caching_data->writelock=1;
nreturn=pthread_cond_broadcast(&(caching_data->cachelockcond));
if ( nreturn!=0 ) {
nerror=-abs(nreturn);
goto out;
}
// unlock
nreturn=pthread_mutex_unlock(&(caching_data->cachelockmutex));
if ( nreturn!=0 ) {
nerror=-abs(nreturn);
goto out;
}
//
// second step down to 0
//
nreturn=pthread_mutex_lock(&(caching_data->cachelockmutex));
if ( nreturn!=0 ) {
nerror=-abs(nreturn);
goto out;
}
if ( caching_data->writelock ) {
caching_data->writelock=0;
nreturn=pthread_cond_broadcast(&(caching_data->cachelockcond));
if ( nreturn!=0 ) {
nerror=-abs(nreturn);
goto out;
}
}
// unlock
nreturn=pthread_mutex_unlock(&(caching_data->cachelockmutex));
if ( nreturn!=0 ) {
nerror=-abs(nreturn);
goto out;
}
out:
logoutput2("release_writelock_caching_data: error: %i return %i", nerror, nreturn);
return (nerror!=0 ) ? nerror : nreturn;
}
//
//
// insert a cached interval/block in the list of existing cached blocks
//
// merging with existing intervals is possible
//
// called from the special cache thread, that takes care of the setting of locks
//
int insert_cached_block_internal(struct caching_data_struct *caching_data, unsigned int startsector, unsigned int endsector)
{
struct cached_block_struct *cached_block=NULL;
struct cached_block_struct *cached_block_found=NULL;
struct cached_block_struct *next_cached_block=NULL;
struct cached_block_struct *before_cached_block=NULL;
struct cached_block_struct *after_cached_block=NULL;
unsigned int nrsectors = endsector - startsector + 1;
unsigned int tmpsectors=0;
int nwritelock;
logoutput2("insert block internal: new block 2 insert from %i to %i", startsector, endsector);
nwritelock=get_writelock_caching_data(caching_data);
if ( nwritelock<0 ) {
// for now ignore the error and just insert without a lock
logoutput2("insert block internal: unable to get a write lock....continue anyway without a lock");
nwritelock=0;
goto out;
}
cached_block=caching_data->cached_block;
while ( cached_block ) {
next_cached_block=cached_block->next; /* keep it cause cached_block might get lost */
// check the cached block is really before
if ( startsector > cached_block->endsector + 1 ) {
logoutput2("insert block internal: before cached block found (%i - %i)", cached_block->startsector, cached_block->endsector);
before_cached_block=cached_block;
cached_block=next_cached_block;
continue;
}
// check the cached block is really after
if ( cached_block->startsector > endsector + 1 ) {
logoutput2("insert block internal: after cached block found (%i - %i)", cached_block->startsector, cached_block->endsector);
after_cached_block=cached_block;
break;
}
// everything else is to merge, is as simple as that
logoutput2("insert block internal: merging with block from %i to %i", cached_block->startsector, cached_block->endsector);
// merge
if ( ! cached_block_found ) {
// adjust cached_block
tmpsectors=cached_block->endsector - cached_block->startsector + 1;
if ( cached_block->startsector > startsector ) {
cached_block->startsector=startsector;
} else {
startsector=cached_block->startsector;
}
if ( cached_block->endsector < endsector ) {
cached_block->endsector=endsector;
} else {
endsector=cached_block->endsector;
}
cached_block_found=cached_block;
// the actual sectors added are the difference
nrsectors=cached_block->endsector - cached_block->startsector + 1 - tmpsectors;
} else {
// merge two existing blocks together
// adjust cached_block_found and
// move cached_block to unused list
// is this ok???
tmpsectors=endsector - startsector + 1;
if ( cached_block->endsector>endsector ) {
cached_block_found->endsector=cached_block->endsector;
endsector=cached_block_found->endsector;
}
if ( cached_block->startsector<startsector ) {
cached_block_found->startsector=cached_block->startsector;
startsector=cached_block_found->startsector;
}
if ( cached_block->prev ) cached_block->prev->next=cached_block->next;
if ( cached_block->next ) cached_block->next->prev=cached_block->prev;
move_cached_block_to_unused_list(cached_block);
nrsectors=cached_block_found->endsector - cached_block_found->startsector + 1 - tmpsectors;
}
cached_block=next_cached_block;
}
//
// no block found to merge with
//
if ( ! cached_block_found ) {
cached_block_found=get_cached_block();
cached_block_found->startsector=startsector;
cached_block_found->endsector=endsector;
cached_block_found->tracknr=caching_data->tracknr;
}
if ( before_cached_block ) {
cached_block_found->prev=before_cached_block;
before_cached_block->next=cached_block_found;
} else {
caching_data->cached_block=cached_block_found;
cached_block_found->prev=NULL;
}
if ( after_cached_block ) {
cached_block_found->next=after_cached_block;
after_cached_block->prev=cached_block_found;
} else {
cached_block_found->next=NULL;
}
//
// update the number of sectors read
//
caching_data->sectorsread+=nrsectors;
cached_block=caching_data->cached_block;
if ( cached_block ) {
// check everything is read
if ( ! cached_block->next &&
cached_block->startsector==caching_data->startsector &&
cached_block->endsector==caching_data->endsector ) {
caching_data->ready=1;
}
}
//
// release the lock
//
if ( nwritelock>0 ) {
nwritelock=release_writelock_caching_data(caching_data);
}
out:
logoutput2("insert block internal: %i sectors added", nrsectors);
return nrsectors;
}
struct cached_block_struct *get_first_cached_block_internal(struct caching_data_struct *caching_data, unsigned int startsector, unsigned int endsector)
{
struct cached_block_struct *cached_block=NULL;
if ( caching_data->cached_block ) {
// there are blocks: look for the first block where
// the endsector is past the first sector we're looking for
cached_block=caching_data->cached_block;
while (cached_block) {
if ( cached_block->endsector >= startsector ) break;
cached_block=cached_block->next;
}
}
return cached_block;