transmission/libtransmission/fdlimit.c

298 lines
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/******************************************************************************
* $Id$
*
* Copyright (c) 2005-2006 Transmission authors and contributors
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*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*****************************************************************************/
#include "transmission.h"
#define TR_MAX_OPEN_FILES 16 /* That is, real files, not sockets */
#define TR_RESERVED_FDS 16 /* Number of sockets reserved for
connections to trackers */
typedef struct tr_openFile_s
{
char path[MAX_PATH_LENGTH];
int file;
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#define STATUS_INVALID 1
#define STATUS_UNUSED 2
#define STATUS_USED 4
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#define STATUS_CLOSING 8
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int status;
uint64_t date;
} tr_openFile_t;
struct tr_fd_s
{
tr_lock_t lock;
int reserved;
int normal;
int normalMax;
tr_openFile_t open[TR_MAX_OPEN_FILES];
};
/***********************************************************************
* tr_fdInit
**********************************************************************/
tr_fd_t * tr_fdInit()
{
tr_fd_t * f;
int i, j, s[4096];
f = calloc( sizeof( tr_fd_t ), 1 );
/* Init lock */
tr_lockInit( &f->lock );
/* Detect the maximum number of open files or sockets */
for( i = 0; i < 4096; i++ )
{
if( ( s[i] = socket( AF_INET, SOCK_STREAM, 0 ) ) < 0 )
{
break;
}
}
for( j = 0; j < i; j++ )
{
tr_netClose( s[j] );
}
tr_dbg( "%d usable file descriptors", i );
f->reserved = 0;
f->normal = 0;
f->normalMax = i - TR_RESERVED_FDS - 10;
/* To be safe, in case the UI needs to write a preferences file
or something */
for( i = 0; i < TR_MAX_OPEN_FILES; i++ )
{
f->open[i].status = STATUS_INVALID;
}
return f;
}
/***********************************************************************
* tr_fdFileOpen
**********************************************************************/
int tr_fdFileOpen( tr_fd_t * f, char * path )
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{
int i, winner;
uint64_t date;
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tr_lockLock( &f->lock );
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/* Is it already open? */
for( i = 0; i < TR_MAX_OPEN_FILES; i++ )
{
if( f->open[i].status > STATUS_INVALID &&
!strcmp( path, f->open[i].path ) )
{
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if( f->open[i].status & STATUS_CLOSING )
{
/* Wait until the file is closed */
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tr_lockUnlock( &f->lock );
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tr_wait( 10 );
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tr_lockLock( &f->lock );
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i = -1;
continue;
}
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winner = i;
goto done;
}
}
/* Can we open one more file? */
for( i = 0; i < TR_MAX_OPEN_FILES; i++ )
{
if( f->open[i].status & STATUS_INVALID )
{
winner = i;
goto open;
}
}
for( ;; )
{
/* Close the oldest currently unused file */
date = tr_date() + 1;
winner = -1;
for( i = 0; i < TR_MAX_OPEN_FILES; i++ )
{
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if( !( f->open[i].status & STATUS_UNUSED ) )
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{
continue;
}
if( f->open[i].date < date )
{
winner = i;
date = f->open[i].date;
}
}
if( winner >= 0 )
{
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/* Close the file: we mark it as closing then release the
lock while doing so, because close may take same time
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and we don't want to block other threads */
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tr_dbg( "Closing %s", f->open[winner].path );
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f->open[winner].status = STATUS_CLOSING;
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tr_lockUnlock( &f->lock );
close( f->open[winner].file );
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tr_lockLock( &f->lock );
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goto open;
}
/* All used! Wait a bit and try again */
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tr_lockUnlock( &f->lock );
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tr_wait( 10 );
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tr_lockLock( &f->lock );
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}
open:
tr_dbg( "Opening %s", path );
snprintf( f->open[winner].path, MAX_PATH_LENGTH, "%s", path );
f->open[winner].file = open( path, O_RDWR, 0 );
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done:
f->open[winner].status = STATUS_USED;
f->open[winner].date = tr_date();
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tr_lockUnlock( &f->lock );
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return f->open[winner].file;
}
/***********************************************************************
* tr_fdFileRelease
**********************************************************************/
void tr_fdFileRelease( tr_fd_t * f, int file )
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{
int i;
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tr_lockLock( &f->lock );
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for( i = 0; i < TR_MAX_OPEN_FILES; i++ )
{
if( f->open[i].file == file )
{
f->open[i].status = STATUS_UNUSED;
break;
}
}
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tr_lockUnlock( &f->lock );
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}
/***********************************************************************
* tr_fdFileClose
**********************************************************************/
void tr_fdFileClose( tr_fd_t * f, char * path )
{
int i;
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tr_lockLock( &f->lock );
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/* Is it already open? */
for( i = 0; i < TR_MAX_OPEN_FILES; i++ )
{
if( f->open[i].status & STATUS_INVALID )
{
continue;
}
if( !strcmp( path, f->open[i].path ) )
{
tr_dbg( "Closing %s", path );
close( f->open[i].file );
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f->open[i].status = STATUS_INVALID;
break;
}
}
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tr_lockUnlock( &f->lock );
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}
int tr_fdSocketWillCreate( tr_fd_t * f, int reserved )
{
int ret;
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tr_lockLock( &f->lock );
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if( reserved )
{
if( f->reserved < TR_RESERVED_FDS )
{
ret = 0;
(f->reserved)++;
}
else
{
ret = 1;
}
}
else
{
if( f->normal < f->normalMax )
{
ret = 0;
(f->normal)++;
}
else
{
ret = 1;
}
}
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tr_lockUnlock( &f->lock );
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return ret;
}
void tr_fdSocketClosed( tr_fd_t * f, int reserved )
{
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tr_lockLock( &f->lock );
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if( reserved )
{
(f->reserved)--;
}
else
{
(f->normal)--;
}
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tr_lockUnlock( &f->lock );
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}
void tr_fdClose( tr_fd_t * f )
{
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tr_lockClose( &f->lock );
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free( f );
}