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transmission/libtransmission/peer.c

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/******************************************************************************
* $Id$
*
* Copyright (c) 2005-2007 Transmission authors and contributors
*
* 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 <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdarg.h>
#include "transmission.h"
#include "bencode.h"
#include "clients.h" /* for tr_clientForId() */
#include "peertree.h"
#include "list.h"
#include "net.h"
/*****
******
*****/
/**
*** The "SWIFT" system is described by Karthik Tamilmani,
*** Vinay Pai, and Alexander Mohr of Stony Brook University
*** in their paper "SWIFT: A System With Incentives For Trading"
*** http://citeseer.ist.psu.edu/tamilmani04swift.html
**/
/**
* Use SWIFT?
*/
static const int SWIFT_ENABLED = 1;
/**
* For every byte the peer uploads to us,
* allow them to download this many bytes from us
*/
static const double SWIFT_REPAYMENT_RATIO = 1.33;
/**
* Allow new peers to download this many bytes from
* us when getting started. This can prevent gridlock
* with other peers using tit-for-tat algorithms
*/
static const int SWIFT_INITIAL_CREDIT = 64 * 1024; /* 64 KiB */
/**
* We expend a fraction of our torrent's total upload speed
* on largesse by uniformly distributing free credit to
* all of our peers. This too helps prevent gridlock.
*/
static const double SWIFT_LARGESSE = 0.10; /* 10% of our UL */
/**
* How frequently to extend largesse-based credit
*/
static const int SWIFT_REFRESH_INTERVAL_SEC = 5;
/*****
******
*****/
#define PERCENT_PEER_WANTED 25 /* Percent before we start relax peers min activeness */
#define MIN_UPLOAD_IDLE 60000 /* In high peer situations we wait only 1 min
until dropping peers for idling */
#define MAX_UPLOAD_IDLE 240000 /* In low peer situations we wait the
4 mins until dropping peers for idling */
#define MIN_KEEP_ALIVE 180000 /* In high peer situations we wait only 3 min
without a keep-alive */
#define MAX_KEEP_ALIVE 360000 /* In low peer situations we wait the
6 mins without a keep-alive */
#define MIN_CON_TIMEOUT 8000 /* Time to timeout connecting to peer,
during low peer situations */
#define MAX_CON_TIMEOUT 30000 /* Time to timeout connecting to peer,
during high peer situations */
#define PEX_PEER_CUTOFF 50 /* only try to add new peers from pex if
we have fewer existing peers than this */
#define PEX_INTERVAL 60 /* don't send pex messages more frequently
than PEX_INTERVAL +
rand( PEX_INTERVAL / 10 ) seconds */
#define PEER_SUPPORTS_EXTENDED_MESSAGES( bits ) ( (bits)[5] & 0x10 )
#define PEER_SUPPORTS_AZUREUS_PROTOCOL( bits ) ( (bits)[0] & 0x80 )
#define PEER_MSG_CHOKE 0
#define PEER_MSG_UNCHOKE 1
#define PEER_MSG_INTERESTED 2
#define PEER_MSG_UNINTERESTED 3
#define PEER_MSG_HAVE 4
#define PEER_MSG_BITFIELD 5
#define PEER_MSG_REQUEST 6
#define PEER_MSG_PIECE 7
#define PEER_MSG_CANCEL 8
#define PEER_MSG_PORT 9
#define PEER_MSG_EXTENDED 20
typedef struct tr_request_s
{
int index;
int begin;
int length;
} tr_request_t;
struct tr_peer_s
{
tr_torrent_t * tor;
struct in_addr addr;
in_port_t port; /* peer's listening port, 0 if not known */
#define PEER_STATUS_IDLE 1 /* Need to connect */
#define PEER_STATUS_CONNECTING 2 /* Trying to send handshake */
#define PEER_STATUS_HANDSHAKE 3 /* Waiting for peer's handshake */
#define PEER_STATUS_AZ_GIVER 4 /* Sending Azureus handshake */
#define PEER_STATUS_AZ_RECEIVER 5 /* Receiving Azureus handshake */
#define PEER_STATUS_CONNECTED 6 /* Got peer's handshake */
int status;
int socket;
char from;
char private;
char azproto; /* azureus peer protocol is being used */
uint64_t date;
uint64_t keepAlive;
#define EXTENDED_NOT_SUPPORTED 0 /* extended messages not supported */
#define EXTENDED_SUPPORTED 1 /* waiting to send extended handshake */
#define EXTENDED_HANDSHAKE 2 /* sent extended handshake */
uint8_t extStatus;
uint8_t pexStatus; /* peer's ut_pex id, 0 if not supported */
uint64_t lastPex; /* time when last pex packet was sent */
int advertisedPort; /* listening port we last told peer */
tr_peertree_t sentPeers;
char isChokedByUs;
char isChokingUs;
char isInteresting;
char isInterested;
int optimistic;
int timesChoked;
uint64_t lastChoke;
uint8_t id[TR_ID_LEN];
/* The pieces that the peer has */
tr_bitfield_t * bitfield;
/* blocks we've requested from this peer */
tr_bitfield_t * reqfield;
int pieceCount;
float progress;
int goodPcs;
int badPcs;
int banned;
/* The pieces that the peer is contributing to */
tr_bitfield_t * blamefield;
/* The bad pieces that the peer has contributed to */
tr_bitfield_t * banfield;
uint8_t * buf;
int size;
int pos;
uint8_t * outMessages;
int outMessagesSize;
int outMessagesPos;
uint8_t outBlock[25+16384];
int outBlockSize;
int outBlockLoaded;
int outBlockSending;
int inRequestCount;
int inRequestMax;
int inRequestAlloc;
tr_request_t * inRequests;
int inIndex;
int inBegin;
int inLength;
tr_list_t * outRequests;
uint64_t outDate;
tr_ratecontrol_t * download;
tr_ratecontrol_t * upload;
char * client;
int64_t credit;
};
#define peer_dbg( a... ) __peer_dbg( peer, ## a )
static void __peer_dbg( tr_peer_t * peer, char * msg, ... ) PRINTF( 2, 3 );
static void __peer_dbg( tr_peer_t * peer, char * msg, ... )
{
char string[256];
va_list args;
va_start( args, msg );
snprintf( string, sizeof string, "%08x:%04x ",
(uint32_t) peer->addr.s_addr, peer->port );
vsnprintf( &string[14], sizeof( string ) - 14, msg, args );
va_end( args );
tr_dbg( "%s", string );
}
/* utilities for endian conversions with char pointers */
static uint32_t tr_ntohl( const void * p )
{
uint32_t u;
memcpy( &u, p, sizeof( uint32_t ) );
return ntohl( u );
}
static void tr_htonl( uint32_t a, void * p )
{
const uint32_t u = htonl( a );
memcpy ( p, &u, sizeof( uint32_t ) );
}
#include "peerext.h"
#include "peeraz.h"
#include "peermessages.h"
#include "peerutils.h"
#include "peerparse.h"
/***********************************************************************
* tr_peerInit
***********************************************************************
* Initializes a new peer.
**********************************************************************/
tr_peer_t * tr_peerInit( const struct in_addr * addr, in_port_t port,
int s, int from )
{
tr_peer_t * peer;
assert( 0 <= from && TR_PEER_FROM__MAX > from );
peer = tr_new0( tr_peer_t, 1 );
peer->isChokedByUs = TRUE;
peer->isChokingUs = TRUE;
peer->date = tr_date();
peer->keepAlive = peer->date;
peer->download = tr_rcInit();
peer->upload = tr_rcInit();
peertreeInit( &peer->sentPeers );
peer->inRequestMax = peer->inRequestAlloc = 2;
peer->inRequests = tr_new0( tr_request_t, peer->inRequestAlloc );
peer->socket = s;
peer->addr = *addr;
peer->port = port;
peer->from = from;
peer->credit = SWIFT_INITIAL_CREDIT;
if( s >= 0 )
{
assert( TR_PEER_FROM_INCOMING == from );
peer->status = PEER_STATUS_CONNECTING;
}
else
{
peer->status = PEER_STATUS_IDLE;
}
return peer;
}
void tr_peerDestroy( tr_peer_t * peer )
{
tr_torrent_t * tor = peer->tor;
tr_request_t * r;
int i, block;
peertreeFree( &peer->sentPeers );
for( i = 0; i < peer->inRequestCount; i++ )
{
r = &peer->inRequests[i];
block = tr_block( r->index, r->begin );
if( tor != NULL )
tr_cpDownloaderRem( tor->completion, block );
}
tr_bitfieldFree( peer->bitfield );
tr_bitfieldFree( peer->blamefield );
tr_bitfieldFree( peer->banfield );
tr_bitfieldFree( peer->reqfield );
tr_list_foreach( peer->outRequests, tr_free );
tr_list_free( peer->outRequests );
tr_free( peer->inRequests );
tr_free( peer->buf );
tr_free( peer->outMessages );
if( peer->status > PEER_STATUS_IDLE )
{
tr_netClose( peer->socket );
}
tr_rcClose( peer->download );
tr_rcClose( peer->upload );
free( peer->client );
memset( peer, '\0', sizeof(tr_peer_t) );
free( peer );
}
const char *
tr_peerClient( tr_peer_t * peer )
{
if( PEER_STATUS_HANDSHAKE >= peer->status )
{
return "not connected";
}
if( NULL == peer->client )
{
peer->client = tr_clientForId( peer->id );
}
return peer->client;
}
void tr_peerSetPrivate( tr_peer_t * peer, int private )
{
if( peer->private == private )
{
return;
}
peer->private = private;
if( !private )
{
peer->lastPex = 0;
}
if( EXTENDED_HANDSHAKE == peer->extStatus )
{
sendExtended( peer->tor, peer, EXTENDED_HANDSHAKE_ID );
}
}
void tr_peerSetTorrent( tr_peer_t * peer, tr_torrent_t * tor )
{
peer->tor = tor;
}
/***********************************************************************
* tr_peerRead
***********************************************************************
*
**********************************************************************/
int tr_peerRead( tr_peer_t * peer )
{
tr_torrent_t * tor = peer->tor;
int ret;
uint64_t date;
/* Try to read */
for( ;; )
{
if( tor )
{
int canDL;
switch( tor->downloadLimitMode ) {
case TR_SPEEDLIMIT_GLOBAL:
canDL = !tor->handle->useDownloadLimit ||
tr_rcCanTransfer( tor->handle->download ); break;
case TR_SPEEDLIMIT_SINGLE:
canDL = tr_rcCanTransfer( tor->download ); break;
default: /* unlimited */
canDL = TRUE;
}
if( !canDL )
break;
}
if( peer->size < 1 )
{
peer->size = 1024;
peer->buf = malloc( peer->size );
}
else if( peer->pos >= peer->size )
{
peer->size *= 2;
peer->buf = realloc( peer->buf, peer->size );
}
/* Read in smallish chunks, otherwise we might read more
* than the download cap is supposed to allow us */
ret = tr_netRecv( peer->socket, &peer->buf[peer->pos],
MIN( 1024, peer->size - peer->pos ) );
if( ret & TR_NET_CLOSE )
{
peer_dbg( "connection closed" );
return TR_ERROR;
}
else if( ret & TR_NET_BLOCK )
{
break;
}
date = tr_date();
peer->date = date;
peer->pos += ret;
if( NULL != tor )
{
if( peer->isInteresting && !peer->isChokingUs )
{
tor->activityDate = date;
}
if( ( ret = parseBuf( tor, peer ) ) )
{
return ret;
}
}
else
{
if( ( ret = parseBufHeader( peer ) ) )
{
return ret;
}
}
}
return TR_OK;
}
uint64_t tr_peerDate( const tr_peer_t * peer )
{
return peer->date;
}
/***********************************************************************
* tr_peerAddress
***********************************************************************
*
**********************************************************************/
struct in_addr * tr_peerAddress( tr_peer_t * peer )
{
return &peer->addr;
}
/***********************************************************************
* tr_peerHash
***********************************************************************
*
**********************************************************************/
const uint8_t * tr_peerHash( const tr_peer_t * peer )
{
return parseBufHash( peer );
}
/***********************************************************************
* tr_peerPulse
***********************************************************************
*
**********************************************************************/
int tr_peerPulse( tr_peer_t * peer )
{
tr_torrent_t * tor = peer->tor;
int ret, size;
uint8_t * p;
uint64_t date;
int isSeeding;
assert( peer != NULL );
assert( peer->tor != NULL );
isSeeding = tr_cpGetStatus( tor->completion ) != TR_CP_INCOMPLETE;
if( ( ret = checkPeer( peer ) ) )
{
return ret;
}
/* Connect */
if( PEER_STATUS_IDLE == peer->status )
{
peer->socket = tr_netOpenTCP( &peer->addr, peer->port, 0 );
if( peer->socket < 0 )
{
return TR_ERROR;
}
peer->status = PEER_STATUS_CONNECTING;
}
/* Disconnect if seeder and torrent is seeding */
if( ( peer->progress >= 1.0 )
&& ( peer->tor->cpStatus != TR_CP_INCOMPLETE ) )
{
return TR_ERROR;
}
/* Try to send handshake */
if( PEER_STATUS_CONNECTING == peer->status )
{
uint8_t buf[68];
tr_info_t * inf = &tor->info;
buf[0] = 19;
memcpy( &buf[1], "BitTorrent protocol", 19 );
memset( &buf[20], 0, 8 );
buf[20] = 0x80; /* azureus protocol */
buf[25] = 0x10; /* extended messages */
memcpy( &buf[28], inf->hash, 20 );
memcpy( &buf[48], tor->peer_id, 20 );
switch( tr_netSend( peer->socket, buf, 68 ) )
{
case 68:
peer_dbg( "SEND handshake" );
peer->status = PEER_STATUS_HANDSHAKE;
break;
case TR_NET_BLOCK:
break;
default:
peer_dbg( "connection closed" );
return TR_ERROR;
}
}
if( peer->status < PEER_STATUS_HANDSHAKE )
{
/* Nothing more we can do till we sent the handshake */
return TR_OK;
}
/* Read incoming messages */
if( ( ret = tr_peerRead( peer ) ) )
{
return ret;
}
/* Try to send Azureus handshake */
if( PEER_STATUS_AZ_GIVER == peer->status )
{
switch( sendAZHandshake( tor, peer ) )
{
case TR_NET_BLOCK:
break;
case TR_NET_CLOSE:
peer_dbg( "connection closed" );
return TR_ERROR;
default:
peer->status = PEER_STATUS_AZ_RECEIVER;
break;
}
}
if( peer->status < PEER_STATUS_CONNECTED )
{
/* Nothing more we can do till we got the other guy's handshake */
return TR_OK;
}
/* Try to write */
writeBegin:
/* Send all smaller messages regardless of the upload cap */
while( ( p = messagesPending( peer, &size ) ) )
{
ret = tr_netSend( peer->socket, p, size );
if( ret & TR_NET_CLOSE )
{
return TR_ERROR;
}
else if( ret & TR_NET_BLOCK )
{
goto writeEnd;
}
messagesSent( peer, ret );
}
/* Send pieces if we can */
while( ( p = blockPending( tor, peer, &size ) ) )
{
int canUL;
if( SWIFT_ENABLED && !isSeeding && (peer->credit<0) )
canUL = FALSE;
else switch( tor->uploadLimitMode )
{
case TR_SPEEDLIMIT_GLOBAL:
canUL = !tor->handle->useUploadLimit ||
tr_rcCanTransfer( tor->handle->upload ); break;
case TR_SPEEDLIMIT_SINGLE:
canUL = tr_rcCanTransfer( tor->upload ); break;
default: /* unlimited */
canUL = TRUE;
}
if( !canUL )
break;
ret = tr_netSend( peer->socket, p, size );
if( ret & TR_NET_CLOSE )
return TR_ERROR;
if( ret & TR_NET_BLOCK )
break;
blockSent( peer, ret );
if( ret > 0 )
tr_peerGotBlockFromUs( peer, ret );
date = tr_date();
peer->outDate = date;
if( !tr_peerIsChokedByUs( peer ) )
tor->activityDate = date;
/* In case this block is done, you may have messages
pending. Send them before we start the next block */
goto writeBegin;
}
writeEnd:
/* Ask for a block whenever possible */
if( !isSeeding
&& !peer->isInteresting
&& tor->peerCount > TR_MAX_PEER_COUNT - 2 )
{
/* This peer is no use to us, and it seems there are
more */
peer_dbg( "not interesting" );
return TR_ERROR;
}
if( peer->isInteresting
&& !peer->isChokingUs
&& !peer->banned
&& peer->inRequestCount < peer->inRequestMax )
{
int poolSize = 0;
int endgame = FALSE;
int openSlots = peer->inRequestMax - peer->inRequestCount;
int * pool = getPreferredPieces ( tor, peer, &poolSize, &endgame );
if( !endgame )
{
/* pool is sorted from most to least desirable pieces,
so work our way through starting at beginning */
int p;
for( p=0; p<poolSize && openSlots>0; )
{
const int piece = pool[p];
const int block = tr_cpMissingBlockInPiece ( tor->completion, piece );
if( block < 0 )
++p;
else {
sendRequest( tor, peer, block );
--openSlots;
}
}
}
else
{
/* During endgame we remove the constraint of not asking for
pieces we've already requested from a different peer.
So if we follow the non-endgame approach of walking through
[0..poolCount) we'll bog down asking all peers for 1, then
all peers for 2, and so on. Randomize our starting point
into "pool" to reduce such overlap */
int piecesLeft = poolSize;
int p = piecesLeft ? tr_rand(piecesLeft) : 0;
for( ; openSlots>0 && piecesLeft>0; --piecesLeft, p=(p+1)%poolSize )
{
const int piece = pool[p];
const int firstBlock = TOR_PIECE_FIRST_BLOCK( tor, piece );
const int n = TR_BLOCKS_IN_PIECE( tor, piece );
const int end = firstBlock + n;
int block;
for( block=firstBlock; openSlots>0 && block<end; ++block )
{
/* don't ask for it if we've already got it */
if( tr_cpBlockIsComplete( tor->completion, block ))
continue;
/* don't ask for it twice from the same peer */
if( tr_bitfieldHas( peer->reqfield, block ) )
continue;
/* ask peer for the piece */
if( !peer->reqfield )
peer->reqfield = tr_bitfieldNew( tor->blockCount );
tr_bitfieldAdd( peer->reqfield, block );
sendRequest( tor, peer, block );
--openSlots;
}
}
}
tr_free( pool );
}
assert( peer->inRequestCount <= peer->inRequestAlloc );
assert( peer->inRequestMax <= peer->inRequestAlloc );
return TR_OK;
}
int tr_peerIsConnected( const tr_peer_t * peer )
{
return peer && (peer->status == PEER_STATUS_CONNECTED);
}
int tr_peerIsFrom( const tr_peer_t * peer )
{
return peer->from;
}
int tr_peerIsChokedByUs( const tr_peer_t * peer )
{
return peer->isChokedByUs;
}
int tr_peerIsInteresting( const tr_peer_t * peer )
{
return peer->isInteresting;
}
int tr_peerIsChokingUs( const tr_peer_t * peer )
{
return peer->isChokingUs;
}
int tr_peerIsInterested( const tr_peer_t * peer )
{
return peer->isInterested;
}
float tr_peerProgress( const tr_peer_t * peer )
{
return peer->progress;
}
int tr_peerPort( const tr_peer_t * peer )
{
return ntohs( peer->port );
}
int tr_peerHasPiece( const tr_peer_t * peer, int pieceIndex )
{
return tr_bitfieldHas( peer->bitfield, pieceIndex );
}
float tr_peerDownloadRate( const tr_peer_t * peer )
{
return tr_rcRate( peer->download );
}
float tr_peerUploadRate( const tr_peer_t * peer )
{
return tr_rcRate( peer->upload );
}
int tr_peerTimesChoked( const tr_peer_t * peer )
{
return peer->timesChoked;
}
void tr_peerChoke( tr_peer_t * peer )
{
sendChoke( peer, 1 );
peer->lastChoke = tr_date();
++peer->timesChoked;
}
void tr_peerUnchoke( tr_peer_t * peer )
{
sendChoke( peer, 0 );
peer->lastChoke = tr_date();
}
uint64_t tr_peerLastChoke( const tr_peer_t * peer )
{
return peer->lastChoke;
}
void tr_peerSetOptimistic( tr_peer_t * peer, int o )
{
peer->optimistic = o;
}
int tr_peerIsOptimistic( const tr_peer_t * peer )
{
return peer->optimistic;
}
static int peerIsBad( const tr_peer_t * peer )
{
return peer->badPcs > 4 + 2 * peer->goodPcs;
}
static int peerIsGood( const tr_peer_t * peer )
{
return peer->goodPcs > 3 * peer->badPcs;
}
void tr_peerBlame( tr_peer_t * peer, int piece, int success )
{
tr_torrent_t * tor = peer->tor;
if( !peer->blamefield || !tr_bitfieldHas( peer->blamefield, piece ) )
{
return;
}
if( success )
{
peer->goodPcs++;
if( peer->banfield && peerIsGood( peer ) )
{
/* Assume the peer wasn't responsible for the bad pieces
we was banned for */
tr_bitfieldClear( peer->banfield );
}
}
else
{
peer->badPcs++;
/* Ban the peer for this piece */
if( !peer->banfield )
{
peer->banfield = tr_bitfieldNew( tor->info.pieceCount );
}
tr_bitfieldAdd( peer->banfield, piece );
if( peerIsBad( peer ) )
{
/* Full ban */
peer_dbg( "banned (%d / %d)", peer->goodPcs, peer->badPcs );
peer->banned = TRUE;
peer->isInteresting = FALSE;
peer->isInterested = FALSE;
}
}
tr_bitfieldRem( peer->blamefield, piece );
}
int tr_peerGetConnectable( const tr_torrent_t * tor, uint8_t ** _buf )
{
int count = 0;
uint8_t * buf;
tr_peer_t * peer;
int i;
if( tor->peerCount < 1 )
{
*_buf = NULL;
return 0;
}
buf = malloc( 6 * tor->peerCount );
for( i = 0; i < tor->peerCount; i++ )
{
peer = tor->peers[i];
/* Skip peers with no known listening port */
if( 0 == peer->port )
continue;
memcpy( &buf[count*6], &peer->addr, 4 );
memcpy( &buf[count*6+4], &peer->port, 2 );
count++;
}
if( count < 1 )
{
free( buf ); buf = NULL;
}
*_buf = buf;
return count * 6;
}
/***
****
***/
void
tr_peerSentBlockToUs ( tr_peer_t * peer, int byteCount )
{
tr_torrent_t * tor = peer->tor;
assert( byteCount >= 0 );
assert( byteCount <= tor->info.pieceSize );
tor->downloadedCur += byteCount;
tr_rcTransferred( peer->download, byteCount );
tr_rcTransferred( tor->download, byteCount );
tr_rcTransferred( tor->handle->download, byteCount );
peer->credit += (int)(byteCount * SWIFT_REPAYMENT_RATIO);
}
void
tr_peerGotBlockFromUs ( tr_peer_t * peer, int byteCount )
{
tr_torrent_t * tor = peer->tor;
assert( byteCount >= 0 );
assert( byteCount <= tor->info.pieceSize );
tor->uploadedCur += byteCount;
tr_rcTransferred( peer->upload, byteCount );
tr_rcTransferred( tor->upload, byteCount );
tr_rcTransferred( tor->handle->upload, byteCount );
peer->credit -= byteCount;
}
static void
tr_torrentSwiftPulse ( tr_torrent_t * tor )
{
/* Preferred # of seconds for the request queue's turnaround time.
This is just an arbitrary number. */
const int queueTimeSec = 5;
const int blockSizeKiB = tor->blockSize / 1024;
const int isSeeding = tr_cpGetStatus( tor->completion ) != TR_CP_INCOMPLETE;
int i;
tr_torrentWriterLock( tor );
for( i=0; i<tor->peerCount; ++i )
{
double outboundSpeedKiBs;
int size;
tr_peer_t * peer = tor->peers[ i ];
if( !tr_peerIsConnected( peer ) )
continue;
/* decide how many blocks we'll concurrently ask this peer for */
outboundSpeedKiBs = tr_rcRate(peer->upload);
size = queueTimeSec * outboundSpeedKiBs / blockSizeKiB;
if( size < 4 ) /* don't let it get TOO small */
size = 4;
size += 4; /* and always leave room to grow */
peer->inRequestMax = size;
if( peer->inRequestAlloc < peer->inRequestMax ) {
peer->inRequestAlloc = peer->inRequestMax;
peer->inRequests = tr_renew( tr_request_t, peer->inRequests, peer->inRequestAlloc );
}
}
/* if we're not seeding, decide on how much
bandwidth to allocate for leechers */
if( !isSeeding )
{
tr_peer_t ** deadbeats = tr_new( tr_peer_t*, tor->peerCount );
int deadbeatCount = 0;
for( i=0; i<tor->peerCount; ++i ) {
tr_peer_t * peer = tor->peers[ i ];
if( tr_peerIsConnected( peer ) && ( peer->credit < 0 ) )
deadbeats[deadbeatCount++] = peer;
}
if( deadbeatCount )
{
const double ul_KiBsec = tr_rcRate( tor->download );
const double ul_KiB = ul_KiBsec * SWIFT_REFRESH_INTERVAL_SEC;
const double ul_bytes = ul_KiB * 1024;
const double freeCreditTotal = ul_bytes * SWIFT_LARGESSE;
const int freeCreditPerPeer = (int)( freeCreditTotal / deadbeatCount );
for( i=0; i<deadbeatCount; ++i )
deadbeats[i]->credit = freeCreditPerPeer;
tr_dbg( "torrent %s has %d deadbeats, "
"who are each being granted %d bytes' credit "
"for a total of %.1f KiB, "
"%d%% of the torrent's ul speed %.1f\n",
tor->info.name, deadbeatCount, freeCreditPerPeer,
ul_KiBsec*SWIFT_LARGESSE, (int)(SWIFT_LARGESSE*100), ul_KiBsec );
}
tr_free( deadbeats );
}
tr_torrentWriterUnlock( tor );
}
void
tr_swiftPulse( tr_handle_t * h )
{
static time_t lastPulseTime = 0;
if( lastPulseTime + SWIFT_REFRESH_INTERVAL_SEC <= time( NULL ) )
{
tr_torrent_t * tor;
for( tor=h->torrentList; tor; tor=tor->next )
tr_torrentSwiftPulse( tor );
lastPulseTime = time( NULL );
}
}
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