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transmission/libtransmission/bandwidth.c

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/*
* This file Copyright (C) 2008 Charles Kerr <charles@transmissionbt.com>
*
* This file is licensed by the GPL version 2. Works owned by the
* Transmission project are granted a special exemption to clause 2(b)
* so that the bulk of its code can remain under the MIT license.
* This exemption does not extend to derived works not owned by
* the Transmission project.
*
* $Id$
*/
#include <assert.h>
#include <limits.h>
#include "event.h"
#include "transmission.h"
#include "bandwidth.h"
#include "crypto.h"
#include "peer-io.h"
#include "ptrarray.h"
#include "utils.h"
/***
****
***/
enum
{
HISTORY_MSEC = 2000,
INTERVAL_MSEC = HISTORY_MSEC,
GRANULARITY_MSEC = 50,
HISTORY_SIZE = ( INTERVAL_MSEC / GRANULARITY_MSEC ),
MAGIC_NUMBER = 43143
};
struct bratecontrol
{
int newest;
struct { uint64_t date, size; } transfers[HISTORY_SIZE];
};
static float
getSpeed( const struct bratecontrol * r, int interval_msec )
{
uint64_t bytes = 0;
const uint64_t cutoff = tr_date ( ) - interval_msec;
int i = r->newest;
for( ;; )
{
if( r->transfers[i].date <= cutoff )
break;
bytes += r->transfers[i].size;
if( --i == -1 ) i = HISTORY_SIZE - 1; /* circular history */
if( i == r->newest ) break; /* we've come all the way around */
}
return ( bytes / 1024.0 ) * ( 1000.0 / interval_msec );
}
static void
bytesUsed( struct bratecontrol * r, size_t size )
{
const uint64_t now = tr_date ( );
if( r->transfers[r->newest].date + GRANULARITY_MSEC >= now )
r->transfers[r->newest].size += size;
else
{
if( ++r->newest == HISTORY_SIZE ) r->newest = 0;
r->transfers[r->newest].date = now;
r->transfers[r->newest].size = size;
}
}
/******
*******
*******
******/
struct tr_band
{
tr_bool isLimited;
tr_bool honorParentLimits;
size_t bytesLeft;
double desiredSpeed;
struct bratecontrol raw;
struct bratecontrol piece;
};
struct tr_bandwidth
{
struct tr_band band[2];
struct tr_bandwidth * parent;
int magicNumber;
tr_session * session;
tr_ptrArray children; /* struct tr_bandwidth */
tr_ptrArray peers; /* tr_peerIo */
};
/***
****
***/
static int
comparePointers( const void * a, const void * b )
{
if( a != b )
return a < b ? -1 : 1;
return 0;
}
tr_bool
tr_isBandwidth( const tr_bandwidth * b )
{
return ( b != NULL ) && ( b->magicNumber == MAGIC_NUMBER );
}
/***
****
***/
tr_bandwidth*
tr_bandwidthNew( tr_session * session, tr_bandwidth * parent )
{
tr_bandwidth * b = tr_new0( tr_bandwidth, 1 );
b->session = session;
b->children = TR_PTR_ARRAY_INIT;
b->peers = TR_PTR_ARRAY_INIT;
b->magicNumber = MAGIC_NUMBER;
b->band[TR_UP].honorParentLimits = TRUE;
b->band[TR_DOWN].honorParentLimits = TRUE;
tr_bandwidthSetParent( b, parent );
return b;
}
void
tr_bandwidthFree( tr_bandwidth * b )
{
assert( tr_isBandwidth( b ) );
tr_bandwidthSetParent( b, NULL );
tr_ptrArrayDestruct( &b->peers, NULL );
tr_ptrArrayDestruct( &b->children, NULL );
b->magicNumber = 0xDEAD;
tr_free( b );
}
/***
****
***/
void
tr_bandwidthSetParent( tr_bandwidth * b,
tr_bandwidth * parent )
{
assert( tr_isBandwidth( b ) );
assert( b != parent );
if( b->parent )
{
assert( tr_isBandwidth( b->parent ) );
tr_ptrArrayRemoveSorted( &b->parent->children, b, comparePointers );
b->parent = NULL;
}
if( parent )
{
assert( tr_isBandwidth( parent ) );
assert( parent->parent != b );
tr_ptrArrayInsertSorted( &parent->children, b, comparePointers );
b->parent = parent;
}
}
void
tr_bandwidthHonorParentLimits( tr_bandwidth * b,
tr_direction dir,
tr_bool honorParentLimits )
{
assert( tr_isBandwidth( b ) );
assert( tr_isDirection( dir ) );
b->band[dir].honorParentLimits = honorParentLimits;
}
/***
****
***/
void
tr_bandwidthSetDesiredSpeed( tr_bandwidth * b,
tr_direction dir,
double desiredSpeed )
{
assert( tr_isBandwidth( b ) );
assert( tr_isDirection( dir ) );
b->band[dir].desiredSpeed = desiredSpeed;
}
double
tr_bandwidthGetDesiredSpeed( const tr_bandwidth * b,
tr_direction dir )
{
assert( tr_isBandwidth( b ) );
assert( tr_isDirection( dir ) );
return b->band[dir].desiredSpeed;
}
void
tr_bandwidthSetLimited( tr_bandwidth * b,
tr_direction dir,
tr_bool isLimited )
{
assert( tr_isBandwidth( b ) );
assert( tr_isDirection( dir ) );
b->band[dir].isLimited = isLimited;
}
tr_bool
tr_bandwidthIsLimited( const tr_bandwidth * b,
tr_direction dir )
{
assert( tr_isBandwidth( b ) );
assert( tr_isDirection( dir ) );
return b->band[dir].isLimited;
}
#if 0
#warning do not check the code in with this enabled
#define DEBUG_DIRECTION TR_UP
#endif
static void
allocateBandwidth( tr_bandwidth * b,
tr_direction dir,
int period_msec,
tr_ptrArray * peer_pool )
{
assert( tr_isBandwidth( b ) );
assert( tr_isDirection( dir ) );
/* set the available bandwidth */
if( b->band[dir].isLimited )
{
const double desiredSpeed = b->band[dir].desiredSpeed;
const double nextPulseSpeed = desiredSpeed;
b->band[dir].bytesLeft = MAX( 0.0, nextPulseSpeed * 1024.0 * period_msec / 1000.0 );
#ifdef DEBUG_DIRECTION
if( dir == DEBUG_DIRECTION )
fprintf( stderr, "bandwidth %p currentPieceSpeed(%5.2f of %5.2f) desiredSpeed(%5.2f), allocating %5.2f\n",
b, currentSpeed, tr_bandwidthGetRawSpeed( b, dir ), desiredSpeed,
b->band[dir].bytesLeft/1024.0 );
#endif
}
/* traverse & repeat for the subtree */
{
int i;
const int n = TR_PTR_ARRAY_LENGTH( &b->peers );
for( i=0; i<n; ++i )
tr_ptrArrayAppend( peer_pool, tr_ptrArrayNth( &b->peers, i ) );
}
#ifdef DEBUG_DIRECTION
if( ( dir == DEBUG_DIRECTION ) && ( n > 1 ) )
fprintf( stderr, "bandwidth %p has %d peers\n", b, n );
#endif
/* all children should reallocate too */
if( 1 ) {
int i;
struct tr_bandwidth ** children = (struct tr_bandwidth**) TR_PTR_ARRAY_DATA( &b->children );
const int n = TR_PTR_ARRAY_LENGTH( &b->children );
for( i=0; i<n; ++i )
allocateBandwidth( children[i], dir, period_msec, peer_pool );
}
}
void
tr_bandwidthAllocate( tr_bandwidth * b,
tr_direction dir,
int period_msec )
{
int i, n, peerCount;
tr_ptrArray tmp = TR_PTR_ARRAY_INIT;
struct tr_peerIo ** peers;
const uint64_t now = tr_date( );
const uint64_t cutoff = now + 100; /* 1/10th of a second */
/* allocateBandwidth() is a helper function with two purposes:
* 1. allocate bandwidth to b and its subtree
* 2. accumulate an array of all the peerIos from b and its subtree. */
allocateBandwidth( b, dir, period_msec, &tmp );
peers = (struct tr_peerIo**) tr_ptrArrayPeek( &tmp, &peerCount );
/* Stop all peers from listening for the socket to be ready for IO.
* See "Second phase of IO" lower in this function for more info. */
for( i=0; i<peerCount; ++i )
tr_peerIoSetEnabled( peers[i], dir, FALSE );
/* First phase of IO. Tries to distribute bandwidth fairly to keep faster
* peers from starving the others. Loop through the peers, giving each a
* small chunk of bandwidth. Keep looping until we reach the cutoff or
* run out of bandwidth and/or peers that can use it */
n = peerCount;
i = n ? tr_cryptoWeakRandInt( n ) : 0; /* pick a random starting point */
for( ; n>0 && tr_date()<=cutoff; )
{
const int increment = n==1 ? 4096 : 1024;
const int byteCount = tr_peerIoFlush( peers[i], dir, increment);
if( byteCount == increment )
++i;
else {
/* peer is done writing for now; move it to the end of the list */
tr_peerIo * tmp = peers[i];
peers[i] = peers[n-1];
peers[n-1] = tmp;
--n;
}
assert( i <= n );
if( i == n )
i = 0;
}
/* Second phase of IO. To help us scale in high bandwidth situations,
* enable on-demand IO for peers with bandwidth left to burn.
* This on-demand IO is enabled until (1) the peer runs out of bandwidth,
* or (2) the next tr_bandwidthAllocate() call, when we start over again. */
for( i=0; i<peerCount; ++i )
if( tr_peerIoHasBandwidthLeft( peers[i], dir ) )
tr_peerIoSetEnabled( peers[i], dir, TRUE );
/* cleanup */
tr_ptrArrayDestruct( &tmp, NULL );
}
/***
****
***/
void
tr_bandwidthAddPeer( tr_bandwidth * b,
tr_peerIo * peerIo )
{
assert( tr_isBandwidth( b ) );
assert( tr_isPeerIo( peerIo ) );
tr_ptrArrayInsertSorted( &b->peers, peerIo, comparePointers );
}
void
tr_bandwidthRemovePeer( tr_bandwidth * b,
tr_peerIo * peerIo )
{
assert( tr_isBandwidth( b ) );
assert( tr_isPeerIo( peerIo ) );
tr_ptrArrayRemoveSorted( &b->peers, peerIo, comparePointers );
}
/***
****
***/
size_t
tr_bandwidthClamp( const tr_bandwidth * b,
tr_direction dir,
size_t byteCount )
{
assert( tr_isBandwidth( b ) );
assert( tr_isDirection( dir ) );
if( b )
{
if( b->band[dir].isLimited )
byteCount = MIN( byteCount, b->band[dir].bytesLeft );
if( b->parent && b->band[dir].honorParentLimits )
byteCount = tr_bandwidthClamp( b->parent, dir, byteCount );
}
return byteCount;
}
double
tr_bandwidthGetRawSpeed( const tr_bandwidth * b, tr_direction dir )
{
assert( tr_isBandwidth( b ) );
assert( tr_isDirection( dir ) );
return getSpeed( &b->band[dir].raw, HISTORY_MSEC );
}
double
tr_bandwidthGetPieceSpeed( const tr_bandwidth * b, tr_direction dir )
{
assert( tr_isBandwidth( b ) );
assert( tr_isDirection( dir ) );
return getSpeed( &b->band[dir].piece, HISTORY_MSEC );
}
void
tr_bandwidthUsed( tr_bandwidth * b,
tr_direction dir,
size_t byteCount,
tr_bool isPieceData )
{
struct tr_band * band;
size_t oldBytesLeft;
assert( tr_isBandwidth( b ) );
assert( tr_isDirection( dir ) );
band = &b->band[dir];
oldBytesLeft = band->bytesLeft;
if( band->isLimited && isPieceData )
band->bytesLeft -= MIN( band->bytesLeft, byteCount );
#ifdef DEBUG_DIRECTION
if( ( dir == DEBUG_DIRECTION ) && ( band->isLimited ) )
fprintf( stderr, "%p consumed %5zu bytes of %5s data... was %6zu, now %6zu left\n",
b, byteCount, (isPieceData?"piece":"raw"), oldBytesLeft, band->bytesLeft );
#endif
bytesUsed( &band->raw, byteCount );
if( isPieceData )
bytesUsed( &band->piece, byteCount );
if( b->parent != NULL )
tr_bandwidthUsed( b->parent, dir, byteCount, isPieceData );
}
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