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transmission/libtransmission/bandwidth.c

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/*
* This file Copyright (C) Mnemosyne LLC
*
* 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 <string.h> /* memset() */
#include "transmission.h"
#include "bandwidth.h"
#include "crypto.h" /* tr_cryptoWeakRandInt() */
#include "peer-io.h"
#include "utils.h"
#define dbgmsg( ... ) \
do { \
if( tr_deepLoggingIsActive( ) ) \
tr_deepLog( __FILE__, __LINE__, NULL, __VA_ARGS__ ); \
} while( 0 )
/***
****
***/
static unsigned int
getSpeed_Bps( const struct bratecontrol * r, unsigned int interval_msec, uint64_t now )
{
if( !now )
now = tr_time_msec();
if( now != r->cache_time )
{
int i = r->newest;
uint64_t bytes = 0;
const uint64_t cutoff = now - interval_msec;
struct bratecontrol * rvolatile = (struct bratecontrol*) r;
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 */
}
rvolatile->cache_val = (unsigned int)(( bytes * 1000u ) / interval_msec);
rvolatile->cache_time = now;
}
return r->cache_val;
}
static void
bytesUsed( const uint64_t now, struct bratecontrol * r, size_t size )
{
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;
}
/* invalidate cache_val*/
r->cache_time = 0;
}
/******
*******
*******
******/
static int
compareBandwidth( const void * va, const void * vb )
{
const tr_bandwidth * a = va;
const tr_bandwidth * b = vb;
return a->uniqueKey - b->uniqueKey;
}
/***
****
***/
void
tr_bandwidthConstruct( tr_bandwidth * b, tr_session * session, tr_bandwidth * parent )
{
static unsigned int uniqueKey = 0;
b->session = session;
b->children = TR_PTR_ARRAY_INIT;
b->magicNumber = BANDWIDTH_MAGIC_NUMBER;
b->uniqueKey = uniqueKey++;
b->band[TR_UP].honorParentLimits = true;
b->band[TR_DOWN].honorParentLimits = true;
tr_bandwidthSetParent( b, parent );
}
void
tr_bandwidthDestruct( tr_bandwidth * b )
{
assert( tr_isBandwidth( b ) );
tr_bandwidthSetParent( b, NULL );
tr_ptrArrayDestruct( &b->children, NULL );
memset( b, ~0, sizeof( tr_bandwidth ) );
}
/***
****
***/
void
tr_bandwidthSetParent( tr_bandwidth * b,
tr_bandwidth * parent )
{
assert( tr_isBandwidth( b ) );
assert( b != parent );
if( b->parent )
{
void * removed;
assert( tr_isBandwidth( b->parent ) );
removed = tr_ptrArrayRemoveSorted( &b->parent->children, b, compareBandwidth );
assert( removed == b );
assert( tr_ptrArrayFindSorted( &b->parent->children, b, compareBandwidth ) == NULL );
b->parent = NULL;
}
if( parent )
{
assert( tr_isBandwidth( parent ) );
assert( parent->parent != b );
assert( tr_ptrArrayFindSorted( &parent->children, b, compareBandwidth ) == NULL );
tr_ptrArrayInsertSorted( &parent->children, b, compareBandwidth );
assert( tr_ptrArrayFindSorted( &parent->children, b, compareBandwidth ) == b );
b->parent = parent;
}
}
/***
****
***/
static void
allocateBandwidth( tr_bandwidth * b,
tr_priority_t parent_priority,
tr_direction dir,
unsigned int period_msec,
tr_ptrArray * peer_pool )
{
const tr_priority_t priority = MAX( parent_priority, b->priority );
assert( tr_isBandwidth( b ) );
assert( tr_isDirection( dir ) );
/* set the available bandwidth */
if( b->band[dir].isLimited )
{
const unsigned int nextPulseSpeed = b->band[dir].desiredSpeed_Bps;
b->band[dir].bytesLeft = ( nextPulseSpeed * period_msec ) / 1000u;
}
/* add this bandwidth's peer, if any, to the peer pool */
if( b->peer != NULL ) {
b->peer->priority = priority;
tr_ptrArrayAppend( peer_pool, b->peer );
}
/* traverse & repeat for the subtree */
if( 1 ) {
int i;
struct tr_bandwidth ** children = (struct tr_bandwidth**) tr_ptrArrayBase( &b->children );
const int n = tr_ptrArraySize( &b->children );
for( i=0; i<n; ++i )
allocateBandwidth( children[i], priority, dir, period_msec, peer_pool );
}
}
static void
phaseOne( tr_ptrArray * peerArray, tr_direction dir )
{
int i, n;
int peerCount = tr_ptrArraySize( peerArray );
struct tr_peerIo ** peers = (struct tr_peerIo**) tr_ptrArrayBase( peerArray );
/* 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 run out of bandwidth
* and/or peers that can use it */
n = peerCount;
dbgmsg( "%d peers to go round-robin for %s", n, (dir==TR_UP?"upload":"download") );
i = n ? tr_cryptoWeakRandInt( n ) : 0; /* pick a random starting point */
while( n > 0 )
{
/* value of 3000 bytes chosen so that when using uTP we'll send a full-size
* frame right away and leave enough buffered data for the next frame to go
* out in a timely manner. */
const size_t increment = 3000;
const int bytesUsed = tr_peerIoFlush( peers[i], dir, increment );
dbgmsg( "peer #%d of %d used %d bytes in this pass", i, n, bytesUsed );
if( bytesUsed == (int)increment )
++i;
else {
/* peer is done writing for now; move it to the end of the list */
tr_peerIo * pio = peers[i];
peers[i] = peers[n-1];
peers[n-1] = pio;
--n;
}
if( i >= n )
i = 0;
}
}
void
tr_bandwidthAllocate( tr_bandwidth * b,
tr_direction dir,
unsigned int period_msec )
{
int i, peerCount;
tr_ptrArray tmp = TR_PTR_ARRAY_INIT;
tr_ptrArray low = TR_PTR_ARRAY_INIT;
tr_ptrArray high = TR_PTR_ARRAY_INIT;
tr_ptrArray normal = TR_PTR_ARRAY_INIT;
struct tr_peerIo ** peers;
/* 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, TR_PRI_LOW, dir, period_msec, &tmp );
peers = (struct tr_peerIo**) tr_ptrArrayBase( &tmp );
peerCount = tr_ptrArraySize( &tmp );
for( i=0; i<peerCount; ++i )
{
tr_peerIo * io = peers[i];
tr_peerIoRef( io );
tr_peerIoFlushOutgoingProtocolMsgs( io );
switch( io->priority ) {
case TR_PRI_HIGH: tr_ptrArrayAppend( &high, io ); /* fall through */
case TR_PRI_NORMAL: tr_ptrArrayAppend( &normal, io ); /* fall through */
default: tr_ptrArrayAppend( &low, io );
}
}
/* 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 run out of bandwidth
* and/or peers that can use it */
phaseOne( &high, dir );
phaseOne( &normal, dir );
phaseOne( &low, dir );
/* 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 )
tr_peerIoSetEnabled( peers[i], dir, tr_peerIoHasBandwidthLeft( peers[i], dir ) );
for( i=0; i<peerCount; ++i )
tr_peerIoUnref( peers[i] );
/* cleanup */
tr_ptrArrayDestruct( &normal, NULL );
tr_ptrArrayDestruct( &high, NULL );
tr_ptrArrayDestruct( &low, NULL );
tr_ptrArrayDestruct( &tmp, NULL );
}
void
tr_bandwidthSetPeer( tr_bandwidth * b, tr_peerIo * peer )
{
assert( tr_isBandwidth( b ) );
assert( ( peer == NULL ) || tr_isPeerIo( peer ) );
b->peer = peer;
}
/***
****
***/
static unsigned int
bandwidthClamp( const tr_bandwidth * b,
uint64_t now,
tr_direction dir,
unsigned int byteCount )
{
assert( tr_isBandwidth( b ) );
assert( tr_isDirection( dir ) );
if( b )
{
if( b->band[dir].isLimited )
{
byteCount = MIN( byteCount, b->band[dir].bytesLeft );
/* if we're getting close to exceeding the speed limit,
* clamp down harder on the bytes available */
if( byteCount > 0 )
{
double current;
double desired;
double r;
if( now == 0 )
now = tr_time_msec( );
current = tr_bandwidthGetRawSpeed_Bps( b, now, TR_DOWN );
desired = tr_bandwidthGetDesiredSpeed_Bps( b, TR_DOWN );
r = desired >= 1 ? current / desired : 0;
if( r > 1.0 ) byteCount = 0;
else if( r > 0.9 ) byteCount *= 0.8;
else if( r > 0.8 ) byteCount *= 0.9;
}
}
if( b->parent && b->band[dir].honorParentLimits && ( byteCount > 0 ) )
byteCount = bandwidthClamp( b->parent, now, dir, byteCount );
}
return byteCount;
}
unsigned int
tr_bandwidthClamp( const tr_bandwidth * b,
tr_direction dir,
unsigned int byteCount )
{
return bandwidthClamp( b, 0, dir, byteCount );
}
unsigned int
tr_bandwidthGetRawSpeed_Bps( const tr_bandwidth * b, const uint64_t now, const tr_direction dir )
{
assert( tr_isBandwidth( b ) );
assert( tr_isDirection( dir ) );
return getSpeed_Bps( &b->band[dir].raw, HISTORY_MSEC, now );
}
unsigned int
tr_bandwidthGetPieceSpeed_Bps( const tr_bandwidth * b, const uint64_t now, const tr_direction dir )
{
assert( tr_isBandwidth( b ) );
assert( tr_isDirection( dir ) );
return getSpeed_Bps( &b->band[dir].piece, HISTORY_MSEC, now );
}
void
tr_bandwidthUsed( tr_bandwidth * b,
tr_direction dir,
size_t byteCount,
bool isPieceData,
uint64_t now )
{
struct tr_band * band;
assert( tr_isBandwidth( b ) );
assert( tr_isDirection( dir ) );
band = &b->band[dir];
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( now, &band->raw, byteCount );
if( isPieceData )
bytesUsed( now, &band->piece, byteCount );
if( b->parent != NULL )
tr_bandwidthUsed( b->parent, dir, byteCount, isPieceData, now );
}
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