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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 "log.h"
#include "peer-io.h"
#include "utils.h"
#define dbgmsg(...) \
do \
{ \
if (tr_logGetDeepEnabled ()) \
tr_logAddDeep (__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 uint64_t 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 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"));
while (n > 0)
{
const int i = tr_cryptoWeakRandInt (n); /* pick a peer at random */
/* 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)
{
/* 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;
}
}
}
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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