source: trunk/libtransmission/bandwidth.c @ 7748

Last change on this file since 7748 was 7748, checked in by charles, 12 years ago

(trunk libT) prefer int' over ssize_t'

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File size: 9.3 KB
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1/*
2 * This file Copyright (C) 2008-2009 Charles Kerr <charles@transmissionbt.com>
3 *
4 * This file is licensed by the GPL version 2.  Works owned by the
5 * Transmission project are granted a special exemption to clause 2(b)
6 * so that the bulk of its code can remain under the MIT license.
7 * This exemption does not extend to derived works not owned by
8 * the Transmission project.
9 *
10 * $Id: bandwidth.c 7748 2009-01-19 14:05:43Z charles $
11 */
12
13#include <assert.h>
14#include <limits.h>
15
16#include "event.h"
17
18#include "transmission.h"
19#include "bandwidth.h"
20#include "crypto.h"
21#include "peer-io.h"
22#include "ptrarray.h"
23#include "utils.h"
24
25#define dbgmsg( ... ) \
26    do { \
27        if( tr_deepLoggingIsActive( ) ) \
28            tr_deepLog( __FILE__, __LINE__, NULL, __VA_ARGS__ ); \
29    } while( 0 )
30
31/***
32****
33***/
34
35static float
36getSpeed( const struct bratecontrol * r, int interval_msec, uint64_t now )
37{
38    uint64_t       bytes = 0;
39    const uint64_t cutoff = (now?now:tr_date()) - interval_msec;
40    int            i = r->newest;
41
42    for( ;; )
43    {
44        if( r->transfers[i].date <= cutoff )
45            break;
46
47        bytes += r->transfers[i].size;
48
49        if( --i == -1 ) i = HISTORY_SIZE - 1; /* circular history */
50        if( i == r->newest ) break; /* we've come all the way around */
51    }
52
53    return ( bytes / 1024.0 ) * ( 1000.0 / interval_msec );
54}
55
56static void
57bytesUsed( const uint64_t now, struct bratecontrol * r, size_t size )
58{
59    if( r->transfers[r->newest].date + GRANULARITY_MSEC >= now )
60        r->transfers[r->newest].size += size;
61    else
62    {
63        if( ++r->newest == HISTORY_SIZE ) r->newest = 0;
64        r->transfers[r->newest].date = now;
65        r->transfers[r->newest].size = size;
66    }
67}
68
69/******
70*******
71*******
72******/
73
74static TR_INLINE int
75comparePointers( const void * a, const void * b )
76{
77    if( a != b )
78        return a < b ? -1 : 1;
79
80    return 0;
81}
82
83/***
84****
85***/
86
87tr_bandwidth*
88tr_bandwidthConstruct( tr_bandwidth * b, tr_session * session, tr_bandwidth * parent )
89{
90    b->session = session;
91    b->children = TR_PTR_ARRAY_INIT;
92    b->magicNumber = MAGIC_NUMBER;
93    b->band[TR_UP].honorParentLimits = TRUE;
94    b->band[TR_DOWN].honorParentLimits = TRUE;
95    tr_bandwidthSetParent( b, parent );
96    return b;
97}
98
99tr_bandwidth*
100tr_bandwidthDestruct( tr_bandwidth * b )
101{
102    assert( tr_isBandwidth( b ) );
103
104    tr_bandwidthSetParent( b, NULL );
105    tr_ptrArrayDestruct( &b->children, NULL );
106    b->magicNumber = 0xDEAD;
107
108    return b;
109}
110
111/***
112****
113***/
114
115void
116tr_bandwidthSetParent( tr_bandwidth  * b,
117                       tr_bandwidth  * parent )
118{
119    assert( tr_isBandwidth( b ) );
120    assert( b != parent );
121
122    if( b->parent )
123    {
124        assert( tr_isBandwidth( b->parent ) );
125
126        tr_ptrArrayRemoveSorted( &b->parent->children, b, comparePointers );
127        b->parent = NULL;
128    }
129
130    if( parent )
131    {
132        assert( tr_isBandwidth( parent ) );
133        assert( parent->parent != b );
134
135        tr_ptrArrayInsertSorted( &parent->children, b, comparePointers );
136        b->parent = parent;
137    }
138}
139
140/***
141****
142***/
143
144#if 0
145#warning do not check the code in with this enabled
146#define DEBUG_DIRECTION TR_UP
147#endif
148
149static void
150allocateBandwidth( tr_bandwidth  * b,
151                   tr_direction    dir,
152                   int             period_msec,
153                   tr_ptrArray   * peer_pool )
154{
155    assert( tr_isBandwidth( b ) );
156    assert( tr_isDirection( dir ) );
157
158    /* set the available bandwidth */
159    if( b->band[dir].isLimited )
160    {
161        const double desiredSpeed = b->band[dir].desiredSpeed;
162        const double nextPulseSpeed = desiredSpeed;
163        b->band[dir].bytesLeft = MAX( 0.0, nextPulseSpeed * 1024.0 * period_msec / 1000.0 );
164
165#ifdef DEBUG_DIRECTION
166        if( dir == DEBUG_DIRECTION )
167                fprintf( stderr, "bandwidth %p currentPieceSpeed(%5.2f of %5.2f) desiredSpeed(%5.2f), allocating %5.2f\n",
168                         b, currentSpeed, tr_bandwidthGetRawSpeed( b, dir ), desiredSpeed,
169                         b->band[dir].bytesLeft/1024.0 );
170#endif
171    }
172
173    /* add this bandwidth's peer, if any, to the peer pool */
174    if( b->peer != NULL )
175        tr_ptrArrayAppend( peer_pool, b->peer );
176
177#ifdef DEBUG_DIRECTION
178if( ( dir == DEBUG_DIRECTION ) && ( n > 1 ) )
179fprintf( stderr, "bandwidth %p has %d peers\n", b, n );
180#endif
181
182    /* traverse & repeat for the subtree */
183    if( 1 ) {
184        int i;
185        struct tr_bandwidth ** children = (struct tr_bandwidth**) tr_ptrArrayBase( &b->children );
186        const int n = tr_ptrArraySize( &b->children );
187        for( i=0; i<n; ++i )
188            allocateBandwidth( children[i], dir, period_msec, peer_pool );
189    }
190}
191
192void
193tr_bandwidthAllocate( tr_bandwidth  * b,
194                      tr_direction    dir,
195                      int             period_msec )
196{
197    int i, n, peerCount;
198    tr_ptrArray tmp = TR_PTR_ARRAY_INIT;
199    struct tr_peerIo ** peers;
200
201    /* allocateBandwidth() is a helper function with two purposes:
202     * 1. allocate bandwidth to b and its subtree
203     * 2. accumulate an array of all the peerIos from b and its subtree. */
204    allocateBandwidth( b, dir, period_msec, &tmp );
205    peers = (struct tr_peerIo**) tr_ptrArrayBase( &tmp );
206    peerCount = tr_ptrArraySize( &tmp );
207
208    for( i=0; i<peerCount; ++i )
209        tr_peerIoRef( peers[i] );
210
211    /* Stop all peers from listening for the socket to be ready for IO.
212     * See "Second phase of IO" lower in this function for more info. */
213    for( i=0; i<peerCount; ++i )
214        tr_peerIoSetEnabled( peers[i], dir, FALSE );
215
216    /* First phase of IO.  Tries to distribute bandwidth fairly to keep faster
217     * peers from starving the others.  Loop through the peers, giving each a
218     * small chunk of bandwidth.  Keep looping until we run out of bandwidth
219     * and/or peers that can use it */
220    n = peerCount;
221    dbgmsg( "%d peers to go round-robin for %s", n, (dir==TR_UP?"upload":"download") );
222    i = n ? tr_cryptoWeakRandInt( n ) : 0; /* pick a random starting point */
223    while( n > 1 )
224    {
225        const size_t increment = 1024;
226        const int bytesUsed = tr_peerIoFlush( peers[i], dir, increment );
227
228        dbgmsg( "peer #%d of %d used %d bytes in this pass", i, n, bytesUsed );
229
230        if( bytesUsed == (int)increment )
231            ++i;
232        else {
233            /* peer is done writing for now; move it to the end of the list */
234            tr_peerIo * pio = peers[i];
235            peers[i] = peers[n-1];
236            peers[n-1] = pio;
237            --n;
238        }
239
240        if( i == n )
241            i = 0;
242    }
243
244    /* Second phase of IO.  To help us scale in high bandwidth situations,
245     * enable on-demand IO for peers with bandwidth left to burn.
246     * This on-demand IO is enabled until (1) the peer runs out of bandwidth,
247     * or (2) the next tr_bandwidthAllocate() call, when we start over again. */
248    for( i=0; i<peerCount; ++i )
249        if( tr_peerIoHasBandwidthLeft( peers[i], dir ) )
250            tr_peerIoSetEnabled( peers[i], dir, TRUE );
251
252    for( i=0; i<peerCount; ++i )
253        tr_peerIoUnref( peers[i] );
254
255    /* cleanup */
256    tr_ptrArrayDestruct( &tmp, NULL );
257}
258
259void
260tr_bandwidthSetPeer( tr_bandwidth * b, tr_peerIo * peer )
261{
262    assert( tr_isBandwidth( b ) );
263    assert( ( peer == NULL ) || tr_isPeerIo( peer ) );
264
265    b->peer = peer;
266}
267
268/***
269****
270***/
271
272size_t
273tr_bandwidthClamp( const tr_bandwidth  * b,
274                   tr_direction          dir,
275                   size_t                byteCount )
276{
277    assert( tr_isBandwidth( b ) );
278    assert( tr_isDirection( dir ) );
279
280    if( b )
281    {
282        if( b->band[dir].isLimited )
283            byteCount = MIN( byteCount, b->band[dir].bytesLeft );
284
285        if( b->parent && b->band[dir].honorParentLimits )
286            byteCount = tr_bandwidthClamp( b->parent, dir, byteCount );
287    }
288
289    return byteCount;
290}
291
292double
293tr_bandwidthGetRawSpeed( const tr_bandwidth * b, const uint64_t now, const tr_direction dir )
294{
295    assert( tr_isBandwidth( b ) );
296    assert( tr_isDirection( dir ) );
297
298    return getSpeed( &b->band[dir].raw, HISTORY_MSEC, now );
299}
300
301double
302tr_bandwidthGetPieceSpeed( const tr_bandwidth * b, const uint64_t now, const tr_direction dir )
303{
304    assert( tr_isBandwidth( b ) );
305    assert( tr_isDirection( dir ) );
306
307    return getSpeed( &b->band[dir].piece, HISTORY_MSEC, now );
308}
309
310static void
311bandwidthUsedImpl( tr_bandwidth  * b,
312                   tr_direction    dir,
313                   size_t          byteCount,
314                   tr_bool         isPieceData,
315                   uint64_t        now )
316{
317    struct tr_band * band;
318    size_t oldBytesLeft;
319
320    assert( tr_isBandwidth( b ) );
321    assert( tr_isDirection( dir ) );
322
323    band = &b->band[dir];
324
325    oldBytesLeft = band->bytesLeft;
326
327    if( band->isLimited && isPieceData )
328        band->bytesLeft -= MIN( band->bytesLeft, byteCount );
329
330#ifdef DEBUG_DIRECTION
331if( ( dir == DEBUG_DIRECTION ) && ( band->isLimited ) )
332fprintf( stderr, "%p consumed %5zu bytes of %5s data... was %6zu, now %6zu left\n",
333         b, byteCount, (isPieceData?"piece":"raw"), oldBytesLeft, band->bytesLeft );
334#endif
335
336    bytesUsed( now, &band->raw, byteCount );
337
338    if( isPieceData )
339        bytesUsed( now, &band->piece, byteCount );
340
341    if( b->parent != NULL )
342        bandwidthUsedImpl( b->parent, dir, byteCount, isPieceData, now );
343}
344
345void
346tr_bandwidthUsed( tr_bandwidth  * b,
347                  tr_direction    dir,
348                  size_t          byteCount,
349                  tr_bool         isPieceData )
350{
351    bandwidthUsedImpl( b, dir, byteCount, isPieceData, tr_date( ) );
352}
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