source: trunk/libtransmission/bandwidth.c @ 7594

Last change on this file since 7594 was 7594, checked in by charles, 12 years ago

(trunk libT) use ssize_t where appropriate in tr_peerIoFlush()

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1/*
2 * This file Copyright (C) 2008 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 7594 2009-01-03 04:57:40Z 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 )
37{
38    uint64_t       bytes = 0;
39    const uint64_t cutoff = 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 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_PTR_ARRAY_DATA( &b->children );
186        const int n = TR_PTR_ARRAY_LENGTH( &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_PTR_ARRAY_DATA( &tmp );
206    peerCount = TR_PTR_ARRAY_LENGTH( &tmp );
207
208    /* Stop all peers from listening for the socket to be ready for IO.
209     * See "Second phase of IO" lower in this function for more info. */
210    for( i=0; i<peerCount; ++i )
211        tr_peerIoSetEnabled( peers[i], dir, FALSE );
212
213    /* First phase of IO.  Tries to distribute bandwidth fairly to keep faster
214     * peers from starving the others.  Loop through the peers, giving each a
215     * small chunk of bandwidth.  Keep looping until we run out of bandwidth
216     * and/or peers that can use it */
217    n = peerCount;
218    dbgmsg( "%d peers to go round-robin for %s", n, (dir==TR_UP?"upload":"download") );
219    i = n ? tr_cryptoWeakRandInt( n ) : 0; /* pick a random starting point */
220    while( n > 1 )
221    {
222        const size_t increment = 1024;
223        const ssize_t bytesUsed = tr_peerIoFlush( peers[i], dir, increment );
224
225        dbgmsg( "peer #%d of %d used %zd bytes in this pass", i, n, bytesUsed );
226
227        if( bytesUsed == (ssize_t)increment )
228            ++i;
229        else {
230            /* peer is done writing for now; move it to the end of the list */
231            tr_peerIo * pio = peers[i];
232            peers[i] = peers[n-1];
233            peers[n-1] = pio;
234            --n;
235        }
236
237        if( i == n )
238            i = 0;
239    }
240
241    /* Second phase of IO.  To help us scale in high bandwidth situations,
242     * enable on-demand IO for peers with bandwidth left to burn.
243     * This on-demand IO is enabled until (1) the peer runs out of bandwidth,
244     * or (2) the next tr_bandwidthAllocate() call, when we start over again. */
245    for( i=0; i<peerCount; ++i )
246        if( tr_peerIoHasBandwidthLeft( peers[i], dir ) )
247            tr_peerIoSetEnabled( peers[i], dir, TRUE );
248
249    /* cleanup */
250    tr_ptrArrayDestruct( &tmp, NULL );
251}
252
253void
254tr_bandwidthSetPeer( tr_bandwidth * b, tr_peerIo * peer )
255{
256    assert( tr_isBandwidth( b ) );
257    assert( ( peer == NULL ) || tr_isPeerIo( peer ) );
258
259    b->peer = peer;
260}
261
262/***
263****
264***/
265
266size_t
267tr_bandwidthClamp( const tr_bandwidth  * b,
268                   tr_direction          dir,
269                   size_t                byteCount )
270{
271    assert( tr_isBandwidth( b ) );
272    assert( tr_isDirection( dir ) );
273
274    if( b )
275    {
276        if( b->band[dir].isLimited )
277            byteCount = MIN( byteCount, b->band[dir].bytesLeft );
278
279        if( b->parent && b->band[dir].honorParentLimits )
280            byteCount = tr_bandwidthClamp( b->parent, dir, byteCount );
281    }
282
283    return byteCount;
284}
285
286double
287tr_bandwidthGetRawSpeed( const tr_bandwidth * b, tr_direction dir )
288{
289    assert( tr_isBandwidth( b ) );
290    assert( tr_isDirection( dir ) );
291
292    return getSpeed( &b->band[dir].raw, HISTORY_MSEC );
293}
294
295double
296tr_bandwidthGetPieceSpeed( const tr_bandwidth * b, tr_direction dir )
297{
298    assert( tr_isBandwidth( b ) );
299    assert( tr_isDirection( dir ) );
300
301    return getSpeed( &b->band[dir].piece, HISTORY_MSEC );
302}
303
304static void
305bandwidthUsedImpl( tr_bandwidth  * b,
306                   tr_direction    dir,
307                   size_t          byteCount,
308                   tr_bool         isPieceData,
309                   uint64_t        now )
310{
311    struct tr_band * band;
312    size_t oldBytesLeft;
313
314    assert( tr_isBandwidth( b ) );
315    assert( tr_isDirection( dir ) );
316
317    band = &b->band[dir];
318
319    oldBytesLeft = band->bytesLeft;
320
321    if( band->isLimited && isPieceData )
322        band->bytesLeft -= MIN( band->bytesLeft, byteCount );
323
324#ifdef DEBUG_DIRECTION
325if( ( dir == DEBUG_DIRECTION ) && ( band->isLimited ) )
326fprintf( stderr, "%p consumed %5zu bytes of %5s data... was %6zu, now %6zu left\n",
327         b, byteCount, (isPieceData?"piece":"raw"), oldBytesLeft, band->bytesLeft );
328#endif
329
330    bytesUsed( now, &band->raw, byteCount );
331
332    if( isPieceData )
333        bytesUsed( now, &band->piece, byteCount );
334
335    if( b->parent != NULL )
336        bandwidthUsedImpl( b->parent, dir, byteCount, isPieceData, now );
337}
338
339void
340tr_bandwidthUsed( tr_bandwidth  * b,
341                  tr_direction    dir,
342                  size_t          byteCount,
343                  tr_bool         isPieceData )
344{
345    bandwidthUsedImpl( b, dir, byteCount, isPieceData, tr_date( ) );
346}
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