BandwidthBucket.cc
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1 /*
2  * Copyright (C) 1996-2020 The Squid Software Foundation and contributors
3  *
4  * Squid software is distributed under GPLv2+ license and includes
5  * contributions from numerous individuals and organizations.
6  * Please see the COPYING and CONTRIBUTORS files for details.
7  */
8 
9 #include "squid.h"
10 
11 #if USE_DELAY_POOLS
12 
13 #include "BandwidthBucket.h"
14 #include "ClientInfo.h"
15 #include "comm/Connection.h"
16 #include "Debug.h"
17 #include "fde.h"
18 
19 BandwidthBucket::BandwidthBucket(const int speed, const int initialLevelPercent, const double sizeLimit) :
20  bucketLevel( sizeLimit * (initialLevelPercent / 100.0)),
21  selectWaiting(false),
22  writeSpeedLimit(speed),
23  bucketSizeLimit(sizeLimit)
24 {
26  /* put current time to have something sensible here */
28 }
29 
30 void
32 {
33  if (noLimit())
34  return;
35  // all these times are in seconds, with double precision
36  const double currTime = current_dtime;
37  const double timePassed = currTime - prevTime;
38 
39  // Calculate allowance for the time passed. Use double to avoid
40  // accumulating rounding errors for small intervals. For example, always
41  // adding 1 byte instead of 1.4 results in 29% bandwidth allocation error.
42  const double gain = timePassed * writeSpeedLimit;
43 
44  // to further combat error accumulation during micro updates,
45  // quit before updating time if we cannot add at least one byte
46  if (gain < 1.0)
47  return;
48 
49  prevTime = currTime;
50 
51  // for "first" connections, drain initial fat before refilling but keep
52  // updating prevTime to avoid bursts after the fat is gone
54  debugs(77, 4, "not refilling while draining initial fat");
55  return;
56  }
57 
58  bucketLevel += gain;
59 
60  // obey quota limits
63 }
64 
65 bool
67 {
68  const int q = quota();
69  if (!q)
70  return false;
71  else if (q < 0)
72  return true;
73  const int nleft_corrected = min(nleft, q);
74  if (nleft != nleft_corrected) {
75  debugs(77, 5, state->conn << " writes only " <<
76  nleft_corrected << " out of " << nleft);
77  nleft = nleft_corrected;
78  }
79  return true;
80 }
81 
82 void
84 {
85  if (len <= 0 || noLimit())
86  return;
87  bucketLevel -= len;
88  if (bucketLevel < 0.0) {
89  debugs(77, DBG_IMPORTANT, "drained too much"); // should not happen
90  bucketLevel = 0;
91  }
92 }
93 
96 {
98  if (!bucket) {
99  ClientInfo *clientInfo = f->clientInfo;
100  if (clientInfo && clientInfo->writeLimitingActive)
101  bucket = clientInfo;
102  }
103  return bucket;
104 }
105 
106 #endif /* USE_DELAY_POOLS */
107 
bool noLimit() const
Whether this bucket will not do bandwidth limiting.
ClientInfo * clientInfo
pointer to client info used in client write limiter or nullptr if not present
Definition: fde.h:143
C * getRaw() const
Definition: RefCount.h:80
time_t getCurrentTime(void)
Get current time.
#define DBG_IMPORTANT
Definition: Debug.h:46
Definition: fde.h:51
double writeSpeedLimit
Write speed limit in bytes per second.
Comm::ConnectionPointer conn
Definition: IoCallback.h:33
BandwidthBucket(const int speed, const int initialLevelPercent, const double sizeLimit)
#define debugs(SECTION, LEVEL, CONTENT)
Definition: Debug.h:128
Details about a particular Comm IO callback event.
Definition: IoCallback.h:29
virtual void reduceBucket(const int len)
Decreases the bucket level.
virtual bool applyQuota(int &nleft, Comm::IoCallback *state)
bool writeLimitingActive
Is write limiter active.
Definition: ClientInfo.h:65
virtual int quota()=0
Base class for Squid-to-client bandwidth limiting.
double bucketSizeLimit
maximum bucket size
static BandwidthBucket * SelectBucket(fde *f)
double prevTime
previous time when we checked
void refillBucket()
Increases the bucket level with the writeSpeedLimit speed.
double bucketLevel
how much can be written now
int unsigned int const char *desc STUB void int len
Definition: stub_fd.cc:20
MessageBucket::Pointer writeQuotaHandler
response write limiter, if configured
Definition: fde.h:144
#define false
Definition: GnuRegex.c:233
const A & min(A const &lhs, A const &rhs)
double current_dtime
Definition: stub_time.cc:16

 

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