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Moved a part of AIPerService::wantsMoreHTTPRequestsFor to a new function.

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The new function is AIPerService::checkBandwidthUsage.
No functional changes were made.
This commit is contained in:
Aleric Inglewood
2013-05-05 21:06:13 +02:00
parent fd3e8e4a23
commit 75a45f501e
2 changed files with 67 additions and 58 deletions
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2
indra/llmessage/aicurlperservice.h
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@@ -172,6 +172,8 @@ class AIPerService {
// Should return false if the maximum allowed HTTP bandwidth is reached, or when
// the latency between request and actual delivery becomes too large.
static bool wantsMoreHTTPRequestsFor(AIPerServicePtr const& per_service);
// Return true if too much bandwidth is being used.
static bool checkBandwidthUsage(U64 sTime_40ms, AIAverage* http_bandwidth_ptr);
// Accessor for when curl_max_total_concurrent_connections changes.
static LLAtomicS32& maxPipelinedRequests(void) { return sMaxPipelinedRequests; }

123
indra/llmessage/aicurlthread.cpp
View File

@@ -2673,68 +2673,15 @@ bool AIPerService::wantsMoreHTTPRequestsFor(AIPerServicePtr const& per_service)
}
if (reject)
{
// Too many request for this host already.
// Too many request for this service already.
return false;
}
if (!sNoHTTPBandwidthThrottling)
// Throttle on bandwidth usage.
if (checkBandwidthUsage(sTime_40ms, http_bandwidth_ptr))
{
// Throttle on bandwidth usage.
// Truncate the sums to the last second, and get their value.
size_t const max_bandwidth = AIPerService::getHTTPThrottleBandwidth125();
size_t const total_bandwidth = BufferedCurlEasyRequest::sHTTPBandwidth.truncateData(sTime_40ms); // Bytes received in the past second.
size_t const service_bandwidth = http_bandwidth_ptr->truncateData(sTime_40ms); // Idem for just this service.
if (sTime_40ms > sLastTime_ThrottleFractionAverage_add)
{
sThrottleFractionAverage.addData(sThrottleFraction, sTime_40ms);
// Only add sThrottleFraction once every 40 ms at most.
// It's ok to ignore other values in the same 40 ms because the value only changes on the scale of 1 second.
sLastTime_ThrottleFractionAverage_add = sTime_40ms;
}
double fraction_avg = sThrottleFractionAverage.getAverage(1024.0); // sThrottleFraction averaged over the past second, or 1024 if there is no data.
// Adjust sThrottleFraction based on total bandwidth usage.
if (total_bandwidth == 0)
sThrottleFraction = 1024;
else
{
// This is the main formula. It can be made plausible by assuming
// an equilibrium where total_bandwidth == max_bandwidth and
// thus sThrottleFraction == fraction_avg for more than a second.
//
// Then, more bandwidth is being used (for example because another
// service starts downloading). Assuming that all services that use
// a significant portion of the bandwidth, the new service included,
// must be throttled (all using the same bandwidth; note that the
// new service is immediately throttled at the same value), then
// the limit should be reduced linear with the fraction:
// max_bandwidth / total_bandwidth.
//
// For example, let max_bandwidth be 1. Let there be two throttled
// services, each using 0.5 (fraction_avg = 1024/2). Let the new
// service use what it can: also 0.5 - then without reduction the
// total_bandwidth would become 1.5, and sThrottleFraction would
// become (1024/2) * 1/1.5 = 1024/3: from 2 to 3 services.
//
// In reality, total_bandwidth would rise linear from 1.0 to 1.5 in
// one second if the throttle fraction wasn't changed. However it is
// changed here. The end result is that any change more or less
// linear fades away in one second.
sThrottleFraction = fraction_avg * max_bandwidth / total_bandwidth;
}
if (sThrottleFraction > 1024)
sThrottleFraction = 1024;
if (total_bandwidth > max_bandwidth)
{
sThrottleFraction *= 0.95;
}
// Throttle this service if it uses too much bandwidth.
if (service_bandwidth > (max_bandwidth * sThrottleFraction / 1024))
{
return false; // wait
}
// Too much bandwidth is being used, either in total or for this service.
return false;
}
// Check if it's ok to get a new request based on the total number of requests and increment the threshold if appropriate.
@@ -2770,3 +2717,63 @@ bool AIPerService::wantsMoreHTTPRequestsFor(AIPerServicePtr const& per_service)
return !reject;
}
bool AIPerService::checkBandwidthUsage(U64 sTime_40ms, AIAverage* http_bandwidth_ptr)
{
if (sNoHTTPBandwidthThrottling)
return false;
using namespace AICurlPrivate;
// Truncate the sums to the last second, and get their value.
size_t const max_bandwidth = AIPerService::getHTTPThrottleBandwidth125();
size_t const total_bandwidth = BufferedCurlEasyRequest::sHTTPBandwidth.truncateData(sTime_40ms); // Bytes received in the past second.
size_t const service_bandwidth = http_bandwidth_ptr->truncateData(sTime_40ms); // Idem for just this service.
if (sTime_40ms > sLastTime_ThrottleFractionAverage_add)
{
sThrottleFractionAverage.addData(sThrottleFraction, sTime_40ms);
// Only add sThrottleFraction once every 40 ms at most.
// It's ok to ignore other values in the same 40 ms because the value only changes on the scale of 1 second.
sLastTime_ThrottleFractionAverage_add = sTime_40ms;
}
double fraction_avg = sThrottleFractionAverage.getAverage(1024.0); // sThrottleFraction averaged over the past second, or 1024 if there is no data.
// Adjust sThrottleFraction based on total bandwidth usage.
if (total_bandwidth == 0)
sThrottleFraction = 1024;
else
{
// This is the main formula. It can be made plausible by assuming
// an equilibrium where total_bandwidth == max_bandwidth and
// thus sThrottleFraction == fraction_avg for more than a second.
//
// Then, more bandwidth is being used (for example because another
// service starts downloading). Assuming that all services that use
// a significant portion of the bandwidth, the new service included,
// must be throttled (all using the same bandwidth; note that the
// new service is immediately throttled at the same value), then
// the limit should be reduced linear with the fraction:
// max_bandwidth / total_bandwidth.
//
// For example, let max_bandwidth be 1. Let there be two throttled
// services, each using 0.5 (fraction_avg = 1024/2). Let the new
// service use what it can: also 0.5 - then without reduction the
// total_bandwidth would become 1.5, and sThrottleFraction would
// become (1024/2) * 1/1.5 = 1024/3: from 2 to 3 services.
//
// In reality, total_bandwidth would rise linear from 1.0 to 1.5 in
// one second if the throttle fraction wasn't changed. However it is
// changed here. The end result is that any change more or less
// linear fades away in one second.
sThrottleFraction = fraction_avg * max_bandwidth / total_bandwidth;
}
if (sThrottleFraction > 1024)
sThrottleFraction = 1024;
if (total_bandwidth > max_bandwidth)
{
sThrottleFraction *= 0.95;
}
// Throttle this service if it uses too much bandwidth.
return (service_bandwidth > (max_bandwidth * sThrottleFraction / 1024));
}