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| author | jar@chromium.org <jar@chromium.org@0039d316-1c4b-4281-b951-d872f2087c98> | 2009-04-30 23:06:01 +0000 |
|---|---|---|
| committer | jar@chromium.org <jar@chromium.org@0039d316-1c4b-4281-b951-d872f2087c98> | 2009-04-30 23:06:01 +0000 |
| commit | 5b90b5d3473f3f846618092e79d4c5fcff7d3969 (patch) | |
| tree | 2d8c6e9118f8062399e6a89103e212d78479938e /net/url_request/url_request_http_job.cc | |
| parent | 6165e2ab4af4c217e21c0ec167b7eced8fca491c (diff) | |
| download | chromium_src-5b90b5d3473f3f846618092e79d4c5fcff7d3969.zip chromium_src-5b90b5d3473f3f846618092e79d4c5fcff7d3969.tar.gz chromium_src-5b90b5d3473f3f846618092e79d4c5fcff7d3969.tar.bz2 | |
Hand craft an A/B test of SDCH compression
After we're sure we can do SDCH compression to a given URL, toss
a 50-50 coin each time we have a chance to advertise SDCH, and
either completely avoid advertisement, or advertise (including
the dictionary). Histogram both compression download times, as
well as the download times for the "completely avoid" case.
http://crbug.com/11236
bug=11236
r=wtc,openvcdiff
Review URL: http://codereview.chromium.org/100004
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@15010 0039d316-1c4b-4281-b951-d872f2087c98
Diffstat (limited to 'net/url_request/url_request_http_job.cc')
| -rw-r--r-- | net/url_request/url_request_http_job.cc | 62 |
1 files changed, 48 insertions, 14 deletions
diff --git a/net/url_request/url_request_http_job.cc b/net/url_request/url_request_http_job.cc index c0a2080..9c81e00 100644 --- a/net/url_request/url_request_http_job.cc +++ b/net/url_request/url_request_http_job.cc @@ -10,6 +10,7 @@ #include "base/file_util.h" #include "base/file_version_info.h" #include "base/message_loop.h" +#include "base/rand_util.h" #include "base/string_util.h" #include "net/base/cookie_monster.h" #include "net/base/filter.h" @@ -63,10 +64,19 @@ URLRequestHttpJob::URLRequestHttpJob(URLRequest* request) ALLOW_THIS_IN_INITIALIZER_LIST( read_callback_(this, &URLRequestHttpJob::OnReadCompleted)), read_in_progress_(false), - context_(request->context()) { + context_(request->context()), + sdch_dictionary_advertised_(false), + sdch_test_activated_(false), + sdch_test_control_(false) { } URLRequestHttpJob::~URLRequestHttpJob() { + DCHECK(!sdch_test_control_ || !sdch_test_activated_); + if (sdch_test_control_) + RecordPacketStats(SDCH_EXPERIMENT_HOLDBACK); + if (sdch_test_activated_) + RecordPacketStats(SDCH_EXPERIMENT_DECODE); + if (sdch_dictionary_url_.is_valid()) { // Prior to reaching the destructor, request_ has been set to a NULL // pointer, so request_->url() is no longer valid in the destructor, and we @@ -215,8 +225,7 @@ bool URLRequestHttpJob::GetContentEncodings( } bool URLRequestHttpJob::IsSdchResponse() const { - return response_info_ && - (request_info_.load_flags & net::LOAD_SDCH_DICTIONARY_ADVERTISED); + return sdch_dictionary_advertised_; } bool URLRequestHttpJob::IsRedirectResponse(GURL* location, @@ -546,29 +555,54 @@ void URLRequestHttpJob::StartTransaction() { } void URLRequestHttpJob::AddExtraHeaders() { + // TODO(jar): Consider optimizing away SDCH advertising bytes when the URL is + // probably an img or such (and SDCH encoding is not likely). + bool advertise_sdch = SdchManager::Global() && + SdchManager::Global()->IsInSupportedDomain(request_->url()); + std::string avail_dictionaries; + if (advertise_sdch) { + SdchManager::Global()->GetAvailDictionaryList(request_->url(), + &avail_dictionaries); + + // The AllowLatencyExperiment() is only true if we've successfully done a + // full SDCH compression recently in this browser session for this host. + // Note that for this path, there might be no applicable dictionaries, and + // hence we can't participate in the experiment. + if (!avail_dictionaries.empty() && + SdchManager::Global()->AllowLatencyExperiment(request_->url())) { + // We are participating in the test (or control), and hence we'll + // eventually record statistics via either SDCH_EXPERIMENT_DECODE or + // SDCH_EXPERIMENT_HOLDBACK, and we'll need some packet timing data. + EnablePacketCounting(kSdchPacketHistogramCount); + if (base::RandDouble() < .5) { + sdch_test_control_ = true; + advertise_sdch = false; + } else { + sdch_test_activated_ = true; + } + } + } + // Supply Accept-Encoding headers first so that it is more likely that they // will be in the first transmitted packet. This can sometimes make it easier // to filter and analyze the streams to assure that a proxy has not damaged // these headers. Some proxies deliberately corrupt Accept-Encoding headers. - if (!SdchManager::Global() || - !SdchManager::Global()->IsInSupportedDomain(request_->url())) { + if (!advertise_sdch) { // Tell the server what compression formats we support (other than SDCH). request_info_.extra_headers += "Accept-Encoding: gzip,deflate,bzip2\r\n"; } else { - // Supply SDCH related headers, as well as accepting that encoding. - // Tell the server what compression formats we support. + // Include SDCH in acceptable list. request_info_.extra_headers += "Accept-Encoding: " "gzip,deflate,bzip2,sdch\r\n"; - - // TODO(jar): See if it is worth optimizing away these bytes when the URL is - // probably an img or such. (and SDCH encoding is not likely). - std::string avail_dictionaries; - SdchManager::Global()->GetAvailDictionaryList(request_->url(), - &avail_dictionaries); if (!avail_dictionaries.empty()) { request_info_.extra_headers += "Avail-Dictionary: " + avail_dictionaries + "\r\n"; - request_info_.load_flags |= net::LOAD_SDCH_DICTIONARY_ADVERTISED; + sdch_dictionary_advertised_ = true; + // Since we're tagging this transaction as advertising a dictionary, we'll + // definately employ an SDCH filter (or tentative sdch filter) when we get + // a response. When done, we'll record histograms via SDCH_DECODE or + // SDCH_PASSTHROUGH. Hence we need to record packet arrival times. + EnablePacketCounting(kSdchPacketHistogramCount); } } |