src/net/instaweb/rewriter/add_instrumentation_filter.cc - incubator-pagespeed-mod - Git at Google

 /**
  * Copyright 2010 Google Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 // Author: abliss@google.com (Adam Bliss)

 #include "public/add_instrumentation_filter.h"

 #include "net/instaweb/htmlparse/public/html_parse.h"
 #include "net/instaweb/htmlparse/public/html_element.h"
 #include "net/instaweb/util/public/statistics.h"
 #include "net/instaweb/util/public/string_util.h"

 namespace net_instaweb {

 namespace {

 // The javascript tag to insert in the top of the <head> element.  We want this
 // as early as possible in the html.  It must be short and fast.
 const char kHeadScript[] =
     "<script type='text/javascript'>"
     "window.mod_pagespeed_start = Number(new Date());"
     "</script>";

 // The javascript tag to insert at the bottom of document.  The %s will be
 // replaced with the custom beacon url, by default
 // "./mod_pagespeed_beacon?ets=".  Then our timing info, e.g. "load:123", will
 // be appended.
 const char kTailScript[] =
     "<script type='text/javascript'>"
     "function g(){new Image().src='%sload:'+"
     "(Number(new Date())-window.mod_pagespeed_start);};"
     "var f=window.addEventListener;if(f){f('load',g,false);}else{"
     "f=window.attachEvent;if(f){f('onload',g);}}"
     "</script>";

 // Timing tag for total page load time.  Also embedded in kTailScript above!
 const char kLoadTag[] = "load:";

 // Variables for the beacon to increment.  These are currently handled in
 // mod_pagespeed_handler on apache.  The average load time in milliseconds is
 // total_page_load_ms / page_load_count.  Note that these are not updated
 // together atomically, so you might get a slightly bogus value.
 const char kTotalPageLoadMs[] = "total_page_load_ms";
 const char kPageLoadCount[] = "page_load_count";

 }  // namespace

 AddInstrumentationFilter::AddInstrumentationFilter(
     HtmlParse* html_parse, const StringPiece& beacon_url, Statistics* stats)
     : html_parse_(html_parse),
       found_head_(false),
       s_head_(html_parse->Intern("head")),
       s_body_(html_parse->Intern("body")),
       total_page_load_ms_((stats == NULL) ? NULL :
                           stats->GetVariable(kTotalPageLoadMs)),
       page_load_count_((stats == NULL) ? NULL :
                        stats->GetVariable(kPageLoadCount)) {
   beacon_url.CopyToString(&beacon_url_);
 }

 void AddInstrumentationFilter::Initialize(Statistics* statistics) {
   statistics->AddVariable(kTotalPageLoadMs);
   statistics->AddVariable(kPageLoadCount);
 }

 void AddInstrumentationFilter::StartDocument() {
   found_head_ = false;
 }

 void AddInstrumentationFilter::StartElement(HtmlElement* element) {
   if (!found_head_) {
     if (element->tag() == s_head_) {
       found_head_ = true;
       // TODO(abliss): add an actual element instead, so other filters can
       // rewrite this JS
       HtmlCharactersNode* script =
           html_parse_->NewCharactersNode(element, kHeadScript);
       html_parse_->InsertElementAfterCurrent(script);
     }
   }
 }

 void AddInstrumentationFilter::EndElement(HtmlElement* element) {
   if (element->tag() == s_body_) {
     // We relied on the existence of a <head> element.  This should have been
     // assured by add_head_filter.
     CHECK(found_head_) << "Reached end of document without finding <head>."
         "  Please turn on the add_head filter.";
     std::string tailScript = StringPrintf(kTailScript, beacon_url_.c_str());
     HtmlCharactersNode* script =
         html_parse_->NewCharactersNode(element, tailScript);
     html_parse_->InsertElementBeforeCurrent(script);
   }
 }

 bool AddInstrumentationFilter::HandleBeacon(const StringPiece& unparsed_url) {
   if ((total_page_load_ms_ == NULL) || (page_load_count_ == NULL)) {
     return false;
   }
   std::string url = unparsed_url.as_string();
   // TODO(abliss): proper query parsing
   size_t index = url.find(kLoadTag);
   if (index == std::string::npos) {
     return false;
   }
   url = url.substr(index + strlen(kLoadTag));
   int value = 0;
   if (!StringToInt(url, &value)) {
     return false;
   }
   total_page_load_ms_->Add(value);
   page_load_count_->Add(1);
   return true;
 }

 }  // namespace net_instaweb
	/**
	* Copyright 2010 Google Inc.
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	// Author: abliss@google.com (Adam Bliss)

	#include "public/add_instrumentation_filter.h"

	#include "net/instaweb/htmlparse/public/html_parse.h"
	#include "net/instaweb/htmlparse/public/html_element.h"
	#include "net/instaweb/util/public/statistics.h"
	#include "net/instaweb/util/public/string_util.h"

	namespace net_instaweb {

	namespace {

	// The javascript tag to insert in the top of the <head> element. We want this
	// as early as possible in the html. It must be short and fast.
	const char kHeadScript[] =
	"<script type='text/javascript'>"
	"window.mod_pagespeed_start = Number(new Date());"
	"</script>";

	// The javascript tag to insert at the bottom of document. The %s will be
	// replaced with the custom beacon url, by default
	// "./mod_pagespeed_beacon?ets=". Then our timing info, e.g. "load:123", will
	// be appended.
	const char kTailScript[] =
	"<script type='text/javascript'>"
	"function g(){new Image().src='%sload:'+"
	"(Number(new Date())-window.mod_pagespeed_start);};"
	"var f=window.addEventListener;if(f){f('load',g,false);}else{"
	"f=window.attachEvent;if(f){f('onload',g);}}"
	"</script>";

	// Timing tag for total page load time. Also embedded in kTailScript above!
	const char kLoadTag[] = "load:";

	// Variables for the beacon to increment. These are currently handled in
	// mod_pagespeed_handler on apache. The average load time in milliseconds is
	// total_page_load_ms / page_load_count. Note that these are not updated
	// together atomically, so you might get a slightly bogus value.
	const char kTotalPageLoadMs[] = "total_page_load_ms";
	const char kPageLoadCount[] = "page_load_count";

	} // namespace

	AddInstrumentationFilter::AddInstrumentationFilter(
	HtmlParse* html_parse, const StringPiece& beacon_url, Statistics* stats)
	: html_parse_(html_parse),
	found_head_(false),
	s_head_(html_parse->Intern("head")),
	s_body_(html_parse->Intern("body")),
	total_page_load_ms_((stats == NULL) ? NULL :
	stats->GetVariable(kTotalPageLoadMs)),
	page_load_count_((stats == NULL) ? NULL :
	stats->GetVariable(kPageLoadCount)) {
	beacon_url.CopyToString(&beacon_url_);
	}

	void AddInstrumentationFilter::Initialize(Statistics* statistics) {
	statistics->AddVariable(kTotalPageLoadMs);
	statistics->AddVariable(kPageLoadCount);
	}

	void AddInstrumentationFilter::StartDocument() {
	found_head_ = false;
	}

	void AddInstrumentationFilter::StartElement(HtmlElement* element) {
	if (!found_head_) {
	if (element->tag() == s_head_) {
	found_head_ = true;
	// TODO(abliss): add an actual element instead, so other filters can
	// rewrite this JS
	HtmlCharactersNode* script =
	html_parse_->NewCharactersNode(element, kHeadScript);
	html_parse_->InsertElementAfterCurrent(script);
	}
	}
	}

	void AddInstrumentationFilter::EndElement(HtmlElement* element) {
	if (element->tag() == s_body_) {
	// We relied on the existence of a <head> element. This should have been
	// assured by add_head_filter.
	CHECK(found_head_) << "Reached end of document without finding <head>."
	" Please turn on the add_head filter.";
	std::string tailScript = StringPrintf(kTailScript, beacon_url_.c_str());
	HtmlCharactersNode* script =
	html_parse_->NewCharactersNode(element, tailScript);
	html_parse_->InsertElementBeforeCurrent(script);
	}
	}

	bool AddInstrumentationFilter::HandleBeacon(const StringPiece& unparsed_url) {
	if ((total_page_load_ms_ == NULL) \|\| (page_load_count_ == NULL)) {
	return false;
	}
	std::string url = unparsed_url.as_string();
	// TODO(abliss): proper query parsing
	size_t index = url.find(kLoadTag);
	if (index == std::string::npos) {
	return false;
	}
	url = url.substr(index + strlen(kLoadTag));
	int value = 0;
	if (!StringToInt(url, &value)) {
	return false;
	}
	total_page_load_ms_->Add(value);
	page_load_count_->Add(1);
	return true;
	}

	} // namespace net_instaweb