src/net/instaweb/rewriter/add_instrumentation_filter.cc - incubator-pagespeed-debian - 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 "net/instaweb/rewriter/public/add_instrumentation_filter.h"

 #include "base/logging.h"
 #include "net/instaweb/http/public/request_context.h"
 #include "net/instaweb/http/public/request_timing_info.h"
 #include "net/instaweb/rewriter/public/experiment_util.h"
 #include "net/instaweb/rewriter/public/request_properties.h"
 #include "net/instaweb/rewriter/public/rewrite_driver.h"
 #include "net/instaweb/rewriter/public/rewrite_options.h"
 #include "net/instaweb/rewriter/public/server_context.h"
 #include "net/instaweb/rewriter/public/static_asset_manager.h"
 #include "pagespeed/kernel/base/escaping.h"
 #include "pagespeed/kernel/base/ref_counted_ptr.h"
 #include "pagespeed/kernel/base/statistics.h"
 #include "pagespeed/kernel/base/string.h"
 #include "pagespeed/kernel/base/string_util.h"
 #include "pagespeed/kernel/html/html_element.h"
 #include "pagespeed/kernel/html/html_name.h"
 #include "pagespeed/kernel/html/html_node.h"
 #include "pagespeed/kernel/http/google_url.h"
 #include "pagespeed/kernel/http/http_names.h"
 #include "pagespeed/kernel/http/response_headers.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>";

 }  // namespace

 // Timing tag for total page load time.  Also embedded in kTailScriptFormat
 // above via the second %s.
 // TODO(jud): These values would be better set to "load" and "beforeunload".
 const char AddInstrumentationFilter::kLoadTag[] = "load:";
 const char AddInstrumentationFilter::kUnloadTag[] = "unload:";

 // Counters.
 const char AddInstrumentationFilter::kInstrumentationScriptAddedCount[] =
     "instrumentation_filter_script_added_count";
 AddInstrumentationFilter::AddInstrumentationFilter(RewriteDriver* driver)
     : CommonFilter(driver),
       found_head_(false),
       added_head_script_(false),
       added_unload_script_(false) {
   Statistics* stats = driver->server_context()->statistics();
   instrumentation_script_added_count_ = stats->GetVariable(
       kInstrumentationScriptAddedCount);
 }

 AddInstrumentationFilter::~AddInstrumentationFilter() {}

 void AddInstrumentationFilter::InitStats(Statistics* statistics) {
   statistics->AddVariable(kInstrumentationScriptAddedCount);
 }

 void AddInstrumentationFilter::StartDocumentImpl() {
   found_head_ = false;
   added_head_script_ = false;
   added_unload_script_ = false;
 }

 void AddInstrumentationFilter::AddHeadScript(HtmlElement* element) {
   // IE doesn't like tags other than title or meta at the start of the
   // head. The MSDN page says:
   //   The X-UA-Compatible header isn't case sensitive; however, it must appear
   //   in the header of the webpage (the HEAD section) before all other elements
   //   except for the title element and other meta elements.
   // Reference: http://msdn.microsoft.com/en-us/library/jj676915(v=vs.85).aspx
   if (element->keyword() != HtmlName::kTitle &&
       element->keyword() != HtmlName::kMeta) {
     added_head_script_ = true;
     // TODO(abliss): add an actual element instead, so other filters can
     // rewrite this JS
     HtmlCharactersNode* script = driver()->NewCharactersNode(NULL, kHeadScript);
     driver()->InsertNodeBeforeCurrent(script);
     instrumentation_script_added_count_->Add(1);
   }
 }

 void AddInstrumentationFilter::StartElementImpl(HtmlElement* element) {
   if (found_head_ && !added_head_script_) {
     AddHeadScript(element);
   }
   if (!found_head_ && element->keyword() == HtmlName::kHead) {
     found_head_ = true;
   }
 }

 void AddInstrumentationFilter::EndElementImpl(HtmlElement* element) {
   if (found_head_ && element->keyword() == HtmlName::kHead) {
     if (!added_head_script_) {
       AddHeadScript(element);
     }
     if (driver()->options()->report_unload_time() &&
         !added_unload_script_) {
       GoogleString js = GetScriptJs(kUnloadTag);
       HtmlElement* script = driver()->NewElement(element, HtmlName::kScript);
       if (!driver()->defer_instrumentation_script()) {
         driver()->AddAttribute(script, HtmlName::kDataPagespeedNoDefer, NULL);
       }
       driver()->InsertNodeBeforeCurrent(script);
       AddJsToElement(js, script);
       added_unload_script_ = true;
     }
   }
 }

 void AddInstrumentationFilter::EndDocument() {
   // We relied on the existence of a <head> element.  This should have been
   // assured by add_head_filter.
   if (!found_head_) {
     LOG(WARNING) << "No <head> found for URL " << driver()->url();
     return;
   }
   GoogleString js = GetScriptJs(kLoadTag);
   HtmlElement* script = driver()->NewElement(NULL, HtmlName::kScript);
   if (!driver()->defer_instrumentation_script()) {
     driver()->AddAttribute(script, HtmlName::kDataPagespeedNoDefer, NULL);
   }
   InsertNodeAtBodyEnd(script);
   AddJsToElement(js, script);
 }

 GoogleString AddInstrumentationFilter::GetScriptJs(StringPiece event) {
   GoogleString js;
   StaticAssetManager* static_asset_manager =
       driver()->server_context()->static_asset_manager();
   // Only add the static JS once.
   if (!added_unload_script_) {
     if (driver()->options()->enable_extended_instrumentation()) {
       js = static_asset_manager->GetAsset(
           StaticAssetEnum::EXTENDED_INSTRUMENTATION_JS, driver()->options());
     }
     StrAppend(&js, static_asset_manager->GetAsset(
         StaticAssetEnum::ADD_INSTRUMENTATION_JS, driver()->options()));
   }

   GoogleString js_event = (event == kLoadTag) ? "load" : "beforeunload";

   const RewriteOptions::BeaconUrl& beacons = driver()->options()->beacon_url();
   const GoogleString* beacon_url =
       driver()->IsHttps() ? &beacons.https : &beacons.http;
   GoogleString extra_params;
   if (driver()->options()->running_experiment()) {
     int experiment_state = driver()->options()->experiment_id();
     if (experiment_state != experiment::kExperimentNotSet &&
         experiment_state != experiment::kNoExperiment) {
       StrAppend(&extra_params, "&exptid=",
                 IntegerToString(driver()->options()->experiment_id()));
     }
   }

   const RequestTimingInfo& timing_info =
       driver()->request_context()->timing_info();
   int64 header_fetch_ms;
   if (timing_info.GetFetchHeaderLatencyMs(&header_fetch_ms)) {
     // If time taken to fetch the http header is not set, then the response
     // came from cache.
     StrAppend(&extra_params, "&hft=", Integer64ToString(header_fetch_ms));
   }
   int64 fetch_ms;
   if (timing_info.GetFetchLatencyMs(&fetch_ms)) {
     // If time taken to fetch the resource is not set, then the response
     // came from cache.
     StrAppend(&extra_params, "&ft=", Integer64ToString(fetch_ms));
   }
   int64 ttfb_ms;
   if (timing_info.GetTimeToFirstByte(&ttfb_ms)) {
     StrAppend(&extra_params, "&s_ttfb=", Integer64ToString(ttfb_ms));
   }

   // Append the http response code.
   if (driver()->response_headers() != NULL &&
       driver()->response_headers()->status_code() > 0 &&
       driver()->response_headers()->status_code() != HttpStatus::kOK) {
     StrAppend(&extra_params, "&rc=", IntegerToString(
         driver()->response_headers()->status_code()));
   }
   // Append the request id.
   if (driver()->request_context()->request_id() > 0) {
     StrAppend(&extra_params, "&id=", Integer64ToString(
         driver()->request_context()->request_id()));
   }

   GoogleString html_url;
   EscapeToJsStringLiteral(driver()->google_url().Spec(),
                           false, /* no quotes */
                           &html_url);

   StrAppend(&js, "\npagespeed.addInstrumentationInit(");
   StrAppend(&js, "'", *beacon_url, "', ");
   StrAppend(&js, "'", js_event, "', ");
   StrAppend(&js, "'", extra_params, "', ");
   StrAppend(&js, "'", html_url, "');");

   return js;
 }

 void AddInstrumentationFilter::DetermineEnabled(GoogleString* disabled_reason) {
   set_is_enabled(!driver()->request_properties()->IsBot());
 }

 }  // 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 "net/instaweb/rewriter/public/add_instrumentation_filter.h"

	#include "base/logging.h"
	#include "net/instaweb/http/public/request_context.h"
	#include "net/instaweb/http/public/request_timing_info.h"
	#include "net/instaweb/rewriter/public/experiment_util.h"
	#include "net/instaweb/rewriter/public/request_properties.h"
	#include "net/instaweb/rewriter/public/rewrite_driver.h"
	#include "net/instaweb/rewriter/public/rewrite_options.h"
	#include "net/instaweb/rewriter/public/server_context.h"
	#include "net/instaweb/rewriter/public/static_asset_manager.h"
	#include "pagespeed/kernel/base/escaping.h"
	#include "pagespeed/kernel/base/ref_counted_ptr.h"
	#include "pagespeed/kernel/base/statistics.h"
	#include "pagespeed/kernel/base/string.h"
	#include "pagespeed/kernel/base/string_util.h"
	#include "pagespeed/kernel/html/html_element.h"
	#include "pagespeed/kernel/html/html_name.h"
	#include "pagespeed/kernel/html/html_node.h"
	#include "pagespeed/kernel/http/google_url.h"
	#include "pagespeed/kernel/http/http_names.h"
	#include "pagespeed/kernel/http/response_headers.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>";

	} // namespace

	// Timing tag for total page load time. Also embedded in kTailScriptFormat
	// above via the second %s.
	// TODO(jud): These values would be better set to "load" and "beforeunload".
	const char AddInstrumentationFilter::kLoadTag[] = "load:";
	const char AddInstrumentationFilter::kUnloadTag[] = "unload:";

	// Counters.
	const char AddInstrumentationFilter::kInstrumentationScriptAddedCount[] =
	"instrumentation_filter_script_added_count";
	AddInstrumentationFilter::AddInstrumentationFilter(RewriteDriver* driver)
	: CommonFilter(driver),
	found_head_(false),
	added_head_script_(false),
	added_unload_script_(false) {
	Statistics* stats = driver->server_context()->statistics();
	instrumentation_script_added_count_ = stats->GetVariable(
	kInstrumentationScriptAddedCount);
	}

	AddInstrumentationFilter::~AddInstrumentationFilter() {}

	void AddInstrumentationFilter::InitStats(Statistics* statistics) {
	statistics->AddVariable(kInstrumentationScriptAddedCount);
	}

	void AddInstrumentationFilter::StartDocumentImpl() {
	found_head_ = false;
	added_head_script_ = false;
	added_unload_script_ = false;
	}

	void AddInstrumentationFilter::AddHeadScript(HtmlElement* element) {
	// IE doesn't like tags other than title or meta at the start of the
	// head. The MSDN page says:
	// The X-UA-Compatible header isn't case sensitive; however, it must appear
	// in the header of the webpage (the HEAD section) before all other elements
	// except for the title element and other meta elements.
	// Reference: http://msdn.microsoft.com/en-us/library/jj676915(v=vs.85).aspx
	if (element->keyword() != HtmlName::kTitle &&
	element->keyword() != HtmlName::kMeta) {
	added_head_script_ = true;
	// TODO(abliss): add an actual element instead, so other filters can
	// rewrite this JS
	HtmlCharactersNode* script = driver()->NewCharactersNode(NULL, kHeadScript);
	driver()->InsertNodeBeforeCurrent(script);
	instrumentation_script_added_count_->Add(1);
	}
	}

	void AddInstrumentationFilter::StartElementImpl(HtmlElement* element) {
	if (found_head_ && !added_head_script_) {
	AddHeadScript(element);
	}
	if (!found_head_ && element->keyword() == HtmlName::kHead) {
	found_head_ = true;
	}
	}

	void AddInstrumentationFilter::EndElementImpl(HtmlElement* element) {
	if (found_head_ && element->keyword() == HtmlName::kHead) {
	if (!added_head_script_) {
	AddHeadScript(element);
	}
	if (driver()->options()->report_unload_time() &&
	!added_unload_script_) {
	GoogleString js = GetScriptJs(kUnloadTag);
	HtmlElement* script = driver()->NewElement(element, HtmlName::kScript);
	if (!driver()->defer_instrumentation_script()) {
	driver()->AddAttribute(script, HtmlName::kDataPagespeedNoDefer, NULL);
	}
	driver()->InsertNodeBeforeCurrent(script);
	AddJsToElement(js, script);
	added_unload_script_ = true;
	}
	}
	}

	void AddInstrumentationFilter::EndDocument() {
	// We relied on the existence of a <head> element. This should have been
	// assured by add_head_filter.
	if (!found_head_) {
	LOG(WARNING) << "No <head> found for URL " << driver()->url();
	return;
	}
	GoogleString js = GetScriptJs(kLoadTag);
	HtmlElement* script = driver()->NewElement(NULL, HtmlName::kScript);
	if (!driver()->defer_instrumentation_script()) {
	driver()->AddAttribute(script, HtmlName::kDataPagespeedNoDefer, NULL);
	}
	InsertNodeAtBodyEnd(script);
	AddJsToElement(js, script);
	}

	GoogleString AddInstrumentationFilter::GetScriptJs(StringPiece event) {
	GoogleString js;
	StaticAssetManager* static_asset_manager =
	driver()->server_context()->static_asset_manager();
	// Only add the static JS once.
	if (!added_unload_script_) {
	if (driver()->options()->enable_extended_instrumentation()) {
	js = static_asset_manager->GetAsset(
	StaticAssetEnum::EXTENDED_INSTRUMENTATION_JS, driver()->options());
	}
	StrAppend(&js, static_asset_manager->GetAsset(
	StaticAssetEnum::ADD_INSTRUMENTATION_JS, driver()->options()));
	}

	GoogleString js_event = (event == kLoadTag) ? "load" : "beforeunload";

	const RewriteOptions::BeaconUrl& beacons = driver()->options()->beacon_url();
	const GoogleString* beacon_url =
	driver()->IsHttps() ? &beacons.https : &beacons.http;
	GoogleString extra_params;
	if (driver()->options()->running_experiment()) {
	int experiment_state = driver()->options()->experiment_id();
	if (experiment_state != experiment::kExperimentNotSet &&
	experiment_state != experiment::kNoExperiment) {
	StrAppend(&extra_params, "&exptid=",
	IntegerToString(driver()->options()->experiment_id()));
	}
	}

	const RequestTimingInfo& timing_info =
	driver()->request_context()->timing_info();
	int64 header_fetch_ms;
	if (timing_info.GetFetchHeaderLatencyMs(&header_fetch_ms)) {
	// If time taken to fetch the http header is not set, then the response
	// came from cache.
	StrAppend(&extra_params, "&hft=", Integer64ToString(header_fetch_ms));
	}
	int64 fetch_ms;
	if (timing_info.GetFetchLatencyMs(&fetch_ms)) {
	// If time taken to fetch the resource is not set, then the response
	// came from cache.
	StrAppend(&extra_params, "&ft=", Integer64ToString(fetch_ms));
	}
	int64 ttfb_ms;
	if (timing_info.GetTimeToFirstByte(&ttfb_ms)) {
	StrAppend(&extra_params, "&s_ttfb=", Integer64ToString(ttfb_ms));
	}

	// Append the http response code.
	if (driver()->response_headers() != NULL &&
	driver()->response_headers()->status_code() > 0 &&
	driver()->response_headers()->status_code() != HttpStatus::kOK) {
	StrAppend(&extra_params, "&rc=", IntegerToString(
	driver()->response_headers()->status_code()));
	}
	// Append the request id.
	if (driver()->request_context()->request_id() > 0) {
	StrAppend(&extra_params, "&id=", Integer64ToString(
	driver()->request_context()->request_id()));
	}

	GoogleString html_url;
	EscapeToJsStringLiteral(driver()->google_url().Spec(),
	false, /* no quotes */
	&html_url);

	StrAppend(&js, "\npagespeed.addInstrumentationInit(");
	StrAppend(&js, "'", *beacon_url, "', ");
	StrAppend(&js, "'", js_event, "', ");
	StrAppend(&js, "'", extra_params, "', ");
	StrAppend(&js, "'", html_url, "');");

	return js;
	}

	void AddInstrumentationFilter::DetermineEnabled(GoogleString* disabled_reason) {
	set_is_enabled(!driver()->request_properties()->IsBot());
	}

	} // namespace net_instaweb