Make content_extractor support a multiple-url request

This adds the --urls flag which accepts a space-separated list of urls
to distill.

This adds a pretty straightforward approach to having multiple of these
requests happening at the same time.

Once all requests are finished, they will be printed (in the order that
they appeared in --urls). If printing binary, each serialized protobuf
will be preceded by its size (as a varint32).

TBR=ben@

Review URL: https://codereview.chromium.org/276553002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@276819 0039d316-1c4b-4281-b951-d872f2087c98

components/dom_distiller/DEPS

 include_rules = [
+  "+google", # For third_party/protobuf.
   "+grit",  # For generated headers.
   "+jni",
   "+sync/api",

components/dom_distiller/standalone/content_extractor.cc

@@ -10,6 +10,7 @@
 #include "base/path_service.h"
 #include "base/run_loop.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/strings/string_split.h"
 #include "components/dom_distiller/content/distiller_page_web_contents.h"
 #include "components/dom_distiller/core/distiller.h"
 #include "components/dom_distiller/core/dom_distiller_database.h"
@@ -22,6 +23,8 @@
 #include "content/public/browser/browser_thread.h"
 #include "content/public/test/content_browser_test.h"
 #include "content/shell/browser/shell.h"
+#include "google/protobuf/io/coded_stream.h"
+#include "google/protobuf/io/zero_copy_stream_impl_lite.h"
 #include "net/dns/mock_host_resolver.h"
 #include "third_party/dom_distiller_js/dom_distiller.pb.h"
 #include "ui/base/resource/resource_bundle.h"
@@ -35,6 +38,9 @@ namespace {
 // The url to distill.
 const char* kUrlSwitch = "url";
 
+// A space-separated list of urls to distill.
+const char* kUrlsSwitch = "urls";
+
 // Indicates that DNS resolution should be disabled for this test.
 const char* kDisableDnsSwitch = "disable-dns";
 
@@ -51,6 +57,9 @@ const char* kExtractTextOnly = "extract-text-only";
 // Indicates to include debug output.
 const char* kDebugLevel = "debug-level";
 
+// Maximum number of concurrent started extractor requests.
+const int kMaxExtractorTasks = 8;
+
 scoped_ptr<DomDistillerService> CreateDomDistillerService(
     content::BrowserContext* context,
     const base::FilePath& db_path) {
@@ -100,29 +109,30 @@ void AddComponentsResources() {
       pak_file, ui::SCALE_FACTOR_NONE);
 }
 
-void LogArticle(const DistilledArticleProto& article_proto) {
-  std::stringstream output;
-  if (CommandLine::ForCurrentProcess()->HasSwitch(kShouldOutputBinary)) {
-    output << article_proto.SerializeAsString();
-  } else {
-    output << "Article Title: " << article_proto.title() << std::endl;
-    output << "# of pages: " << article_proto.pages_size() << std::endl;
-    for (int i = 0; i < article_proto.pages_size(); ++i) {
-      const DistilledPageProto& page = article_proto.pages(i);
-      output << "Page " << i << std::endl;
-      output << "URL: " << page.url() << std::endl;
-      output << "Content: " << page.html() << std::endl;
-    }
-  }
+bool WriteProtobufWithSize(
+    const google::protobuf::MessageLite& message,
+    google::protobuf::io::ZeroCopyOutputStream* output_stream) {
+  google::protobuf::io::CodedOutputStream coded_output(output_stream);
+
+  // Write the size.
+  const int size = message.ByteSize();
+  coded_output.WriteLittleEndian32(size);
+  message.SerializeWithCachedSizes(&coded_output);
+  return !coded_output.HadError();
+}
 
-  std::string data = output.str();
-  if (CommandLine::ForCurrentProcess()->HasSwitch(kOutputFile)) {
-    base::FilePath filename =
-        CommandLine::ForCurrentProcess()->GetSwitchValuePath(kOutputFile);
-    base::WriteFile(filename, data.c_str(), data.size());
-  } else {
-    VLOG(0) << data;
+std::string GetReadableArticleString(
+    const DistilledArticleProto& article_proto) {
+  std::stringstream output;
+  output << "Article Title: " << article_proto.title() << std::endl;
+  output << "# of pages: " << article_proto.pages_size() << std::endl;
+  for (int i = 0; i < article_proto.pages_size(); ++i) {
+    const DistilledPageProto& page = article_proto.pages(i);
+    output << "Page " << i << std::endl;
+    output << "URL: " << page.url() << std::endl;
+    output << "Content: " << page.html() << std::endl;
   }
+  return output.str();
 }
 
 }  // namespace
@@ -139,19 +149,34 @@ class ContentExtractionRequest : public ViewRequestDelegate {
     return *article_proto_;
   }
 
-  static scoped_ptr<ContentExtractionRequest> CreateForCommandLine(
+  static ScopedVector<ContentExtractionRequest> CreateForCommandLine(
       const CommandLine& command_line) {
-    GURL url;
+    ScopedVector<ContentExtractionRequest> requests;
     if (command_line.HasSwitch(kUrlSwitch)) {
+      GURL url;
       std::string url_string = command_line.GetSwitchValueASCII(kUrlSwitch);
       url = GURL(url_string);
+      if (url.is_valid()) {
+        requests.push_back(new ContentExtractionRequest(url));
+      }
+    } else if (command_line.HasSwitch(kUrlsSwitch)) {
+      std::string urls_string = command_line.GetSwitchValueASCII(kUrlsSwitch);
+      std::vector<std::string> urls;
+      base::SplitString(urls_string, ' ', &urls);
+      for (size_t i = 0; i < urls.size(); ++i) {
+        GURL url(urls[i]);
+        if (url.is_valid()) {
+          requests.push_back(new ContentExtractionRequest(url));
+        } else {
+          ADD_FAILURE() << "Bad url";
+        }
+      }
     }
-    if (!url.is_valid()) {
+    if (requests.empty()) {
       ADD_FAILURE() << "No valid url provided";
-      return scoped_ptr<ContentExtractionRequest>();
     }
-    return scoped_ptr<ContentExtractionRequest>(
-        new ContentExtractionRequest(url));
+
+    return requests.Pass();
   }
 
  private:
@@ -175,6 +200,15 @@ class ContentExtractionRequest : public ViewRequestDelegate {
 };
 
 class ContentExtractor : public ContentBrowserTest {
+ public:
+  ContentExtractor()
+      : pending_tasks_(0),
+        max_tasks_(kMaxExtractorTasks),
+        next_request_(0),
+        output_data_(),
+        protobuf_output_stream_(
+            new google::protobuf::io::StringOutputStream(&output_data_)) {}
+
   // Change behavior of the default host resolver to avoid DNS lookup errors, so
   // we can make network calls.
   virtual void SetUpOnMainThread() OVERRIDE {
@@ -198,10 +232,18 @@ class ContentExtractor : public ContentBrowserTest {
     service_ = CreateDomDistillerService(context,
                                          db_dir_.path());
     const CommandLine& command_line = *CommandLine::ForCurrentProcess();
-    request_ = ContentExtractionRequest::CreateForCommandLine(command_line);
-    request_->Start(
-        service_.get(),
-        base::Bind(&ContentExtractor::Finish, base::Unretained(this)));
+    requests_ = ContentExtractionRequest::CreateForCommandLine(command_line);
+    PumpQueue();
+  }
+
+  void PumpQueue() {
+    while (pending_tasks_ < max_tasks_ && next_request_ < requests_.size()) {
+      requests_[next_request_]->Start(
+          service_.get(),
+          base::Bind(&ContentExtractor::FinishRequest, base::Unretained(this)));
+      ++next_request_;
+      ++pending_tasks_;
+    }
   }
 
  private:
@@ -221,18 +263,55 @@ class ContentExtractor : public ContentBrowserTest {
     mock_host_resolver_override_.reset();
   }
 
+  void FinishRequest() {
+    --pending_tasks_;
+    if (next_request_ == requests_.size() && pending_tasks_ == 0) {
+      Finish();
+    } else {
+      PumpQueue();
+    }
+  }
+
+  void DoArticleOutput() {
+    for (size_t i = 0; i < requests_.size(); ++i) {
+      const DistilledArticleProto& article = requests_[i]->GetArticleCopy();
+      if (CommandLine::ForCurrentProcess()->HasSwitch(kShouldOutputBinary)) {
+        WriteProtobufWithSize(article, protobuf_output_stream_.get());
+      } else {
+        output_data_ += GetReadableArticleString(article) + "\n";
+      }
+    }
+
+    if (CommandLine::ForCurrentProcess()->HasSwitch(kOutputFile)) {
+      base::FilePath filename =
+          CommandLine::ForCurrentProcess()->GetSwitchValuePath(kOutputFile);
+      ASSERT_EQ(
+          (int)output_data_.size(),
+          base::WriteFile(filename, output_data_.c_str(), output_data_.size()));
+    } else {
+      VLOG(0) << output_data_;
+    }
+  }
+
   void Finish() {
-    LogArticle(request_->GetArticleCopy());
-    request_.reset();
+    DoArticleOutput();
+    requests_.clear();
     service_.reset();
     base::MessageLoop::current()->PostTask(
         FROM_HERE, base::MessageLoop::QuitWhenIdleClosure());
   }
 
+  size_t pending_tasks_;
+  size_t max_tasks_;
+  size_t next_request_;
+
   base::ScopedTempDir db_dir_;
   scoped_ptr<net::ScopedDefaultHostResolverProc> mock_host_resolver_override_;
   scoped_ptr<DomDistillerService> service_;
-  scoped_ptr<ContentExtractionRequest> request_;
+  ScopedVector<ContentExtractionRequest> requests_;
+
+  std::string output_data_;
+  scoped_ptr<google::protobuf::io::StringOutputStream> protobuf_output_stream_;
 };
 
 IN_PROC_BROWSER_TEST_F(ContentExtractor, MANUAL_ExtractUrl) {