root/samples/process.cc

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DEFINITIONS

This source file includes following definitions.
  1. LogCallback
  2. Initialize
  3. ExecuteScript
  4. InstallMaps
  5. WrapMap
  6. UnwrapMap
  7. ObjectToString
  8. MapGet
  9. MapSet
  10. MakeMapTemplate
  11. WrapRequest
  12. UnwrapRequest
  13. GetPath
  14. GetReferrer
  15. GetHost
  16. GetUserAgent
  17. MakeRequestTemplate
  18. Log
  19. Path
  20. Referrer
  21. Host
  22. UserAgent
  23. user_agent_
  24. ParseOptions
  25. ReadFile
  26. ProcessEntries
  27. PrintMap
  28. main

// Copyright 2012 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
//       copyright notice, this list of conditions and the following
//       disclaimer in the documentation and/or other materials provided
//       with the distribution.
//     * Neither the name of Google Inc. nor the names of its
//       contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include <v8.h>

#include <string>
#include <map>

#ifdef COMPRESS_STARTUP_DATA_BZ2
#error Using compressed startup data is not supported for this sample
#endif

using namespace std;
using namespace v8;

// These interfaces represent an existing request processing interface.
// The idea is to imagine a real application that uses these interfaces
// and then add scripting capabilities that allow you to interact with
// the objects through JavaScript.

/**
 * A simplified http request.
 */
class HttpRequest {
 public:
  virtual ~HttpRequest() { }
  virtual const string& Path() = 0;
  virtual const string& Referrer() = 0;
  virtual const string& Host() = 0;
  virtual const string& UserAgent() = 0;
};

/**
 * The abstract superclass of http request processors.
 */
class HttpRequestProcessor {
 public:
  virtual ~HttpRequestProcessor() { }

  // Initialize this processor.  The map contains options that control
  // how requests should be processed.
  virtual bool Initialize(map<string, string>* options,
                          map<string, string>* output) = 0;

  // Process a single request.
  virtual bool Process(HttpRequest* req) = 0;

  static void Log(const char* event);
};

/**
 * An http request processor that is scriptable using JavaScript.
 */
class JsHttpRequestProcessor : public HttpRequestProcessor {
 public:
  // Creates a new processor that processes requests by invoking the
  // Process function of the JavaScript script given as an argument.
  explicit JsHttpRequestProcessor(Handle<String> script) : script_(script) { }
  virtual ~JsHttpRequestProcessor();

  virtual bool Initialize(map<string, string>* opts,
                          map<string, string>* output);
  virtual bool Process(HttpRequest* req);

 private:
  // Execute the script associated with this processor and extract the
  // Process function.  Returns true if this succeeded, otherwise false.
  bool ExecuteScript(Handle<String> script);

  // Wrap the options and output map in a JavaScript objects and
  // install it in the global namespace as 'options' and 'output'.
  bool InstallMaps(map<string, string>* opts, map<string, string>* output);

  // Constructs the template that describes the JavaScript wrapper
  // type for requests.
  static Handle<ObjectTemplate> MakeRequestTemplate();
  static Handle<ObjectTemplate> MakeMapTemplate();

  // Callbacks that access the individual fields of request objects.
  static Handle<Value> GetPath(Local<String> name, const AccessorInfo& info);
  static Handle<Value> GetReferrer(Local<String> name,
                                   const AccessorInfo& info);
  static Handle<Value> GetHost(Local<String> name, const AccessorInfo& info);
  static Handle<Value> GetUserAgent(Local<String> name,
                                    const AccessorInfo& info);

  // Callbacks that access maps
  static Handle<Value> MapGet(Local<String> name, const AccessorInfo& info);
  static Handle<Value> MapSet(Local<String> name,
                              Local<Value> value,
                              const AccessorInfo& info);

  // Utility methods for wrapping C++ objects as JavaScript objects,
  // and going back again.
  static Handle<Object> WrapMap(map<string, string>* obj);
  static map<string, string>* UnwrapMap(Handle<Object> obj);
  static Handle<Object> WrapRequest(HttpRequest* obj);
  static HttpRequest* UnwrapRequest(Handle<Object> obj);

  Handle<String> script_;
  Persistent<Context> context_;
  Persistent<Function> process_;
  static Persistent<ObjectTemplate> request_template_;
  static Persistent<ObjectTemplate> map_template_;
};

// -------------------------
// --- P r o c e s s o r ---
// -------------------------


static Handle<Value> LogCallback(const Arguments& args) {
  if (args.Length() < 1) return v8::Undefined();
  HandleScope scope;
  Handle<Value> arg = args[0];
  String::Utf8Value value(arg);
  HttpRequestProcessor::Log(*value);
  return v8::Undefined();
}


// Execute the script and fetch the Process method.
bool JsHttpRequestProcessor::Initialize(map<string, string>* opts,
                                        map<string, string>* output) {
  // Create a handle scope to hold the temporary references.
  HandleScope handle_scope;

  // Create a template for the global object where we set the
  // built-in global functions.
  Handle<ObjectTemplate> global = ObjectTemplate::New();
  global->Set(String::New("log"), FunctionTemplate::New(LogCallback));

  // Each processor gets its own context so different processors don't
  // affect each other. Context::New returns a persistent handle which
  // is what we need for the reference to remain after we return from
  // this method. That persistent handle has to be disposed in the
  // destructor.
  context_ = Context::New(NULL, global);

  // Enter the new context so all the following operations take place
  // within it.
  Context::Scope context_scope(context_);

  // Make the options mapping available within the context
  if (!InstallMaps(opts, output))
    return false;

  // Compile and run the script
  if (!ExecuteScript(script_))
    return false;

  // The script compiled and ran correctly.  Now we fetch out the
  // Process function from the global object.
  Handle<String> process_name = String::New("Process");
  Handle<Value> process_val = context_->Global()->Get(process_name);

  // If there is no Process function, or if it is not a function,
  // bail out
  if (!process_val->IsFunction()) return false;

  // It is a function; cast it to a Function
  Handle<Function> process_fun = Handle<Function>::Cast(process_val);

  // Store the function in a Persistent handle, since we also want
  // that to remain after this call returns
  process_ = Persistent<Function>::New(process_fun);

  // All done; all went well
  return true;
}


bool JsHttpRequestProcessor::ExecuteScript(Handle<String> script) {
  HandleScope handle_scope;

  // We're just about to compile the script; set up an error handler to
  // catch any exceptions the script might throw.
  TryCatch try_catch;

  // Compile the script and check for errors.
  Handle<Script> compiled_script = Script::Compile(script);
  if (compiled_script.IsEmpty()) {
    String::Utf8Value error(try_catch.Exception());
    Log(*error);
    // The script failed to compile; bail out.
    return false;
  }

  // Run the script!
  Handle<Value> result = compiled_script->Run();
  if (result.IsEmpty()) {
    // The TryCatch above is still in effect and will have caught the error.
    String::Utf8Value error(try_catch.Exception());
    Log(*error);
    // Running the script failed; bail out.
    return false;
  }
  return true;
}


bool JsHttpRequestProcessor::InstallMaps(map<string, string>* opts,
                                         map<string, string>* output) {
  HandleScope handle_scope;

  // Wrap the map object in a JavaScript wrapper
  Handle<Object> opts_obj = WrapMap(opts);

  // Set the options object as a property on the global object.
  context_->Global()->Set(String::New("options"), opts_obj);

  Handle<Object> output_obj = WrapMap(output);
  context_->Global()->Set(String::New("output"), output_obj);

  return true;
}


bool JsHttpRequestProcessor::Process(HttpRequest* request) {
  // Create a handle scope to keep the temporary object references.
  HandleScope handle_scope;

  // Enter this processor's context so all the remaining operations
  // take place there
  Context::Scope context_scope(context_);

  // Wrap the C++ request object in a JavaScript wrapper
  Handle<Object> request_obj = WrapRequest(request);

  // Set up an exception handler before calling the Process function
  TryCatch try_catch;

  // Invoke the process function, giving the global object as 'this'
  // and one argument, the request.
  const int argc = 1;
  Handle<Value> argv[argc] = { request_obj };
  Handle<Value> result = process_->Call(context_->Global(), argc, argv);
  if (result.IsEmpty()) {
    String::Utf8Value error(try_catch.Exception());
    Log(*error);
    return false;
  } else {
    return true;
  }
}


JsHttpRequestProcessor::~JsHttpRequestProcessor() {
  // Dispose the persistent handles.  When noone else has any
  // references to the objects stored in the handles they will be
  // automatically reclaimed.
  context_.Dispose();
  process_.Dispose();
}


Persistent<ObjectTemplate> JsHttpRequestProcessor::request_template_;
Persistent<ObjectTemplate> JsHttpRequestProcessor::map_template_;


// -----------------------------------
// --- A c c e s s i n g   M a p s ---
// -----------------------------------

// Utility function that wraps a C++ http request object in a
// JavaScript object.
Handle<Object> JsHttpRequestProcessor::WrapMap(map<string, string>* obj) {
  // Handle scope for temporary handles.
  HandleScope handle_scope;

  // Fetch the template for creating JavaScript map wrappers.
  // It only has to be created once, which we do on demand.
  if (map_template_.IsEmpty()) {
    Handle<ObjectTemplate> raw_template = MakeMapTemplate();
    map_template_ = Persistent<ObjectTemplate>::New(raw_template);
  }
  Handle<ObjectTemplate> templ = map_template_;

  // Create an empty map wrapper.
  Handle<Object> result = templ->NewInstance();

  // Wrap the raw C++ pointer in an External so it can be referenced
  // from within JavaScript.
  Handle<External> map_ptr = External::New(obj);

  // Store the map pointer in the JavaScript wrapper.
  result->SetInternalField(0, map_ptr);

  // Return the result through the current handle scope.  Since each
  // of these handles will go away when the handle scope is deleted
  // we need to call Close to let one, the result, escape into the
  // outer handle scope.
  return handle_scope.Close(result);
}


// Utility function that extracts the C++ map pointer from a wrapper
// object.
map<string, string>* JsHttpRequestProcessor::UnwrapMap(Handle<Object> obj) {
  Handle<External> field = Handle<External>::Cast(obj->GetInternalField(0));
  void* ptr = field->Value();
  return static_cast<map<string, string>*>(ptr);
}


// Convert a JavaScript string to a std::string.  To not bother too
// much with string encodings we just use ascii.
string ObjectToString(Local<Value> value) {
  String::Utf8Value utf8_value(value);
  return string(*utf8_value);
}


Handle<Value> JsHttpRequestProcessor::MapGet(Local<String> name,
                                             const AccessorInfo& info) {
  // Fetch the map wrapped by this object.
  map<string, string>* obj = UnwrapMap(info.Holder());

  // Convert the JavaScript string to a std::string.
  string key = ObjectToString(name);

  // Look up the value if it exists using the standard STL ideom.
  map<string, string>::iterator iter = obj->find(key);

  // If the key is not present return an empty handle as signal
  if (iter == obj->end()) return Handle<Value>();

  // Otherwise fetch the value and wrap it in a JavaScript string
  const string& value = (*iter).second;
  return String::New(value.c_str(), static_cast<int>(value.length()));
}


Handle<Value> JsHttpRequestProcessor::MapSet(Local<String> name,
                                             Local<Value> value_obj,
                                             const AccessorInfo& info) {
  // Fetch the map wrapped by this object.
  map<string, string>* obj = UnwrapMap(info.Holder());

  // Convert the key and value to std::strings.
  string key = ObjectToString(name);
  string value = ObjectToString(value_obj);

  // Update the map.
  (*obj)[key] = value;

  // Return the value; any non-empty handle will work.
  return value_obj;
}


Handle<ObjectTemplate> JsHttpRequestProcessor::MakeMapTemplate() {
  HandleScope handle_scope;

  Handle<ObjectTemplate> result = ObjectTemplate::New();
  result->SetInternalFieldCount(1);
  result->SetNamedPropertyHandler(MapGet, MapSet);

  // Again, return the result through the current handle scope.
  return handle_scope.Close(result);
}


// -------------------------------------------
// --- A c c e s s i n g   R e q u e s t s ---
// -------------------------------------------

/**
 * Utility function that wraps a C++ http request object in a
 * JavaScript object.
 */
Handle<Object> JsHttpRequestProcessor::WrapRequest(HttpRequest* request) {
  // Handle scope for temporary handles.
  HandleScope handle_scope;

  // Fetch the template for creating JavaScript http request wrappers.
  // It only has to be created once, which we do on demand.
  if (request_template_.IsEmpty()) {
    Handle<ObjectTemplate> raw_template = MakeRequestTemplate();
    request_template_ = Persistent<ObjectTemplate>::New(raw_template);
  }
  Handle<ObjectTemplate> templ = request_template_;

  // Create an empty http request wrapper.
  Handle<Object> result = templ->NewInstance();

  // Wrap the raw C++ pointer in an External so it can be referenced
  // from within JavaScript.
  Handle<External> request_ptr = External::New(request);

  // Store the request pointer in the JavaScript wrapper.
  result->SetInternalField(0, request_ptr);

  // Return the result through the current handle scope.  Since each
  // of these handles will go away when the handle scope is deleted
  // we need to call Close to let one, the result, escape into the
  // outer handle scope.
  return handle_scope.Close(result);
}


/**
 * Utility function that extracts the C++ http request object from a
 * wrapper object.
 */
HttpRequest* JsHttpRequestProcessor::UnwrapRequest(Handle<Object> obj) {
  Handle<External> field = Handle<External>::Cast(obj->GetInternalField(0));
  void* ptr = field->Value();
  return static_cast<HttpRequest*>(ptr);
}


Handle<Value> JsHttpRequestProcessor::GetPath(Local<String> name,
                                              const AccessorInfo& info) {
  // Extract the C++ request object from the JavaScript wrapper.
  HttpRequest* request = UnwrapRequest(info.Holder());

  // Fetch the path.
  const string& path = request->Path();

  // Wrap the result in a JavaScript string and return it.
  return String::New(path.c_str(), static_cast<int>(path.length()));
}


Handle<Value> JsHttpRequestProcessor::GetReferrer(Local<String> name,
                                                  const AccessorInfo& info) {
  HttpRequest* request = UnwrapRequest(info.Holder());
  const string& path = request->Referrer();
  return String::New(path.c_str(), static_cast<int>(path.length()));
}


Handle<Value> JsHttpRequestProcessor::GetHost(Local<String> name,
                                              const AccessorInfo& info) {
  HttpRequest* request = UnwrapRequest(info.Holder());
  const string& path = request->Host();
  return String::New(path.c_str(), static_cast<int>(path.length()));
}


Handle<Value> JsHttpRequestProcessor::GetUserAgent(Local<String> name,
                                                   const AccessorInfo& info) {
  HttpRequest* request = UnwrapRequest(info.Holder());
  const string& path = request->UserAgent();
  return String::New(path.c_str(), static_cast<int>(path.length()));
}


Handle<ObjectTemplate> JsHttpRequestProcessor::MakeRequestTemplate() {
  HandleScope handle_scope;

  Handle<ObjectTemplate> result = ObjectTemplate::New();
  result->SetInternalFieldCount(1);

  // Add accessors for each of the fields of the request.
  result->SetAccessor(String::NewSymbol("path"), GetPath);
  result->SetAccessor(String::NewSymbol("referrer"), GetReferrer);
  result->SetAccessor(String::NewSymbol("host"), GetHost);
  result->SetAccessor(String::NewSymbol("userAgent"), GetUserAgent);

  // Again, return the result through the current handle scope.
  return handle_scope.Close(result);
}


// --- Test ---


void HttpRequestProcessor::Log(const char* event) {
  printf("Logged: %s\n", event);
}


/**
 * A simplified http request.
 */
class StringHttpRequest : public HttpRequest {
 public:
  StringHttpRequest(const string& path,
                    const string& referrer,
                    const string& host,
                    const string& user_agent);
  virtual const string& Path() { return path_; }
  virtual const string& Referrer() { return referrer_; }
  virtual const string& Host() { return host_; }
  virtual const string& UserAgent() { return user_agent_; }
 private:
  string path_;
  string referrer_;
  string host_;
  string user_agent_;
};


StringHttpRequest::StringHttpRequest(const string& path,
                                     const string& referrer,
                                     const string& host,
                                     const string& user_agent)
    : path_(path),
      referrer_(referrer),
      host_(host),
      user_agent_(user_agent) { }


void ParseOptions(int argc,
                  char* argv[],
                  map<string, string>& options,
                  string* file) {
  for (int i = 1; i < argc; i++) {
    string arg = argv[i];
    size_t index = arg.find('=', 0);
    if (index == string::npos) {
      *file = arg;
    } else {
      string key = arg.substr(0, index);
      string value = arg.substr(index+1);
      options[key] = value;
    }
  }
}


// Reads a file into a v8 string.
Handle<String> ReadFile(const string& name) {
  FILE* file = fopen(name.c_str(), "rb");
  if (file == NULL) return Handle<String>();

  fseek(file, 0, SEEK_END);
  int size = ftell(file);
  rewind(file);

  char* chars = new char[size + 1];
  chars[size] = '\0';
  for (int i = 0; i < size;) {
    int read = static_cast<int>(fread(&chars[i], 1, size - i, file));
    i += read;
  }
  fclose(file);
  Handle<String> result = String::New(chars, size);
  delete[] chars;
  return result;
}


const int kSampleSize = 6;
StringHttpRequest kSampleRequests[kSampleSize] = {
  StringHttpRequest("/process.cc", "localhost", "google.com", "firefox"),
  StringHttpRequest("/", "localhost", "google.net", "firefox"),
  StringHttpRequest("/", "localhost", "google.org", "safari"),
  StringHttpRequest("/", "localhost", "yahoo.com", "ie"),
  StringHttpRequest("/", "localhost", "yahoo.com", "safari"),
  StringHttpRequest("/", "localhost", "yahoo.com", "firefox")
};


bool ProcessEntries(HttpRequestProcessor* processor, int count,
                    StringHttpRequest* reqs) {
  for (int i = 0; i < count; i++) {
    if (!processor->Process(&reqs[i]))
      return false;
  }
  return true;
}


void PrintMap(map<string, string>* m) {
  for (map<string, string>::iterator i = m->begin(); i != m->end(); i++) {
    pair<string, string> entry = *i;
    printf("%s: %s\n", entry.first.c_str(), entry.second.c_str());
  }
}


int main(int argc, char* argv[]) {
  map<string, string> options;
  string file;
  ParseOptions(argc, argv, options, &file);
  if (file.empty()) {
    fprintf(stderr, "No script was specified.\n");
    return 1;
  }
  HandleScope scope;
  Handle<String> source = ReadFile(file);
  if (source.IsEmpty()) {
    fprintf(stderr, "Error reading '%s'.\n", file.c_str());
    return 1;
  }
  JsHttpRequestProcessor processor(source);
  map<string, string> output;
  if (!processor.Initialize(&options, &output)) {
    fprintf(stderr, "Error initializing processor.\n");
    return 1;
  }
  if (!ProcessEntries(&processor, kSampleSize, kSampleRequests))
    return 1;
  PrintMap(&output);
}

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