Improve performance of proxy resolver by tracing DNS dependencies.

net/proxy/proxy_resolver_v8.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #define V8_DISABLE_DEPRECATIONS 1
 
 #include "net/proxy/proxy_resolver_v8.h"
 
 #include <algorithm>
 #include <cstdio>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/logging.h"
 #include "base/string_tokenizer.h"
 #include "base/string_util.h"
 #include "base/synchronization/lock.h"
 #include "base/utf_string_conversions.h"
 #include "googleurl/src/gurl.h"
 #include "googleurl/src/url_canon.h"
-#include "net/base/host_cache.h"
 #include "net/base/net_errors.h"
 #include "net/base/net_log.h"
 #include "net/base/net_util.h"
 #include "net/proxy/proxy_info.h"
-#include "net/proxy/proxy_resolver_js_bindings.h"
-#include "net/proxy/proxy_resolver_request_context.h"
 #include "net/proxy/proxy_resolver_script.h"
 #include "v8/include/v8.h"
 
 // Notes on the javascript environment:
 //
 // For the majority of the PAC utility functions, we use the same code
 // as Firefox. See the javascript library that proxy_resolver_scipt.h
 // pulls in.
 //
 // In addition, we implement a subset of Microsoft's extensions to PAC.
@@ skipping 292 matching lines @@
 
   return IPNumberMatchesPrefix(address, prefix, prefix_length_in_bits);
 }
 
 }  // namespace
 
 // ProxyResolverV8::Context ---------------------------------------------------
 
 class ProxyResolverV8::Context {
  public:
-  explicit Context(ProxyResolverJSBindings* js_bindings)
-      : is_resolving_host_(false),
-        js_bindings_(js_bindings) {
-    DCHECK(js_bindings != NULL);
+  explicit Context(ProxyResolverV8* parent)
+      : parent_(parent) {
   }
 
   ~Context() {
     v8::Locker locked;
 
     v8_this_.Dispose();
     v8_context_.Dispose();
 
     // Run the V8 garbage collector. We do this to be sure the
     // ExternalStringResource objects we allocated get properly disposed.
     // Otherwise when running the unit-tests they may get leaked.
     // See crbug.com/48145.
     PurgeMemory();
   }
 
+  JSBindings* js_bindings() {
+    return parent_->js_bindings_;
+  }
+
   int ResolveProxy(const GURL& query_url, ProxyInfo* results) {
     v8::Locker locked;
     v8::HandleScope scope;
 
     v8::Context::Scope function_scope(v8_context_);
 
     v8::Local<v8::Value> function;
     if (!GetFindProxyForURL(&function)) {
-      js_bindings_->OnError(
+      js_bindings()->OnError(
           -1, ASCIIToUTF16("FindProxyForURL() is undefined."));
       return ERR_PAC_SCRIPT_FAILED;
     }
 
     v8::Handle<v8::Value> argv[] = {
       ASCIIStringToV8String(query_url.spec()),
       ASCIIStringToV8String(query_url.HostNoBrackets()),
     };
 
     v8::TryCatch try_catch;
     v8::Local<v8::Value> ret = v8::Function::Cast(*function)->Call(
         v8_context_->Global(), arraysize(argv), argv);
 
     if (try_catch.HasCaught()) {
       HandleError(try_catch.Message());
       return ERR_PAC_SCRIPT_FAILED;
     }
 
     if (!ret->IsString()) {
-      js_bindings_->OnError(
+      js_bindings()->OnError(
           -1, ASCIIToUTF16("FindProxyForURL() did not return a string."));
       return ERR_PAC_SCRIPT_FAILED;
     }
 
     string16 ret_str = V8StringToUTF16(ret->ToString());
 
     if (!IsStringASCII(ret_str)) {
       // TODO(eroman): Rather than failing when a wide string is returned, we
       //               could extend the parsing to handle IDNA hostnames by
       //               converting them to ASCII punycode.
       //               crbug.com/47234
       string16 error_message =
           ASCIIToUTF16("FindProxyForURL() returned a non-ASCII string "
                        "(crbug.com/47234): ") + ret_str;
-      js_bindings_->OnError(-1, error_message);
+      js_bindings()->OnError(-1, error_message);
       return ERR_PAC_SCRIPT_FAILED;
     }
 
     results->UsePacString(UTF16ToASCII(ret_str));
     return OK;
   }
 
   int InitV8(const scoped_refptr<ProxyResolverScriptData>& pac_script) {
     v8::Locker locked;
     v8::HandleScope scope;
@@ skipping 57 matching lines @@
 
     // Add the user's PAC code to the environment.
     rv = RunScript(ScriptDataToV8String(pac_script), kPacResourceName);
     if (rv != OK)
       return rv;
 
     // At a minimum, the FindProxyForURL() function must be defined for this
     // to be a legitimiate PAC script.
     v8::Local<v8::Value> function;
     if (!GetFindProxyForURL(&function)) {
-      js_bindings_->OnError(
+      js_bindings()->OnError(
           -1, ASCIIToUTF16("FindProxyForURL() is undefined."));
       return ERR_PAC_SCRIPT_FAILED;
     }
 
     return OK;
   }
 
-  void SetCurrentRequestContext(ProxyResolverRequestContext* context) {
-    js_bindings_->set_current_request_context(context);
-  }
-
   void PurgeMemory() {
     v8::Locker locked;
     v8::V8::LowMemoryNotification();
   }
 
-  bool is_resolving_host() const {
-    base::AutoLock auto_lock(lock_);
-    return is_resolving_host_;
-  }
-
  private:
-  class ScopedHostResolve {
-   public:
-    explicit ScopedHostResolve(Context* context)
-        : context_(context) {
-      context_->BeginHostResolve();
-    }
-
-    ~ScopedHostResolve() {
-      context_->EndHostResolve();
-    }
-
-   private:
-    Context* const context_;
-    DISALLOW_COPY_AND_ASSIGN(ScopedHostResolve);
-  };
-
-  void BeginHostResolve() {
-    base::AutoLock auto_lock(lock_);
-    DCHECK(!is_resolving_host_);
-    is_resolving_host_ = true;
-  }
-
-  void EndHostResolve() {
-    base::AutoLock auto_lock(lock_);
-    DCHECK(is_resolving_host_);
-    is_resolving_host_ = false;
-  }
-
   bool GetFindProxyForURL(v8::Local<v8::Value>* function) {
     *function = v8_context_->Global()->Get(
         ASCIILiteralToV8String("FindProxyForURL"));
     return (*function)->IsFunction();
   }
 
   // Handle an exception thrown by V8.
   void HandleError(v8::Handle<v8::Message> message) {
     if (message.IsEmpty())
       return;
 
     // Otherwise dispatch to the bindings.
     int line_number = message->GetLineNumber();
     string16 error_message;
     V8ObjectToUTF16String(message->Get(), &error_message);
-    js_bindings_->OnError(line_number, error_message);
+    js_bindings()->OnError(line_number, error_message);
   }
 
   // Compiles and runs |script| in the current V8 context.
   // Returns OK on success, otherwise an error code.
   int RunScript(v8::Handle<v8::String> script, const char* script_name) {
     v8::TryCatch try_catch;
 
     // Compile the script.
     v8::ScriptOrigin origin =
         v8::ScriptOrigin(ASCIILiteralToV8String(script_name));
@@ skipping 20 matching lines @@
     // Like firefox we assume "undefined" if no argument was specified, and
     // disregard any arguments beyond the first.
     string16 message;
     if (args.Length() == 0) {
       message = ASCIIToUTF16("undefined");
     } else {
       if (!V8ObjectToUTF16String(args[0], &message))
         return v8::Undefined();  // toString() threw an exception.
     }
 
-    context->js_bindings_->Alert(message);
+    context->js_bindings()->Alert(message);
     return v8::Undefined();
   }
 
   // V8 callback for when "myIpAddress()" is invoked by the PAC script.
   static v8::Handle<v8::Value> MyIpAddressCallback(const v8::Arguments& args) {
     Context* context =
         static_cast<Context*>(v8::External::Cast(*args.Data())->Value());
 
     std::string result;
     bool success;
 
     {
       v8::Unlocker unlocker(args.GetIsolate());
-      ScopedHostResolve scoped_host_resolve(context);
-
       // We shouldn't be called with any arguments, but will not complain if
       // we are.
-      success = context->js_bindings_->MyIpAddress(&result);
+      success = context->js_bindings()->ResolveDns(
+          "", JSBindings::MY_IP_ADDRESS, &result);
     }
 
     if (!success)
       return ASCIILiteralToV8String("127.0.0.1");
     return ASCIIStringToV8String(result);
   }
 
   // V8 callback for when "myIpAddressEx()" is invoked by the PAC script.
   static v8::Handle<v8::Value> MyIpAddressExCallback(
       const v8::Arguments& args) {
     Context* context =
         static_cast<Context*>(v8::External::Cast(*args.Data())->Value());
 
     std::string ip_address_list;
     bool success;
 
     {
       v8::Unlocker unlocker(args.GetIsolate());
-      ScopedHostResolve scoped_host_resolve(context);
-
       // We shouldn't be called with any arguments, but will not complain if
       // we are.
-      success = context->js_bindings_->MyIpAddressEx(&ip_address_list);
+      success = context->js_bindings()->ResolveDns(
+          "", JSBindings::MY_IP_ADDRESS_EX, &ip_address_list);
     }
 
     if (!success)
       ip_address_list = std::string();
     return ASCIIStringToV8String(ip_address_list);
   }
 
   // V8 callback for when "dnsResolve()" is invoked by the PAC script.
   static v8::Handle<v8::Value> DnsResolveCallback(const v8::Arguments& args) {
     Context* context =
         static_cast<Context*>(v8::External::Cast(*args.Data())->Value());
 
     // We need at least one string argument.
     std::string hostname;
     if (!GetHostnameArgument(args, &hostname))
       return v8::Null();
 
     std::string ip_address;
     bool success;
 
     {
       v8::Unlocker unlocker(args.GetIsolate());
-      ScopedHostResolve scoped_host_resolve(context);
-      success = context->js_bindings_->DnsResolve(hostname, &ip_address);
+      success = context->js_bindings()->ResolveDns(
+          hostname, JSBindings::DNS_RESOLVE, &ip_address);
     }
 
     return success ? ASCIIStringToV8String(ip_address) : v8::Null();
   }
 
   // V8 callback for when "dnsResolveEx()" is invoked by the PAC script.
   static v8::Handle<v8::Value> DnsResolveExCallback(const v8::Arguments& args) {
     Context* context =
         static_cast<Context*>(v8::External::Cast(*args.Data())->Value());
 
     // We need at least one string argument.
     std::string hostname;
     if (!GetHostnameArgument(args, &hostname))
       return v8::Undefined();
 
     std::string ip_address_list;
     bool success;
 
     {
       v8::Unlocker unlocker(args.GetIsolate());

[mmenke, 2013/01/29 20:19:08]

If we're running v8 on only one thread...This is still needed to be compatible
with using v8 outside of net, I assume, like in --single-process?

[eroman, 2013/01/29 22:51:23]

Note that we disable v8-proxy resolver in --single-process mode

Both WebKit and this code are using the "default isolate". Although this code is
careful to lock entries into V8, the webkit bindings DO NOT, so it is not safe
to run them together.

I would like to use a self-contained isolate for ProxyResolverV8, but that isn't
possible yet -- It would be too expensive to create a new isolate, since V8 is
going to create a default one anyway (see http://crbug.com/171457).

Once that can be addressed however, we can get rid of all the scary comments
explaining why it is not safe to use in single-process mode, and simply enable
it everywhere.

-      ScopedHostResolve scoped_host_resolve(context);
-      success = context->js_bindings_->DnsResolveEx(hostname, &ip_address_list);
+      success = context->js_bindings()->ResolveDns(
+          hostname, JSBindings::DNS_RESOLVE_EX, &ip_address_list);
     }
 
     if (!success)
       ip_address_list = std::string();
 
     return ASCIIStringToV8String(ip_address_list);
   }
 
   // V8 callback for when "sortIpAddressList()" is invoked by the PAC script.
   static v8::Handle<v8::Value> SortIpAddressListCallback(
@@ skipping 22 matching lines @@
     std::string ip_address = V8StringToUTF8(args[0]->ToString());
     if (!IsStringASCII(ip_address))
       return v8::False();
     std::string ip_prefix = V8StringToUTF8(args[1]->ToString());
     if (!IsStringASCII(ip_prefix))
       return v8::False();
     return IsInNetEx(ip_address, ip_prefix) ? v8::True() : v8::False();
   }
 
   mutable base::Lock lock_;
-  bool is_resolving_host_;
-  ProxyResolverJSBindings* js_bindings_;
+  ProxyResolverV8* parent_;
   v8::Persistent<v8::External> v8_this_;
   v8::Persistent<v8::Context> v8_context_;
 };
 
 // ProxyResolverV8 ------------------------------------------------------------
 
-ProxyResolverV8::ProxyResolverV8(
-    ProxyResolverJSBindings* custom_js_bindings)
+ProxyResolverV8::ProxyResolverV8()
     : ProxyResolver(true /*expects_pac_bytes*/),
-      js_bindings_(custom_js_bindings) {
+      js_bindings_(NULL) {
 }
 
 ProxyResolverV8::~ProxyResolverV8() {}
 
 int ProxyResolverV8::GetProxyForURL(
     const GURL& query_url, ProxyInfo* results,
     const CompletionCallback& /*callback*/,
     RequestHandle* /*request*/,
     const BoundNetLog& net_log) {
+  DCHECK(js_bindings_);
+
   // If the V8 instance has not been initialized (either because
   // SetPacScript() wasn't called yet, or because it failed.
   if (!context_.get())
     return ERR_FAILED;
 
-  // Associate some short-lived context with this request. This context will be
-  // available to any of the javascript "bindings" that are subsequently invoked
-  // from the javascript.
-  //
-  // In particular, we create a HostCache to aggressively cache failed DNS
-  // resolves.
-  const unsigned kMaxCacheEntries = 50;
-  HostCache host_cache(kMaxCacheEntries);
-
-  ProxyResolverRequestContext request_context(&net_log, &host_cache);
-
   // Otherwise call into V8.
-  context_->SetCurrentRequestContext(&request_context);
   int rv = context_->ResolveProxy(query_url, results);
-  context_->SetCurrentRequestContext(NULL);
 
   return rv;
 }
 
 void ProxyResolverV8::CancelRequest(RequestHandle request) {
   // This is a synchronous ProxyResolver; no possibility for async requests.
   NOTREACHED();
 }
 
 LoadState ProxyResolverV8::GetLoadState(RequestHandle request) const {
   NOTREACHED();
   return LOAD_STATE_IDLE;
 }
 
-LoadState ProxyResolverV8::GetLoadStateThreadSafe(RequestHandle request) const {
-  if (context_->is_resolving_host())
-    return LOAD_STATE_RESOLVING_HOST_IN_PROXY_SCRIPT;
-  return LOAD_STATE_RESOLVING_PROXY_FOR_URL;
-}
-
 void ProxyResolverV8::CancelSetPacScript() {
   NOTREACHED();
 }
 
 void ProxyResolverV8::PurgeMemory() {
   context_->PurgeMemory();
 }
 
-void ProxyResolverV8::Shutdown() {
-  js_bindings_->Shutdown();
-}
-
 int ProxyResolverV8::SetPacScript(
     const scoped_refptr<ProxyResolverScriptData>& script_data,
     const CompletionCallback& /*callback*/) {
   DCHECK(script_data.get());
+  DCHECK(js_bindings_);
+
   context_.reset();
   if (script_data->utf16().empty())
     return ERR_PAC_SCRIPT_FAILED;
 
   // Try parsing the PAC script.
-  scoped_ptr<Context> context(new Context(js_bindings_.get()));
+  scoped_ptr<Context> context(new Context(this));
   int rv = context->InitV8(script_data);
   if (rv == OK)
     context_.reset(context.release());
   return rv;
 }
 
 }  // namespace net