Defer asynchronous loading when the buffer in PPB_URLLoader_Impl exceeds an optionally-specified threshold and re-enable it when the buffer drops below a lower threshold.

BUG=80684
TEST=Set the thresholds to 4 MB and 2 MB, respectively from a plugin then download a large file (> 200 MB). Observe that the renderer/plugin process memory usage in Task Manager does not exceed ~100MB and that network traffic drops to 0 then picks up again briefly after 10 MB are used.

Review URL: http://codereview.chromium.org/6923002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@84071 0039d316-1c4b-4281-b951-d872f2087c98

6 files changed, 106 insertions, 2 deletions

diff --git a/ppapi/c/ppb_url_request_info.h b/ppapi/c/ppb_url_request_info.h
index b577376..dea3ee7 100644
--- a/ppapi/c/ppb_url_request_info.h
+++ b/ppapi/c/ppb_url_request_info.h
@@ -117,7 +117,34 @@ typedef enum {
    * custom content transfer encoding; if given to a loader without universal
    * access, PP_ERROR_BADARGUMENT will result.
    */
-  PP_URLREQUESTPROPERTY_CUSTOMCONTENTTRANSFERENCODING
+  PP_URLREQUESTPROPERTY_CUSTOMCONTENTTRANSFERENCODING,
+
+  /**
+   * This corresponds to an integer (PP_VARTYPE_INT32); default is not defined
+   * and is set by the browser, possibly depending on system capabilities.
+   * Set it to an integer to set an upper threshold for the prefetched buffer
+   * of an asynchronous load. When exceeded, the browser will defer loading
+   * until PP_URLREQUESTPROPERTY_PREFETCHBUFFERLOWERERTHRESHOLD is hit, at which
+   * time it will begin prefetching again.
+   * When setting this property,
+   * PP_URLREQUESTPROPERTY_PREFETCHBUFFERLOWERERTHRESHOLD must also be set.
+   * Behavior is undefined if the former is <= the latter.
+   */
+  PP_URLREQUESTPROPERTY_PREFETCHBUFFERUPPERTHRESHOLD,
+
+  /**
+   * This corresponds to an integer (PP_VARTYPE_INT32); default is not defined
+   * and is set by the browser to a value appropriate for the default
+   * PP_URLREQUESTPROPERTY_PREFETCHBUFFERUPPERTHRESHOLD.
+   * Set it to an integer to set a lower threshold for the prefetched buffer
+   * of an asynchronous load. When reached, the browser will resume loading if
+   * If PP_URLREQUESTPROPERTY_PREFETCHBUFFERLOWERERTHRESHOLD had previously been
+   * reached.
+   * When setting this property,
+   * PP_URLREQUESTPROPERTY_PREFETCHBUFFERUPPERTHRESHOLD must also be set.
+   * Behavior is undefined if the former is >= the latter.
+   */
+  PP_URLREQUESTPROPERTY_PREFETCHBUFFERLOWERTHRESHOLD
 } PP_URLRequestProperty;
 PP_COMPILE_ASSERT_SIZE_IN_BYTES(PP_URLRequestProperty, 4);
 /**
diff --git a/ppapi/cpp/url_request_info.h b/ppapi/cpp/url_request_info.h
index cce4e91..f0922a5 100644
--- a/ppapi/cpp/url_request_info.h
+++ b/ppapi/cpp/url_request_info.h
@@ -70,6 +70,14 @@ class URLRequestInfo : public Resource {
     return SetProperty(PP_URLREQUESTPROPERTY_CUSTOMCONTENTTRANSFERENCODING,
                        content_transfer_encoding);
   }
+  bool SetPrefetchBufferUpperThreshold(int32_t size) {
+    return SetProperty(PP_URLREQUESTPROPERTY_PREFETCHBUFFERUPPERTHRESHOLD,
+                       size);
+  }
+  bool SetPrefetchBufferLowerThreshold(int32_t size) {
+    return SetProperty(PP_URLREQUESTPROPERTY_PREFETCHBUFFERLOWERTHRESHOLD,
+                       size);
+  }
 };
 
 }  // namespace pp
diff --git a/webkit/plugins/ppapi/ppb_url_loader_impl.cc b/webkit/plugins/ppapi/ppb_url_loader_impl.cc
index 27ec617..5684d40 100644
--- a/webkit/plugins/ppapi/ppb_url_loader_impl.cc
+++ b/webkit/plugins/ppapi/ppb_url_loader_impl.cc
@@ -208,6 +208,8 @@ PPB_URLLoader_Impl::PPB_URLLoader_Impl(PluginInstance* instance,
       user_buffer_(NULL),
       user_buffer_size_(0),
       done_status_(PP_OK_COMPLETIONPENDING),
+      is_streaming_to_file_(false),
+      is_asynchronous_load_suspended_(false),
       has_universal_access_(false),
       status_callback_(NULL) {
 }
@@ -268,6 +270,7 @@ int32_t PPB_URLLoader_Impl::Open(PPB_URLRequestInfo_Impl* request,
     options.allowCredentials = request->allow_credentials();
   }
 
+  is_asynchronous_load_suspended_ = false;
   loader_.reset(frame->createAssociatedURLLoader(options));
   if (!loader_.get())
     return PP_ERROR_FAILED;
@@ -365,6 +368,12 @@ int32_t PPB_URLLoader_Impl::FinishStreamingToFile(
   if (done_status_ != PP_OK_COMPLETIONPENDING)
     return done_status_;
 
+  is_streaming_to_file_ = true;
+  if (is_asynchronous_load_suspended_) {
+    loader_->setDefersLoading(false);
+    is_asynchronous_load_suspended_ = false;
+  }
+
   // Wait for didFinishLoading / didFail.
   RegisterCallback(callback);
   return PP_OK_COMPLETIONPENDING;
@@ -440,6 +449,20 @@ void PPB_URLLoader_Impl::didReceiveData(WebURLLoader* loader,
   } else {
     DCHECK(!pending_callback_.get() || pending_callback_->completed());
   }
+
+  // To avoid letting the network stack download an entire stream all at once,
+  // defer loading when we have enough buffer.
+  // Check the buffer size after potentially moving some to the user buffer.
+  DCHECK(request_info_->prefetch_buffer_lower_threshold() <
+         request_info_->prefetch_buffer_upper_threshold());
+  if (!is_streaming_to_file_ &&
+      !is_asynchronous_load_suspended_ &&
+      buffer_.size() >= static_cast<size_t>(
+          request_info_->prefetch_buffer_upper_threshold())) {
+    DVLOG(1) << "Suspending async load - buffer size: " << buffer_.size();
+    loader->setDefersLoading(true);
+    is_asynchronous_load_suspended_ = true;
+  }
 }
 
 void PPB_URLLoader_Impl::didFinishLoading(WebURLLoader* loader,
@@ -498,6 +521,15 @@ size_t PPB_URLLoader_Impl::FillUserBuffer() {
   std::copy(buffer_.begin(), buffer_.begin() + bytes_to_copy, user_buffer_);
   buffer_.erase(buffer_.begin(), buffer_.begin() + bytes_to_copy);
 
+  // If the buffer is getting too empty, resume asynchronous loading.
+  if (is_asynchronous_load_suspended_ &&
+      buffer_.size() <= static_cast<size_t>(
+          request_info_->prefetch_buffer_lower_threshold())) {
+    DVLOG(1) << "Resuming async load - buffer size: " << buffer_.size();
+    loader_->setDefersLoading(false);
+    is_asynchronous_load_suspended_ = false;
+  }
+
   // Reset for next time.
   user_buffer_ = NULL;
   user_buffer_size_ = 0;
diff --git a/webkit/plugins/ppapi/ppb_url_loader_impl.h b/webkit/plugins/ppapi/ppb_url_loader_impl.h
index fae3628..878ce65 100644
--- a/webkit/plugins/ppapi/ppb_url_loader_impl.h
+++ b/webkit/plugins/ppapi/ppb_url_loader_impl.h
@@ -137,6 +137,8 @@ class PPB_URLLoader_Impl : public Resource, public WebKit::WebURLLoaderClient {
   char* user_buffer_;
   size_t user_buffer_size_;
   int32_t done_status_;
+  bool is_streaming_to_file_;
+  bool is_asynchronous_load_suspended_;
 
   bool has_universal_access_;
 
diff --git a/webkit/plugins/ppapi/ppb_url_request_info_impl.cc b/webkit/plugins/ppapi/ppb_url_request_info_impl.cc
index 7bae8ba..90a0ec6 100644
--- a/webkit/plugins/ppapi/ppb_url_request_info_impl.cc
+++ b/webkit/plugins/ppapi/ppb_url_request_info_impl.cc
@@ -34,6 +34,9 @@ namespace ppapi {
 
 namespace {
 
+const int32_t kDefaultPrefetchBufferUpperThreshold = 100 * 1000 * 1000;
+const int32_t kDefaultPrefetchBufferLowerThreshold = 50 * 1000 * 1000;
+
 // A header string containing any of the following fields will cause
 // an error. The list comes from the XMLHttpRequest standard.
 // http://www.w3.org/TR/XMLHttpRequest/#the-setrequestheader-method
@@ -113,6 +116,10 @@ PP_Bool SetProperty(PP_Resource request_id,
           request->SetBooleanProperty(property,
                                       PPBoolToBool(var.value.as_bool)));
       break;
+    case PP_VARTYPE_INT32:
+      result = BoolToPPBool(
+          request->SetIntegerProperty(property, var.value.as_int));
+      break;
     case PP_VARTYPE_STRING: {
       scoped_refptr<StringVar> string(StringVar::FromPPVar(var));
       if (string)
@@ -203,7 +210,9 @@ PPB_URLRequestInfo_Impl::PPB_URLRequestInfo_Impl(PluginInstance* instance)
       has_custom_referrer_url_(false),
       allow_cross_origin_requests_(false),
       allow_credentials_(false),
-      has_custom_content_transfer_encoding_(false) {
+      has_custom_content_transfer_encoding_(false),
+      prefetch_buffer_upper_threshold_(kDefaultPrefetchBufferUpperThreshold),
+      prefetch_buffer_lower_threshold_(kDefaultPrefetchBufferLowerThreshold) {
 }
 
 PPB_URLRequestInfo_Impl::~PPB_URLRequestInfo_Impl() {
@@ -260,6 +269,20 @@ bool PPB_URLRequestInfo_Impl::SetBooleanProperty(PP_URLRequestProperty property,
   }
 }
 
+bool PPB_URLRequestInfo_Impl::SetIntegerProperty(PP_URLRequestProperty property,
+                                                 int32_t value) {
+  switch (property) {
+    case PP_URLREQUESTPROPERTY_PREFETCHBUFFERUPPERTHRESHOLD:
+      prefetch_buffer_upper_threshold_ = value;
+      return true;
+    case PP_URLREQUESTPROPERTY_PREFETCHBUFFERLOWERTHRESHOLD:
+      prefetch_buffer_lower_threshold_ = value;
+      return true;
+    default:
+      return false;
+  }
+}
+
 bool PPB_URLRequestInfo_Impl::SetStringProperty(PP_URLRequestProperty property,
                                                 const std::string& value) {
   // TODO(darin): Validate input.  Perhaps at a different layer?
diff --git a/webkit/plugins/ppapi/ppb_url_request_info_impl.h b/webkit/plugins/ppapi/ppb_url_request_info_impl.h
index 9d6c766..2cdf3e4 100644
--- a/webkit/plugins/ppapi/ppb_url_request_info_impl.h
+++ b/webkit/plugins/ppapi/ppb_url_request_info_impl.h
@@ -37,6 +37,7 @@ class PPB_URLRequestInfo_Impl : public Resource {
   // PPB_URLRequestInfo implementation.
   bool SetUndefinedProperty(PP_URLRequestProperty property);
   bool SetBooleanProperty(PP_URLRequestProperty property, bool value);
+  bool SetIntegerProperty(PP_URLRequestProperty property, int32_t value);
   bool SetStringProperty(PP_URLRequestProperty property,
                          const std::string& value);
   bool AppendDataToBody(const std::string& data);
@@ -60,6 +61,13 @@ class PPB_URLRequestInfo_Impl : public Resource {
   }
   bool allow_credentials() const { return allow_credentials_; }
 
+  int32_t prefetch_buffer_upper_threshold() const {
+      return prefetch_buffer_upper_threshold_;
+  }
+  int32_t prefetch_buffer_lower_threshold() const {
+      return prefetch_buffer_lower_threshold_;
+  }
+
  private:
   struct BodyItem;
   typedef std::vector<BodyItem> Body;
@@ -89,6 +97,10 @@ class PPB_URLRequestInfo_Impl : public Resource {
   bool has_custom_content_transfer_encoding_;
   std::string custom_content_transfer_encoding_;
 
+  // Specify permitted range for the size of the buffer unconsumed by plugin.
+  int32_t prefetch_buffer_upper_threshold_;
+  int32_t prefetch_buffer_lower_threshold_;
+
   DISALLOW_COPY_AND_ASSIGN(PPB_URLRequestInfo_Impl);
 };