Change URLRequest to use a ref-counted buffer for actual IO....

chrome/browser/renderer_host/async_resource_handler.cc

 // Copyright (c) 2006-2008 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.
 
 #include "chrome/browser/renderer_host/async_resource_handler.h"
 
 #include "base/process.h"
+#include "net/base/io_buffer.h"
 
-base::SharedMemory* AsyncResourceHandler::spare_read_buffer_;
+SharedIOBuffer* AsyncResourceHandler::spare_read_buffer_;
+
+// Our version of IOBuffer that uses shared memory.
+class SharedIOBuffer : public net::IOBuffer {
+ public:
+  SharedIOBuffer(int buffer_size) : net::IOBuffer(NULL), ok_(false) {
+    if (shared_memory_.Create(std::wstring(), false, false, buffer_size) &&
+        shared_memory_.Map(buffer_size)) {
+      ok_ = true;
+      data_ = reinterpret_cast<char*>(shared_memory_.memory());
+    }
+  }
+  ~SharedIOBuffer() {
+    data_ = NULL;
+  }
+
+  base::SharedMemory* shared_memory() { return &shared_memory_; }
+  bool ok() { return ok_; }
+
+ private:
+  base::SharedMemory shared_memory_;
+  bool ok_;
+};
 
 AsyncResourceHandler::AsyncResourceHandler(
     ResourceDispatcherHost::Receiver* receiver,
     int render_process_host_id,
     int routing_id,
     base::ProcessHandle render_process,
     const GURL& url,
     ResourceDispatcherHost* resource_dispatcher_host)
     : receiver_(receiver),
       render_process_host_id_(render_process_host_id),
@@ skipping 17 matching lines @@
                                                                new_url));
 }
 
 bool AsyncResourceHandler::OnResponseStarted(int request_id,
                                              ResourceResponse* response) {
   receiver_->Send(new ViewMsg_Resource_ReceivedResponse(
       routing_id_, request_id, response->response_head));
   return true;
 }
 
-bool AsyncResourceHandler::OnWillRead(int request_id,
-                                      char** buf, int* buf_size,
-                                      int min_size) {
+bool AsyncResourceHandler::OnWillRead(int request_id, net::IOBuffer** buf,
+                                      int* buf_size, int min_size) {
   DCHECK(min_size == -1);
   static const int kReadBufSize = 32768;
   if (spare_read_buffer_) {
-    read_buffer_.reset(spare_read_buffer_);
-    spare_read_buffer_ = NULL;
+    DCHECK(!read_buffer_);
+    read_buffer_.swap(&spare_read_buffer_);
   } else {
-    read_buffer_.reset(new base::SharedMemory);
-    if (!read_buffer_->Create(std::wstring(), false, false, kReadBufSize))
-      return false;
-    if (!read_buffer_->Map(kReadBufSize))
+    read_buffer_ = new SharedIOBuffer(kReadBufSize);
+    if (!read_buffer_->ok())
       return false;
   }
-  *buf = static_cast<char*>(read_buffer_->memory());
+  *buf = read_buffer_.get();
   *buf_size = kReadBufSize;
   return true;
 }
 
 bool AsyncResourceHandler::OnReadCompleted(int request_id, int* bytes_read) {
   if (!*bytes_read)
     return true;
   DCHECK(read_buffer_.get());
 
   if (!rdh_->WillSendData(render_process_host_id_, request_id)) {
     // We should not send this data now, we have too many pending requests.
     return true;
   }
 
   base::SharedMemoryHandle handle;
-  if (!read_buffer_->GiveToProcess(render_process_, &handle)) {
+  if (!read_buffer_->shared_memory()->GiveToProcess(render_process_, &handle)) {
     // We wrongfully incremented the pending data count. Fake an ACK message
     // to fix this. We can't move this call above the WillSendData because
     // it's killing our read_buffer_, and we don't want that when we pause
     // the request.
     rdh_->OnDataReceivedACK(render_process_host_id_, request_id);
     return false;
   }
+  // We just unmapped the memory.
+  read_buffer_ = NULL;
 
   receiver_->Send(new ViewMsg_Resource_DataReceived(
       routing_id_, request_id, handle, *bytes_read));
 
   return true;
 }
 
 bool AsyncResourceHandler::OnResponseCompleted(int request_id,
                                                const URLRequestStatus& status) {
   receiver_->Send(new ViewMsg_Resource_RequestComplete(routing_id_,
                                                        request_id, status));
 
   // If we still have a read buffer, then see about caching it for later...
   if (spare_read_buffer_) {
-    read_buffer_.reset();
-  } else if (read_buffer_.get() && read_buffer_->memory()) {
-    spare_read_buffer_ = read_buffer_.release();
+    read_buffer_ = NULL;
+  } else if (read_buffer_.get()) {
+    read_buffer_.swap(&spare_read_buffer_);
   }
   return true;
 }
 
 // static
 void AsyncResourceHandler::GlobalCleanup() {
-  delete spare_read_buffer_;
   spare_read_buffer_ = NULL;
 }