net: Don't merge HTTP headers and body if the body is not in memory.

net/http/http_stream_parser.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.
 
 #include "net/http/http_stream_parser.h"
 
 #include "base/compiler_specific.h"
 #include "base/metrics/histogram.h"
 #include "base/string_util.h"
 #include "net/base/address_list.h"
@@ skipping 121 matching lines @@
   if (request_body_ != NULL && request_body_->is_chunked()) {
     request_body_->set_chunk_callback(this);
     chunk_buf_ = new IOBuffer(chunk_buffer_size_);
   }
 
   io_state_ = STATE_SENDING_HEADERS;
 
   // If we have a small request body, then we'll merge with the headers into a
   // single write.
   bool did_merge = false;
-  if (request_body_ != NULL &&
-      !request_body_->is_chunked() &&
-      request_body_->size() > 0) {
-    size_t merged_size = request.size() + request_body_->size();
-    if (merged_size <= kMaxMergedHeaderAndBodySize) {
-      scoped_refptr<IOBuffer> merged_request_headers_and_body(
-          new IOBuffer(merged_size));
-      // We'll repurpose |request_headers_| to store the merged headers and
-      // body.
-      request_headers_ = new DrainableIOBuffer(
-          merged_request_headers_and_body, merged_size);
+  if (ShouldMerge(request, request_body_.get())) {
+    size_t merged_size = request.size() + request_body->size();
+    scoped_refptr<IOBuffer> merged_request_headers_and_body(
+        new IOBuffer(merged_size));
+    // We'll repurpose |request_headers_| to store the merged headers and
+    // body.
+    request_headers_ = new DrainableIOBuffer(
+        merged_request_headers_and_body, merged_size);
 
-      char *buf = request_headers_->data();
-      memcpy(buf, request.data(), request.size());
-      buf += request.size();
+    char *buf = request_headers_->data();
+    memcpy(buf, request.data(), request.size());
+    buf += request.size();
 
-      size_t todo = request_body_->size();
-      while (todo) {
-        size_t buf_len = request_body_->buf_len();
-        memcpy(buf, request_body_->buf()->data(), buf_len);
-        todo -= buf_len;
-        buf += buf_len;
-        request_body_->MarkConsumedAndFillBuffer(buf_len);
-      }
-      DCHECK(request_body_->eof());
+    size_t todo = request_body_->size();
+    while (todo) {
+      size_t buf_len = request_body_->buf_len();
+      memcpy(buf, request_body_->buf()->data(), buf_len);
+      todo -= buf_len;
+      buf += buf_len;
+      request_body_->MarkConsumedAndFillBuffer(buf_len);
+    }
+    DCHECK(request_body_->eof());
 
-      did_merge = true;
-    }
+    did_merge = true;
   }
 
   if (!did_merge) {
     // If we didn't merge the body with the headers, then |request_headers_|
     // contains just the HTTP headers.
     scoped_refptr<StringIOBuffer> headers_io_buf(new StringIOBuffer(request));
     request_headers_ = new DrainableIOBuffer(headers_io_buf,
                                              headers_io_buf->size());
   }
 
@@ skipping 627 matching lines @@
     memcpy(cursor, payload.data(), payload.size());
     cursor += payload.size();
   }
   // Add the trailing CRLF.
   memcpy(cursor, "\r\n", 2);
   cursor += 2;
 
   return cursor - output;
 }
 
+// static
+bool HttpStreamParser::ShouldMerge(const std::string& request,
+                                   const UploadDataStream* request_body) {
+  if (request_body != NULL &&
+      // IsInMemory() ensures that the request body is not chunked.

[wtc, 2012/01/24 19:08:04]

This comment doesn't seem useful -- or it should also mention
that the request body is not in a file (so we can avoid file
I/O).  This motivation should be documented somewhere, and this
function seems like a good place to do that.

+      request_body->IsInMemory() &&
+      request_body->size() > 0) {
+    size_t merged_size = request.size() + request_body->size();
+    if (merged_size <= kMaxMergedHeaderAndBodySize)
+      return true;
+  }
+  return false;
+}
+
 }  // namespace net