Revert "net: merge HTTP headers and body when the sum is small enough."

This reverts commit 118099 becauase it may have broken some layout
tests.

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@118149 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 36 insertions, 45 deletions

diff --git a/net/http/http_stream_parser.cc b/net/http/http_stream_parser.cc
index bdd0f86..64248ff 100644
--- a/net/http/http_stream_parser.cc
+++ b/net/http/http_stream_parser.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 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.
 
@@ -22,8 +22,6 @@
 
 namespace {
 
-static const size_t kMaxMergedHeaderAndBodySize = 1400;
-
 std::string GetResponseHeaderLines(const net::HttpResponseHeaders& headers) {
   std::string raw_headers = headers.raw_headers();
   const char* null_separated_headers = raw_headers.c_str();
@@ -124,6 +122,9 @@ int HttpStreamParser::SendRequest(const std::string& request_line,
   response_->socket_address = HostPortPair::FromAddrInfo(address.head());
 
   std::string request = request_line + headers.ToString();
+  scoped_refptr<StringIOBuffer> headers_io_buf(new StringIOBuffer(request));
+  request_headers_ = new DrainableIOBuffer(headers_io_buf,
+                                           headers_io_buf->size());
   request_body_.reset(request_body);
   if (request_body_ != NULL && request_body_->is_chunked()) {
     request_body_->set_chunk_callback(this);
@@ -133,48 +134,6 @@ int HttpStreamParser::SendRequest(const std::string& request_line,
   }
 
   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);
-
-      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);
-      }
-
-      request_body_.reset();
-      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());
-  }
-
   result = DoLoop(OK);
   if (result == ERR_IO_PENDING)
     callback_ = callback;
@@ -321,6 +280,38 @@ int HttpStreamParser::DoSendHeaders(int result) {
     // out the first bytes of the request headers.
     if (bytes_remaining == request_headers_->size()) {
       response_->request_time = base::Time::Now();
+
+      // We'll record the count of uncoalesced packets IFF coalescing will help,
+      // and otherwise we'll use an enum to tell why it won't help.
+      enum COALESCE_POTENTIAL {
+        // Coalescing won't reduce packet count.
+        NO_ADVANTAGE = 0,
+        // There is only a header packet or we have a request body but the
+        // request body isn't available yet (can't coalesce).
+        HEADER_ONLY = 1,
+        // Various cases of coalasced savings.
+        COALESCE_POTENTIAL_MAX = 30
+      };
+      size_t coalesce = HEADER_ONLY;
+      if (request_body_ != NULL && !request_body_->is_chunked()) {
+        const size_t kBytesPerPacket = 1430;
+        uint64 body_packets = (request_body_->size() + kBytesPerPacket - 1) /
+                              kBytesPerPacket;
+        uint64 header_packets = (bytes_remaining + kBytesPerPacket - 1) /
+                                kBytesPerPacket;
+        uint64 coalesced_packets = (request_body_->size() + bytes_remaining +
+                                    kBytesPerPacket - 1) / kBytesPerPacket;
+        if (coalesced_packets < header_packets + body_packets) {
+          if (coalesced_packets > COALESCE_POTENTIAL_MAX)
+            coalesce = COALESCE_POTENTIAL_MAX;
+          else
+            coalesce = static_cast<size_t>(header_packets + body_packets);
+        } else {
+          coalesce = NO_ADVANTAGE;
+        }
+      }
+      UMA_HISTOGRAM_ENUMERATION("Net.CoalescePotential", coalesce,
+                                COALESCE_POTENTIAL_MAX);
     }
     result = connection_->socket()->Write(request_headers_,
                                           bytes_remaining,