IPC pickling optimization for render passes.

base/pickle.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 "base/pickle.h"
 
 #include <stdlib.h>
 
 #include <algorithm>  // for max()
 
@@ skipping 286 matching lines @@
   if (new_length < 0 || new_length > *cur_length) {
     NOTREACHED() << "Invalid length in TrimWriteData.";
     return;
   }
 
   // Update the payload size and variable buffer size
   header_->payload_size -= (*cur_length - new_length);
   *cur_length = new_length;
 }
 
+void Pickle::Reserve(size_t additional_capacity) {
+  // Write at a uint32-aligned offset from the beginning of the header.
+  size_t offset = AlignInt(header_->payload_size, sizeof(uint32));
+
+  size_t new_size = offset + additional_capacity;
+  size_t needed_size = header_size_ + new_size;
+  if (needed_size > capacity_)
+    Resize(capacity_ * 2 + needed_size);
+}
+
 char* Pickle::BeginWrite(size_t length) {
-  // write at a uint32-aligned offset from the beginning of the header
+  // Write at a uint32-aligned offset from the beginning of the header.
   size_t offset = AlignInt(header_->payload_size, sizeof(uint32));
 
   size_t new_size = offset + length;
   size_t needed_size = header_size_ + new_size;
   if (needed_size > capacity_ && !Resize(std::max(capacity_ * 2, needed_size)))
     return NULL;
 
 #ifdef ARCH_CPU_64_BITS
   DCHECK_LE(length, kuint32max);
 #endif
@@ skipping 33 matching lines @@
     return NULL;
 
   const Header* hdr = reinterpret_cast<const Header*>(start);
   const char* payload_base = start + header_size;
   const char* payload_end = payload_base + hdr->payload_size;
   if (payload_end < payload_base)
     return NULL;
 
   return (payload_end > end) ? NULL : payload_end;
 }