IPC pickling optimization for render passes.

base/pickle.cc

Index: base/pickle.cc
diff --git a/base/pickle.cc b/base/pickle.cc
index af3191b9d86db2785fe375ecbcb045cf0a420870..e0cb47382137ae91bd3eabb2c8a0743d42426062 100644
--- a/base/pickle.cc
+++ b/base/pickle.cc
@@ -195,8 +195,7 @@ Pickle::Pickle(const Pickle& other)
       capacity_(0),
       variable_buffer_offset_(other.variable_buffer_offset_) {
   size_t payload_size = header_size_ + other.header_->payload_size;
-  bool resized = Resize(payload_size);
-  CHECK(resized);  // Realloc failed.
+  Resize(payload_size);
   memcpy(header_, other.header_, payload_size);
 }
 
@@ -219,8 +218,7 @@ Pickle& Pickle::operator=(const Pickle& other) {
     header_ = NULL;
     header_size_ = other.header_size_;
   }
-  bool resized = Resize(other.header_size_ + other.header_->payload_size);
-  CHECK(resized);  // Realloc failed.
+  Resize(other.header_size_ + other.header_->payload_size);
   memcpy(header_, other.header_,
          other.header_size_ + other.header_->payload_size);
   variable_buffer_offset_ = other.variable_buffer_offset_;
@@ -304,14 +302,24 @@ void Pickle::TrimWriteData(int new_length) {
   *cur_length = new_length;
 }
 
+void Pickle::Reserve(size_t length) {
+  // 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(capacity_ * 2 + needed_size);

[Tom Sepez, 2013/10/24 17:48:06]

Why 2x? Also, this should be a bool return value, see below.

[danakj, 2013/10/24 17:51:38]

Same reason as in BeginWrite, in order to amortize the cost of expanding the
size of the array.

+}
+
 char* Pickle::BeginWrite(size_t length) {
   // 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;
+  if (needed_size > capacity_)
+    Resize(std::max(capacity_ * 2, needed_size));
 
 #ifdef ARCH_CPU_64_BITS
   DCHECK_LE(length, kuint32max);
@@ -328,17 +336,13 @@ void Pickle::EndWrite(char* dest, int length) {
     memset(dest + length, 0, sizeof(uint32) - (length % sizeof(uint32)));
 }
 
-bool Pickle::Resize(size_t new_capacity) {
-  new_capacity = AlignInt(new_capacity, kPayloadUnit);
-
+void Pickle::Resize(size_t new_capacity) {
   CHECK_NE(capacity_, kCapacityReadOnly);

[Tom Sepez, 2013/10/24 17:48:06]

There's a minor problem here in that if realloc fails, the old memory block is
not freed.  So you'd leak here if you don't check the return codes as was done
previously.

[danakj, 2013/10/24 17:51:38]

if realloc fails, we will crash inside tcmalloc no?

-  void* p = realloc(header_, new_capacity);
-  if (!p)
-    return false;
 
+  new_capacity = AlignInt(new_capacity, kPayloadUnit);
+  void* p = realloc(header_, new_capacity);
   header_ = reinterpret_cast<Header*>(p);
   capacity_ = new_capacity;
-  return true;
 }
 
 // static